Apolocystis cognetti sp. nov. (Apicomplexa: Monocystinae) a new aseptate gregarine species from the earthworm Amynthas hawayanus (Annelida: Oligochaeta) from West Bengal, India.

During the course of surveys of endoparasitic aseptate gregarines in Darjeeling district of West Bengal, India, seminal vesicles of Amynthas hawayanus (Rosa 1891) found to be infested with a new species of the genus Apolocystis (Cognetti de Martiis 1923). Trophozoites are spherical or rounded and without any polar differentiation. Diameter of the trophozoite ranges from 65.4 to 126.7 (91.8 ± 17.5) μm. Nucleus diameter measures 12.2-20.4 (14.4 ± 2.2) μm. Gametocyst is round and measures 73.6-110.4 (93.3 ± 14.0) μm and contains two unequal gametocytes. Oocyst measures 7.7-10.7 (9.5 ± 0.9) μm × 3.8-5.3 (4.6 ± 0.4) μm.