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 samples from 23 adult and 20 young captive Yemen chameleons, Chamaeleo calyptratus Duméril et Duméril, 1851, were examined for coccidian parasites. Two of the adult (8.7 %) and 16 (80.0 %) of the young chameleons were found to be passing oocysts of the Isospora species. Sporulated oocysts of Isospora jaracimrmani sp. n. are ellipsoidal or pyriform, 38.4 x 25.6 (35.2-42.8 x 23.8-27.0) pm, with smooth bilayered and colourless oocyst wall. A micropyle, oocyst residuum and polar granule are absent. Sporocysts are ellipsoidal to ovoid, 15.9 x 11.2 (14.8-17.0 x 10.4-12.0) pm, with dome-like Stieda and homogenous spherical substieda bodies. The posterior end of the sporocyst is draw out. Sporocyst residuum is present, consisting either of a compact mass or of scattered granules. Sporozoites, with faint transverse striations anteriorly, are vermiform, 13.1 x 3.4 (12.4-16.5 x 2.8-4.0) pm. Most oocysts are to sporulate when excreted; sporulation was completed within 12 to 24 h at 25 ± 2"C. Endogenous stages develop inside the nuclei of enterocytes in the small intestine. Prepatent period in experimentally infected young chameleon was 7 days. Comparison with other species of the genus Isospora found in chameleons indicates that it is a new species.