Pyrenomycetes Species Page

Acanthostigma filiforme

Small separate ascomata
Promputtha & A.N. Mill.

Figure from ANM101 (ILLS 59352, HOLOTYPE) Type Specimen: ILLS 59352 (ANM101); Paratype = ILLS 59353 (ANM514)
Genbank Accession: GQ850495 (LSU)
Complete Description
Ascomata superficial, scattered or gregarious, globose to subglobose, 150–300 µm diam, 150–300 µm high, shiny black when dry, densely setose, non-collapsing. Setae 1-celled or rarely 1-septate, thick-walled, brown to dark brown, straight to slightly curved, with acute tip, (45–)70–130 µm long, 5–7 µm wide in the middle. Ascomatal wall two-layered in longitudinal section, inner layer composed of 3–5 rows of light brown, thin-walled, flattened to angular cells; outer layer composed of 1–2 rows of dark brown, angular to elongated cells which sometimes produce setae. Pseudoparaphyses numerous among asci, branched, anastomosing, hyaline, septate, up to 2 µm wide. Asci bitunicate, cylindrical to cylindrical-clavate, broadly rounded and thickened at the apex, short-stipitate, 8-spored, 100–115 × 11.5–13 µm [109 × 12.5 ?m, n = 10]. Ascospores long fusiform-filiform to cylindrical-filiform, straight or curved or sometimes sigmoidal, tapering and narrowly rounded at both ends, ends symmetrical, 12–16 septate, not constricted at the septa, hyaline, (75–)85–135(–150) × 2.5–4 µm [105 × 3.5 ?m, n = 190].
This species is commonly found throughout the Great Smoky Mountains National Park where it occurs scattered to gregarious on decorticated wood in mixed coniferous-deciduous forests.
Similar Taxa Comments
Acanthostigma filiforme is unique in that it possesses the longest ascospores in the genus. It is most similar to A. scopulum (Cook & Peck) Peck, but differs in having wider setae and longer ascospores with more septa.
Promputtha & Miller 2009, Mycologia 102(3): 574–587.