Phaeodothis tricuspidis Syd. & P. Syd., Annls mycol. 2(2): 166 (1904).

Index Fungorum number: IF 185110; MycoBank number: MB 185110; Facesoffungi number: FoF 00060

Saprobic on dead wood or grasses. Sexual state: Ascostromata 235–290 × 120−180 µm (= 254 × 137 µm, n = 10), immersed to nearly superficial under clypeus, scattered to gregarious, subglobose to hemispherical, dark brown to black, papillate, smooth. Papilla black, with a pore-like ostioles, ostiolar canal filled with periphyses. Peridium 15−28 µm (= 22 µm, n = 20) wide, comprising several layers of hyaline compressed cells. Hamathecium of dense, 2−4 µm (= 2.5 µm, n=20), aseptate, narrow, cellular pseudoparaphyses often in a gelatinous matrix. Asci 55−80 × 7−12 µm (= 68 × 10 µm, n = 20), 8-spored, bitunicate, fissitunicate, cylindrical, short pedicellate with a minute ocular chamber. Ascospores 14.5−17.5 × 4−5 µm (= 15.8 × 4.4 µm, n = 30), biseriate and partially overlapping, fusiform with rounded ends, olivaceous brown, 1-septate, slightly constricted at the septum. Asexual state: unknown.

Material examined − ARGENTINA, San José, Salta, 12 February 1873, P.G. Lorentz (S F125876, holotype).

Notes − Phaeodothis is characterized by its immersed to nearly superficial ascostromata, a sparse hamathecium consisting of thin pseudoparaphyses and 1-septate ascospores (Aptroot 1995). The genus was placed in Didymosphaeria by Niessl (1875), but Aptroot (1995) transferred the genus to Phaeosphaeriaceae. Phaeodothis has similarities with Montagnulaceae in having ascomata immersed under a clypeus, a pseudoparenchymatous peridium with small cells, cylindrical asci and brown ascospores. Phaeodothis however, differs from the other genera of Montagnulaceae in having a hamathecium consisting of thin, sparse pseudoparaphyses and 1-septate ascospores. Recent phylogenetic analysis based on LSU, SSU, RBP1, RBP2 and EF-1 concluded that a strain named Phaeodothis winteri (a synonym of P. tricuspidis Syd. & P. Syd.) clustered within the clade of Montagnulaceae(Schoch et al. 2009). Currently 27 epithets are listed for the genus in Index Fungorum (2014), while GenBank has seven hits for the genus including the putative strain of Phaeodothis winteri (CBS 182.58). Based on the above morphological characters and available molecular data, we suggest that Phaeodothis can be referred to Montagnulaceae.

Fig. 1  Phaeodothis tricuspidis (holotype). a Herbarium packet and specimen. b Close up of ascomata. c, d Sections through ascoma. e Peridium comprises hyaline compressed cells. f−h Mature and immature asci surrounded by pseudoparaphyses. i−l Fusiform, olivaceous-brown ascospores. Scale bars: c−d= 100 µm, e = 50 µm, f−h= 25 µm, i−l= 5 µm.