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Re-evaluation of Geaster florissantensis (Oligocene, North America)
Notes and brief articles
493
RE-EVALUATION OF GEASTER FLORISSANTENSIS (OLIGOCENE, NORTH AMERICA) BRUCE H. TIFFNEY
Department of Biology and Peabody Museum, Yale University, 260 Whitney Avenue, Box 6666, New Haven, Connecticut 06511, USA
While the fossil record of the fungi is relatively sparse, it is of some value in providing a check to phylogenetic schemes derived from the study of modern taxa. The contribution of this record to our understanding of the gasteromycetes would be of particular significance as the phylogeny of this group is a subject of debate, including a consideration of their probable polyphyletic constitution (Savile, 1955; Singer & Smith, 1960; Ingold, 1971). The gasteromycetes are presently represented in the fossil record by five species. Of these Geaster fiorissantensis Cockerell is of the greatest potential significance by virtue of its age and apparent preservational detail. This significance is best introduced by a review of the other reported fossils. The oldest fossil gasteromycete is Gasteromyces farinosus Ludwig reported by Ludwig (1861) from an Upper Carboniferous coal of the Urals. The , sporocarps' are described as being both spherical and tubular, while the' spores' are quite variable in shape and structure. Both the account and the accompanying illustrations are thoroughly unconvincing, and this may perhaps best be judged as an erroneous citation. The next oldest evidence is provided by spores identified as Scleroderma echinosporites Rouse from the Late Cretaceous (Late Campanian) Burrard Formation of southwestern British Columbia (Rouse, 1962). The 11-15 /lm diam, circular spores are finely spinose and lack a pore. While there is no strong evidence to disbelieve this report, it would perhaps be more satisfying if the identification were based on an examination with the Scanning Electron Microscope, or better yet, if the whole fruiting structure was known. Berry (1929) reported an unnamed sporocarp from Late Eocene sediments in Peru. He did not provide an identification beyond 'this single specimen ... undoubtedly represents a fungus, probably of the puff ball tribe', and the accompanying illustration bears out the vagueness of the description. While this report cannot be completely dismissed without an examination of the actual specimen (whereabouts unknown), the published evidence is unconvincing. Chaney & Mason (1936) described a specimen of Bovista Tram. Br. mycol. Soc. 76 (3), (1981).
plumbea Pers. from a Pleistocene deposit near Fairbanks, Alaska. While the identification was based on both macro- and microscopic characters and is undoubtedly correct, the relatively recent origin restricts its phylogenetic significance. This summary leaves Geaster fiorissantensis as potentially the most interesting fossil member of the group. The specimen was described by Cockerell (1908) from the Oligocene Florissant Formation of central Colorado, long famed for its exquisite preservation of plant and insect material in water- and wind-deposited volcanic ash. Cockerell (1908) provided an indistinct picture of the specimen together with a very brief description, concluding that 'the appearance is exactly that of a modern Geaster in the expanded condition'. This judgement was accepted with reservation by Pia (1927) in his survey of fossil fungi, although he altered the generic name to Geasterites. However, MacGinitie (1953) dismissed the identification in his revision of the Florissant flora. He placed G. fiorissantensis in the category 'species rejected from the flora' with the general statement that 'unless otherwise stated, the specimen is too poor for identification; an indefinable object'. The present author, in a broad summary of the fossil record of the fungi (Tiffney & Barghoorn, 1974), accepted Cockerell's identification on the basis of the illustration provided, but witha degree of scepticism (unpub1.). In his description, Cockerell (1908) failed to cite the place of deposition of the type specimen, but a search revealed that it is no. 18550 in the Paleobotanical Collections of the Museum of the University of Colorado, Boulder, USA. The type consists of a part and counterpart impression. Although the position of the fossil on the slab is indicated by a dark stain as well as by limited relief on the substratum, no organic matter is retained on the counterpart and very little on the part (Fig. 1). Cockerell illustrated the part specimen as he found it, noting that it possessed perhaps eight segments of which five were visible. Preparation of this specimen revealed that eight rays are present, two of which are overlapped. These rays average 27 mm (range 23-30 mm) in
Printed in Great Britain
0007-1536/81/2828-7520 $00.35 © 1981 The British Mycological Society
Notes and briefarticles
494
Fig. 1. Geasterflorissantensis, part specimen; note two rays arc superimposed (x 1). Fig. 2. Detail of inner portion; note the central protrusion and the obscuring fold ( x 2'2 ).
