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A revision of the genus Neocosmospora (Hypocreales)
[ 673 ] Trans. Br. mycol. Soc. 82 (4) 673-688 (1984)
Printed in Great Britain
A REVISION OF THE GENUS NEOCOSMOSPORA (HYPOCREALES) By P. F. CANNON AND D. L. HAWKSWOR TH Commonwealth Mycological Institute, Ferry Lane, Kew, Surrey TW9 lAF, U.K. A revision of the genus Neocosmospora (Ascomycotina, Hypocreales) is presented. Five species are accepted and a key provided, and N. africana von Arx is treated as a variety of N. vasinfeeta E.F.Sm., on the basis of SEM investigation of ascospore ornamentation. Short notes on nomenclature, relationships and pathogenicity are included. The existence of diploid and tetraploid races of N. vasinfecta corresponding to small and large ascop ore morphs is postulated. The genus Neocosmospora was established by Smith (1899) for a single species apparently pathogenic to various crops in the south-eastern United States. Since then, a number of other taxa have been added to the genus, and five species and one variety are recognized here. Most authors have placed the genus in the Hypocreales, with the exception of von Arx & Muller (1954), who favoured a position in the Sordariales close to Neurospora Shear & B. Dodge and Gelasinospora Dowding. Neocosmospora has some similarities to this group, but the usually reddish membranous ascomata, the lack of germpores in the ascospores, and the Acremonium anamorphs, as well as developmental features (Doguet, 1956), firmly unite the genus with the Hypocreales. Species of Neocosmospora are most commonly isolated from soil, often in association with plant roots, and are almost exclusively tropical or subtropical. Many of the early reports of the pathogenicity of Neocosmospora uasinfecta E.F.Sm., the type species of the genus, are now discredited, the crop diseases being caused by the unrelated Fusarium vasinfeetum Atk., which Smith (1899) erroneously regarded as an anamorph of the Neocosmospora, However, modern studies, e.g.
Kern, Naef-Rath & Defago (1971), Thakur & Sastry (1971), have established N. oasinfecta as a pathogen in its own right, causing stem- and root-rots, especially of Leguminosae. However, it rarely seems to have a serious effect on crops. See Cannon (1984) and Domsch, Gams & Anderson (1980) for further details. . NEOCOSMOSPORA E.F.Sm., Bull. U.S. Dep. Agric. 17: 45 (1899)· Ascomata perithecial, formed freely in culture, orange to red, rarely dark brown; globose to pyriform; ostiolate, with a short neck lined with periphyses. Ascornatal wall several-layered, with an outer pigmented layer, sometimes covered with rhizoidal hyphae, and hyaline inner layers; periphysoids present in most species. Asci cylindrical, rarely clavate, with a short stalk, apical structures lacking except for an inconspicuous ring in one species; 8-spored. Ascospores uniseriate, rarely biseriate, pale brown to almost hyaline, 1-(2-)celled, ± globose to ellipsoidal, ornamented. Anamorph: Acremonium spp.; demonstrated in four taxa. Conidiogenous cells long-cylindrical; conidia 0- (to 1-) septate, hyaline, variable in shape. Chlamydospores present in most species. Type species: Neocosmospora uasinfecta E.F.Sm.
KEY TO SPECIES OF NEOCOSMOSPORA Ascospores with a transversely striate ornamentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Ascospores with a rugose or cerebriform ornamentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Ascospores 7'5-12 x 5-6-5 j1m, with 6-10 transverse hyaline flanges; ascomata dark brown. _ N. striata 2. Ascospores 13'5-17x10-11-5j1m, with many inconspicuous transverse ridges; ascomata orange to red . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., N. tenuicristata 3. Asci clavate; ascospores biseriate; ascospore wall markedly irregular in thickness. . . . . . . . . N. indica 3- Asci cylindrical; ascospores uniseriate; ascospore wall j regular in thickness 4 4. Ascospores 8-10 X 5-5' 5 usn; outer layer of ascomatal walI composed of textura intricata . . . . N. parua 4. Ascospores (g-)10-15'5(-18) x (7-)7'5-12(-13'5) j1m; outer layer of ascomatal walI composed of textura angularis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 N. oasinfecta var. vasinfr ia 5. Ascospores with a rugose ornamentation . . . 5. Ascospores with a cerebriform ornamentation __ . _ _ N. vasinfecta var. afr.cana 1.
Revision of Neocosmospora NEOCOSMOSPORA VASINFECTA E. F. Sm., Bull. U.S. Dep, Agric. 17 : 45 (1899). Non Fusarium uasinfe ctum Atk., Bull. Ala. agr ic. Exp. Sen 41 : 19 (1892) (see below). N ectriella tracheiphila E. F. Sm ., Proc. Am. Ass. Advmt S ci. 1895 : 190 (1895) ; nom. inval. (Art s 32, 34) (as ' trocheiph ila '). N eocosmospora vasinfeeta var .tracheiphila E. F. Sm., Bull. U.S. Dep. Agric. 17 : 45 (1899). N . v asinfe cta var. nivea E. F . Sm., Bull. U.S. Dep. Agric. 17 : 45 (1899). N on Fu sarium niv eum E. F. Sm., Bull. U .S. Dep , A gric. 17: 12 (1899) ( = F. niveum E. F. Srn., Pr oc. Am. Ass. Advmt Sci. 1894 : 289 (1894); nom. in val. (Art. 34 ; see below). ? Pseudonectria ornata Bat . & Maia, Anais Soc. Bioi. Pernamb. 13: 74 (1955). Neocosmospora vasinfeeta var. major Rama Rao, Mycopath. Mycol. appl, 21 : 218 (1963). N. ornamentata Barbosa, Garcia de Orto 13: 17 (1965); nom. inval. (Art. 37). My celium white to pale buff, floccose . Hyphae 1-4(-5 ) /lm diam, septate, tending to aggregate in strands, there anastomosing. Ascomata orangebrown to red , ±globose, (200-)300-500 Itm tall , (170-)280--480 /lm diam, glabrous but for a number of rhizoidal hyphae, ostiolate, neck (20--)30--70(- 100 ) /l m long, 40--100(-150) 11m diam, lined with periphyses. Ascomatal wall severallayered, outer pigmented wall of ± thick-walled textura angularis with cells 8-20 /lm diam, sometimes with an inconspicuous covering hyphal web, inner layers ± hyaline, also of textura angularis. Periphysoids (see below) present but evanescent at an earl y stage, consisting of vertically-oriented rows of hyaline thin-walled cells . Asci cylindrical, thin-walled, stalk 8-15/lm long, body 800-95 (- 105) x 10'5-15(-16) /lm , without discernable apical structures, not evanescent, 8-(rarely 6-7) spored. Ascospores uniseriately arranged, buff to salmon pink in mass, pale yellow individually, globose to ellipsoidal, (9-) 10--15' 5(- 18) x (7-) 7'5-12 (-13'5) /lm, most spores with lengths falling either in the ranges 10--11 /lm or 13-15'5/lm, the spore size apparently being affected by the ploidy level (see below). Ascospore wall 0'S-2'5/lm thick, germ pores absent. The spore nearest the apex of the ascus commonly has an irregularly thickened wall, so that although the
inner surface of the wall is ellipsoidal, the spore itself is cylindrical in shape. Anamorph: A cremonium sp . Conidiogenous cells elongate-cylindrical, (20--)30--100(- 150) Itm long, 1-2/lm diam, hyaline, usually arising directly from the vegetative mycelium. Conidia cylindrical to oblong-ellipsoidal, sometimes allantoid, hyaline, i-celled, 5-13 x (1'5-)2- 3' 5 pm, aggregating in a gummy mass on the tip of the conidiogenous cell. Chlamydospores often present, hyaline to pale yellow, globose to obovoid, terminal or intercalary, smooth, 5-10 x 4-8 /lm.
VAR. VASINFECTA (F igs 1-5,7-10, 18-21 ) Ascospore walls with a rugulose to strongly rugose, rarely faintly reticulate, ornamentation. Illustrations: Smith (1899: pI. 1-S ), Butler (1910 : pl. 1-3), Moreau & Moreau (1950), Doguet (1956), Udagawa (1963), Cannon (1984). Distribution: Common throughout the tropics and warm temperate regions, usually isolated from soil or plant roots, especially of leguminous crops. Sp ecimens examin ed : U.S.A. : South Car olina, Cameron, on Gossypium herbaceum , Oct . 1902, 'W.A.O .' (BP I neotype, here selected) ; Monetta, on roots of Vigna unguiculate, Aug . 1895, E. F. Sm. (BP I -lectotype of N . uasinfecta v ar. tracheiphila E. F . Sm ., here selected) ; Ell. & Ev ., Fungi Columbiani no . 14343 [ ? same collection, dated Aug . 1899, ? a sphalm , for 1895] (BP I, K - ? isolectotypes). Sin e loc., culture grown on potato, Jan. 1896, E. F . Smith (BP I - syntype of N. uasinf ecta var . tracheiphila ). Ell. & Ev., Fungi Columbiani no. 1434b; same collection (BP I,K - isosynt ypes ). Sine loc., culture grown on potato, Dec . 1895 ; E. F. Smith (BP I - syntype of N . uasinfec ta var . tracheiph ila ). Ell . & Ev ., Fungi Columbiani no. 1434C; same collect ion (BP I,K - isosynt ypes ). U .S .A. : South Carolina, Jame s Island, on stems of Vigna unguiculate, Aug . 1895, E. F . Smith (BP I - syntype of N . uasinfec ta var .tracheiphila ; anamorph). Ell. & Ev ., Fungi Columbiani no. 1434d ; same collection (BP I ,K - isosyntypes). U .S .A. : South Carolina, Monetta, on Citrullus v ulgaris, 10 Oct. 1904, W. N. Gilbert (BP I - neotype of N. uasinfecta var. nivea E. F. Sm., here selected). Guinea Bissau : sine loc., isol. ex stored peanuts, M. A. de Freitas Barbosa (IM I 251387, = ATCC 32363, CBS 562.70-type culture of N . ornamentata Barbosa). Australia : IMI 54708, 229696. Bangladesh: IMI 49786 . Guyana: IMI 16928. Hong Kong : IMI 109594. India : IMI 75007, 75143, 93058, 93402, 100947, 100951, 104170, 1118° 9, 112026, 113518, 113519, 114772, 115670, 115924, 123953, 128943, 132134, 145068, 17°987, 171536,
Figs 1-6 . Ascospores of Ne ocosmospora spp .; scanning electron micrographs. 1-4 N . oasinfec ta var. uasinfecta. 1, IMI 215098 , x 4000 . 2, IMI 240752, x 1730. 3, IMI 251387 (isotype of N . ornamentata Barbosa), x 3330, 4, IMI 240752, x 6670. 5, Fractured ascospore of N. v asinfect a (I M I 144973,? intermediate between var. uasinfec ta and var. africana ), showing areolate structure of spore wall. x 6670. 6, N . par oa. IMI 212608 - isotype , x 4600 .
P. F. Cannon and D. L. Hawksworth
Figs 1--6. For legend see opposite.
Revision of Neocosmospora 179669, 189026, 189254, 19005°, 199565, 226126, 229339, 240751, 240752, 244579, 2467°5, 25 6486, 263173. Nigeria: IMI 93078, 215097, 215098. Pakistan: IMI 60460, 60464, 94518, 102193. Sierra Leone: IMI 58494, 1475455. Tanzania: IMI 170137. U.S.A.: IMI 113928. Zaire: IMI 85122.
Specimens examined apparently intermediate between var. uasinfecta and var. africana (see below). Australia: IMI 54709, 126527. Bangladesh: IMI 128126. India: IMI 101609, 144973, 184001, 269162. Zimbabwe: IMI 95924, 19 1524.
