Polyphyletic origin, intracellular invasion, and meiotic genes in the putatively asexual agamococcidians (Apicomplexa incertae sedis).

Agamococcidians are enigmatic and poorly studied parasites of marine invertebrates with unexplored diversity and unclear relationships to other sporozoans such as the human pathogens Plasmodium and Toxoplasma. It is believed that agamococcidians are not capable of sexual reproduction, which is essential for life cycle completion in all well studied parasitic apicomplexans. Here, we describe three new species of agamococcidians belonging to the genus Rhytidocystis. We examined their cell morphology and ultrastructure, resolved their phylogenetic position by using near-complete rRNA operon sequences, and searched for genes associated with meiosis and oocyst wall formation in two rhytidocystid transcriptomes. Phylogenetic analyses consistently recovered rhytidocystids as basal coccidiomorphs and away from the corallicolids, demonstrating that the order Agamococcidiorida Levine, 1979 is polyphyletic. Light and transmission electron microscopy revealed that the development of rhytidocystids begins inside the gut epithelial cells, a characteristic which links them specifically with other coccidiomorphs to the exclusion of gregarines and suggests that intracellular invasion evolved early in the coccidiomorphs. We propose a new superorder Eococcidia for early coccidiomorphs. Transcriptomic analysis demonstrated that both the meiotic machinery and oocyst wall proteins are preserved in rhytidocystids. The conservation of meiotic genes and ultrastructural similarity of rhytidocystid trophozoites to macrogamonts of true coccidians point to an undescribed, cryptic sexual process in the group.

The Coccidia (Apicomplexa) of the Archosauria (Crocodylia: Eusuchia) of the World.

The order Crocodylia (suborder Eusuchia) includes 27 species of alligators, caimans, crocodiles, and gharials that are cosmopolitan in distribution, inhabiting subtropical and tropical locations. Numerous surveys (many of them trivial, with small sample sizes) have reported a wide variety of blood and intestinal apicomplexans from 17/27 (63%) crocodilian hosts, but neither a summation for the group nor a revisionary systematic approach to species evaluation has ever been provided. Herein, we summarize information on the 16 species of apicomplexans that we consider to be valid, including 8 Eimeria, 1 Haemogregarina (that eventually may be transferred to Hepatozoon), 4 Hepatozoon, 2 Isospora, and 1 Progarnia species. In addition, there are 46 apicomplexan forms that we have relegated to species inquirendae and/or only partially identified forms that await further study. We hope this review provides a foundation for future research between parasitologists and herpetologists on parasitism of all reptiles and their relatives. Since many apicomplexans seem to be reasonably host-specific, knowledge of shared species and/or genera may assist herpetologists to better understand the phylogenetic relationships among the New World crocodilians and the direction of their dispersal in the New World.

Ultrastructural analysis of Apicomplexa-Like parasites in two conch species Laevistrombus canarium and canarium urceus from Johor Straits, Malaysia.

The tropical conch, Laevistrombus canarium (Linnaeus, 1758) and Canarium urceus (Linneaus, 1758) are ecologically and economically important shellfish species in Malaysia and neighboring region. Their populations, however are currently declining and this histopathological study investigates the aspect of parasitism and diseases that may affect their well-being. Conch samples were randomly collected from their natural habitat and histological sections (4-5 µm) of various organs and tissues were examined under light microscope. This was followed by ultrastructure analysis on infected tissues using transmission electron microscope (TEM). Based on the histological analysis, large numbers of gamonts, sporocysts and trophozoites of Apicomplexa-like parasites were observed in the vacuolated cells and pyramidal crypt cells of the digestive tubules, and in the digestive ducts. Furthermore, coccidian and oocysts-like Pseudoklossia sp. stages were also observed in the cells of the kidney. Apart from that, spores with cyst-like structure were observed in the digestive gland and kidney. Although the parasites were present in most of the organs analyzed, there was no obvious symptom, inflammatory response or mortality incurred on both species, which implies the possibility of a non-virulent relationship like commensalisms or mutualism. However, more investigations, including molecular studies, are needed to confirm the parasite identification and dynamics, and to further evaluate the nature of relationship between Apicomplexa parasites and their host.