length and are 8'S mm (7-11 nun) in width at their widest, basal, point. The whole structure is S4 mm diam, and the central body (intern al to the mutual juncture of the rays) is about 20 nun diam, In the immediate centre is a small conical protrusion (Fig. 2) which is 5 mm diam. The lack of relief in the fossil suggests that the original structure was neither particularly thick or fleshy, nor very rigid. The rays show no sign of superficial fissuring or cracking, although these features might be expected of the inner surface of the exoperidium of a Geaster. Indeed, the rays give evidence of being quite thin, and in two cases take on the contour of the matrix which they overlie. The flexibility of the original structure is also attested to by the fact that it has been folded upon itself to a slight degree, such that the bases of the rays of one side of the 'disk ' obscure one half of the central protrusion (Fig. 2). On one ray there is faint evidence for lineation (? venation) parallel to the long axis, but this is not a pronounced feature. No sign is present of an endoperidium or similar structure. Since the spores of most gasterornycetes possess a fairly distinctive morphology (Coker & Couch, 1928; Eckblad, 1971), a palynologic analysis of the matrix immediately adjacent to the specimen was made . The preparation was poor in palynomorphs and lacked any evidence of spores immediately referable to the gasteromycetes,
Trans. Br, mycol, Soc. 76 (3), (1981).
The foregoing evidence suggests that th e fossil does not represent a specimen of a gasteromycete. The rays appear to be thin and papery, rather than thick or leathery as one would expect of an exoperidium. No evidence is present for an endoperidium. There is no sign of spores in the associated matrix, an unusual feature if this was indeed a gasterornycete sporocarp. While it could be argued that the specimen had been blown into the site of deposition from a distant source, losing its spores and endoperidium in the proce ss, there is no indication of any curling of the rays as would be expected if the exoperidium were in a dried state amenable to wind transport. While Cockerell (1908) was correct in observ ing that 'the irregularity of the segments is unlike that of any calyx ', this is not sufficient reason for assuming the fossil to be an earth star. Although on close examination the specimen is fairly poor in many respects and lacks sufficient detail to permit its placement in any other taxon familiar to the author, it possesses enough detail to make it clear that it is not a gasteromycete. I am grateful to Dr J. Van Couvering, Curator of the Paleobotanical Collections of the Museum at the University of Colorado, Boulder for the loan of the specimen of Geaster florissantensis, permission to prepare it, and permission to publi sh the photographs used in this paper.
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0007-1536/81/2828-7520 $00.35 © 1981 The British Mycological Society
Notes and brief articles REFERENCES
BERRY, E. W. (1929). Early Tertiary fruits and seeds from Belen, Peru. The Johns Hopkins University Studies in Geology 10, 137-179. CHANEY, R. W. & MASON, H. L. (1936). A Pleistocene flora from Fairbanks, Alaska. American Museum Nouitates 887, 1-17. COCKERELL, T. D. A. (1908). Descriptions of Tertiary plants. II. American Journal of Science, Fourth Series 26, 537-544. COKER, W. C. & COUCH, J. N. (1928). The Gasteromycetes of the Eastern United States and Canada. Chapel Hill: The University of North Carolina Press. ECKBLAD, F. E. (1971). Spores of gasteromycetes studied in the scanning electron microscope (SEM). I. NorwegianJournal of Botany 18, 145-151. INGOLD, C. T. (1971). Fungal Sp ores. Their Liberation and Dispersal. Oxford: Clarendon Press.