VAR. africana (von Arx) comb.nov. (Figs 11-17, 22-25)
Neocosmospora africana von Arx, Antonie van Leeuwenhoek 21: 161 (1955). N. vasinfecta forma conidiifera Kamyschko, Nov. Sisto niz. Rast. 1965: 115 (1965).
Ascospore walls with a cerebriform ornamentation, appearing almost smooth under LM. Illustrations: von Arx (1955), Doguet (1956), Udagawa (1963). Distribution: Widely distributed throughout the tropics and warm temperate regions. Usually isolated from soil, often associated with leguminous crops. Specimens examined: South Africa: Johannesburg, Frankenwald, isol. ex soil, sine diem, W. J. Lutjeharrns (IMI 251386, = CBS 325'54, ATCC 162388, IFO 7591 - isotype), U.S.S.R.: Uzbhekistan: Bukhara, Gizhduran, isol. ex soil soc. Ficus carica, 1961, L. A. Beljakova (IMI 251388, = ATCC 32362, CBS 602'67 - isotype of N. vasinfeeta forma conidiifera Kamyschko). Egypt: IMI 172482,172484,172486. Ethiopia: IMI 215738. Gambia: IMI 110845. Guyana: IMI 257000. India: IMI 100538, 137647. Nigeria: IMI 83938, 111938, 124887. Pakistan: IMI 123161. Sierra Leone: IMI 16929. South Africa: IMI 63344. Sri Lanka: IMI 191894, 191896, 191927. Venezuela: IMI 267939, 267940. Zambia: IMI 134571, 197827. See also specimens apparently intermediate between var. oasinfecta and var. africana listed above.
N eocosmospora vasinfecta, the type species of the genus, was isolated by Smith (1899) from three diseased crops in South Carolina, U.S.A.: cotton (Gossypium sp.), cowpea (Vigna unguiculata) and watermelon (Citrullus lanatus). Smith attributed the crop diseases to Neocosmospora, but it appears that the causal agent was Fusarium vasinfectum Atk., a taxon Smith erroneously regarded as an anamorph of the Neocosmospora. Most subsequent reports of the serious pathogenicity of N. vasinfecta are probably due to the same misconception. Fusarium vasinfectum is now regarded as a synonym of F. oxysporum Schlecht. (Booth, 1971), as F. oxysporum f. sp. vasinfectum (Atk.) Snyder & Hansen, which causes serious loss in a wide variety of crops. The pathogenicity of N. vasinfecta has not
at present been completely investigated; it is most probably a weak pathogen of roots causing little crop loss, though it may have a significant effect in conjunction with otherpathogens. Gray, RodriguezKabana & Adams (1980) suggested that at least in some cases, the Neocosmospora entered the host plants through lesions caused by parasitic nematodes. Kern et al. (1971) and Kern (1978) reported various naphtharizine derivatives in N eocosmospora, which seemed to be related to pathogenic activity, but Roos (1977) found no correlation between production of these phytotoxins and virulence of the fungal strain. Physiological races of N. vasinfecta may well occur. Smith (1899) distinguished three varieties of N. vasinfecta: var. vasinfecta on cotton, var. tracheiphila on cowpea and var. nivea on watermelon. Though these were each given formal diagnoses, Smith recognized that they were not satisfactorily separable except on a host basis. He conducted cross-inoculation experiments and established that none of the three races would infect the hosts of the others. It would be of interest to conduct greenhouse trials of isolates from various host genera to confirm and extend Smith's results, in an attempt to recognize morphological and pathogenetic distinctions between any races thus identified. The nomenclature of the three varieties of N. vasinfecta recognized by Smith is not completely straightforward. Article 59 of the International Code of Botanical Nomenclature, pertaining to anamorph and teleomorph states of fungi, was altered at the Sydney Congress in 1981 with the effect that anamorphs published in a teleomorph genus and vice oersa are no longer automatically illegitimate or invalid, assuming that all other criteria for valid publication and legitimacy are satisfied. Teleomorph names published with previously published anamorph names as synonyms are regarded as typified by the anamorph unless it is clear that the intent was to describe a new genetic form of the anamorph, correlated with it by the author, and criteria for the valid publication of a new taxon were also fulfilled. In these cases, a citation of' comb.nov. ' is treated as a bibliographic error, and the new name is attributed to the author of the teleomorph alone. Smith (1899), in his original work on Neocosmospora, published the type variety (and hence the species) as a new combination based on Fusarium vasinfectum Atk. (Atkinson, 1892). However, it is clear that Smith intended to describe the newly discovered presumed teleomorph of the Fusarium, and so his teleomorph name should not be typified by the type of the Fusarium name. The species is therefore correctly cited as N. vasinfecta E. F. Sm. and not as (Atk.) E. F. Sm. That N. vasinfecta is not
P. F. Cannon and D. L. Hawksworth
Figs. 7-10. Ascospores of Neocosmospora vasinf eeta ; scanning electron micrographs. Possible intermediates between var . vasinfecta and var. africana . 7, IMI 144973, x 6670. 8, IMI 126527, x 3670 . 9, IMI 269162, x 3670 . 10, IMI 95924, x 4330 .
actually the teleomorph of Fusarium uasinfectum does not affect the nomenclatural situation, as in the revised Art. 59, the intent of the author rather than the actual genetic connection is regarded as critical. Neocosmospora vasinfeeta var. tracheiphila E. F. Sm. was published with the synonym Nectriella tracheiphila E. F. Sm., a name mentioned 22
by Smith (1895). This latter work contained no description of the fungus, although it is referred to as ' ascomycetous'; we do not regard this as fulfilling the obligations of Art. 32 of the Code. It is clear that this paper was a preliminary report of Smith's 1899 work, and that he did not intend to formally introduce the name at this stage. It must MY C 82
Revision of Neocosmospora
Figs
11-17.
For legend see opposite.
P. F. Cannon and D. L. Hawksworth therefore be regarded as invalidly published under Art. 34, as well as Art. 32. N eocosmosporauasinfecta var. nivea E. F. Sm. was treated as a new combination of Fusarium niveum E. F . Sm., first validly published, though without a clear diagnosis, in the same paper (Smith, 1899: 12). The name was not validly published in Smith (1894) as it was there regarded as a provisional name (Art. 34). It is again clear that Smith regarded N. uasinfecta var. nivea as a teleomorph of the Fusarium, and so this can be taken as the name of a new taxon rather than a combination of the Fusarium into an inappropriate genus. Similarly, there appears to be no genetic connexion between the Neocosmospora and the Fusarium . No type collections were cited for N . uasinfecta (var . vasinfecra) by Smith. We have therefore designated a neotype on Gossypium, the type host, collected from the same region as were Smith's fungi (see above). This was gathered only three years after Smith's publication of the name, and incorporated into the same herbarium (BP I) as were Smith's collections. It is not unlikely that he saw the specimen concerned, and it agrees in all respects with the original description of the species . A series of five specimens was designated by Smith as type material of N . uasinfe cta var. tracheiphila. These are preserved in BPI, and duplicates of each were issued as Ellis & Everhart's Fungi Columbiani no . 1434a-e. Of the five collections, the first was of ascomata on stems of Vigna unguiculate, the second and third were cultures containing immature and mature ascomata respectively, the fourth was of an anamorphic fungus within the vessels of V. unguiculata , and the fifth was ofthe supposed anamorph Fusarium uasinfectum Atk . The provenance of the cultures was not detailed; they mayor may not have been derived from the collection of the ascomata on V . unguiculata. The identity of the unnamed anamorphic fungus is not clear; our examination could not resolve the question as to whether it was the Acremonium anamorph of the Neocosmospora, or a microconidial stage of the Fusarium. Judging from the description and illustrations in Smith's work, the former seems more likely. The collection of Fusarium on Vigna is obviously unsuitable for recognition as type material of the Neocosmospora. The collection of ascomata on Vigna in Smith's herbarium (BP I) is here designated as lectotype of N. oasinfe cta var. tracheiphila; examples of Ellis & Everhart's Fungi Columbiani no. 1434a are therefore isolectotypes.
Smith designated no type material for N. uasinfecta var. nivea. We have therefore chosen a specimen on Citrullus lanatus collected in the same region as Smith's fungus as neotype (see above ). The specimen was collected in 1904 and incorporated into BPI; it is likely, as with var oasinfecta, that Smith saw the collection in question. It agrees in all respects with Smith's description. No further significant advances were made in the classification of Neocosmospora vasinfeeta until the 1950's. Von Arx (1955) described a new taxon, N . africana, which he distinguished from N . uasinfe cta by its smooth (actually cerebriform) rather than rugose ascospores. It is here treated at varietal level (see below ). In the same year, Batista, Chaves, Maia & Vital (1955) published Pseudonectria ornata Bat. & Maia, which is a probable synonym of N. vasinfecta; we have not seen type material of this taxon and the description is not sufficient to be absolutely sure of the synonymy. Doguet (1956) published a detailed morphological and developmental investigation of N. uasinfecta and N. africana, including a short discussion on paraphysis-like structures found in between the asci. He established that these chains of thin-walled hyaline cells between the asci, evanescent at maturity, originate from the upper part 'of the ascoma. He therefore referred to them as pseudoparaphyses. However, Luttrell (1965) decided that they were not homologous with the similarly-named structures found in the Loculoascomycetes, and suggested that they be referred to as apical paraphyses. The most recent work on this subject, however (Eriksson, 1981), prefers the term 'periphysoid " and this is adopted here as in the recent Dictionary of the Fungi (Hawksworth et al., 1983 ). These structures appear to be of little taxonomic value below the genus level, and are found in a number of genera of the Hypocreales. Udagawa (1963) found both N . vasinfeeta and N . africana in Japan, and published an account of the genus in that country. Rama Rao (1963) described N. uasinfecta var . major, supposedly differing in ascospore size. In fact, the sizes he quoted are well within the range of variation of the species found by us. Barbosa (1965) described a new taxon, N . ornamentata, apparently differing in the shape and degree of rugoseness of the spores, but there does not appear to be a definable division between the type isolate we have examined and N. uasinfecta, so we reduce it to synonymy here . In any case, the name was invalidly published as no type specimen was cited. Kamyschko (1965) published N. vas-
Figs 11-17.Ascospores ofN. vasinfecra var. africana ; scanningelectronmicrographs. 11, IMI 172482, x 2670. 12, IMI 100538, x 3330. 13 IMI 191894, x 2070. 14, IMI 257000, x 3330. 15, IMI 111938, x 3330. 16, IMI 137647, x 6670. 17, IMI 123161, x 3330. 22-2