Induced Aberrant Organisms with Novel Ability to Protect Intestinal Integrity from Inflammation in an Animal Model.

Robust and balanced gut microbiota are required to support health and growth. Overgrowth of gut microbial or pathogens can change ecosystem balance, and compromise gut integrity to initiate gastrointestinal (GI) complications. There is no safe and effective modality against coccidiosis. Antibiotic additives routinely fed to food animals to protect against infection, are entered into the food chain, contaminate food products and pass to the consumers. HYPOTHESIS: induced aberrant organisms possess distinct ultrastructure and are tolerated by immunodeficient-animals yet are non-pathogenic, but immunogenic in various strains of chicks to act as a preventive (vaccine) and eliminating the needs for antibiotic additives. Methods: cyclophosphamide-immunodeficient and immune-intact-chicks were inoculated with induced aberrant or normal Coccidal-organisms. Immune-intact-chicks were immunized with escalating-doses of organisms. Results: Aberrant organisms showed distinct ultrastructure with 8-free-sporozoites which lacked sporocysts walls and veils. Immunodeficient-chicks inoculated with normal-organisms developed severe GI complications but tolerated aberrant-organisms (p < 0.001) while they had no detectable antibodies. Naïve-animals challenged with a pathogenic-dose showed GI complications, bloody diarrhea, severe lesions and weight loss. Immune-intact-animals immunized with aberrant forms were protected against high dose normal-pathogenic-challenge infection and gained more weight compared to those immunized with normal-organisms (p < 0.05). Conclusions: Aberrant organisms possess a distinct ultrastructure and are tolerated in immunodeficient-chicks, yet provide novel immune-protection against pathogenic challenges including diarrhea, malnutrition and weight loss in immune-intact-animals to warrant further investigations toward vaccine production.

Microscopic and molecular characterization of Hepatozoon domerguei (Apicomplexa) and Foleyella furcata (Nematoda) in wild endemic reptiles from Madagascar.

Madagascar is one of the world's top twelve "megadiversity" hot spots hosting unique and threatened flora and fauna. Parasites are a major component of biodiversity but remain largely uncharacterized in wildlife. In this study we combine microscopic and molecular assessment of hemoparasites in endemic reptile species from Madagascar. We detected three distinct parasites: the apicomplexans Hepatozoon and Sarcocystis, and filarial nematodes. The prevalence and intensity of these apicomplexans were low overall, while microfilarial infections in chameleons were relatively high. We detected mixed infections of two Hepatozoon haplotypes in Madagascarophis colubrinus, and of Hepatozoon and microfilariae in a Furcifer sp. Phylogenetic analyses of Hepatozoon showed evidence of prey-predator transmission, with identical sequences found in the snakes M. colubrinus and Ithycyphus oursi, and their prey Furcifer sp. Based on previous studies regarding the life cycle of Hepatozoon domerguei Landau, Chabaud, Michel, and Brygoo, 1970 in these hosts and due to their morphological similarity, we propose that this Hepatozoon haplotype is Hepatozoon domerguei. Future studies, including the examination of invertebrate hosts, are needed to verify this preliminary taxonomic identification. A distinct hemogregarine haplotype was found in Oplurus sp., which displayed morphologically different gametocytes, some of which were apparently inside leukocytes. The Sarcocystis identified from Tracheloptychus petersi was identical to that reported in a North African snake, indicating that the same lineage is found in geographically distinct regions. By combining morphological and genetic information, Foleyella furcata (Linstow, 1899) filarial nematodes were identified in several Furcifer chameleons. This study provides insights into the distribution, diversity and host-parasite interactions of hemoparasites in wild reptile populations from Madagascar.

Life cycle of Cystoisospora felis (Coccidia: Apicomplexa) in cats and mice.

