A new coccidian parasite of the genus Caryospora is described from a long nosed vine snake, Ahaetulla nasuta, Lacépède, 1789 from Thailand. Oocysts of Caryospora ahaetullae sp. n. are spherical or slightly subspherical, 24.8 (22.5-26.0) pm in diameter, with a single-layered wall about 0.75 pm thick. A micropyle or oocyst residuum is absent. One, rarely two, polar granules are present, 1.5-2.0 pm. Sporocysts are ellipsoidal, 18.5 x 14.2 (18.0-19.5 x 13.0-15.0) pm with prominent Stieda and substieda bodies. Sporocyst residuum present, consisting of numerous very small granules scattered among 8 sporozoites. Sporo-zoites, with prominent transverse striations anteriorly, are vermiform, 15.0 x 3.8 (13.5-16.5 x 3.5—4.5) pm (in situ), lying lengthwise and parallel within sporocyst. Each sporozoite contains a spherical anterior and spherical to subspherical posterior refractile bodies.
Faecal examination of the long nosed vine snake Ahaetulla nasuta Lacépède, 1789 revealed two species of caryosporan coccidia. The morphology of one species fits well with a description of Caryospora ahaetullae Modrý et Koudela, 1994, the second is a previously undescribed species. Oocysts of Caryospora veselyi sp. n. were spherical, 18.9 (16.5-21.5) pm in diameter, with pitted and brownish oocyst wall about 1.5 pm thick. An irregular polar granule about 2,0 x 1.0 pm was observed in 35% of the oocysts examined. Sporocysts were octozoic, ovoidal to ellipsoidal, 13.7 (13.0-15.5) x 10.3 (9.0-11.0) pm with a shape index 1.3 (1.2-1.4). Stieda and substieda bodies were present. Sporocyst residuum was present as small granules of irregular size scattered among sporozoiles. Both species sporulated within 72 hours. The infected snake did not show clinical signs of disease.