Pyrenomycetes Species Page

Chaetosphaerella phaeostroma

Large clustered ascomata
(Durieu & Mont.) E. Müll. & C. Booth, Trans. Br. mycol. Soc. 58(1): 77 (1972)
Sphaeria phaeostroma Durieu & Mont.
Figure from EN2869 (Costa Rica); SMH4585 (England) Material Examined: SMH2180, SMH4257, SMH4585
Genbank Accession: AY346274 (LSU), AY780112 (Btub), AY780172 (RPB2), FJ969003 (tef1)
Complete Description
Ascomata obovoid to vertically elongate, with a thick sterile base, not collapsing when dry, dark brown to black, 250-350 µm diam., 400-500 µm high, superficial, with a roughened, tuberculate surface, occurring in large clusters on abundant, subicular hyphae. Subiculum extensive, forming large and dense, glistening patches, hyphae brown to black, wide, septate, dichotomously branched, distinctly spinulose with long, tapering, non-septate, pointed setae. Ascomatal wall of textura globosa in surface view; in longitudinal section a single layer, composed of pale brown, pseudoparenchymatic cells, with smaller, darker cells at the outer surface, almost crust-like, cells at base radiate from the bottom; Munk pores present, few per cell. Ascomatal apex rounded, external ostiole indistinct but visible in longitudinal section, periphyses absent. Centrum with paraphyses hyaline, inflated, unbranched. Asci cylindrical, short-stipitate, 110-120 x 15-17 µm, with an indistinct apical ring, with 8 biseriate ascospores. Ascospores fusiform, 3- septate, septa unevenly distributed with end cells much shorter than central cells, central cells brown, end cells hyaline, 32-35 x 6-9 µm.
Found on decaying wood. Our collections are from Costa Rica and we have compared these to one collection from the UK. Most collections are reported from temperate locations.
Similar Taxa Comments
Chaetosphaerella phaeostroma is recognized by its glistening, black colonies with abundant subiculum that have clustered ascomata that are roughened but not setose. The setae are only on the subiculum, one of the characteristics that distinguish this from Crassochaeta nigrita. Both species have versicolorous ascospores. In C. phaeostroma the ascomata do not collapse, which distinguishes it from Chaetosphaerella fusca where the ascomata become collabent. The tropical and temperate collections of C. phaeostroma are morphologically alike.
Réblová, M. (1999a) Studies in Chaetosphaeria sensu lato I. The genera Chaetosphaerella and Tengiomyces gen. nov. of the Helminthosphaeriaceae. Mycotaxon 70: 387-420.