680
Revision of Neocosmospora
20
21
22
-
~
23 Figs 18-25. For legend see opposite.
P. F. Cannon and D. L. Hawksworth infecta forma conidiifera with an Acremonium anamorph, differing from Smith's fungus in the absence of a Fusarium anamorph. However, as the Fusarium is not genetically connected with the Neocosmospora, no distinction remains between the two taxa. In fact, we have found from examination of type material that Kamyschko's fungus is a particularly large-spored example of N. vasinfecta var. africana. Van Warmelo (1976) made a comparative study of a South African isolate of a Neocosmospora with isolates named as N. uasinfecta and N. africana using LM and SEM, and found no significant difference between the ascospores of the three isolates. He therefore recommended that N. africana be reduced to synonymy with N. uasinfecta. However, it is clear from our studies that the isolate of N. uasinfecta he examined was misidentified, and in fact belonged to N. africana. His conclusions must therefore be rejected. At first sight, the differences in ascospore ornamentation between the rugose N. oasinfecta and the cerebriform N. africana seem ample indication that the two taxa are separate species. However, an extensive analysis of the variation in ascospore ornamentation showed a certain degree of intergradation. This is illustrated in Figs 7-10. While most specimens examined were easily assigned to one or other taxon, a proportion had only a very faintly rugose ornamentation, and some of these appeared very weakly reticulate. In many of these cases, examination with the light microscope was either not sufficient to clearly elucidate the ornamentation, or, more importantly, gave an inaccurate impression of it, so that specimens appearing weakly rugose under LM were shown to have a cerebriform ornamentation under SEM. Van Warmelo (1976) went some way towards an explanation of this difficulty, when he showed that while fresh air-dried ascospores of one of his collections of N. africana (Isolate P) showed the typical cerebriform ascospores, spores from old desiccated specimens of the same isolate appeared weakly rugose, as in some of the intermediates found in our own study. He attributed this to a partial breakdown of the spore wall in the desiccated specimens. TEM studies on the development of the ascospore wall in N. vasinfeeta and N. africana could well contribute to a greater understanding of this problem. It therefore appears that a proportion of
681
specimens cannot definitely be assigned to one or other taxon without SEM examination of fresh material. This was unfortunately impossible with the great majority of specimens available to us. In itself, though, the difficulty of examination is not a valid criterion for the merging of taxa with definable distinctions. The specimens available to us were therefore closely examined to find correlating distinctions to support the separation of the taxa at specific level, but without success. Not only were the variations in all dimensions measured almost exactly the same, but var. vasinfecta had two ascospore size morphs which seemed to be mirrored by var. africana, though the relatively small number of specimens of this variety available made comparison difficult. The difference in ascospore size was not related to the number of spores in the ascus, this being commonly encountered in the Hypocreales (Booth, pers. comm.); ascospores in the rare 6- and 7-spored asci were not larger than those in 8-spored asci. Specimens with the large ascospore morph tended to have larger ascomata, but the two morphs could not be satisfactorily separated using this character. Ascospore ornamentation was not correlated with ascoma size. Thus, the only definable difference between the two taxa we have found is the ascospore ornamentation, a feature itself difficult to determine in a number of instances. It therefore seems more appropriate to treat the two taxa as varieties of N. oasinfecta rather than as separate species. The necessary new combination has been made. However, further information, such as that gained from subjecting isolates to closely defined growth conditions, physiological tests found advantageous in the classification of Penicillium Link (Pitt, 1980) and Monascus v. Tieghem (Hawksworth & Pitt, 1983), as well as biochemical and pathogenicity investigations, could cause this conclusion to be reviewed. Examinations of this specialised nature were unfortunately not possible during the present study. Preliminary examinations strongly suggest that N. oasinfecta has diploid and tetraploid races, which correspond to the two ascospore size morphs mentioned above. Analysis of 510 measurements of ascospore length (10 selected at random from each of 51 isolates) ofvar. vasinfecta showed a two-peaked frequency distribution (see Fig. 26), with the vast majority of ascospores measuring between either
Figs 18-25. Ascospores of N. uasinfecta ; light micrographs (Nomarski D.Le.), all x 1000. 18-21, var. vasinfecta.s.S, 19, Small ascospore morph (lMl 244579). 20,21, Large ascospore morph (lMl 199565).22-25., var. africana. 22-23, Small ascospore morph (lMl 251386 - isotype). 24, 25, Large ascospore morph (lMl 251388 - isotype of N. uasinfecta forma conidiifera).
682
Revision of Neocosmospora
80
>. u t:
60 - - - var. vasinfecta
"0'w ;:l
Lt
--- ------- var. africana
40
20
---' 8 8.8
9 9.9
10 11.0
II 12.1
...... .. - .. _-_ ...... 12 13.2
..-
13 14.3
-------14 15.4
15 16.5
16 17.6
17 units 18.7 jim
Fig. 26. Graph showing frequency distribution of asco sp ore lengths of N. oasinfecta vars. uasinf ecta and africana.
9' 5-1 1'5 pm or 12 '5-15 '5 pm. A similar analysis of 17 samples of var. africana also showed a strongly non-normal distribution, although the small number of samples did not allow an accurate assessment of the frequency distribution of ascospore length. A strong peak between 9'5 and u '5 Ilm was noted, as with var . uasinfe cta, but the second peak was not in evidence, although the frequency of ascospore measurements seemed to increase slightly between about 15 and 18 pm. The microscope graticule used was divided into units of 1'1 /lm at a magnification of x tOOO; half-units (corresp onding to 0'55 11m ) were esti mated. The lower figures for the non-whole number unit measurements are probably due to an unconscious tendency on the part of the observer to round up or down to the nearest whole number rather than to the half-unit. A smaller sample (10 measurements of ascospore length in each of 9 isolates of var . vasinfeeta and 12 of var. africana) was subjected to statistical analyses by Dr P . B. Topham (Sco ttish Crop Research Institute, I nvergowrie). Analysis of variance and a subsequent variance ratio (F ) test showed that there was no statistical significance, even at the 10 % level, between the samples of var . uasinfe cta and var. africana, but the differences between samples within each ascospore ornament type were highly significant, reflecting the non-normal frequency distributions of ascospore length discussed above . The chromosomes of N . uasinfec ta have already been examined by van Warmelo (1977) , who investigated the somatic chromosomes in macerated mycelium of three isolate s (the same as used in his
1976 work on ascospore ornamentation cited above ), all of which we now recognize as belonging to the small ascospore morph of var . africana, and found an estimated number of n = 6 in all three samples. This number was later confirmed (van Warmelo, 1981 ) in work on young asci of the same isolates. A single isolate belonging to the large ascospore morph of var. oasinfe cta (I M I 147455) was examined by us, using the Giemsa staining technique as described by Johnston & Booth (1983). As van Warmelo found, the chromosomes were very small and difficult to separate, but preparations of nuclei in young asci of our isolate showed a chromosome number certainly in excess of n = 6, with a strong possible number of n = 12, the number one would therefore expect in a tetraploid race of N. uasinfecta. Although only a limited degree of reliance should be placed on this singl e observation, it seems fairly cer tain that polyploid races of N. uasinfecta occur and that, in the limited number of samples so far examined, the ploidy level is related to ascospore size . However, we cannot at this stage exclude the possibility that the ploidy level is connected with ornamentation type rather than ascospore size, though this seems most unlikely in the light of the statistical data d iscuss ed above.
Veda & Udagawa, M y coraxon 16: 38 7 (1983) . (F igs 27-28). M yc elium white to buff. Hyphae tending to aggregate in strands, there ana stomosing. A scomara orange-red to reddish brown, ± glob ose, NEOCOSMOSPORA TENUICRISTATA
P. F. Cannon and D. L. Hawksworth 330-400(-450) pm tall, 260-320 pm diamv-j glabrous or covered with an inconspicuous web of hyaline hyphae, ostiolate, neck 50-80 pm long, 80-110 pm diam, lined with periphyses. Ascomatal wall several-layered, outer pigmented wall of ±thick-walled textura angularis with cells 7-20 pm diam, inner layers hyaline, also of textura angularis. Periphysoids present at maturity, composed of very thin-walled hyaline cells. Asci cylindrical, thin-walled, stalk 5-12(-20) pm long, body 85-100 x 12'5-15 pm, without discernible apical structures, not evanescent, 8-spored. Ascospores uniseriately arranged, yellowish-brown, globoseellipsoidal to ellipsoidal, (13'5-)15'5-16'5 (-17) x (10-)11-12 pm. Ascospore wall 1-1'5 pm thick, without germ-pores, often somewhat irregular in thickness, with an ornamentation of transverselyarranged ridges 0'25--0'5 pm wide. Apical spores often abnormal in shape as in N, vasinfecta.
Anamorph: Acremonium tenuicristatum Veda & Vdagawa, Mycotaxon 16: 389 (1983). Conidiogenous cells elongate-cylindrical, 30-50 (-140) x 2'5-4 pm, hyaline, with a minute apical collarette, occasionally proliferating sympodially, emanating either directly from the hyphae or from a short cylindrical hyaline conidiophore, rarely absent, the conidia being produced directly from the mycelium. Conidia hyaline, 5-15(-19) x 2'54 pm, oblong-ellipsoidal to cylindrical, often slightly allantoid, smooth-walled, aggregating in a gummy mass on the tips of the conidiogenous cells. Chlamydospores not observed. Illustrations: Veda & Vdagawa (1983). Distribution: Japan (only known from the type collection). Specimen examined: 1apan: Nagasaki pref.: Higashis-
onogi-gun: Oomura Bay, isoJ. ex marine sludge, 26 Ian. 1981, S. Veda (IMI 277708, = NHL 2911 - isotype culture).
Neocosmospora tenuicristata, recently isolated from marine sludge in Japan, is closely related to N. uasinfecta, differing in the ascospore wall ornamentation, which consists of a series of transversely oriented ridges. In addition, the anamorph has an unusual characteristic in that the conidiogenous cells proliferate to a small degree, a situation not encountered in other Neocosmospora anamorphs. The significance of this feature is unclear; it is known in a few other species of Acremonium (Gams, 1971). Neocosmospora tenuicristata was contrasted with N. striata Vdagawa & Rorie by Veda & Vdagawa (1983), but it is doubtful that these species are closely related.
Mahoney, Mycologia 68: 1111 (1976). (Figs 6, 31-32). Mycelium very inconspicuous, hyaline. Hyphae 1-2 pm diam, septate, tending to aggregate in strands. Ascomata orange-brown, very fragile, ovoid to pyriform, glabrous but for a number of rhizoidalhyphae,(iOo-)130-18o(-210) x (80-)120150(-180) j.tm, ostiolate, neck 10-30 j.tm long, 50-70 j.tm diam, lined with periphyses. Ascomatal wall several-layered, with a pigmented outer wall of irregular textura intricata with hyphae 3-5 pm diam, and inner layer almost hyaline, consisting of an ill-defined intermediate between textura intracata and textura angularis. Periphysoids not observed. Asci 47-60 x 6'5-10 j.tm, cylindrical to cylindric-clavate, thin-walled, short-stalked, without discernible apical structures, not evanescent, 8-spored. Ascospores obliquely uniseriately or partially biseriately arranged, orange-yellow to orange-buff en masse, golden yellow individually, ellipsoidal, 8-10 x 5-5'5 pm, without germ pores, wall 0'5--0'75 j.tm thick, with a reticulate ornamentation mostly obscured by a weakly verrucose epispore layer.
NEOCOSMOSPORA PARVA
Anamorph: Acremonium sp. Conidiogenous cells usually arising directly from vegetative hyphae (i.e. conidiophores absent), elongate-cylindrical, 20-70(-150) j.tm long, 1-1' 5 j.tm diam, hyaline, with a slightly flared collarette, ca 1 j.tm long. Conidia usually cylindrical to oblong-ellipsoidal, sometimes allantoid, occasionally reniform or obovoid, hyaline, smooth-walled, r-celled, 4-10 x 1'5-3(-5) j.tm, aggregating in a gummy mass on the tips of the conidiogenous cells. Chlamydospores not observed. Illustrations: Mahoney (1976). Distribution: Galapagos Islands (only known from the type collection). Specimen examined: Galapagos Islands: Isla Santa Cruz, near Charles Darwin Research Station, isoJ. ex soil, Dec. 1968, T. de Vries (IMI 212608- isotype).
Neocosmospora parua Mahoney, only known from a single soil isolate from the Galapagos Islands, is easily distinguished from other species by its small, relatively narrow ascospores which have a weakly verrucose epispore ornamentation covering a reticulately patterned spore wall. It may well be most closely related to N. indica Wadhwani, which has a some-what similar ascospore wall structure, and also shares the characteristic of the outer layers of the ascomatal wall being composed of textura intricata.
