Ophiocordyceps tabani Mongkolsamrit, Liangsiri, Thanakitpipattana & Luangsa-ard, 2025

Mongkolsamrit, Suchada, Thanakitpipattana, Donnaya, Noisripoom, Wasana, Tasanathai, Kanoksri, Liangsiri, Kanraya, Jaiyen, Somruetai, Rungjindamai, Nattawut, Stadler, Marc & Luangsa-ard, Jennifer, 2025, Multi-locus molecular phylogenetic analysis reveals four new species and a new record of Ophiocordyceps (Ophiocordycipitaceae, Hypocreales) on dipteran hosts in Thailand, MycoKeys 119, pp. 235-261 : 235-261

Ophiocordyceps tabani Mongkolsamrit, Liangsiri, Thanakitpipattana & Luangsa-ard sp. nov.

Fig. 5

Etymology.

Named after the host genus, Tabanus .

Typus.

Thailand • Nakhon Ratchasima Province, Khao Yai National Park, Mo Singto Nature Trail , on horsefly ( Tabanidae , Tabanus sp. ) attached to a twig of a forest tree, 4 November 2010, P. Srikitikulchai, S. Mongkolsamrit, A. Khonsanit, R. Somnuk, K. Sansatchanon, W. Noisripoom, MY 6380.01 ( BBH 30055 , ex-type culture BCC 45127 ) .

Description.

Stromata stipitate, usually two stromata arising from the thorax region of host, beneath the wings, capitate, unbranched. Stipes cylindrical, smooth, tough, brownish-orange (165 A – B), 4–10 mm long, 1.5–2 mm wide. Sexual morph: Fertile head hemispherical to globoid, upper surface slightly convex, moderate orange (167 B – C), located at the terminal part of stipes, 2–3 mm thick, 3–4 mm diam. Perithecia immersed, ovoid to obclavate, (1000 –) 1025–1148 (– 1180) × (320 –) 325–380 (– 450) μm (n = 15, 1087 ± 61.6 × 361 ± 43.2 μm). Asci cylindrical, (550 –) 636–870 (– 880) × (4 –) 4.5–6 μm (n = 30, 753.5 ± 116.8 × 5 ± 0.5 μm) with cap 3–6 μm thick. Ascospores filiform, multi-septate, breaking into 64 part-spores, cylindrical to fusoid, (10 –) 11–13 (– 14) × (1 –) 1.5–2 μm (n = 50, 11.8 ± 1.3 × 1.8 ± 0.3 μm). Asexual morph: Synnemata usually arising from posterior abdomen region of host, solitary, cylindrical, unbranched, uneven and rough when aged, brown to dark brown at the base, moderate orange at the apex, 5–10 × 0.5–2 mm, fertile part located at the terminal ends of the synnemata. Conidiogenous cells Hymenostilbe - like, phialidic, forming a hymenial layer. Phialides cylindrical with short crowded denticles, (12 –) 13–17 (– 20) × 3–4 μm (n = 30, 15 ± 2.4 × 3 ± 0.2 μm). Conidia hyaline smooth-walled, fusoid, (5 –) 7–9 (– 10) × 3–4 μm (n = 30, 8 ± 1.2 × 3.3 ± 0.4 μm).

Culture characteristics.

Colonies on OA attaining a diam. of 8–10 mm in 30 days, mycelium sparse, white, reverse pale yellow (165 D). Conidia and reproductive structures not observed. Colonies on PDA attaining a diam. of 7–10 mm in 30 days, high mycelium density, white, reverse pale yellow (165 D). Conidia and reproductive structures not observed.

Host.

Horsefly ( Tabanidae , Tabanus sp. ).

Habitat.

Specimens were found on the twig of a tree in a forest.

Additional materials examined.

• Nakhon Ratchasima Province, Khao Yai National Park, Mo Singto Nature Trail , horsefly ( Tabanidae , Tabanus sp. ) attached to a twig of a forest tree, 22 July 2009, K. Tasanathai, S. Mongkolsamrit, P. Srikitikulchai, R. Ridkaew, MY 4999.01 ( BBH 26791 , Culture BCC 38243 ), MY 4999.02 (paratype BBH 26791 , ex-paratype culture BCC 39918 ) ; • idem, 30 June 2010, K. Tasanathai, P. Srikitikulchai, S. Mongkolsamrit, A. Khonsanit, R. Somnuk, K. Sansatchanon, MY 6098.01, MY 6098.02 ( BBH 29675 , Culture BCC 43730 , Culture BCC 45070 ) ; • idem, 4 November 2010, P. Srikitikulchai, S. Mongkolsamrit, A. Khonsanit, R. Somnuk, K. Sansatchanon, W. Noisripoom, MY 6380.01 ( BBH 30055 , Culture BCC 45127 ) .

Notes.

Ophiocordyceps tabani predominantly produces both sexual morphs and asexual morphs on the same specimen. Both Ophiocordyceps tabani and O. philippinensis are commonly found attached to the twigs of trees. However, these two fungi differ in their hosts. Ophiocordyceps tabani infects horseflies ( Tabanidae , Tabanus sp. ), while O. philippinensis infects Clephydroneura sp. and Asilus sp. , both belonging to the Asilidae . The synnemata of O. tabani are tougher than those of other species. Notably, the reproductive structures of the asexual morph are located at the terminal ends of the synnemata, which often become uneven and rough with age. Among the specimens collected from the field, the hosts typically have no wings.

Figures

Figure 5. Ophiocordyceps tabani. A – C. Fungus on a horsefly (Tabanidae, Tabanus sp., Holotype BBH 30055); D. Perithecia; E. Ascus; F. Ascus cap; G. Part-spores; H, I. Conidiogenous cells forming a hymenial layer; J. Conidia; K, L. Colonies on OA at 30 days (K obverse, L reverse); M, N. Colonies on PDA at 30 days (M obverse, N reverse). Scale bars: 15 mm (A – C); 500 µm (D); 100 µm (E); 10 µm (F); 20 µm (G); 15 µm (H, I); 10 µm (J); 10 mm (K – N).