LIGHT AND ELECTRON-MICROSCOPE STUDY ON GURLEYA-DAPHNIAE SP-NOV (MICROSPORA, GURLEYIDAE), A PARASITE OF DAPHNIA-PULEX (CRUSTACEA, PHYLLOPODA)

The life cycle of a new microsporidian species parasitizing in the epi dermis of the cladoceran Daphnia pulex from the southeast region of Au stria is described using light and electron microscopical methods. Mer ogonial stages have one or two single nuclei. Sporonts produce the spo rophorous vesicle and normally develop into lobed sporongial plasmodia with four single nuclei. These plasmodia divide into four monokaryoti c sporoblasts. The envelope of the sporophorous vesicle is of about th e same thickness as the plasma membrane. Spores are pyriform, monokary otic and measure between 3.8 x 2.3 and 4.6 x 2.6 mu m. The polaroplast is composed of two parts. The anterior part is lamellar, the posterio r parr consists of sac like structures. The polar filament is anisofil ar and consists of 3-4 thick and 2-5 narrow coils. The spore wall is u p to 415 nm thick and composed of three layers. The episporontal space contains tubules and fibres. Abnormal spores with regard to size, sha pe and number within the envelope frequently can be observed. Because of the differences to microsporidian species previously reported from the epidermis of cladocerans the parasite of Daphnia pulex is describe d as a new species and named Gurleya daphniae.