Plasmodium saurocaudatum sp. n., a Parasite of Mabuya multifasciata in Southeast Asia

Abstract

Plasmodium saurocaudatum sp. n. is a parasite of Mabuya multifasciata (Sauria: Scincidae) in Southeast Asia. It is distinguished from all other saurian malarias by producing tiny, fan-shaped or cruciform schizonts that were less than one-half the size of an erythrocyte's nucleus, containing three or four merozoites, in combination with disproportionately large gametocytes that may reach sizes exceeding eight times the host cell's nucleus. The elongate gametocytes of active infections enlarge to become round or oval and bulky, nearly filling the host cell, and resemble gametocytes of saurian species of Haemoproteus. Schizonts were marginal in position, with the asexual phase evidently of short duration but recrudescent. Infections typically were comprised entirely of gametocytes at low parasitemias. On morphological aspects, P. saurocaudatum most closely resembles P. lygosomae Laird, 1951, and it is suggested that both species may be derived from a common precursor which parasitized Southeast Asian skinks. In both the Neotropical and Ethiopian regions, scincid lizards of the genus Mabuya commonly serve as hosts to plasmodiid parasites. In Panama, Brazil, and Colombia, Mabuya mabouya is parasitized by Plasmodium diploglossi (Telford, 1970; Lainson and Shaw, 1969; Ayala, 1978). An unpigmented erythrocytic parasite, Plasmodium morulum, has been found in this host in Panama and Brazil (Telford, 1970; Lainson et al., 1974), whereas the leucocytic Saurocytozoon mabuyi was described from M. mabouya in Brazil (Lainson et al., 1974). In Africa, Plasmodium mabuiae, P. pitmani, and P. maculilabre have been reported from several Mabuya species from the Sudan to Tanzania, and in the Congo (Gamham, 1966; Telford, 1983a). No Plasmodium parasites have been described from the many Mabuya species in Southeast Asia. Telford (1983b) reported the presence of Saurocytozoon mabuyi in Mabuya multifasciata in Singapore and Thailand. As mentioned there, a Plasmodium infection was detected in smears of caudal blood from a M. multifasciata in Singapore in June 1976. The parasite was found again in samples of the same host in Thailand in 1977 and 1980, and in the latter year, adequate material was obtained to permit the description below of this unusual Plasmodium species. MATERIALS AND METHODS Acquisition, processing and examination of material are described in Telford (1983b). Taxonomic characters used are those described by Telford (1974, 1979). Measurements are expressed below in p,m or /m2 for LW values. Parasitemias were calculated from counts Received 9 September 1982; revised 7 March 1983; accepted 10 March 1983. of 600 to 1,600 red blood cells at x 1,000, except in the case of some chronic infections where up to 50 fields at x 400 were examined to provide crude esti-