495
LUDWIG, R. (1861). Zur Palaeontologie des Urals. Palaeontographica 10, 17-36. MACGlNITIE, H. D. (1953). Fossil plants of the Florissant beds, Colorado. Contributions to Paleontology; Carnegie Institute of Washington Publication 599, 1-198. PIA, J. (1927). Klasse Fungi. In Handbu ch der Paldobotanik (by M. Hirmer), pp. 112-130. Munich and Berlin: R. Oldenbourg.
ROUSE, G. E. (1962). Plant microfossils from the Burrard Formation of western British Columbia. M icropaleontology 8, 187-218. SAVILE, D. B. O. (1955). A phylogeny of the basidiomycetes. Canadian Journal of Botany 33, 60-104. SINGER, R. & SMITH, A. H. (1960). Studies on secotiaceous fungi in the asterogastraceous series. Memo irs of the Torrey Botanical Club :U, 1-112. TIFFNEY, B. H. & BARGHOORN, E. S. (1974). The fossil record of the fungi. Occasional Papers of the Farlow Herbarium of Cryptogamic Botany 7, 1-4 2 •
PATHOGENICITY OF FUNGI ASSOCIATED WITH CITRUS GREASY SPOT IN NEW SOUTH WALES C. R. WELLINGS
N .S.W. D epartment of Agriculture, Agricultural Research Centre, Tamworth, Australia 2340
Greasy spot of citrus in New South Wales is a leaf disease which has been known for many years, although its incidence has increased since 1972. Detailed descriptions of symptoms, host range and distribution in New South Wales have been published (Wellings & Emmett, 1978). Comparison with descriptions of the diseases called greasy spot in Japan (Tanaka & Yamada, 1952) and the USA (Whiteside, 1977) leads to the conclusion that citrus greasy spot in New South Wales is distinct from that found elsewhere (Wellings & Emmett, 1978). Several fungi may be isolated from diseased leaf tissue and from leaf litter under trees affected with greasy spot (Wellings & Emmett, 1978). Colletotrichum gloeosporioides (Penz.) Sacco is the species most frequently isolated from diseased leaves . However, this fungus is probably of little significance in greasy spot as it occurs commonly as a latent infection on citrus in all districts of New South Wales (Wellings & Emmett, 1978) and was cons idered a contaminant in greasy spot studies in Florida (F isher, 1961). Septaria citri Pass. and an unidentified Mycosphaerella sp. were isolated at a low frequency, but were consistently associated Tr ans. Br. my col. Soc. 76 (3), (1981).
007-1536/81 /2828-7520 $00.35
~I
with the disease in the field (Wellings & Emmett, 1978). This article reports pathogenicity tests with these isolates, and compares the histology of field and artificially induced lesions. Cultures of Septaria citri (DAR 29826(b), DAR 30594, DAR 30723, DAR 31981) isolated from greasy spot lesions (Wellings & Emmett, 1978) were maintained by transferring single germinated conidia to potato dextrose agar containing 1 % dextrose and 0-1 % 'vegemite' yeast extract (PVDA). Cultures were incubated for 10-15 days on the laboratory bench at approximately 25 °C. Conidial suspensions were prepared by centrifuging and resuspending conidia in three changes of sterile distilled water. The final suspension was adjusted to a concentration of 2 x 10 7 conidia per ml using a haemocytometer. Isolates of M ycosphaerella sp . (DAR 30870, DAR 3°875, DAR 30877, DAR 30878 and unaccessioned isolate M 96) were grown from single germinated ascospores obtained from ascocarps on leaf litter collected under infected trees. An additional isolate (M 8) from fresh greasy spot lesions was also used. After 10-15 days growth on PVDA in Petri dishes, surface mycelium was aseptically
Printed in Great Britain
1981 The British Mycological Society
493
RE-EVALUATION OF GEASTER FLORISSANTENSIS (OLIGOCENE, NORTH AMERICA) BRUCE H. TIFFNEY
Department of Biology and Peabody Museum, Yale University, 260 Whitney Avenue, Box 6666, New Haven, Connecticut 06511, USA
