Penicillium cecidicola, a new species on cynipid insect galls on Quercus pacifica in the western United States

A synnematous species of Penicillium subgenus Biverticillium was found inside emergence tunnels from insect galls (Cynipidae, Hymenoptera, the so-called gall wasps) on scrub oaks (Quercus pacifica Nixon & C.H. Muller) collected in the western United States. The fungus produces synnemata with white or creamish stipes, biverticillate conidiophores with lanceolate phialides typical of subgenus Biverticillium, and small, ellipsoidal, slightly roughened dark green conidia.

In culture, the fungus produces velutinous, dark green colonies, with synnemata near the margins of the colonies, particularly in fresh isolates exposed to light after 10 days. The fungus produces the extrolite apiculide A and a series of unidentified extrolites also produced by P. panamense. The oak gall species is described here as Penicillium cecidicola and compared with similar species.

An ITS phylogeny suggests that P. cecidicola is a sister species to P. dendriticum, an Australian species with yellow synnemata that also sometimes occurs on insect galls. Notes are included on other Penicillium species we have isolated from insect galls.