A new genus of the Piptocephalidaceae (Zoopagales) from Japan

A previously undescribed haustorial mycoparasite of Mucorales was studied at the light-microscopic level, based on dural cultures with three hosts, Mucor hiemalis, Mortierella remanniana, and Cunninghamella elegans. Sporangial and zygosporic development of the parasite are described and illustrated, and salient features of the fungus are compared with those of Piptocephalis and Syncephalis. The new fungus appears more nearly related to Piptocephalis in possessing similar hyphal and haustorial characteristics, dichotomously branched sporangiophores, and a nearly identical form of zygospore. Like a few species of Piptocephalis, the fungus lacks a head-cell, and it forms branched merosporangia one or two terminally on ultimate branches of the sporangiophore. However, merosporangial development in the fungus is unique for the Piptocephalidaceae in that it proceeds by a process of sequential acropetal budding leading to the formation of a more or less highly branched, moniliform sporangiole. Sporangiospores mature simultaneously, are multinucleate, and are liberated by merosporangial disarticulation. Because of its distinctive merosporangium, the Japanese isolate is placed in a new genus and species, huzuhaea moniliformis.