While the fossil record of the fungi is relatively sparse, it is of some value in providing a check to phylogenetic schemes derived from the study of modern taxa. The contribution of this record to our understanding of the gasteromycetes would be of particular significance as the phylogeny of this group is a subject of debate, including a consideration of their probable polyphyletic constitution (Savile, 1955; Singer & Smith, 1960; Ingold, 1971). The gasteromycetes are presently represented in the fossil record by five species. Of these Geaster fiorissantensis Cockerell is of the greatest potential significance by virtue of its age and apparent preservational detail. This significance is best introduced by a review of the other reported fossils. The oldest fossil gasteromycete is Gasteromyces farinosus Ludwig reported by Ludwig (1861) from an Upper Carboniferous coal of the Urals. The , sporocarps' are described as being both spherical and tubular, while the' spores' are quite variable in shape and structure. Both the account and the accompanying illustrations are thoroughly unconvincing, and this may perhaps best be judged as an erroneous citation. The next oldest evidence is provided by spores identified as Scleroderma echinosporites Rouse from the Late Cretaceous (Late Campanian) Burrard Formation of southwestern British Columbia (Rouse, 1962). The 11-15 /lm diam, circular spores are finely spinose and lack a pore. While there is no strong evidence to disbelieve this report, it would perhaps be more satisfying if the identification were based on an examination with the Scanning Electron Microscope, or better yet, if the whole fruiting structure was known. Berry (1929) reported an unnamed sporocarp from Late Eocene sediments in Peru. He did not provide an identification beyond 'this single specimen ... undoubtedly represents a fungus, probably of the puff ball tribe', and the accompanying illustration bears out the vagueness of the description. While this report cannot be completely dismissed without an examination of the actual specimen (whereabouts unknown), the published evidence is unconvincing. Chaney & Mason (1936) described a specimen of Bovista Tram. Br. mycol. Soc. 76 (3), (1981).
plumbea Pers. from a Pleistocene deposit near Fairbanks, Alaska. While the identification was based on both macro- and microscopic characters and is undoubtedly correct, the relatively recent origin restricts its phylogenetic significance. This summary leaves Geaster fiorissantensis as potentially the most interesting fossil member of the group. The specimen was described by Cockerell (1908) from the Oligocene Florissant Formation of central Colorado, long famed for its exquisite preservation of plant and insect material in water- and wind-deposited volcanic ash. Cockerell (1908) provided an indistinct picture of the specimen together with a very brief description, concluding that 'the appearance is exactly that of a modern Geaster in the expanded condition'. This judgement was accepted with reservation by Pia (1927) in his survey of fossil fungi, although he altered the generic name to Geasterites. However, MacGinitie (1953) dismissed the identification in his revision of the Florissant flora. He placed G. fiorissantensis in the category 'species rejected from the flora' with the general statement that 'unless otherwise stated, the specimen is too poor for identification; an indefinable object'. The present author, in a broad summary of the fossil record of the fungi (Tiffney & Barghoorn, 1974), accepted Cockerell's identification on the basis of the illustration provided, but witha degree of scepticism (unpub1.). In his description, Cockerell (1908) failed to cite the place of deposition of the type specimen, but a search revealed that it is no. 18550 in the Paleobotanical Collections of the Museum of the University of Colorado, Boulder, USA. The type consists of a part and counterpart impression. Although the position of the fossil on the slab is indicated by a dark stain as well as by limited relief on the substratum, no organic matter is retained on the counterpart and very little on the part (Fig. 1). Cockerell illustrated the part specimen as he found it, noting that it possessed perhaps eight segments of which five were visible. Preparation of this specimen revealed that eight rays are present, two of which are overlapped. These rays average 27 mm (range 23-30 mm) in
Printed in Great Britain
0007-1536/81/2828-7520 $00.35 © 1981 The British Mycological Society
Notes and briefarticles
494
Fig. 1. Geasterflorissantensis, part specimen; note two rays arc superimposed (x 1). Fig. 2. Detail of inner portion; note the central protrusion and the obscuring fold ( x 2'2 ).
