Hysteriales » Hysteriaceae

Ostreichnion

Ostreichnion Duby, Mém. Soc. Phys. Hist. nat. Genève 16(1): 33 (1862).

Index Fungorum number: IF 3645; Facesoffungi number: FoF 00163, 3 morphological species (Species Fungorum 2022), 3 species with molecular data.

Saprobic on wood. Sexual morph: Ascomata hysterothecial, semi-immersed to superficial, bases attached to substrate, conchate to nearly dolabrate, black, fragile fruit bodies, not shining, rough with horizontal striation, occasionally triradiate, apex compressed along length, opening by long slit, subiculum, solitary to aggregated. Exciple composed of cells of textura intricata, charcoal-like, carbonaceous, dark brown to reddish brown. Hamathecium comprising numerous, filiform, hypha-like, septate, branched and anastomosing pseudoparaphyses, in a gelatinous matrix. Asci 8-spored, clavate to cylindrical, bitunicate, with thickened and rounded apex, short to mostly long-pedicellate, with an ocular chamber, arising from the ascoma base. Ascospores uniseriate, yellowish or pale brown to dark brown, broadly cylindrical to fusiform, occasionally ellipsoidal, tapering to rounded ends, obvious septum at median, thickened and dark, slightly constricted at septum, secondary septa cutting off end cells, tertiary septa intermediate and often one or two in end cells, transverse septa, longitudinal septa, with apical plug, wall surface somewhat roughened and irregular. Asexual morph: Unknown (adapted from Doilom et al. 2018).

 Type species: Ostreichnion americanum Duby

Notes: Ostreichnion is characterised by hysterothecial, semi-immersed to superficial ascomata, clavate to cylindrical asci and yellowish or pale brown to dark brown ascospores. Ostreichnion was revised by numerous authors such as Saccardo (1883), Rehm (1886), Clements and Shear (1931), Zogg (1962). Lohman (1934) provided sequence data for O. curtisii (CBS 198.34) and O. sassafras (CBS 322.34). Barr (1975) relegated the earlier name Ostreichnion sassafras to O. americanum. Boehm et al. (2009) transferred Ostreichnion from Mytilinidiaceae to Hysteriaceae based on phylogenetic analysis. Barr (1975) and Boehm et al. (2009) accepted O. curtisii and provided a key to the species. In the phylogenetic analysis based on SSU, LSU, TEF1 and RPB2 of Boehm et al. (2009a, b) O. curtisii was distantly related to O. sassafras in a subclade with Hysterium. O. curtisii differs from O. sassafras and O. nova-caesariense in having ascospores with 1 septum whereas the latter two species have dictyospores (Barr 1975, Doilom et al. 2018). Doilom et al. (2018) suggested that Ostreichnion curtisii might belong to Hysterium that was initially called as Hysterium curtisii by Duby (1862). Jayasiri et al. (2018) suggested Hysterium curtisii as the current name for Ostreichnion curtisii. Ostreichnion is currently a distinct genus in Hysteriaceae but fresh collections and sequence data from more taxa are needed to confirm the natural placement of Ostreichnion. Molecular markers available for Ostreichnion are ITS, LSU, SSU, RPB2 and TEF-1.

 

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