A new Haemoproteid of Malaysian Microchiroptera (Hepatochstis rodhaini n. sp.) is described; it is classified in the genus Hepatocystis because of the morphology of its gametocytes and tissue schizonts.
Malaysian Sciuridae are often parasitised by 2 species of Hepatocystis which were described as a single species Hepatocystis vassali malayensis by Field and Edeson, (1950). One of them corresponds to the majority of forms seen by Field and Edeson; it is redescribed herein and raised to specific status: H. v. malayensis becomes H. malayensis Field and Edeson, 1950. By the morphological characteristics of its gametocytes and schizonts, H. malayensis is related to H. kochi. The evolution of tissue schizonts studied at liver biopsies and autopsies of squirrels captured shortly before examination is of a peculiar type: an immunological tissue reaction appears with the hyperinfestation of the Rodents and controls the growth of the schizonts.
Hepatocystis brayi n. sp. is described and separated from the second species parasitising Malaysian Sciuridae, H. malayensis Field and Edeson, 1950. H. brayi is characterized by: 1) the evolution of its tissue schizonts which are intracellular throughout all their development; the cytoplasm and the nucleus of the host cell are highly hypertrophied; 2) the scarcity of the colloid. The schizogony persists for several months in the liver of infected animals and the gametocytaemia apparently undergoes seasonal relapses. H. brayi is a parasite of hosts occurring in the middle and under canopy, H. malayensis the middle and top canopy.