684
Revision of Neocosmospora
27
28
30
,.'
33
31
32
,
.
34
68 5
P. F. Cannon and D . L. Hawksworth
B
100 pm
D
c 10 pm 10 pm Fig . 35. Drawing of N . indica (lMl 13Z135-holotype). A, ascoma . B, detail of stru ctu re of hyaline inner layers of ascoma wall. C, asci. D , ascospores.
Figs 27-34. Ascospores of Neocosmospora spp.; light micrographs (Nomarski D.LC.), all x 1000.27,28, N. tenuicristata (lMl 277708-isotype). 29, 30, N. indica (IM l 132135-holotype). 31, 32, N . parua (lMl 212608-isotype). 33,34, N. striata (IM l 210879-isotype).
686
Revision of N eocosmospora
F igs 36-39. Ascospore s of N. indica (1M 1 132135-holot ype ) ; scanning electron micrographs. 36, x 1330. 37, x 3330, 38,39, x 6670.
NEOCOSMOSPORA INDICA Wadhwani, 2:
Ind. Bot. Reptr
158 (1983) 1984.
Mycelium very pale buff (dried culture), somewhat darker towards the edges , floccose. Hyphae 1-4'5 /lm diam, septate, tending to aggregate in rope-like strands, there anastomosing. Ascomata formed freely at edge of mycelium, orange to red, globo se, 170--240(-300) pm diam, glabrous but for a number of rhizoidal hyphae; ostiolate, with a short neck 30--7° pm long, 70--100 Ilm diam, lined with periphyses. Ascomatal wall several-layered, with a pigmented outer layer of textura intricata
with hyphae 1'5-4 /lm diam and thin hyaline inner layer (s) of textura angularis with cells 8-18 /lm in size. Periphysoids evanescent at an early stage. A sci clavate, 38-49 x 15'5-22 pm, the longer asci tending to be thinner, very thin-walled, without discernible apical stru ctures, evanescent, 8-spored. A scospores biseriately arranged, orange-brown en masse, yellow-brown individually, irregularly ellipsoidal, 12'5-16 x ~10 um, without germ pores, inner edge of wall elliptical in section, wall very irregular in thickness, ranging from 0'75-2'25 /lm, reticulate, the reticulations obscured in irregular patches by a weakly verrucose epispore layer .
P. F. Cannon and D. L. Hawksworth Anamorphi] Acremonium sp.; a few cylindrical conidia 4-6 x l' 5-2 pm in size were observed, but none were seen attached to the mycelium and could conceivably have contaminants. Chlamydospores: Not observed.
Distribution: N. and N.E. India. Specimens examined: India: Lucknow, isol. ex Eruca sativa soil; cornrn. 14 Mar. 1968; J. N. Rai 12 (IMI 132135 - holotype). Bhagalpur University, isol. ex soil; comm. 18 Mar. 1980; K. S. BilgramiB25 (IMI 246703).
This taxon, found to date in two isolations from India, is superficially similar to N. vasinfecta E. F. Sm., but may be more closely related to N. parva Mahoney. It shares the unusual verrucose epispore covering a reticulately patterned ascospore wall with the latter species, but differs by its larger, wider ascospores whose walls are only partially covered by the epispore, the wall therefore appearing very irregular in thickness. NEOCOSMOSPORASTRIATA Udagawa& Horie, Trans. mycol. Soc. Japan 16: 340 (1975)· (Figs 33-34). Mycelium inconspicuous, hyaline. Hyphae 0'5-2'5 pm diam, septate. Ascomata dark brown, pyriform, glabrous but for a number of rhizoidal hyphae, 130-170 x 90-140 pm; ostiolate, neck 30-50 pm long, 50-70 pm diam; periphyses not observed. Ascomatal wall with a pigmented outer layer and an almost hyaline inner layer, both of textura epidermoidea. Periphysoids not observed. Asci 60-85 x 6-10 psn, cylindrical to cylindricclavate, thin-walled, with a small inconspicuous apical ring which does not stain blue in iodine, 8-spored. Ascospores obliquely uniseriately or partially biseriately arranged, very pale yellow to hyaline, ellipsoidal, 7'5-10'5(-12) x 5-6'5 pm, without germ-pores, some spores with a median transverse straight or curved septum, then very slightly constricted at the septum; ascospore wall ca 0'5 pm thick, with 6-10 thin transverse hyaline flanges ca 1 pm wide.
Anamorph: Not known. Chlamydospores: Not observed. Illustrations: Udagawa & Horie (1975). Distribution: Japan (only known from the type collection). Specimen examined: Japan: Nagano, Shimatogai-gun,
Yamanouchi-machi, isol. ex soil; 20 Sept. 1974;Y. Horie (IMI 210879 - isotype). This species is probably not congeneric with the other taxa treated in this work, but is retained in Neocosmospora pending more detailed investigations of its affinities. It may well belong to the Sordariales rather than the Hypocreales. It differs
most particularly from the other species of Neocosmospora in the colour of its ascomatal wall (brown rather than red), the presence of an apical ring in the asci, and in the ascospores which have conspicuous hyaline flanges quite different from the range of wall ornamentation found in the other species of the genus. These flanges seem more similar to those found in Emericella v. Beyma (Eurotiales sensu lata), or may be transverse counterparts ofthose seen in Pteridiosperma Krug & jeng (Sordariales). Critical ontogenetic investigations and TEM studies ofthe apical apparatus in the asci and of the development of the ascospore flanges would be useful in the elucidation of this problem. Useful suggestions on the interpretation of results were made by Dr C. Booth, and Dr D. W. Minter corrected the Latin diagnosis; Dr E. Punithalingam is thanked for advice on the cytological work, Mrs C. Thatcher and Mrs J. Woodhams for technical assistance, and Mr D. Fry for photographic work (all of CMI). We are grateful to Dr P. B. Topham (Scottish Crop Research Institute, Invergowrie) for statistical analyses, and to Dr L. Batra (BPI) for assisting D. L. H. in locating Smith's herbarium material and other help on his visit to BPI in August 1982. REFERENCES ARX, J. A. VON (1955). Ein neuer Ascomycet aus Afrika. Antonie van Leeuwenhoek :U, 161-165. ARX, J. A. VON & MOLLER, E. (1954). Die Gattungen der amerosporen Pyrenomyceten. Beitriige zur Kryptogamenfiora der Schweiz 11 (1), 1-434. ATKINSON, G. F. (1892). Somediseases of cotton. Bulletin of the Alabama agricultural Experiment Station 41, 1-65. BARBOSA, M. A. De Fr. (1965). A new species of Neocosmospora found in stored peanut. Garcia de Orto 13, 17-19. BATISTA, A. C., MAlA, H. Da S. & VITAL, A. F. (1955). Ascomycetidae aliquot novarum, Anais da Sociedade de Biologia de Pernambuco 13 (2), 72-86. BOOTH, C. (1971). The Genus Fusarium. Kew: Commonwealth Mycological Institute. BUTLER, E. J. (1910). The wilt disease of pigeon-pea and the parasitism of Neocosmospora uasinfecta. Memoirs of the Department of Agriculture in India, Botanical Series, 2 (9),1-64. CANNON, P. F. (1984). Neocosmospora oasinfecta. CMI Descriptions of Pathogenic Fungi and Bacteria (In the
Press.)
DOGUET, G. (1956). Morphologie et organogenie du Neocosmospora uasinfecta E. F. Smith et du Neocosmospora africana von Arx. Annales des Sciences Naturelles, serie de Botanique 11, 17,353-370. DOMSCH, K. H., GAMS, W. & ANDERSON, T.-H. (1980). Compendium of Soil Fungi. London etc.: Academic Press. ERIKSSON, O. (1981). The families of bitunicate ascomycetes. Opera Botanica 60, 1-220.
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Revision of Neocosmospora
GAMS, W. (1971). Cephalosporium-artige Schimmelpilze (Hyphomycetes). Stuttgart: Gustav Fischer. GRAY, F. A., RODRIGUEz-KABANA, R. & ADAMS, J. (1980). Neocosmospora stem rot of soybeans in Alabama. Plant Disease 64, 321-322. HAWKSWORTH, D. L. & PITT, J. 1. (1983). A new taxonomy for Monascus species based on cultural and microscopical characters. Australian Journal of Botany 31, 5 1-61. HAWKSWORTH, D. L., SUTTON, B. C. & AINSWORTH, G. C. (1983). Ainsworth & Bisby's Dictionary of the Fungi. Seventh Edition. Kew: Commonwealth Mycological Institute. JOHNSTON, A. & BOOTH, C. (eds) (1983). The Plant Pathologist's Pocket Book. Kew: Commonwealth Mycological Institute. KAMYSCHKO, O. P. (1965). Ascomycetes novi e terris Asiae mediae. Nouitates Systematicae Plantarum non Vascularum 1965, 115-116. KERN, H. (1978). Les naphtharizines des Fusarium. Annales de Phytopathologic 10,327-345. KERN, H., NAEF-RoTH, S. & DEFAGO, G. (1971). Zur Toxinbildung von Neocosmospora uasinfecta und Neocosmospora africana. Phytopathologische Zeitschrift 72, 327-334. LUTTRELL, E. S. (1965). Paraphysoids, pseudoparaphyses, and apical paraphyses. Transactions of the British Mycological Society 48, 135-144. MAHONEY, D. P. (1965). A new Neocosmospora from Galapagos Island soil. Mycologia 68, 1111-1116. MOREAU, C. & MOREAU, M. (1950). Neocosmospora uasinfecta E. F. Sm. Faux wilt du cotonnier. Revue de Mycologie 15, Supplement colonial 2, 1-5. PITT, J. 1. (1980). The Genus Penicillium and Its Teleomorphic States Eupenicillium and Talaromyces. London, New York: Academic Press.
RAMA RAo, P. (1963). Studies on soil fungi. 1. Ascomycetes from soils of Hyderabad (India). Mycopathologic et Mycologia applicate 21, 217-221. Roos, A. (1977). Zur Physiologie und Pathologie von Neocosmospora uasinfecta E. F. Smith. Phytopathologische Zeitschrift 88, 238-271. SMITH, E. F. (1894). The watermelon disease of the South. Proceedings of the American Association for the Advancement of Science 1894,289. SMITH, E. F. (1895). The watermelon wilt and other diseases due to Fusarium. Proceedings of the American Association for the Advancement of Science 1895, 190-191. SMITH, E. F. (1899). Wilt disease of cotton, watermelon and cowpea. United States Department of Agriculture Bulletin 17, 1-53. THAKUR, R. N. & SASTRY, K. S. M. (1971). Studies on wilt disease of Crotalaria mucronata. Indian Journal of Mycology and Plant Pathology 1, 84-86. UDAGAWA, S. (1963). Neocosmospora in Japan. Transactions of the Mycological Society of Japan 4, 121-125. UDAGAWA, S. & HORIE, Y. (1975). Notes on some Japanese ascomycetes XIV. Transactions of the Mycological Society ofJapan 16, 337-347. UEDA, S. & UDAGAWA, S. (1983). A new Japanese species of Neocosmospora from marine sludges. Mycotaxon 16, 387-395. VAN WARMELO, K. T. (1976). Scanning electron microscopy of Neocosmospora ascospores. Mycologia 68, 1181-1187. VAN WARMELO, K. T. (1977). Asexual nuclear division in Neocosmospora. Bothalia 12, 247-250. VAN WARMELO, K. T. (1981). Sexual nuclear division in Neocosmospora. Bothalia 13, 415-429.
