Observations on oocyst development of Eimeria stiedai in rabbits.

The formation of the oocyst wall was examined in Eimeria stiedai in the bile duct epithelium of the rabbit and was found to follow the general eimerian pattern. However from the beginning of the formation of the outer layer of the oocyst wall the parasite was surrounded by a rarely reported veil membrane. Cell damage of the bile ducts at the gamogony stage of parasite development is depicted.

Utrastructural observations on Goussia metchnikovi (Laveran, 1897) in the spleen of gudgeon, Gobio gobio L.

The ultrastructure of gamonts and sporulated oocysts of Goussia metchnikovi in the spleen of gudgeon, Gobio gobio from the river Lee, England is described. In developing microgamonts, small amylopectin granules were grouped centrally and nuclei were often arranged peripherally, close to the surface membrane. Nuclear chromatin condensed into peripheral dense portions that became the nuclei of flagellated microgametes, released to the parasitophorous vacuole. The cytoplasm of macrogametes had larger, scattered amylopectin granules, lipid globules and small electron-dense bodies, but no obvious wall forming bodies; peripheral vesicular structures with the appearance of mitochondria were also present and the parasitophorous vacuole contained flocculent material, but was otherwise free of structures. Sporulated oocysts contained four sporocysts and oocyst walls appeared to consist of a single membrane. Sporocyst walls showed a dehiscence suture, characteristic of the genus Goussia, which had filamentous extensions in places. The sporocyst wall comprised a dense inner layer and a thin outer layer with a fuzzy coat, separated by an electron lucent layer. Groups of oocysts were encapsulated by fibrous layers and inflammatory cells, and many sporocysts and their contained sporozoites showed evidence of elimination by the host.

A new species of Eimeria (Apicomplexa: Eimeriidae) from the western hognose snake, Heterodon nasicus (Serpentes: Xenodontidae), from Texas.

A new species of coccidian (Apicomplexa: Eimeriidae) is described from the feces of a western hognose snake Heterodon nasicus (Serpentes: Xenodontidae) collected from Texas, and housed in the collection of the Zoological Society of London. Oocysts of Eimeria mchenryi n. sp. are cylindrical, 35.0 ± SD 1.4 (32-37) × 17.0 ± 0.7 (16-18) µm; the shape index (length/width) is 2.05. A micropyle, oocyst residuum, and polar granule are absent. Sporocysts are subspherical 9.3 (7-11.5) × 7.7 (6-9) µm, with a shape index of 1.2. There is a sporocyst residuum, but the new species is lacking Stieda bodies. The new species is distinct from those previously named from the Xenodontidae and the allied family, Colubridae.

A new species of Caryospora Léger, 1904 (Apicomplexa: Eimeriidae) from the endangered Round Island boa Casarea dussumieri (Schlegel) (Serpentes: Bolyeridae) of Round Island, Mauritius: an endangered parasite?

A new species of Caryospora Léger, 1904 (Apicomplexa: Eimeriidae), C. durelli n. sp., is described from the endangered Round Island boa Casarea dussumieri (Schlegel) (Serpentes: Bolyeridae) from Round Island, Mauritius. Six of 11 hosts were infected. Oöcysts are spherical to subspherical, 19.2 × 18.2 (17.5-21 × 16-21) µm, n = 20, and have a shape index (mean length/mean width) of 1.05 (1.02-1.09). The bi-layered wall is composed of an outer layer of c.0.6 µm thick and an inner layer of c.0.4 µm thick. A micropyle, oöcyst residuum and polar granule are absent. Sporocysts are ellipsoidal, 14.7 × 11.0 (13-16 × 9.5-11.5) µm, n = 20, and have a shape index of 1.33. Both Stieda and substieda bodies are present. The sporocyst residuum measures c.12 × 4.5 µm, is surrounded by sporozoites and composed of numerous granules. Refractile bodies are present but not clearly visible. This is the first coccidian parasite reported from the family Bolyeridae and the first species of Caryospora durrelli [corrected] reported from the Mascarenes. Conservation issues concerning parasites of endangered host species are discussed.

Six new species of coccidia (Apicomplexa: Eimeriidae) from endangered Phelsuma spp. geckoes (Sauria: Gekkonidae) of the Black River Gorges National Park, Mauritius.

