A new species of aplanosporic Haptoglossa, H. beakesii, with vesiculate spore release

Abstract

A new species of Haptoglossa , Haptoglossa beakesii sp. nov., a nematode parasite found in a sample of compost and rabbit dung at the University of Sussex campus, is described. The species, which infects nematodes of the genus Rhabditis , is unusual because it releases non-motile spores into a retaining vesicle. Aspects of the development and reproduction of the species are illustrated with light microscopy and transmission electron microscopy (TEM). TEM revealed a typical multinucleate thallus which cleaved into un-walled aplanospore initials. Each aplanospore contained a central nucleus closely surrounded by mitochondria and with peripheral dense body vesicles (DBV) and distinctive, layered, encystment vesicles. Aplanospores were expelled into a fine vesicle which later broke down to release cysts. Cysts germinated to produce infective gun cells.