Pyrenomycetes Species Page

Xenolophium applanatum

Large separate ascomata
(Petch) Huhndorf, Mycologia 85(3): 493 (1993)
Schizostoma applanata Petch
Pleosporomycetidae, Incertae sedis
Figure from SMH2200, SMH3696
Complete Description
Ascomata globose, large, 750-1200 _m diameter, 800-1100 _m high, scattered to clustered, numerous, erumpent superficial, with bases immersed in the substrate, papillate, stroma absent; surface glabrous or roughened, ridged to slightly warted. Wall of textura angularis-prismatica in surface view; in longitudinal section 150-175 _m thick, two-layered, composed of polygonal to elongate, pseudoparenchymatic cells (up to 35 x 12-15 _m) or 12-15 _m diameter), with an external brown-melanized crust, outer 5-10 cell layers brown-melanized, irregularly pigmented, inner wall layer uniformly pigmented, composed of hyaline to slightly melanized, parallel to irregularly oriented cells. Papilla low, longitudinally compressed, elongate as strongly developed ridges along each side of the apex which can extend down the sides of the ascoma, almost hysteriform, (600)900-1200 _m long, 350-550 _m wide, 200-350 _m high; wall composed of numerous layers of small, dark-brown, heavily-melanized cells; ostiole elongate, slit-like, 30-60 _m wide, with periphyses. Pseudoparaphyses 1.0-1.5 _m wide, numerous, trabeculate, with gelatinous coating. Asci elongate clavate, (125)135-150(165) x 10-12 _m, long-stalked (stalk 65-90 _m long), numerous, basal and lateral, completely lining the peripheral wall of the centrum, thin-walled, bitunicate, dehiscence unknown; apex rounded, apical chamber present, without ring; with eight ascospores, biseriate above-uniseriate below (in one collection, Samuels 6187, many of the asci are 4-spored). Ascospores fusiod, nearly biconoid, (18.5)20-27(28.5) x 4.5-6 _m, straight to slightly curved, light to dark brown, paler pigmented end cells, darker pigment at primary septum, smooth or striate, without sheath, without appendages, one to three-septate, slightly constricted at mid-septum, primary septum median, secondary septa subterminal-bipolar, central cells slightly longer than end cells, order of septation 2:1:2.