Occultibambusaceae D.Q. Dai & K.D. Hyde, fam. nov. Index Fungorum number: IF552012

Saprobic on dead bamboo culms or teak branches, forming dark, ascostromata on raised areas, with ostiolate oppening. Sexual morph: Ascostromata solitary, scattered or gregarious, subglobose, uni- or multi-loculate, greyish to dark brown, coriaceous, with a central, papillate, rounded ostiole, internally lined with periphyses. Peridium comprising host and fungal tissues or, only fungal tissue brown and thick-walled to hyaline and thin-walled cells of textura angularis. Hamathecium composed of long, septate, cellular pseudoparaphyses, above the asci. Asci 8-spored, bitunicate, broadly cylindrical to clavate, with a short furcate pedicel, with a shallow ocular chamber. Ascospores 2–3-seriate, slightly broad-fusiform, 1–3-septate, hyaline, pale brown to dark brown, surrounded by a gelatinous sheath, with guttulate cells. Asexual morph: Coelomycetous, produced on bamboo pieces on WA. Conidiomata eustromatic, immersed to partly immersed, solitary to gregarious, globose to subglobose, conical in section, dark ostiolate, with a short neck. Conidiomata wall with several layers, composed of dark to hyaline cells of textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells enteroblastic, phialidic, determinate, discrete, ampulliform to cylindrical, smooth-walled. Conidia obovoid, cylindrical to oblong, 0–3-septate, hyaline to palebrown, rounded at the apex, smooth-walled, guttulate.

Notes: Occultibambusaceae is introduced herein to accommodate two new genera Occultibambusa and Seriascoma, a coelomycetous genus Versicolorisporium (Hatakeyama et al. 2008) and Neooccultibambusa introduced in Doilom et al. (2016). Species of the family Occultibambusaceae usually occur on monocotyledons, such as bamboo, but have also been found on hardwood trees such as teak (Tectona grandis L.f., Lamiaceae). This family is characterized by immersed, solitary to gregarious ascomata with black ostioles, broadly cylindrical to clavate, bitunicate asci, cellular pseudoparaphyses and broad-fusiform, hyaline to dark brown ascospores with 1–3 septa. The asexual morphs are morphologically diverse. For example, the conidia in the genus Occultibambusa are oblong and pale brown, whereas Seriascoma has cylindrical and hyaline conidia. Obovoid conidia with a darker middle cell are observed in Versicolorisporium (Hatakeyama et al. 2008). However, they are all formed in eustromatic conidomata and have phialidic conidiogenous cells with enteroblastic conidiogenesis. Members of Occultibambusaceae are similar to species of Bambusicola, Lophiostoma, and Massarina in having fusiform ascospores and clavate asci (Zhang et al. 2009; Dai et al. 2012, 2015). However, Bambusicola has hyaline ascospores and asexual morphs with usually annellidic conidiogenous cells (Dai et al. 2012). Ascospores of the species of Occultibambusaceae are mostly brown, no annellidic conidiogenous cells observed. Lophiostoma has ascomata containing a compressed/crest-like ostiole (Zhang et al.2009; Thambugala et al. 2015), while those in Occultibambusaceae are papillate. Lophiostoma and Massarina differ by cylindrical or oblong asci (Zhang et al. 2009; Thambugala et al. 2015). The family Occultibambusaceae is phylogenetically close to the family Biatriosporaceae (Fig. 13). However, the species of Biatriosporaceae are manglicolous and the dark brown ascospores usually have hyaline, rounded, swollen ends which release mucilage (Hyde et al. 2013). Members of Occultibambusaceae are separated from Biatriosporaceaeby high bootstrap support (100 % MLBP, BYPP greater than 0.90).

Type: Occultibambusa D.Q. Dai & K.D. Hyde