length and are 8'S mm (7-11 nun) in width at their widest, basal, point. The whole structure is S4 mm diam, and the central body (intern al to the mutual juncture of the rays) is about 20 nun diam, In the immediate centre is a small conical protrusion (Fig. 2) which is 5 mm diam. The lack of relief in the fossil suggests that the original structure was neither particularly thick or fleshy, nor very rigid. The rays show no sign of superficial fissuring or cracking, although these features might be expected of the inner surface of the exoperidium of a Geaster. Indeed, the rays give evidence of being quite thin, and in two cases take on the contour of the matrix which they overlie. The flexibility of the original structure is also attested to by the fact that it has been folded upon itself to a slight degree, such that the bases of the rays of one side of the 'disk ' obscure one half of the central protrusion (Fig. 2). On one ray there is faint evidence for lineation (? venation) parallel to the long axis, but this is not a pronounced feature. No sign is present of an endoperidium or similar structure. Since the spores of most gasterornycetes possess a fairly distinctive morphology (Coker & Couch, 1928; Eckblad, 1971), a palynologic analysis of the matrix immediately adjacent to the specimen was made . The preparation was poor in palynomorphs and lacked any evidence of spores immediately referable to the gasteromycetes,
Trans. Br, mycol, Soc. 76 (3), (1981).
The foregoing evidence suggests that th e fossil does not represent a specimen of a gasteromycete. The rays appear to be thin and papery, rather than thick or leathery as one would expect of an exoperidium. No evidence is present for an endoperidium. There is no sign of spores in the associated matrix, an unusual feature if this was indeed a gasterornycete sporocarp. While it could be argued that the specimen had been blown into the site of deposition from a distant source, losing its spores and endoperidium in the proce ss, there is no indication of any curling of the rays as would be expected if the exoperidium were in a dried state amenable to wind transport. While Cockerell (1908) was correct in observ ing that 'the irregularity of the segments is unlike that of any calyx ', this is not sufficient reason for assuming the fossil to be an earth star. Although on close examination the specimen is fairly poor in many respects and lacks sufficient detail to permit its placement in any other taxon familiar to the author, it possesses enough detail to make it clear that it is not a gasteromycete. I am grateful to Dr J. Van Couvering, Curator of the Paleobotanical Collections of the Museum at the University of Colorado, Boulder for the loan of the specimen of Geaster florissantensis, permission to prepare it, and permission to publi sh the photographs used in this paper.
Printed in Great Britain
0007-1536/81/2828-7520 $00.35 © 1981 The British Mycological Society
Notes and brief articles REFERENCES
BERRY, E. W. (1929). Early Tertiary fruits and seeds from Belen, Peru. The Johns Hopkins University Studies in Geology 10, 137-179. CHANEY, R. W. & MASON, H. L. (1936). A Pleistocene flora from Fairbanks, Alaska. American Museum Nouitates 887, 1-17. COCKERELL, T. D. A. (1908). Descriptions of Tertiary plants. II. American Journal of Science, Fourth Series 26, 537-544. COKER, W. C. & COUCH, J. N. (1928). The Gasteromycetes of the Eastern United States and Canada. Chapel Hill: The University of North Carolina Press. ECKBLAD, F. E. (1971). Spores of gasteromycetes studied in the scanning electron microscope (SEM). I. NorwegianJournal of Botany 18, 145-151. INGOLD, C. T. (1971). Fungal Sp ores. Their Liberation and Dispersal. Oxford: Clarendon Press.