(Received for publication 16 September 1983)
Printed in Great Britain
A REVISION OF THE GENUS NEOCOSMOSPORA (HYPOCREALES) By P. F. CANNON AND D. L. HAWKSWOR TH Commonwealth Mycological Institute, Ferry Lane, Kew, Surrey TW9 lAF, U.K. A revision of the genus Neocosmospora (Ascomycotina, Hypocreales) is presented. Five species are accepted and a key provided, and N. africana von Arx is treated as a variety of N. vasinfeeta E.F.Sm., on the basis of SEM investigation of ascospore ornamentation. Short notes on nomenclature, relationships and pathogenicity are included. The existence of diploid and tetraploid races of N. vasinfecta corresponding to small and large ascop ore morphs is postulated. The genus Neocosmospora was established by Smith (1899) for a single species apparently pathogenic to various crops in the south-eastern United States. Since then, a number of other taxa have been added to the genus, and five species and one variety are recognized here. Most authors have placed the genus in the Hypocreales, with the exception of von Arx & Muller (1954), who favoured a position in the Sordariales close to Neurospora Shear & B. Dodge and Gelasinospora Dowding. Neocosmospora has some similarities to this group, but the usually reddish membranous ascomata, the lack of germpores in the ascospores, and the Acremonium anamorphs, as well as developmental features (Doguet, 1956), firmly unite the genus with the Hypocreales. Species of Neocosmospora are most commonly isolated from soil, often in association with plant roots, and are almost exclusively tropical or subtropical. Many of the early reports of the pathogenicity of Neocosmospora uasinfecta E.F.Sm., the type species of the genus, are now discredited, the crop diseases being caused by the unrelated Fusarium vasinfeetum Atk., which Smith (1899) erroneously regarded as an anamorph of the Neocosmospora, However, modern studies, e.g.
Kern, Naef-Rath & Defago (1971), Thakur & Sastry (1971), have established N. oasinfecta as a pathogen in its own right, causing stem- and root-rots, especially of Leguminosae. However, it rarely seems to have a serious effect on crops. See Cannon (1984) and Domsch, Gams & Anderson (1980) for further details. . NEOCOSMOSPORA E.F.Sm., Bull. U.S. Dep. Agric. 17: 45 (1899)· Ascomata perithecial, formed freely in culture, orange to red, rarely dark brown; globose to pyriform; ostiolate, with a short neck lined with periphyses. Ascornatal wall several-layered, with an outer pigmented layer, sometimes covered with rhizoidal hyphae, and hyaline inner layers; periphysoids present in most species. Asci cylindrical, rarely clavate, with a short stalk, apical structures lacking except for an inconspicuous ring in one species; 8-spored. Ascospores uniseriate, rarely biseriate, pale brown to almost hyaline, 1-(2-)celled, ± globose to ellipsoidal, ornamented. Anamorph: Acremonium spp.; demonstrated in four taxa. Conidiogenous cells long-cylindrical; conidia 0- (to 1-) septate, hyaline, variable in shape. Chlamydospores present in most species. Type species: Neocosmospora uasinfecta E.F.Sm.
KEY TO SPECIES OF NEOCOSMOSPORA Ascospores with a transversely striate ornamentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Ascospores with a rugose or cerebriform ornamentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Ascospores 7'5-12 x 5-6-5 j1m, with 6-10 transverse hyaline flanges; ascomata dark brown. _ N. striata 2. Ascospores 13'5-17x10-11-5j1m, with many inconspicuous transverse ridges; ascomata orange to red . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., N. tenuicristata 3. Asci clavate; ascospores biseriate; ascospore wall markedly irregular in thickness. . . . . . . . . N. indica 3- Asci cylindrical; ascospores uniseriate; ascospore wall j regular in thickness 4 4. Ascospores 8-10 X 5-5' 5 usn; outer layer of ascomatal walI composed of textura intricata . . . . N. parua 4. Ascospores (g-)10-15'5(-18) x (7-)7'5-12(-13'5) j1m; outer layer of ascomatal walI composed of textura angularis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 N. oasinfecta var. vasinfr ia 5. Ascospores with a rugose ornamentation . . . 5. Ascospores with a cerebriform ornamentation __ . _ _ N. vasinfecta var. afr.cana 1.
Revision of Neocosmospora NEOCOSMOSPORA VASINFECTA E. F. Sm., Bull. U.S. Dep, Agric. 17 : 45 (1899). Non Fusarium uasinfe ctum Atk., Bull. Ala. agr ic. Exp. Sen 41 : 19 (1892) (see below). N ectriella tracheiphila E. F. Sm ., Proc. Am. Ass. Advmt S ci. 1895 : 190 (1895) ; nom. inval. (Art s 32, 34) (as ' trocheiph ila '). N eocosmospora vasinfeeta var .tracheiphila E. F. Sm., Bull. U.S. Dep. Agric. 17 : 45 (1899). N . v asinfe cta var. nivea E. F . Sm., Bull. U.S. Dep. Agric. 17 : 45 (1899). N on Fu sarium niv eum E. F. Sm., Bull. U .S. Dep , A gric. 17: 12 (1899) ( = F. niveum E. F. Srn., Pr oc. Am. Ass. Advmt Sci. 1894 : 289 (1894); nom. in val. (Art. 34 ; see below). ? Pseudonectria ornata Bat . & Maia, Anais Soc. Bioi. Pernamb. 13: 74 (1955). Neocosmospora vasinfeeta var. major Rama Rao, Mycopath. Mycol. appl, 21 : 218 (1963). N. ornamentata Barbosa, Garcia de Orto 13: 17 (1965); nom. inval. (Art. 37). My celium white to pale buff, floccose . Hyphae 1-4(-5 ) /lm diam, septate, tending to aggregate in strands, there anastomosing. Ascomata orangebrown to red , ±globose, (200-)300-500 Itm tall , (170-)280--480 /lm diam, glabrous but for a number of rhizoidal hyphae, ostiolate, neck (20--)30--70(- 100 ) /l m long, 40--100(-150) 11m diam, lined with periphyses. Ascomatal wall severallayered, outer pigmented wall of ± thick-walled textura angularis with cells 8-20 /lm diam, sometimes with an inconspicuous covering hyphal web, inner layers ± hyaline, also of textura angularis. Periphysoids (see below) present but evanescent at an earl y stage, consisting of vertically-oriented rows of hyaline thin-walled cells . Asci cylindrical, thin-walled, stalk 8-15/lm long, body 800-95 (- 105) x 10'5-15(-16) /lm , without discernable apical structures, not evanescent, 8-(rarely 6-7) spored. Ascospores uniseriately arranged, buff to salmon pink in mass, pale yellow individually, globose to ellipsoidal, (9-) 10--15' 5(- 18) x (7-) 7'5-12 (-13'5) /lm, most spores with lengths falling either in the ranges 10--11 /lm or 13-15'5/lm, the spore size apparently being affected by the ploidy level (see below). Ascospore wall 0'S-2'5/lm thick, germ pores absent. The spore nearest the apex of the ascus commonly has an irregularly thickened wall, so that although the
inner surface of the wall is ellipsoidal, the spore itself is cylindrical in shape. Anamorph: A cremonium sp . Conidiogenous cells elongate-cylindrical, (20--)30--100(- 150) Itm long, 1-2/lm diam, hyaline, usually arising directly from the vegetative mycelium. Conidia cylindrical to oblong-ellipsoidal, sometimes allantoid, hyaline, i-celled, 5-13 x (1'5-)2- 3' 5 pm, aggregating in a gummy mass on the tip of the conidiogenous cell. Chlamydospores often present, hyaline to pale yellow, globose to obovoid, terminal or intercalary, smooth, 5-10 x 4-8 /lm.
VAR. VASINFECTA (F igs 1-5,7-10, 18-21 ) Ascospore walls with a rugulose to strongly rugose, rarely faintly reticulate, ornamentation. Illustrations: Smith (1899: pI. 1-S ), Butler (1910 : pl. 1-3), Moreau & Moreau (1950), Doguet (1956), Udagawa (1963), Cannon (1984). Distribution: Common throughout the tropics and warm temperate regions, usually isolated from soil or plant roots, especially of leguminous crops. Sp ecimens examin ed : U.S.A. : South Car olina, Cameron, on Gossypium herbaceum , Oct . 1902, 'W.A.O .' (BP I neotype, here selected) ; Monetta, on roots of Vigna unguiculate, Aug . 1895, E. F. Sm. (BP I -lectotype of N . uasinfecta v ar. tracheiphila E. F . Sm ., here selected) ; Ell. & Ev ., Fungi Columbiani no . 14343 [ ? same collection, dated Aug . 1899, ? a sphalm , for 1895] (BP I, K - ? isolectotypes). Sin e loc., culture grown on potato, Jan. 1896, E. F . Smith (BP I - syntype of N. uasinf ecta var . tracheiphila ). Ell. & Ev., Fungi Columbiani no. 1434b; same collection (BP I,K - isosynt ypes ). Sine loc., culture grown on potato, Dec . 1895 ; E. F. Smith (BP I - syntype of N . uasinfec ta var . tracheiph ila ). Ell . & Ev ., Fungi Columbiani no. 1434C; same collect ion (BP I,K - isosynt ypes ). U .S .A. : South Carolina, Jame s Island, on stems of Vigna unguiculate, Aug . 1895, E. F . Smith (BP I - syntype of N . uasinfec ta var .tracheiphila ; anamorph). Ell. & Ev ., Fungi Columbiani no. 1434d ; same collection (BP I ,K - isosyntypes). U .S .A. : South Carolina, Monetta, on Citrullus v ulgaris, 10 Oct. 1904, W. N. Gilbert (BP I - neotype of N. uasinfecta var. nivea E. F. Sm., here selected). Guinea Bissau : sine loc., isol. ex stored peanuts, M. A. de Freitas Barbosa (IM I 251387, = ATCC 32363, CBS 562.70-type culture of N . ornamentata Barbosa). Australia : IMI 54708, 229696. Bangladesh: IMI 49786 . Guyana: IMI 16928. Hong Kong : IMI 109594. India : IMI 75007, 75143, 93058, 93402, 100947, 100951, 104170, 1118° 9, 112026, 113518, 113519, 114772, 115670, 115924, 123953, 128943, 132134, 145068, 17°987, 171536,
Figs 1-6 . Ascospores of Ne ocosmospora spp .; scanning electron micrographs. 1-4 N . oasinfec ta var. uasinfecta. 1, IMI 215098 , x 4000 . 2, IMI 240752, x 1730. 3, IMI 251387 (isotype of N . ornamentata Barbosa), x 3330, 4, IMI 240752, x 6670. 5, Fractured ascospore of N. v asinfect a (I M I 144973,? intermediate between var. uasinfec ta and var. africana ), showing areolate structure of spore wall. x 6670. 6, N . par oa. IMI 212608 - isotype , x 4600 .
P. F. Cannon and D. L. Hawksworth
Figs 1--6. For legend see opposite.
Revision of Neocosmospora 179669, 189026, 189254, 19005°, 199565, 226126, 229339, 240751, 240752, 244579, 2467°5, 25 6486, 263173. Nigeria: IMI 93078, 215097, 215098. Pakistan: IMI 60460, 60464, 94518, 102193. Sierra Leone: IMI 58494, 1475455. Tanzania: IMI 170137. U.S.A.: IMI 113928. Zaire: IMI 85122.
Specimens examined apparently intermediate between var. uasinfecta and var. africana (see below). Australia: IMI 54709, 126527. Bangladesh: IMI 128126. India: IMI 101609, 144973, 184001, 269162. Zimbabwe: IMI 95924, 19 1524.
