Plasmodium carmelinoin. sp. (Haemosporida: Plasmodiidae) of the lizardAmeiva ameiva(Squamata: Teiidae) in Amazonian Brazil

Abstract

Plasmodium carmelinoi n. sp. is described in the teiid lizard Ameiva ameiva from north Brazil. Following entry of the merozoites into the erythrocyte, the young, uninucleated trophozoites are at first tear-shaped and already possess a large vacuole: with growth, they may assume an irregular shape, but eventually become spherical or broadly ovoid. The vacuole reduces the cytoplasm of the parasite to a narrow peripheral band in which nuclear division produces a schizont with 8-12 nuclei. At first the dark, brownish-black pigment granules are restricted to this rim of cytoplasm but latterly become conspicuously concentrated within the vacuole. The mature schizonts are spherical to ovoid and predominantly polar in their position in the erythrocyte. They average 5.4 x 4,9 microm (4.4 x 4.4 - 6.6 x 5,9 microm), shape index 1.1, n = 50: 8-12 merozoites are produced and measure approximately 2.0 x 1,0 microm. Mature gametocytes are also polar in position, and spherical to subspherical. The macrogametocytes measure 5.7 x 5,2 microm (4.4 x 4.0- 5.9 x 5,1 microm), shape index 1.1, n = 50 and, following staining by Giemsa's method, possess a compact, pink-staining nucleus and a clear blue, faintly stained cytoplasm. Microgametocytes are slightly larger, 6.0 x 5,0 microm (5.2 x 4.4 - 6.2 x 5,2 microm), shape index 1.2, n = 45. They stain an over-all pink colour due to the dispersed nuclear chromatin. The vacuoles in both the macro- and microgametocytes are considerably smaller than those of the schizonts and of ovoid or spindle shape: they contain most of the pigment granules. The sex ratio, as seen in an inicial intense infection, was 1 male to 2.2 females. Prevalence of infection was low (5%) but, due to the very low parasitaemia which may result in a failure to detect parasites, it is probably higher than this.