Ophiobolus disseminans Riess, Hedwigia 1(6): 27 (1854)
Index Fungorum number: IF 165872; Facesofungi number: FoF 00255
Saprobic on herbaceous plants. Sexual morph: Ascomata 200–280 μm high (excluding papilla), 260–370 μm diam. [type = 140–390 μm high, 160–340 μm diam.], dark brown to black, scattered or sometimes clustered, gregarious, semi-immersed, or erumpent through host tissue, visible as raised, small, black dots on the host surface, uni-loculate, subglobose to ampulliform, covered with hyphal turfs, ostiolate, papillate. Papilla 110–170 μm high, 60–120 μm diam. [type = 60–150 μm high, 85–140 μm diam.], central, mammiform to oblong, rounded to truncate at the apex, with periphyses inside the ostiole, composed of dark brown to black, thick-walled cells, arranged in a textura angularis. Peridium (17–)30–50 μm wide [type = 30–50 μm wide], thick-walled, composed of several layers of dark brown to black, thick pseudoparenchymatous cells, arranged in a textura angularis. Hamathecium composed of numerous, 2–4 μm wide, filamentous, broadly cellular pseudoparaphyses, with distinct septa, embedded in mucilaginous matrix, anastomosing at the apex. Asci (162–)175–200(–220) × 10–12(–13) μm (x̄ = 189.4 × 11.7 μm, n = 30) [type = (156–)170–190(–203) × 10–12(–13) μm (x̄ = 178.9 × 11.4 μm, n = 20)], 8-spored, bitunicate, cylindrical to cylindric-clavate, short pedicellate, apically rounded with indistinct ocular chamber. Ascospores (114–)120–140(–142) × 2–4 μm (x̄ = 129.7 × 2.9 lm, n = 30) [type = (125–)150–160(–163) × 2–3 μm (x̄ = 152.8 × 2.9 μm, n = 15)], fasciculate, in parallel or spiral, scolecosporous, filiform, with two swollen cells near the center, breaking into two half part ascospores in between the swollen cells, yellowish brown to brown, multi-septate, with (18–)20(–23) septa, not constricted at the septa, smooth-walled, with small guttules. Asexual morph: Undetermined.
Culture characteristics: Colonies on PDA reaching 65–70 mm diam. after 4 weeks at 25–30 °C, medium dense, irregular in shape, flattened, surface smooth, with edge fimbriate, velvety to floccose, colony from above cream at the margin, pale yellowish at the center, from below pale orangish at the margin, orangish-brown to dark brown in the centre, producing orangish-brown pigment tinted agar.
Material examined: ITALY, Cassellas Vicinity, on dead stem of Cirsium arvense (L.) Scop. (Asteraceae), 1853, Riess 1823 (BPI 629021, isotype); ibid. Province of Arezzo [AR], Papiano Alto—Stia, on dead and aerial stem of C. arvense, 11 June 2014, E. Camporesi, IT1925 (MFLU 15-2257, epitype designated here), ex-epitype living culture, MFLUCC 17-1787, KUMCC 17-0162; Province of Forlı `-Cesena [FC], Bagno di Romagna, near Monte Comero, on dead stem of Arctium minus (Hill) Bernh (Asteraceae), 2 July 2016, E. Camporesi, IT3008 (MFLU 16-2050), living culture, MFLUCC 17-1790, KUMCC 17-0171
Notes: Ophiobolus disseminans was introduced by Reiss (1854) as the generic type of Ophiobolus. The species was collected from Cirsium arvense and has also been found on Arctium spp. (Phookamsak et al. 2014b, Farr and Rossman 2017). Ophiobolus disseminans was treated as a synonym of O. acuminatus by many authors and O. acuminatus was replaced as the generic type (Mu¨ller 1952, Holm 1957, Shoemaker 1976, Walker 1980, Barr 1987). However, the type epithet could not be changed based on the nomenclatural rules (McNeill et al. 2012). Therefore, we follow Zhang et al. (2012), Ariyawansa et al. (2014a) and Phookamsak et al. (2014b) and treat Ophiobolus disseminans as the type species of the genus Ophiobolus. Ophiobolus disseminans resembles O. ophioboloides as its ascospores can separate into two part spores at the central septum (Shoemaker 1976). However, O. disseminans can be distinguished from O. ophioboloides based on its larger ascospores and asci and greater ascospore septation [(18–)20(–23) septa of O. disseminans versus (11– )15(–17) septa of O. ophioboloides; Shoemaker 1976]. Phylogenetic analyses of a combined LSU, SSU, TEF1-a and ITS sequence data showed that O. disseminans clusters with O. ponticus Petr. with high support (100% ML, 100% ML and 1.00 PP) and shares a close relationship to Entodesmium artemisiae S. Konta, Bulgakov & K.D. Hyde, E. italica Tibpromma, Camporesi & K.D. Hyde and E. rude with high support. Therefore, Entodesmium artemisiae and E. italica are transferred to the genus Ophiobolus as O. artemisiae and O. italicus, while O. rudis (Riess) Rehm is reinstated for Entodesmium rude.