VAR. africana (von Arx) comb.nov. (Figs 11-17, 22-25)
Neocosmospora africana von Arx, Antonie van Leeuwenhoek 21: 161 (1955). N. vasinfecta forma conidiifera Kamyschko, Nov. Sisto niz. Rast. 1965: 115 (1965).
Ascospore walls with a cerebriform ornamentation, appearing almost smooth under LM. Illustrations: von Arx (1955), Doguet (1956), Udagawa (1963). Distribution: Widely distributed throughout the tropics and warm temperate regions. Usually isolated from soil, often associated with leguminous crops. Specimens examined: South Africa: Johannesburg, Frankenwald, isol. ex soil, sine diem, W. J. Lutjeharrns (IMI 251386, = CBS 325'54, ATCC 162388, IFO 7591 - isotype), U.S.S.R.: Uzbhekistan: Bukhara, Gizhduran, isol. ex soil soc. Ficus carica, 1961, L. A. Beljakova (IMI 251388, = ATCC 32362, CBS 602'67 - isotype of N. vasinfeeta forma conidiifera Kamyschko). Egypt: IMI 172482,172484,172486. Ethiopia: IMI 215738. Gambia: IMI 110845. Guyana: IMI 257000. India: IMI 100538, 137647. Nigeria: IMI 83938, 111938, 124887. Pakistan: IMI 123161. Sierra Leone: IMI 16929. South Africa: IMI 63344. Sri Lanka: IMI 191894, 191896, 191927. Venezuela: IMI 267939, 267940. Zambia: IMI 134571, 197827. See also specimens apparently intermediate between var. oasinfecta and var. africana listed above.
N eocosmospora vasinfecta, the type species of the genus, was isolated by Smith (1899) from three diseased crops in South Carolina, U.S.A.: cotton (Gossypium sp.), cowpea (Vigna unguiculata) and watermelon (Citrullus lanatus). Smith attributed the crop diseases to Neocosmospora, but it appears that the causal agent was Fusarium vasinfectum Atk., a taxon Smith erroneously regarded as an anamorph of the Neocosmospora. Most subsequent reports of the serious pathogenicity of N. vasinfecta are probably due to the same misconception. Fusarium vasinfectum is now regarded as a synonym of F. oxysporum Schlecht. (Booth, 1971), as F. oxysporum f. sp. vasinfectum (Atk.) Snyder & Hansen, which causes serious loss in a wide variety of crops. The pathogenicity of N. vasinfecta has not
at present been completely investigated; it is most probably a weak pathogen of roots causing little crop loss, though it may have a significant effect in conjunction with otherpathogens. Gray, RodriguezKabana & Adams (1980) suggested that at least in some cases, the Neocosmospora entered the host plants through lesions caused by parasitic nematodes. Kern et al. (1971) and Kern (1978) reported various naphtharizine derivatives in N eocosmospora, which seemed to be related to pathogenic activity, but Roos (1977) found no correlation between production of these phytotoxins and virulence of the fungal strain. Physiological races of N. vasinfecta may well occur. Smith (1899) distinguished three varieties of N. vasinfecta: var. vasinfecta on cotton, var. tracheiphila on cowpea and var. nivea on watermelon. Though these were each given formal diagnoses, Smith recognized that they were not satisfactorily separable except on a host basis. He conducted cross-inoculation experiments and established that none of the three races would infect the hosts of the others. It would be of interest to conduct greenhouse trials of isolates from various host genera to confirm and extend Smith's results, in an attempt to recognize morphological and pathogenetic distinctions between any races thus identified. The nomenclature of the three varieties of N. vasinfecta recognized by Smith is not completely straightforward. Article 59 of the International Code of Botanical Nomenclature, pertaining to anamorph and teleomorph states of fungi, was altered at the Sydney Congress in 1981 with the effect that anamorphs published in a teleomorph genus and vice oersa are no longer automatically illegitimate or invalid, assuming that all other criteria for valid publication and legitimacy are satisfied. Teleomorph names published with previously published anamorph names as synonyms are regarded as typified by the anamorph unless it is clear that the intent was to describe a new genetic form of the anamorph, correlated with it by the author, and criteria for the valid publication of a new taxon were also fulfilled. In these cases, a citation of' comb.nov. ' is treated as a bibliographic error, and the new name is attributed to the author of the teleomorph alone. Smith (1899), in his original work on Neocosmospora, published the type variety (and hence the species) as a new combination based on Fusarium vasinfectum Atk. (Atkinson, 1892). However, it is clear that Smith intended to describe the newly discovered presumed teleomorph of the Fusarium, and so his teleomorph name should not be typified by the type of the Fusarium name. The species is therefore correctly cited as N. vasinfecta E. F. Sm. and not as (Atk.) E. F. Sm. That N. vasinfecta is not
P. F. Cannon and D. L. Hawksworth
Figs. 7-10. Ascospores of Neocosmospora vasinf eeta ; scanning electron micrographs. Possible intermediates between var . vasinfecta and var. africana . 7, IMI 144973, x 6670. 8, IMI 126527, x 3670 . 9, IMI 269162, x 3670 . 10, IMI 95924, x 4330 .
actually the teleomorph of Fusarium uasinfectum does not affect the nomenclatural situation, as in the revised Art. 59, the intent of the author rather than the actual genetic connection is regarded as critical. Neocosmospora vasinfeeta var. tracheiphila E. F. Sm. was published with the synonym Nectriella tracheiphila E. F. Sm., a name mentioned 22
by Smith (1895). This latter work contained no description of the fungus, although it is referred to as ' ascomycetous'; we do not regard this as fulfilling the obligations of Art. 32 of the Code. It is clear that this paper was a preliminary report of Smith's 1899 work, and that he did not intend to formally introduce the name at this stage. It must MY C 82
Revision of Neocosmospora
Figs
11-17.
For legend see opposite.
P. F. Cannon and D. L. Hawksworth therefore be regarded as invalidly published under Art. 34, as well as Art. 32. N eocosmosporauasinfecta var. nivea E. F. Sm. was treated as a new combination of Fusarium niveum E. F . Sm., first validly published, though without a clear diagnosis, in the same paper (Smith, 1899: 12). The name was not validly published in Smith (1894) as it was there regarded as a provisional name (Art. 34). It is again clear that Smith regarded N. uasinfecta var. nivea as a teleomorph of the Fusarium, and so this can be taken as the name of a new taxon rather than a combination of the Fusarium into an inappropriate genus. Similarly, there appears to be no genetic connexion between the Neocosmospora and the Fusarium . No type collections were cited for N . uasinfecta (var . vasinfecra) by Smith. We have therefore designated a neotype on Gossypium, the type host, collected from the same region as were Smith's fungi (see above). This was gathered only three years after Smith's publication of the name, and incorporated into the same herbarium (BP I) as were Smith's collections. It is not unlikely that he saw the specimen concerned, and it agrees in all respects with the original description of the species . A series of five specimens was designated by Smith as type material of N . uasinfe cta var. tracheiphila. These are preserved in BPI, and duplicates of each were issued as Ellis & Everhart's Fungi Columbiani no . 1434a-e. Of the five collections, the first was of ascomata on stems of Vigna unguiculate, the second and third were cultures containing immature and mature ascomata respectively, the fourth was of an anamorphic fungus within the vessels of V. unguiculata , and the fifth was ofthe supposed anamorph Fusarium uasinfectum Atk . The provenance of the cultures was not detailed; they mayor may not have been derived from the collection of the ascomata on V . unguiculata. The identity of the unnamed anamorphic fungus is not clear; our examination could not resolve the question as to whether it was the Acremonium anamorph of the Neocosmospora, or a microconidial stage of the Fusarium. Judging from the description and illustrations in Smith's work, the former seems more likely. The collection of Fusarium on Vigna is obviously unsuitable for recognition as type material of the Neocosmospora. The collection of ascomata on Vigna in Smith's herbarium (BP I) is here designated as lectotype of N. oasinfe cta var. tracheiphila; examples of Ellis & Everhart's Fungi Columbiani no. 1434a are therefore isolectotypes.
Smith designated no type material for N. uasinfecta var. nivea. We have therefore chosen a specimen on Citrullus lanatus collected in the same region as Smith's fungus as neotype (see above ). The specimen was collected in 1904 and incorporated into BPI; it is likely, as with var oasinfecta, that Smith saw the collection in question. It agrees in all respects with Smith's description. No further significant advances were made in the classification of Neocosmospora vasinfeeta until the 1950's. Von Arx (1955) described a new taxon, N . africana, which he distinguished from N . uasinfe cta by its smooth (actually cerebriform) rather than rugose ascospores. It is here treated at varietal level (see below ). In the same year, Batista, Chaves, Maia & Vital (1955) published Pseudonectria ornata Bat. & Maia, which is a probable synonym of N. vasinfecta; we have not seen type material of this taxon and the description is not sufficient to be absolutely sure of the synonymy. Doguet (1956) published a detailed morphological and developmental investigation of N. uasinfecta and N. africana, including a short discussion on paraphysis-like structures found in between the asci. He established that these chains of thin-walled hyaline cells between the asci, evanescent at maturity, originate from the upper part 'of the ascoma. He therefore referred to them as pseudoparaphyses. However, Luttrell (1965) decided that they were not homologous with the similarly-named structures found in the Loculoascomycetes, and suggested that they be referred to as apical paraphyses. The most recent work on this subject, however (Eriksson, 1981), prefers the term 'periphysoid " and this is adopted here as in the recent Dictionary of the Fungi (Hawksworth et al., 1983 ). These structures appear to be of little taxonomic value below the genus level, and are found in a number of genera of the Hypocreales. Udagawa (1963) found both N . vasinfeeta and N . africana in Japan, and published an account of the genus in that country. Rama Rao (1963) described N. uasinfecta var . major, supposedly differing in ascospore size. In fact, the sizes he quoted are well within the range of variation of the species found by us. Barbosa (1965) described a new taxon, N . ornamentata, apparently differing in the shape and degree of rugoseness of the spores, but there does not appear to be a definable division between the type isolate we have examined and N. uasinfecta, so we reduce it to synonymy here . In any case, the name was invalidly published as no type specimen was cited. Kamyschko (1965) published N. vas-
Figs 11-17.Ascospores ofN. vasinfecra var. africana ; scanningelectronmicrographs. 11, IMI 172482, x 2670. 12, IMI 100538, x 3330. 13 IMI 191894, x 2070. 14, IMI 257000, x 3330. 15, IMI 111938, x 3330. 16, IMI 137647, x 6670. 17, IMI 123161, x 3330. 22-2
