A new species of Harposporium parasitic on nematodes

Abstract

A new species, Harposporium thaumasium X. Li et K.Q. Zhang, was isolated from forest soil in Yunnan, China. This species produces small, curved conidia, singly or in groups, from globose or ellipsoid phialides. Unlike other known Harposporium, this species produced novel arthroconidia that did not disarticulate at septa but germinated to produce typical phialides and infective conidia. Solitary or catenulate chlamydospores were also produced within infected nematodes and in pure culture. Narrowly elliptical to D-shaped accessory conidia were produced, only on potato dextrose agar and dextrose yeast agar, from mono- or poly-phialidic conidiogenous cells resembling Hirsutella; thus, on these nutrient media, four different spore types were formed. Infection tests showed that curved conidia of the species were capable of killing bacteria-feeding nematodes (Panagrellus redivivus) when ingested, and the infection was initiated by lodging of the conidia in the gut region. Accessory conidia were not observed to be infective or adhesive.Key words: endoparasitic fungi, Harposporium thaumasium sp.nov., ingested conidia, nematode.