Ophiobolus Riess, Hedwigia 1(6): 27 (1854).
Saprobic or hemibiotrophic on various hosts. Sexual morph: Ascomata solitary to gregarious, scattered, semi-immersed to erumpent though host tissue with short to long beak, uniloculate, subglobose or ovoid or ampulliform, glabrous or covered by hyphae, dark brown to black, ostiolate, papillate. Peridium thick-walled, composed of dark brown to black, scleroplectenchymatous cells, arrange in textura angularis to textura globulosa. Hamathecium composed of numerous, filiform, cellular pseudoparaphyses, with distinct septa, anastomosing at the apex. Asci 8-spored, bitunicate, cylindrical to cylindric-clavate, short pedicellate, apically rounded with indistinct ocular chamber. Ascospores fasciculate, 3–4-seriate, scolecosporous, filiform or filamentous, with enlarged central cells, yellowish-brown to brown, multi-septate, nonconstricted at the septa, separating into two-part spores, smooth-walled, with or without appendages. Asexual morph: Unknown (Adapted from Phookamsak et al., 2014).
Type species: Ophiobolus disseminans Riess
Notes: Ophiobolus was introduced by Riess (1854) with O. disseminans as type species. Ophiobolus is characterized by solitary to gregarious, scattered, semi-immersed to erumpent ascomata, cylindrical to cylindric-clavate asci and scolecosporous, filiform or filamentous yellowish-brown to brown, multi-septate ascospores separating into two-part spores with or without appendages (Phookamsak et al., 2014). Holm (1948) and Müller (1952) broadened the generic concept of Ophiobolus but Holm (1957) treated Ophiobolus in a narrower sense, based on observation of European specimen. Holm (1957) accepted three species in Ophiobolus and other authors transferred several species of Ophiobolus to Acanthophiobolus, Entodesmium, Gaeumannomyces, Leptosphaeria, Leptospora and Nodulosphaeria. Shoemaker (1976) re-described species of Ophiobolus from Canada and North America and accepted 31 species with two new species and provided five new combinations. Barr (1979) firstly treated Ophiobolus in Phaeosphaeriaceae and later transferred it to Leptosphaeriaceae (Barr, 1987b). Walker (1980) provided drawings of scolecosporous taxa from type material previously accommodated in Ophiobolus. Dong et al. (1998) could not resolve the placement of Ophiobolus due to limited taxon sampling in their phylogeny. Zhang et al. (2012) reinstated Ophiobolus in Phaeosphaeriaceae based on morphological similarity with Nodulosphaeria and Ophiosphaerella. The asexual morph of Ophiobolus is reported as coniothyrium-like, Rhabdospora, phoma-like and Scolecosporiella (Shoemaker, 1976; Sivanesan, 1984; Hyde et al., 2011; Wijayawardene et al., 2012; Zhang et al., 2012; Phookamsak et al., 2014). Phookamsak et al. (2014) provided a detailed description of Ophiobolus and suggested that the genus might be polyphyletic. Molecular data is lacking for the type species of Ophiobolus. Ophiobolus is currently a distinct genus in Phaeosphariaceae but fresh collection is needed for epitypification. Molecular markers available for Ophiobolus include LSU, SSU, ITS and TEF1.