680
Revision of Neocosmospora
20
21
22
-
~
23 Figs 18-25. For legend see opposite.
P. F. Cannon and D. L. Hawksworth infecta forma conidiifera with an Acremonium anamorph, differing from Smith's fungus in the absence of a Fusarium anamorph. However, as the Fusarium is not genetically connected with the Neocosmospora, no distinction remains between the two taxa. In fact, we have found from examination of type material that Kamyschko's fungus is a particularly large-spored example of N. vasinfecta var. africana. Van Warmelo (1976) made a comparative study of a South African isolate of a Neocosmospora with isolates named as N. uasinfecta and N. africana using LM and SEM, and found no significant difference between the ascospores of the three isolates. He therefore recommended that N. africana be reduced to synonymy with N. uasinfecta. However, it is clear from our studies that the isolate of N. uasinfecta he examined was misidentified, and in fact belonged to N. africana. His conclusions must therefore be rejected. At first sight, the differences in ascospore ornamentation between the rugose N. oasinfecta and the cerebriform N. africana seem ample indication that the two taxa are separate species. However, an extensive analysis of the variation in ascospore ornamentation showed a certain degree of intergradation. This is illustrated in Figs 7-10. While most specimens examined were easily assigned to one or other taxon, a proportion had only a very faintly rugose ornamentation, and some of these appeared very weakly reticulate. In many of these cases, examination with the light microscope was either not sufficient to clearly elucidate the ornamentation, or, more importantly, gave an inaccurate impression of it, so that specimens appearing weakly rugose under LM were shown to have a cerebriform ornamentation under SEM. Van Warmelo (1976) went some way towards an explanation of this difficulty, when he showed that while fresh air-dried ascospores of one of his collections of N. africana (Isolate P) showed the typical cerebriform ascospores, spores from old desiccated specimens of the same isolate appeared weakly rugose, as in some of the intermediates found in our own study. He attributed this to a partial breakdown of the spore wall in the desiccated specimens. TEM studies on the development of the ascospore wall in N. vasinfeeta and N. africana could well contribute to a greater understanding of this problem. It therefore appears that a proportion of
681
specimens cannot definitely be assigned to one or other taxon without SEM examination of fresh material. This was unfortunately impossible with the great majority of specimens available to us. In itself, though, the difficulty of examination is not a valid criterion for the merging of taxa with definable distinctions. The specimens available to us were therefore closely examined to find correlating distinctions to support the separation of the taxa at specific level, but without success. Not only were the variations in all dimensions measured almost exactly the same, but var. vasinfecta had two ascospore size morphs which seemed to be mirrored by var. africana, though the relatively small number of specimens of this variety available made comparison difficult. The difference in ascospore size was not related to the number of spores in the ascus, this being commonly encountered in the Hypocreales (Booth, pers. comm.); ascospores in the rare 6- and 7-spored asci were not larger than those in 8-spored asci. Specimens with the large ascospore morph tended to have larger ascomata, but the two morphs could not be satisfactorily separated using this character. Ascospore ornamentation was not correlated with ascoma size. Thus, the only definable difference between the two taxa we have found is the ascospore ornamentation, a feature itself difficult to determine in a number of instances. It therefore seems more appropriate to treat the two taxa as varieties of N. oasinfecta rather than as separate species. The necessary new combination has been made. However, further information, such as that gained from subjecting isolates to closely defined growth conditions, physiological tests found advantageous in the classification of Penicillium Link (Pitt, 1980) and Monascus v. Tieghem (Hawksworth & Pitt, 1983), as well as biochemical and pathogenicity investigations, could cause this conclusion to be reviewed. Examinations of this specialised nature were unfortunately not possible during the present study. Preliminary examinations strongly suggest that N. oasinfecta has diploid and tetraploid races, which correspond to the two ascospore size morphs mentioned above. Analysis of 510 measurements of ascospore length (10 selected at random from each of 51 isolates) ofvar. vasinfecta showed a two-peaked frequency distribution (see Fig. 26), with the vast majority of ascospores measuring between either
Figs 18-25. Ascospores of N. uasinfecta ; light micrographs (Nomarski D.Le.), all x 1000. 18-21, var. vasinfecta.s.S, 19, Small ascospore morph (lMl 244579). 20,21, Large ascospore morph (lMl 199565).22-25., var. africana. 22-23, Small ascospore morph (lMl 251386 - isotype). 24, 25, Large ascospore morph (lMl 251388 - isotype of N. uasinfecta forma conidiifera).
682
Revision of Neocosmospora
80
>. u t:
60 - - - var. vasinfecta
"0'w ;:l
Lt
--- ------- var. africana
40
20
---' 8 8.8
9 9.9
10 11.0
II 12.1
...... .. - .. _-_ ...... 12 13.2
..-
13 14.3
-------14 15.4
15 16.5
16 17.6
17 units 18.7 jim
Fig. 26. Graph showing frequency distribution of asco sp ore lengths of N. oasinfecta vars. uasinf ecta and africana.
9' 5-1 1'5 pm or 12 '5-15 '5 pm. A similar analysis of 17 samples of var. africana also showed a strongly non-normal distribution, although the small number of samples did not allow an accurate assessment of the frequency distribution of ascospore length. A strong peak between 9'5 and u '5 Ilm was noted, as with var . uasinfe cta, but the second peak was not in evidence, although the frequency of ascospore measurements seemed to increase slightly between about 15 and 18 pm. The microscope graticule used was divided into units of 1'1 /lm at a magnification of x tOOO; half-units (corresp onding to 0'55 11m ) were esti mated. The lower figures for the non-whole number unit measurements are probably due to an unconscious tendency on the part of the observer to round up or down to the nearest whole number rather than to the half-unit. A smaller sample (10 measurements of ascospore length in each of 9 isolates of var . vasinfeeta and 12 of var. africana) was subjected to statistical analyses by Dr P . B. Topham (Sco ttish Crop Research Institute, I nvergowrie). Analysis of variance and a subsequent variance ratio (F ) test showed that there was no statistical significance, even at the 10 % level, between the samples of var . uasinfe cta and var. africana, but the differences between samples within each ascospore ornament type were highly significant, reflecting the non-normal frequency distributions of ascospore length discussed above . The chromosomes of N . uasinfec ta have already been examined by van Warmelo (1977) , who investigated the somatic chromosomes in macerated mycelium of three isolate s (the same as used in his
1976 work on ascospore ornamentation cited above ), all of which we now recognize as belonging to the small ascospore morph of var . africana, and found an estimated number of n = 6 in all three samples. This number was later confirmed (van Warmelo, 1981 ) in work on young asci of the same isolates. A single isolate belonging to the large ascospore morph of var. oasinfe cta (I M I 147455) was examined by us, using the Giemsa staining technique as described by Johnston & Booth (1983). As van Warmelo found, the chromosomes were very small and difficult to separate, but preparations of nuclei in young asci of our isolate showed a chromosome number certainly in excess of n = 6, with a strong possible number of n = 12, the number one would therefore expect in a tetraploid race of N. uasinfecta. Although only a limited degree of reliance should be placed on this singl e observation, it seems fairly cer tain that polyploid races of N. uasinfecta occur and that, in the limited number of samples so far examined, the ploidy level is related to ascospore size . However, we cannot at this stage exclude the possibility that the ploidy level is connected with ornamentation type rather than ascospore size, though this seems most unlikely in the light of the statistical data d iscuss ed above.
Veda & Udagawa, M y coraxon 16: 38 7 (1983) . (F igs 27-28). M yc elium white to buff. Hyphae tending to aggregate in strands, there ana stomosing. A scomara orange-red to reddish brown, ± glob ose, NEOCOSMOSPORA TENUICRISTATA
P. F. Cannon and D. L. Hawksworth 330-400(-450) pm tall, 260-320 pm diamv-j glabrous or covered with an inconspicuous web of hyaline hyphae, ostiolate, neck 50-80 pm long, 80-110 pm diam, lined with periphyses. Ascomatal wall several-layered, outer pigmented wall of ±thick-walled textura angularis with cells 7-20 pm diam, inner layers hyaline, also of textura angularis. Periphysoids present at maturity, composed of very thin-walled hyaline cells. Asci cylindrical, thin-walled, stalk 5-12(-20) pm long, body 85-100 x 12'5-15 pm, without discernible apical structures, not evanescent, 8-spored. Ascospores uniseriately arranged, yellowish-brown, globoseellipsoidal to ellipsoidal, (13'5-)15'5-16'5 (-17) x (10-)11-12 pm. Ascospore wall 1-1'5 pm thick, without germ-pores, often somewhat irregular in thickness, with an ornamentation of transverselyarranged ridges 0'25--0'5 pm wide. Apical spores often abnormal in shape as in N, vasinfecta.
Anamorph: Acremonium tenuicristatum Veda & Vdagawa, Mycotaxon 16: 389 (1983). Conidiogenous cells elongate-cylindrical, 30-50 (-140) x 2'5-4 pm, hyaline, with a minute apical collarette, occasionally proliferating sympodially, emanating either directly from the hyphae or from a short cylindrical hyaline conidiophore, rarely absent, the conidia being produced directly from the mycelium. Conidia hyaline, 5-15(-19) x 2'54 pm, oblong-ellipsoidal to cylindrical, often slightly allantoid, smooth-walled, aggregating in a gummy mass on the tips of the conidiogenous cells. Chlamydospores not observed. Illustrations: Veda & Vdagawa (1983). Distribution: Japan (only known from the type collection). Specimen examined: 1apan: Nagasaki pref.: Higashis-
onogi-gun: Oomura Bay, isoJ. ex marine sludge, 26 Ian. 1981, S. Veda (IMI 277708, = NHL 2911 - isotype culture).
Neocosmospora tenuicristata, recently isolated from marine sludge in Japan, is closely related to N. uasinfecta, differing in the ascospore wall ornamentation, which consists of a series of transversely oriented ridges. In addition, the anamorph has an unusual characteristic in that the conidiogenous cells proliferate to a small degree, a situation not encountered in other Neocosmospora anamorphs. The significance of this feature is unclear; it is known in a few other species of Acremonium (Gams, 1971). Neocosmospora tenuicristata was contrasted with N. striata Vdagawa & Rorie by Veda & Vdagawa (1983), but it is doubtful that these species are closely related.
Mahoney, Mycologia 68: 1111 (1976). (Figs 6, 31-32). Mycelium very inconspicuous, hyaline. Hyphae 1-2 pm diam, septate, tending to aggregate in strands. Ascomata orange-brown, very fragile, ovoid to pyriform, glabrous but for a number of rhizoidalhyphae,(iOo-)130-18o(-210) x (80-)120150(-180) j.tm, ostiolate, neck 10-30 j.tm long, 50-70 j.tm diam, lined with periphyses. Ascomatal wall several-layered, with a pigmented outer wall of irregular textura intricata with hyphae 3-5 pm diam, and inner layer almost hyaline, consisting of an ill-defined intermediate between textura intracata and textura angularis. Periphysoids not observed. Asci 47-60 x 6'5-10 j.tm, cylindrical to cylindric-clavate, thin-walled, short-stalked, without discernible apical structures, not evanescent, 8-spored. Ascospores obliquely uniseriately or partially biseriately arranged, orange-yellow to orange-buff en masse, golden yellow individually, ellipsoidal, 8-10 x 5-5'5 pm, without germ pores, wall 0'5--0'75 j.tm thick, with a reticulate ornamentation mostly obscured by a weakly verrucose epispore layer.
NEOCOSMOSPORA PARVA
Anamorph: Acremonium sp. Conidiogenous cells usually arising directly from vegetative hyphae (i.e. conidiophores absent), elongate-cylindrical, 20-70(-150) j.tm long, 1-1' 5 j.tm diam, hyaline, with a slightly flared collarette, ca 1 j.tm long. Conidia usually cylindrical to oblong-ellipsoidal, sometimes allantoid, occasionally reniform or obovoid, hyaline, smooth-walled, r-celled, 4-10 x 1'5-3(-5) j.tm, aggregating in a gummy mass on the tips of the conidiogenous cells. Chlamydospores not observed. Illustrations: Mahoney (1976). Distribution: Galapagos Islands (only known from the type collection). Specimen examined: Galapagos Islands: Isla Santa Cruz, near Charles Darwin Research Station, isoJ. ex soil, Dec. 1968, T. de Vries (IMI 212608- isotype).
Neocosmospora parua Mahoney, only known from a single soil isolate from the Galapagos Islands, is easily distinguished from other species by its small, relatively narrow ascospores which have a weakly verrucose epispore ornamentation covering a reticulately patterned spore wall. It may well be most closely related to N. indica Wadhwani, which has a some-what similar ascospore wall structure, and also shares the characteristic of the outer layers of the ascomatal wall being composed of textura intricata.
