Two new entomopathogenic species of Ophiocordyceps in Thailand

Abstract

Ophiocordyceps is entomopathogenic and the largest studied genus in the family Ophiocordycipitaceae. Many species in this genus have been reported from Thailand. The first new species introduced in this paper, Ophiocordycepsglobiceps, differs from other species based on its smaller perithecia, shorter asci and secondary ascospores and additionally, in parasitising fly species. Phylogenetic analyses of combined LSU, SSU, ITS, TEF1α and RPB1 sequence data indicate that O.globiceps forms a distinct lineage within the genus Ophiocordyceps as a new species. The second new species, Ophiocordycepssporangifera, is distinguished from closely related species by infecting larvae of insects (Coleoptera, Elateridae) and by producing white to brown sporangia, longer secondary synnemata and shorter primary and secondary phialides. We introduce O.sporangifera based on its significant morphological differences from other similar species, even though phylogenetic distinction is not well-supported.

Keywords: Hypocreales; 2 new taxa; morphology; phylogenetic; taxonomy.

Figure 1.

Phylogram of Ophiocordycepsglobiceps and O.sporangifera generated from maximum likelihood (RAxML) analysis of ITS, SSU, LSU, RPB1 and TEF1α sequence data. Tolypocladiuminflatum and T.ophioglossoides were used as outgroup taxon. Maximum likelihood bootstrap values greater than 75% and Bayesian posterior probabilities over 0.90 were indicated above the nodes. The new species are indicated in red.

Figure 2.

Ophiocordycepsglobiceps (holotype MFLU 18–0661). a Habitat b Ascostroma emerging from infected fly c Host d Fertile head of ascostroma e Vertical section of the stroma f Section of ascomata g Peridium h, i Asci k Apical cap of asci l, q Part of ascospore m, n Secondary ascospores o Upper side of the culture p Reverse side of the culture. Scale bars: 1000 µm (b–d), 500 µm (e, f), 100 µm (h, i), 20 µm (g), 10 µm (k, l), 5 µm (m, n, q), 5 cm (o, p).

Figure 3.

Ophiocordycepssporangifera (holotype MFLU 18–0658). a Habitat b Synnemata on host surface c Host d, e Synnemata f Fertile head of primary synnema g Sporangium h Secondary synnema i Sporangium j, k, q Part of secondary synnema l Phialides m Conidia bound by deliquescing mucilaginous material n–p Conidia. Scale bars: 1 cm (c, d), 1000 µm (e), 200 µm (f, h, q), 100 µm (g, i), 50 µm (j), 20 µm (k, l), 10 µm (m–p).

Figure 4.

Ophiocordycepssporangifera (culture) MFLUCC 18–0492. a Upper side of the culture b Reverse side of the culture c, d Synnemata growing on PDA medium e, g Synnemata f Mycelium h–j Phialides k Conidia l–n Conidia form mucilaginous spheres. Scale bars: 1 cm (a, b), 5000 µm (c), 1000 µm (d), 500 µm (e), 100 µm (f, g), 50 µm (h–j), 10 µm (k–n).