Ophiobolus ponticus
Ophiobolus ponticus Petr., Annls mycol. 29(5/6): 371 (1931)
Index Fungorum number: IF 275043; Facesofungi number: FoF 03794
Synonym: Nodulosphaeria pontica (Petr.) L. Holm, Symb. bot. upsal. 14(no. 3): 94 (1957)
Syntype: Bulgaria, on Phlomis pungens Willd. (Lamiaceae), June 1928, J. Hruby no. 170, S-F10065
Saprobic on herbaceous plants. Sexual morph: Ascomata 160–230 μm high (excluding papilla), 190–260 μm diam., dark brown to black, scattered, gregarious, semi-immersed to erumpent through the host epidermis, subglobose to ampulliform, uni-loculate, glabrous, ostiolate, papillate. Papilla 70–125 μm high, 70–120 μm diam., with rounded to truncate apex, composed of several layers of thick, brown to dark brown, pseudoparenchymatous cells, arranged in a textura angularis to textura prismatica, ostiole central, with indistinct periphyses. Peridium 15–40 μm wide, slightly thinner at the base, thick towards the apex, with thick-walled cells, composed of several layers of dark brown to black, pseudoparenchymatous cells, arranged in textura angularis to textura prismatica. Hamathecium composed of dense, 2.5–6 μm wide, broadly cellular pseudoparaphyses, thick at the base, narrower towards the apex, distinctly septate, constricted at the septa, anastomosing at the apex, embedded in a hyaline gelatinous matrix. Asci (88–)95–115(–126) × (9.5–)10–12 μm (x̄ = 107.4 × 11.6 μm, n = 30), 8-spored, bitunicate, fissitunicate, cylindrical to cylindric-clavate, short pedicellate, with truncate to furcate pedicel, apically rounded, with well-developed ocular chamber. Ascospores (65–)70–85 (–94) × (2.5–)3–4.5 μm (x̄ = 77 × 3.6 μm, n = 30), fasciculate, in parallel to slightly spiral, scolecosporous, pale brown to yellowish green, cylindrical, with rounded ends, tapered towards lower cell, curved, swollen at the 4th triangular cell, with 10–12 septa, slightly constricted at the 4th septum, not constricted at the other septa, not separated into part spores, smooth-walled. Asexual morph: Undetermined
Culture characteristics: Colonies on PDA reaching 45–50 mm diam. after 4 weeks at 25–30 °C, medium sparse, slightly dense at the center, circular, flattened, surface smooth, with edge entire, fairly fluffy to woolly, colony from above pale yellowish at the margin, white to cream at the center, colony from below yellowish, not producing pigmentation in agar.
Material examined: ITALY, Province of Forlı `-Cesena [FC], Fiumicello-Premilcuore, on dead stem of Centaurea sp. (Asteraceae), 12 July 2014, E. Camporesi, IT 1986 (MFLU 17-0931; reference specimen designated here), living culture MFLUCC 17-2273 = KUMCC 17-0164.
GenBank:
Notes: Ophiobolus ponticus was collected from Phlomis pungens in Bulgaria and was introduced by Petrak (1931). The syntype is deposited in S (Swedish Museum of Natural History, Stockholm, Sweden). Ophiobolus ponticus resembles O. niesslii Ba¨umler and O. filiformis (Wehm.) Shoemaker, but these two species have appendaged ascospores (Shoemaker 1976), while O. ponticus lacks appendaged ascospores. Ophiobolus ponticus was transferred to Nodulosphaeria pontica by Holm (1957). However, Shoemaker (1976) reinstated the species in the genus Ophiobolus based on its papilla lacking sparse, brown, septate, hair-like periphysate, of which a unique character of Nodulosphaeria (Shoemaker 1984; Phookamsak et al. 2014b, Mapook et al. 2016). Our isolate (MFLU 17-0931) is typical of Ophiobolus ponticus based on its morphological characters including the size range of ascomata, asci and ascospores and ascospore septation. Therefore, the isolate is identified as O. ponticus and designated as a reference specimen. Phylogenetic analyses of a combined LSU, SSU, TEF1- α and ITS depict O. ponticus as a sister taxon to O. disseminans with strong support.
Figure x. Ophiobolus ponticus (MFLU 17-0931, reference specimen). a Appearance of ascomata on the host surface. b Section through ascoma. c Section through peridium. d Pseudoparaphyses stained in congo red. e–g Asci. h–k Ascospores. Scale bars: b = 100 μm, c = 50 μm, e–g = 20 μm, c, h–k = 10 μm.
References:
Phookamsak R, Wanasinghe DN, Hongsanan S, Phukhamsakda C et al. 2017 – Towards a natural classification of Ophiobolus and ophiobolus-like taxa; introducing three novel genera Ophiobolopsis, Paraophiobolus and Pseudoophiobolus in Phaeosphaeriaceae (Pleosporales). Fungal Diversity. 87, 299–339.