Dothiora pyrenophora (Fr.) Fr., Summa veg. Scand., Section Post. (Stockholm): 418 (1849).

Saprobic on branches of Sorbus sp. Sexual state: Ascostromata (639−)650−756.5 µm diam, black, immersed to erumpent, breaking through the host surface through angular splits, multiloculate, cells of ascostromata composed dark brown to black cells of textura angularis. Locules 140−172 µm high × 152−180 µm diam., subglobose or obpyriform, arranged at periphery of stroma in a single layer, widest at the base, short papillate, with small ostiole pores. Peridium of locules 78−88 µm thick, composed cell layers of textura prismatica and textura angularis, thick-walled and black at the outer wall. Hamathecium lacking pseudoparaphyses. Asci (85−)93−108(−112) × (13−)16−20(−23) µm ( = 99 × 18 µm, n = 15), 8-spored, bitunicate, fissitunicate, oblong to subclavate, saccate, short-pedicellate, with a distinct ocular chamber, ca. 2(−3) µm wide. Ascospores (28−)29−36(−40) × 8−10(−11) µm ( = 32 × 10 µm, n = 10), 2−3-seritate overlapping in the ascus, sometime irregularly arranged, hyaline or pale grayish, muriform, 7−transverse septate, with 1−longitudinal septum in upper part, deeply constricted at middle septum, cylindrical to fusiform, pointed at both ends, smooth. Asexual states: Unknown.

Material examined: SWITZERLAND, Graubuenden, Davos, Dischmatal, on Sorbus aucuparia L. (Rosaceae), May 26 1964, E. Müller (BPI 674269).

Notes: Conidiomata with numerous, cylindrical, hyaline conidia were found at the base of the ascostromata (Fig. 6). It is not clear if these are the asexual state, another associated taxon or a fungicolous taxon. We could not loan the type so illustrate a specimen from BPI.

Fig. 1 Dothiora pyrenophora (BPI 674269). a Material label. b Ascostromata on host surface. c Cross section through ascostroma and peridium. d Peridial wall. e, f Immature and mature asci. g-i Muriform ascospores. j Conidia associated with base of ascostromata. Scale bars: b, c = 200 µm, d, g-j = 20 µm, e, f = 50 µm.