495
LUDWIG, R. (1861). Zur Palaeontologie des Urals. Palaeontographica 10, 17-36. MACGlNITIE, H. D. (1953). Fossil plants of the Florissant beds, Colorado. Contributions to Paleontology; Carnegie Institute of Washington Publication 599, 1-198. PIA, J. (1927). Klasse Fungi. In Handbu ch der Paldobotanik (by M. Hirmer), pp. 112-130. Munich and Berlin: R. Oldenbourg.
ROUSE, G. E. (1962). Plant microfossils from the Burrard Formation of western British Columbia. M icropaleontology 8, 187-218. SAVILE, D. B. O. (1955). A phylogeny of the basidiomycetes. Canadian Journal of Botany 33, 60-104. SINGER, R. & SMITH, A. H. (1960). Studies on secotiaceous fungi in the asterogastraceous series. Memo irs of the Torrey Botanical Club :U, 1-112. TIFFNEY, B. H. & BARGHOORN, E. S. (1974). The fossil record of the fungi. Occasional Papers of the Farlow Herbarium of Cryptogamic Botany 7, 1-4 2 •
PATHOGENICITY OF FUNGI ASSOCIATED WITH CITRUS GREASY SPOT IN NEW SOUTH WALES C. R. WELLINGS
N .S.W. D epartment of Agriculture, Agricultural Research Centre, Tamworth, Australia 2340
Greasy spot of citrus in New South Wales is a leaf disease which has been known for many years, although its incidence has increased since 1972. Detailed descriptions of symptoms, host range and distribution in New South Wales have been published (Wellings & Emmett, 1978). Comparison with descriptions of the diseases called greasy spot in Japan (Tanaka & Yamada, 1952) and the USA (Whiteside, 1977) leads to the conclusion that citrus greasy spot in New South Wales is distinct from that found elsewhere (Wellings & Emmett, 1978). Several fungi may be isolated from diseased leaf tissue and from leaf litter under trees affected with greasy spot (Wellings & Emmett, 1978). Colletotrichum gloeosporioides (Penz.) Sacco is the species most frequently isolated from diseased leaves . However, this fungus is probably of little significance in greasy spot as it occurs commonly as a latent infection on citrus in all districts of New South Wales (Wellings & Emmett, 1978) and was cons idered a contaminant in greasy spot studies in Florida (F isher, 1961). Septaria citri Pass. and an unidentified Mycosphaerella sp. were isolated at a low frequency, but were consistently associated Tr ans. Br. my col. Soc. 76 (3), (1981).
007-1536/81 /2828-7520 $00.35
~I
with the disease in the field (Wellings & Emmett, 1978). This article reports pathogenicity tests with these isolates, and compares the histology of field and artificially induced lesions. Cultures of Septaria citri (DAR 29826(b), DAR 30594, DAR 30723, DAR 31981) isolated from greasy spot lesions (Wellings & Emmett, 1978) were maintained by transferring single germinated conidia to potato dextrose agar containing 1 % dextrose and 0-1 % 'vegemite' yeast extract (PVDA). Cultures were incubated for 10-15 days on the laboratory bench at approximately 25 °C. Conidial suspensions were prepared by centrifuging and resuspending conidia in three changes of sterile distilled water. The final suspension was adjusted to a concentration of 2 x 10 7 conidia per ml using a haemocytometer. Isolates of M ycosphaerella sp . (DAR 30870, DAR 3°875, DAR 30877, DAR 30878 and unaccessioned isolate M 96) were grown from single germinated ascospores obtained from ascocarps on leaf litter collected under infected trees. An additional isolate (M 8) from fresh greasy spot lesions was also used. After 10-15 days growth on PVDA in Petri dishes, surface mycelium was aseptically
Printed in Great Britain
1981 The British Mycological Society