Six new species of coccidia are described from endangered Phelsuma spp. geckoes (Sauria: Gekkonidae) endemic to Mauritius, Indian Ocean. Five new species (3 Eimeria and 2 Isospora species) are described from Phelsuma rosagularis Vinson et Vinson; all lack a micropyle and an oocyst residuum, and all have a sporocyst residuum. Oocysts of Eimeria swinnertonae sp. n. are ellipsoidal, 22.2 x 17.8 (20.8-24.8 x 16.8-18.4) microm; SI 1.25; polar granule absent. Sporocysts are ellipsoidal, 8.8 x 7.0 (8.0-9.6 x 6.4-8.0) microm; SI 1.3; Stieda body absent. Oocysts of Eimeria stebbinsi sp. n. are ellipsoidal, 17.4 x 11.7 (16.0-19.2 x 11.2-12.8) microm; SI 1.5; polar granules present. Sporocysts are elongate-ellipsoidal, 7.7 x 4.0 (7.2-8.0 x 3.2-5.6) microm; SI 1.9; Stieda body present. Oocysts of Eimeria raleighi sp. n. are spheroidal to sub-spheroidal, 17.0 x 15.5 (16.0-19.2 x 14.4-16.8) microm; SI 1.1; polar granule present. Sporocysts are sub-spheroidal, 7.8 x 6.6 (7.2-8.0 x 6.4-7.2) microm; SI 1.2; Stieda body absent. Oocysts of Isospora cottinghamae sp. n. are ellipsoidal, 19.8 x 15.5 (17.6-21.6 x 14.4-17.6) microm; SI 1.3; polar granules present. Sporocysts are ellipsoidal, 10.8 x 6.9 (9.6-12.8 x 6.4-8.0) microm; SI 1.6; Stieda body present. Oocysts of Isosporapearlae sp. n. are ellipsoidal, 16.0 x 11.5 (15.2-17.6 x 9.6-12.8) microm; SI 1.4; polar granule present. Sporocysts are ellipsoidal, 8.8 x 5.4 (8.0-9.6 x 4.8-6.4) microm; SI 1.6; Stieda and substieda bodies present. One new Eimeria species is described from the blue-tailed day gecko, Phelsuma cepediana Merrem. Oocysts of Eimeria hartleyi sp. n. are sub-spheroidal to ellipsoidal, 18.2 x 14.5 (16.0-20.8 x 13.6-16.0) microm; SI 1.26; polar granules present. Sporocysts are ellipsoidal to cylindroidal, 7.5 x 5.3 (6.4-8.0 x 4.8-6.4) microm; SI 1.4; Stieda body present. We report the presence of tetrazoic spheroidal to sub-spheroidal oocysts or sporocysts 10.2 x 8.5 (9.9-10.4 x 8.3-8.8) microm; SI 1.2 from an individual of P. cepediana. These oocysts or sporocysts are significantly larger than the Cryptosporidium species so far described from reptiles, and likely represent excretion of spuriously ingested sporocysts of a Sarcocystis or Adelina coccidian.

Historical mammal extinction on Christmas Island (Indian Ocean) correlates with introduced infectious disease.

It is now widely accepted that novel infectious disease can be a leading cause of serious population decline and even outright extinction in some invertebrate and vertebrate groups (e.g., amphibians). In the case of mammals, however, there are still no well-corroborated instances of such diseases having caused or significantly contributed to the complete collapse of species. A case in point is the extinction of the endemic Christmas Island rat (Rattus macleari): although it has been argued that its disappearance ca. AD 1900 may have been partly or wholly caused by a pathogenic trypanosome carried by fleas hosted on recently-introduced black rats (Rattus rattus), no decisive evidence for this scenario has ever been adduced. Using ancient DNA methods on samples from museum specimens of these rodents collected during the extinction window (AD 1888-1908), we were able to resolve unambiguously sequence evidence of murid trypanosomes in both endemic and invasive rats. Importantly, endemic rats collected prior to the introduction of black rats were devoid of trypanosome signal. Hybridization between endemic and black rats was also previously hypothesized, but we found no evidence of this in examined specimens, and conclude that hybridization cannot account for the disappearance of the endemic species. This is the first molecular evidence for a pathogen emerging in a naïve mammal species immediately prior to its final collapse.