Ophiocordyceps karstii T.C. Wen, Y.P. Xiao & K.D. Hyde, sp. nov., Index Fungorum number: IF 551814

Etymology: Name referring to the location which the specimen was collected.

Parasitic in larva of Hepialus jianchuanensis, brown to dark brown, forming yellow to brownish stromata. Sexual morph Thallus within host white, composed of intercalary hyphal bodies. Stromata mostly single, 140–145×2–4 mm, stipitate arising from head of the host. Stipe 12 cm long, 2 mm wide, clavate, with a fertile apex, becoming golden yellow to brownish yellow when mature. Fertile head 20–25 mm long, 2–4 mm diam., clavate, light yellow to yellow-brown, upper surface roughened, covered with white non compact mycelium. Ascomata 600–765 × 247–323 μm (x = 683×285μm, n = 30), superficial, yellow to brown, flask-shaped, thickwalled, ostiole on the top. Peridium 63–42 mm (x = 52 μm, n = 60) wide, three layers. Asci 186–228 × 8–12 μm (x = 207×10 μm, n = 60), 8-spored, hyaline, narrow cylindrical, with a thickened apex. Apical cap 5–7 μm (x =6 μm, n=60) diam. Ascospores 173–202 × 3–5 μm (x = 188×4 μm, n=60) fasciculate, fusiform, smooth, as long as asci, hyaline, 10–18 septate, not breaking into secondly spores. Asexual morph Undetermined.

Material examined: CHINA. Guizhou Province, Chishui, on dead larva of Hepialus jianchuanensis, 23 October 2014,
TingChi Wen CS2014102301 (MFLU 15–3884, holotype); CS2014102304 (MFLU 15–3885, MFLU 15–3886, MFLU
15–3887, paratype).

Notes: Ophiocordyceps was introduced by Petch (1931) with Ophiocordyceps blattae (Petch) Petch as the type species and used by Sung et al. (2007) as the type genus of Ophiocordycipitaceae. According to morphological and phylogenetic analysis, Ophiocordyceps karstii closedly matches O. lanpingensis Hong Yu bis& Z.H. Chen bis and O. robertsii (Hook.) G.H. Sung et al. This species is characterized by fusiform ascospores (173–202 × 3–5 μm, x = 188 × 4 μm, n =60), which do not break into secondly ascospores and superficial ascomata. Phylogenetic analysis of th of combined TEF1, RPB1 and SSU sequence data confirms that Ophiocordyceps karstii clusters with O. robertsii in Ophiocordyceps with high bootstrap support. Therefore, we proposed O. karstii as a new species

Fig. Ophiocordyceps karstii (holotype) a Overview of the host and stromata b Host: Hepialus jianchuanensis c Stroma Vertical section of stroma e Vertical section showing the superficial perithecia f, g Perithecia h–k Asci at immature to mature stages l–n Ascospores. Scale bars: c = 2 mm, d, f = 500 μm, e–g = 200 μm, h–n=50 μm.