Coprophilous isolates of Nectria coccinea

Trans. Brit. mycol. Soc. 48 (I), 35-37 (1965) Printed in Great Britain

COPROPHILOUS ISOLATES OF NECTRIA COCCINEA By D. G. A. WALKEY* AND R. HARVEY Department of Botany, University College, Cardiff (With Plate

2

and

1

Text-figure)

Isolates of Nectria coccinea (Pers. ex Fr.) Fr. have been obtained from horse and rabbit dung. On dung and in culture these isolates are astromatic. Mature perithecia appear in culture within 21 days, together with Cylindrocarpon conidia.

During the course of a survey of pyrenomycetes in the South Wales area, isolates of N. coccinea were obtained from both horse and rabbit dung. The isolates appeared to be sufficiently distinctive to be worthy of consideration as a new species until Dr C. Booth, Commonwealth Mycological Institute, Kew, as a result of cross-mating experiments, established their identity. However, in view of the very unusual sources of isolation for N. coccinea and of certain distinctive features in culture the following description of the isolates has been prepared. On the several agar media used (including corn meal, potato dextrose and malt extract) the isolates grew well, producing both conidia and mature perithecia within 2 I days at 18-240 C. In culture the isolates are astromatic. Perithecia are solitary or gregarious, 225-285# diam. x 295-345# tall. Perithecial primordia are spherical (PI. 2, fig. I) and more or less hyaline; they become ovoid and orange-red. Mature perithecia are smooth externally except for short, protruding papillate cells in the neck region (Text-fig. I b). The neck is short, wide, and surmounted by a conical apex measuring 135-165# diam. at the base. In lateral view the neck appears as a flat-topped collar round the central conical ostiole (PI. 2, fig. 3). In section the lateral perithecial walls are 19'5-26 # thick and consist of two fairly distinct layers: an outer, r-z-cells thick (6-5-13#), of large, irregularly oblong-globose cells, measuring 10-2 I x 6·5-9 #, and an inner, 3-4 cells thick (13-16 #), consisting of smaller, narrow, elongate cells, 6'5-13 x 1-3# (Text-fig. 1 b). On drying, the lateral walls of the perithecium collapse, giving it a 'pinched' appearance. The collar and apical disk are not involved in this collapse and remain complete, the invagination being restricted to the basal regions of the perithecium. The asci are cylindrical, short-stalked, 75-85 x 8-10#. The flattened apex contains a distinctive apparatus, including an apical ring which stains blue in iodine (Text-fig. l'a). The eight ascospores are initially monostichous but become distichous later. They are 12-15 x 5-7 #

*

Now at the National Vegetable Research Station, Wellesbourne, Warwick. 3- 2

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Transactions British Mycological Society

(13 x 6·5# usually), hyaline, ellipsoidal, slightly constricted at the central septum, and become verrucose at maturity (Text-fig. I c). The conidiophores are short, 12-20 x 3-4Jt, and arise laterally from the vegetative mycelium. They branch several times, the short branches bearing phialides (12-23 x 4Jt) at the tips. The phialides are hyaline 12-23Jt long x 4Jt wide, narrowing apically to a thickened collar (Text

10 fI [

10 fI

J

Text-fig. I. N. coccinea. a, Ascus; b, submedian, vertical section through ostiolar disk and collar; c, ascospores; d, conidiophores and phialides; e, Cylindrocarpon conidia.

Trans. Brit. myco!. Soc.

Vol. 48, Plate

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(Facing p. 37)

Nectria coccinea. D. G. A. Walkey and R. Harvey

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fig. I d). Occasionally phialides are found borne directly upon the mycelium. The Cylindrocarpon conidia accumulate in clusters, the elongate spores lying parallel to one another following abstriction. They are hyaline, allantoid, narrowing slightly towards the rounded ends, 3-5-septate, 65-78 x 6·5-8,u. DISCUSSION

The absence of a stroma under a variety of cultural conditions and the general character of the perithecium (other than size) indicated an affinity with the Episphaeria group of species, as described by Booth (1959). Apart from the astromatic habit, the isolates also showed close agreement with previous descriptions of Nectria coccinea. The identity of the isolates was finally established when Dr Booth (personal communication) demonstrated their heterothallic nature by crossing single ascospore isolates with similar isolates of typical N. coccinea and obtaining perithecia. The present isolates are of particular interest in that, apparently for the first time, the coprophilous habit is established for N. coccinea, and the behaviour of isolated perithecia in culture shows that collapse of the lateral wall is not confined to the Episphaeria group of species. In addition, comparison with previous accounts would seem to indicate that the ease with which mature perithecia are formed in culture by these isolates is somewhat unusual among members of the Coccinea series (Lortie, 1964). These features serve to emphasize the variable nature of N. coccinea. Cultures have been deposited at the Commonwealth Mycological Institute, Kew. We are indebted to Dr Booth for establishing the identity of the isolates and for permission to refer to the results of his mating experiments. The survey was carried out during the tenure by D. G. A. Walkey ofa Research Studentship from the Department of Scientific and Industrial Research. REFERENCES 2

BOOTH, C. (1959). Studies of Pyrenomycetes: IV. Nectria (Part I). Mycol. Pap. 73, 1-115· LORTIE, M. (1964). Production of perithecia of Nectria galligena Bres. in pure culture. Can. ]. Bot. 42, 123-124.

EXPLANATION OF PLATE 2

Nectria coccinea Fig. I. Perithecial primordium. Fig. 2. Whole mount of perithecium. Fig. 3. Perithecial collar surrounding conical ostiolar disk.

(Accepted for publication 30 May 1964)