684
Revision of Neocosmospora
27
28
30
,.'
33
31
32
,
.
34
68 5
P. F. Cannon and D . L. Hawksworth
B
100 pm
D
c 10 pm 10 pm Fig . 35. Drawing of N . indica (lMl 13Z135-holotype). A, ascoma . B, detail of stru ctu re of hyaline inner layers of ascoma wall. C, asci. D , ascospores.
Figs 27-34. Ascospores of Neocosmospora spp.; light micrographs (Nomarski D.LC.), all x 1000.27,28, N. tenuicristata (lMl 277708-isotype). 29, 30, N. indica (IM l 132135-holotype). 31, 32, N . parua (lMl 212608-isotype). 33,34, N. striata (IM l 210879-isotype).
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Revision of N eocosmospora
F igs 36-39. Ascospore s of N. indica (1M 1 132135-holot ype ) ; scanning electron micrographs. 36, x 1330. 37, x 3330, 38,39, x 6670.
NEOCOSMOSPORA INDICA Wadhwani, 2:
Ind. Bot. Reptr
158 (1983) 1984.
Mycelium very pale buff (dried culture), somewhat darker towards the edges , floccose. Hyphae 1-4'5 /lm diam, septate, tending to aggregate in rope-like strands, there anastomosing. Ascomata formed freely at edge of mycelium, orange to red, globo se, 170--240(-300) pm diam, glabrous but for a number of rhizoidal hyphae; ostiolate, with a short neck 30--7° pm long, 70--100 Ilm diam, lined with periphyses. Ascomatal wall several-layered, with a pigmented outer layer of textura intricata
with hyphae 1'5-4 /lm diam and thin hyaline inner layer (s) of textura angularis with cells 8-18 /lm in size. Periphysoids evanescent at an early stage. A sci clavate, 38-49 x 15'5-22 pm, the longer asci tending to be thinner, very thin-walled, without discernible apical stru ctures, evanescent, 8-spored. A scospores biseriately arranged, orange-brown en masse, yellow-brown individually, irregularly ellipsoidal, 12'5-16 x ~10 um, without germ pores, inner edge of wall elliptical in section, wall very irregular in thickness, ranging from 0'75-2'25 /lm, reticulate, the reticulations obscured in irregular patches by a weakly verrucose epispore layer .
P. F. Cannon and D. L. Hawksworth Anamorphi] Acremonium sp.; a few cylindrical conidia 4-6 x l' 5-2 pm in size were observed, but none were seen attached to the mycelium and could conceivably have contaminants. Chlamydospores: Not observed.
Distribution: N. and N.E. India. Specimens examined: India: Lucknow, isol. ex Eruca sativa soil; cornrn. 14 Mar. 1968; J. N. Rai 12 (IMI 132135 - holotype). Bhagalpur University, isol. ex soil; comm. 18 Mar. 1980; K. S. BilgramiB25 (IMI 246703).
This taxon, found to date in two isolations from India, is superficially similar to N. vasinfecta E. F. Sm., but may be more closely related to N. parva Mahoney. It shares the unusual verrucose epispore covering a reticulately patterned ascospore wall with the latter species, but differs by its larger, wider ascospores whose walls are only partially covered by the epispore, the wall therefore appearing very irregular in thickness. NEOCOSMOSPORASTRIATA Udagawa& Horie, Trans. mycol. Soc. Japan 16: 340 (1975)· (Figs 33-34). Mycelium inconspicuous, hyaline. Hyphae 0'5-2'5 pm diam, septate. Ascomata dark brown, pyriform, glabrous but for a number of rhizoidal hyphae, 130-170 x 90-140 pm; ostiolate, neck 30-50 pm long, 50-70 pm diam; periphyses not observed. Ascomatal wall with a pigmented outer layer and an almost hyaline inner layer, both of textura epidermoidea. Periphysoids not observed. Asci 60-85 x 6-10 psn, cylindrical to cylindricclavate, thin-walled, with a small inconspicuous apical ring which does not stain blue in iodine, 8-spored. Ascospores obliquely uniseriately or partially biseriately arranged, very pale yellow to hyaline, ellipsoidal, 7'5-10'5(-12) x 5-6'5 pm, without germ-pores, some spores with a median transverse straight or curved septum, then very slightly constricted at the septum; ascospore wall ca 0'5 pm thick, with 6-10 thin transverse hyaline flanges ca 1 pm wide.
Anamorph: Not known. Chlamydospores: Not observed. Illustrations: Udagawa & Horie (1975). Distribution: Japan (only known from the type collection). Specimen examined: Japan: Nagano, Shimatogai-gun,
Yamanouchi-machi, isol. ex soil; 20 Sept. 1974;Y. Horie (IMI 210879 - isotype). This species is probably not congeneric with the other taxa treated in this work, but is retained in Neocosmospora pending more detailed investigations of its affinities. It may well belong to the Sordariales rather than the Hypocreales. It differs
most particularly from the other species of Neocosmospora in the colour of its ascomatal wall (brown rather than red), the presence of an apical ring in the asci, and in the ascospores which have conspicuous hyaline flanges quite different from the range of wall ornamentation found in the other species of the genus. These flanges seem more similar to those found in Emericella v. Beyma (Eurotiales sensu lata), or may be transverse counterparts ofthose seen in Pteridiosperma Krug & jeng (Sordariales). Critical ontogenetic investigations and TEM studies ofthe apical apparatus in the asci and of the development of the ascospore flanges would be useful in the elucidation of this problem. Useful suggestions on the interpretation of results were made by Dr C. Booth, and Dr D. W. Minter corrected the Latin diagnosis; Dr E. Punithalingam is thanked for advice on the cytological work, Mrs C. Thatcher and Mrs J. Woodhams for technical assistance, and Mr D. Fry for photographic work (all of CMI). We are grateful to Dr P. B. Topham (Scottish Crop Research Institute, Invergowrie) for statistical analyses, and to Dr L. Batra (BPI) for assisting D. L. H. in locating Smith's herbarium material and other help on his visit to BPI in August 1982. REFERENCES ARX, J. A. VON (1955). Ein neuer Ascomycet aus Afrika. Antonie van Leeuwenhoek :U, 161-165. ARX, J. A. VON & MOLLER, E. (1954). Die Gattungen der amerosporen Pyrenomyceten. Beitriige zur Kryptogamenfiora der Schweiz 11 (1), 1-434. ATKINSON, G. F. (1892). Somediseases of cotton. Bulletin of the Alabama agricultural Experiment Station 41, 1-65. BARBOSA, M. A. De Fr. (1965). A new species of Neocosmospora found in stored peanut. Garcia de Orto 13, 17-19. BATISTA, A. C., MAlA, H. Da S. & VITAL, A. F. (1955). Ascomycetidae aliquot novarum, Anais da Sociedade de Biologia de Pernambuco 13 (2), 72-86. BOOTH, C. (1971). The Genus Fusarium. Kew: Commonwealth Mycological Institute. BUTLER, E. J. (1910). The wilt disease of pigeon-pea and the parasitism of Neocosmospora uasinfecta. Memoirs of the Department of Agriculture in India, Botanical Series, 2 (9),1-64. CANNON, P. F. (1984). Neocosmospora oasinfecta. CMI Descriptions of Pathogenic Fungi and Bacteria (In the
Press.)
DOGUET, G. (1956). Morphologie et organogenie du Neocosmospora uasinfecta E. F. Smith et du Neocosmospora africana von Arx. Annales des Sciences Naturelles, serie de Botanique 11, 17,353-370. DOMSCH, K. H., GAMS, W. & ANDERSON, T.-H. (1980). Compendium of Soil Fungi. London etc.: Academic Press. ERIKSSON, O. (1981). The families of bitunicate ascomycetes. Opera Botanica 60, 1-220.
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GAMS, W. (1971). Cephalosporium-artige Schimmelpilze (Hyphomycetes). Stuttgart: Gustav Fischer. GRAY, F. A., RODRIGUEz-KABANA, R. & ADAMS, J. (1980). Neocosmospora stem rot of soybeans in Alabama. Plant Disease 64, 321-322. HAWKSWORTH, D. L. & PITT, J. 1. (1983). A new taxonomy for Monascus species based on cultural and microscopical characters. Australian Journal of Botany 31, 5 1-61. HAWKSWORTH, D. L., SUTTON, B. C. & AINSWORTH, G. C. (1983). Ainsworth & Bisby's Dictionary of the Fungi. Seventh Edition. Kew: Commonwealth Mycological Institute. JOHNSTON, A. & BOOTH, C. (eds) (1983). The Plant Pathologist's Pocket Book. Kew: Commonwealth Mycological Institute. KAMYSCHKO, O. P. (1965). Ascomycetes novi e terris Asiae mediae. Nouitates Systematicae Plantarum non Vascularum 1965, 115-116. KERN, H. (1978). Les naphtharizines des Fusarium. Annales de Phytopathologic 10,327-345. KERN, H., NAEF-RoTH, S. & DEFAGO, G. (1971). Zur Toxinbildung von Neocosmospora uasinfecta und Neocosmospora africana. Phytopathologische Zeitschrift 72, 327-334. LUTTRELL, E. S. (1965). Paraphysoids, pseudoparaphyses, and apical paraphyses. Transactions of the British Mycological Society 48, 135-144. MAHONEY, D. P. (1965). A new Neocosmospora from Galapagos Island soil. Mycologia 68, 1111-1116. MOREAU, C. & MOREAU, M. (1950). Neocosmospora uasinfecta E. F. Sm. Faux wilt du cotonnier. Revue de Mycologie 15, Supplement colonial 2, 1-5. PITT, J. 1. (1980). The Genus Penicillium and Its Teleomorphic States Eupenicillium and Talaromyces. London, New York: Academic Press.
RAMA RAo, P. (1963). Studies on soil fungi. 1. Ascomycetes from soils of Hyderabad (India). Mycopathologic et Mycologia applicate 21, 217-221. Roos, A. (1977). Zur Physiologie und Pathologie von Neocosmospora uasinfecta E. F. Smith. Phytopathologische Zeitschrift 88, 238-271. SMITH, E. F. (1894). The watermelon disease of the South. Proceedings of the American Association for the Advancement of Science 1894,289. SMITH, E. F. (1895). The watermelon wilt and other diseases due to Fusarium. Proceedings of the American Association for the Advancement of Science 1895, 190-191. SMITH, E. F. (1899). Wilt disease of cotton, watermelon and cowpea. United States Department of Agriculture Bulletin 17, 1-53. THAKUR, R. N. & SASTRY, K. S. M. (1971). Studies on wilt disease of Crotalaria mucronata. Indian Journal of Mycology and Plant Pathology 1, 84-86. UDAGAWA, S. (1963). Neocosmospora in Japan. Transactions of the Mycological Society of Japan 4, 121-125. UDAGAWA, S. & HORIE, Y. (1975). Notes on some Japanese ascomycetes XIV. Transactions of the Mycological Society ofJapan 16, 337-347. UEDA, S. & UDAGAWA, S. (1983). A new Japanese species of Neocosmospora from marine sludges. Mycotaxon 16, 387-395. VAN WARMELO, K. T. (1976). Scanning electron microscopy of Neocosmospora ascospores. Mycologia 68, 1181-1187. VAN WARMELO, K. T. (1977). Asexual nuclear division in Neocosmospora. Bothalia 12, 247-250. VAN WARMELO, K. T. (1981). Sexual nuclear division in Neocosmospora. Bothalia 13, 415-429.
(Received for publication 16 September 1983)