Myelospermataceae K.D. Hyde & S.W. Wong, Mycol. Res. 44(1): 349 (1999)
MycoBank number: MB 82090; Index Fungorum number: IF 82090; Facesoffungi number: FoF 06193; 5 species.
Pathogenic or saprobic on various plants. Sexual morph: Pseudostromata weakly raised, visible as blackened ostiolar dots, immersed, multiloculate, clustered around a common central pore. Ascomata in vertical section subglobose or ellipsoidal, brown, necks mostly eccentric leading to the common central pore. Peridium comprising mostly brown-walled, elongate cells, inwardly hyaline and becoming textura intricata and fusing with the host tissue at the outside. Paraphyses numerous, hypha-like, filamentous, septate, unbranched, tapering distally. Asci 8- spored, unitunicate, cylindrical, long-pedicellate, apically rounded, with a J-, refractive, subapical, discoid ring. Ascospores overlapping uniseriate, hyaline, irregularly ellipsoidal, curved or straight, some narrower at the center, some lunate, unicellular, and surrounded by a distinct mucilaginous sheath. Asexual morph: Undetermined (adapted from Maharachchikumbura et al. 2016b).
Type genus – Myelosperma Syd.
Notes – Myelospermataceae was introduced by Hyde & Wong (1999) to accommodate Myelosperma. The family has been poorly studied. Four species were reported as saprobic and one species as parasitic (M. parasitica). Most of the species occur on palms (Arecaceae), except M. gigasporum, which was found on unidentified wood. Hyde & Wong (1999) accommodated Myelospermataceae in Diaporthales based on lack of stroma (only pseudostroma present), the valsoid nature of the ascomata, deliquescing paraphyses, and ascus morphology. Subsequently, Kirk et al. (2001) placed the genus in Xylariales, which seemed controversial due to lack of reference taxa and molecular analysis (Eriksson 1999, Kang et al. 2002). Maharachchikumbura et al. (2016b) and Wijayawardene et al. (2017a, 2018a) followed the taxonomy of Kirk et al. (2001) and accepted the family in Xylariales. However, it is still unclear if the family belongs in Xylariales. Due to lack of molecular data, the different morphology from other xylariaceous genera with morphological affinities to Diaporthales, herein we place Myelospermataceae in Xylariomycetidae families, incertae sedis, until further studies can better resolve the placement.