ABSTRACT

Biodiversity studies in search of endoparasitic acephaline gregarines revealed a new species of the genus Monocystis Stein, 1848 in the seminal vesicles of the earthworm Metaphire houlleti (Perrier) residing in alluvial soil of the district of North 24 Parganas. The new species is characterized by having bean-shaped gamonts measuring 94.0-151.0 (119.0±16.0) μm ×53.0-81.0(66.0±8.0) μm. The anterior end of the gamont is always wider than the posterior end. The mucron is always present at the wider end. The occurrence of syzygy (end to end, cauda-frontal) is a very rare feature which has been observed in the life cycle of the new species. The gametocyst is ovoid consisting of two unequal gamonts, measuring 85.0-102.0 μm (93.0±6.0). Oocysts are navicular in shape, measuring 6.5-11.0 (9.0±1.1) μm ×4.0-7.5 (5.5±1.9) μm.