Schellackia landauae sp.nov. (Eimeriorina: Lankesterellidae)in the Brazilian lizard polychrus marmoratus (Iguanidae): experimental transmission by Culex pipiens fatigans

Abstract

A new haemogregarine, Schellackia landauae sp.nov., is described in the Brazilian lizard Polychrus marmoratus (Linn) from Pará State, north Brazil. Sporozoites are found principally in the red blood cells (84%) in the peripheral blood but algo occur in lymphocytes and monocytes. Experimental transmission to three uninfected P. marmoratus was achieved after feeding them with laboratory-bred Culex pipiens fatigans which had engorged on an infected lizard 14 days previously. The cycle of development in the smáll intestine of P. marmoratus takes approximately 30 days: schizogony, gametogony and fertilization of the macrogametocytes is in the epithelial cells of the gut, with zygotes penetrating the lamina propria, where the mature oocysts develop. Living oocysts average 14-3 x 13.3 um, and are approximately 10-0 um as seen in histological sections. During the period of intestinal development, the parasite algo undergoes asexual multiplication within cells of the spleen and liver by a process which appears to be endodyogeny. The exact time required before the first invasion of the peripheral blood by the sporozoites remains to be ascertained, but is some time within 30-45 days after the lizard ingests the infected mosquitoes. Morphology of the sporozoite in the vertebrate host is variable and depends on the host cell occupied; there may be 1 or 2 refractile bodies. Reduction or fusion of these to a single refractile body in those sporozoites within the gut cells of the infected mosquito suggests that the bodies may represent some form of energy source that is used up during this latent phase in the insect vector. Accumulation of sporozoites takes place in the reticulo-endothelial cells of the viscera, in particular the pigmentladen cells of the liver and lung. Attempts to infect other species of lizards, Tropidurus torquatus (Iguanidae) and Ameiva a.meiva (Teiidae) failed. Other specics of Schellackia are comparcd with S. landauae. There is a gradation of predilection for the gut epithelium among the known species which supports the hypothesis of evolution of the 'higher coccidia' (Eimeria, Isospora, etc.) from a line originating from a faecally transmitted, octozoic parasite such as a Tyzzeria.