Teleomorph state: Ophiocordyceps humberti (C.P. Robin) G.H. Sung, J.M. Sung, Hywel-Jones & Spatafora

Specimens were found attached to the margins of leaves of forest plants. Hosts are Hymenoptera (Polistes and vespid wasps). Synnemata arising from various parts of the head, thorax and abdomen including legs, slender, terete, attenuated upward, very variable in length, 1-15 mm long, 50-80 μm wide, light brown to dark brown, composed of compact, parallel, longitudinal hyphae. Synnemata sometimes develop several short side branches. Conidiogeneous cells monophialidic, scattered to moderately crowded, arising laterally from the hyphae, cylindric to ellipsoid, 15-25 um long, forming a thin long neck, 25-40 μm long, 1.5-2.5 μm wide. Conidia hyaline, smooth, one-celled, citriform, 5-10 x 4-7μm. Conidia germinate readily on PDA. Colonies are grey to grey brown with a hyaline margin immersed in the agar, slow-growing reaching 5-6 cm in 3 mo. On reaching the edge of a 6 cm petri plate cultures produce erect synnemata similar to those found on the host and Hirsutella phialides and conidia become clearly visible. Specimens have been found from northern Thailand (Loei Province) to the far south on the Malay border (Hala Bala Wildlife Sanctuary). Usually this is very rare with only solitary specimens being found. However, at Nam Nao National Park (Petchabun Province) an epizootic was observed where 30-40 dead wasps could be found attached to the margin of leaves.

Cooke, M.C. (1892). Vegetable Wasps and Plant Worms. SPCK, London, 364 pp. Speare, A.T. (1920). On certain entomogenous fungi. Mycologia 12: 62-76.