Cystoisospora felis is a ubiquitous apicomplexan protozoon of cats. The endogenous development of C. felis was studied in cats after feeding them infected mice. For this, five newborn cats were killed at 24, 48, 72, 96, and 120 h after having been fed mesenteric lymph nodes and spleens of mice that were inoculated with C. felis sporulated sporocysts. Asexual and sexual development occurred in enterocytes throughout the villi of the small intestine. The number of asexual generations was not determined with certainty, but there were different sized merozoites. At 24 h, merogony was seen only in the duodenum and the jejunum. Beginning at 48 h, the entire small intestine was parasitized. At 24 h, meronts contained 1-4 zoites, and at 48 h up to 12 zoites. Beginning with 72 h, the ileum was more heavily parasitized than the jejunum. At 96 and 120 h, meronts contained many zoites in various stages of development; some divided by endodyogeny. The multiplication was asynchronous, thus both immature multinucleated meronts and mature merozoites were seen in the same parasitophorous vacuole. Gametogony occurred between 96 and 120 h, and oocysts were present at 120 h. For the study of the development of C. felis in murine tissues, mice were killed from day 1 to 720 d after having been fed 10(5) sporocysts, and their tissues were examined for the parasites microscopically, and by bioassay in cats. The following conclusions were drawn. (1) Cystoisospora felis most frequently invaded the mesenteric lymph nodes of mice and remained there for at least 23 mo. (2) It also invaded the spleen, liver, brain, lung, and skeletal muscle of mice, but division was not seen based on microscopical examination. (3) This species could not be passed from mouse to mouse.

First report of Hepatozoon (Apicomplexa: Adeleorina) in caecilians, with description of a new species.

Hepatozoon spp. are identified for the first time in the amphibian order Gymnophiona, or caecilians, from the Seychelles island of Silhouette. Estimate of relationships derived from partial 18S rRNA gene sequences indicate these are not related to Hepatozoon spp. from frogs or to other Hepatozoon spp. from reptiles in the Seychelles. Assessment of mature gamonts from blood smears indicate that these can be recognized as a new species, Hepatozoon seychellensis n. sp.

Pfeifferinella sp. (Pfeifferinellidae, Apicomplexa) infecting the fresh water snail Pirenella conica light and electron microscope studies.

Coccidian oocysts were proved to be found in 70 of 100 collected Pirenella conica snails, with a natural infection of 70%. It was observed that, Pfeifferinella sp. was transferred between hepatopancreas and small intestine of snail. The prepatent period of Pfeifferinella sp. infecting P. conica snails ranged from 14-18 days and the patent period was reached 50 days (P.I.). Merogony stages were the early stages observed in this study. These stages were observed in the hepatopancreas and in a large clear parasiteophorous vacuole (PV). In snails killed 4 days P.I. immature meronts were measured 12 x 10 µm containing 8 nuclei. Meanwhile, mature meronts with about 6 differentiated merozoites were detected as early as 6 days P.I., and measured 3.1 x 1.4 µm. The earliest gametogonic stages were seen in the intestine of Pirenella conica snails killed 12 days P.I. Microgamonts contained about 4 nuclei and measured 7.9 x6.7 µm. The macrogamonts measured 7.3 x 5.6 µm. Macrogametes were characterized by the presence of the vaginal tube, this tube measured 4.3 x 1.1 µm. Fertilization was occurred in the intestine of the infected snails at 12 days P.I. Zygotes developed into young oocysts after fertilization. Sporogony occurred in the intestine. In the earliest stage, the nucleus of young oocyst was occupied the central position that were observed through the examination of the intestine of infected Pirenella snails at 14 day P.I. These oocysts were found to be colorless and ellipsoid or spherical in shape measured 9.5 x 8.5 µm. The oocyst wall consists of two layers, micropyle and micropyle cap were not observed in these oocysts, and wall forming bodies were arranged at the periphery of oocyst directly under the developed oocyst wall. Sporulated oocyst contains 8 sporozoites filling the entire cavity of the oocyst without sporocyst formation. Fully sporulated oocysts were excreted in the faces of infected snails from 14-18 day P.I., these oocysts measured 9.5 x 8.5 µm, Micropyle was absent and while a residual body was observed.

Description of three new species of Hepatozoon (Apicomplexa, Hepatozoidae) from Rattlesnakes (Crotalus durissus terrificus) based on molecular, morphometric and morphologic characters.

Hepatozoon spp. are commonly found infecting snakes. Since the latter are parasitized by diverse forms and data in the literature show divergence, we studied Hepatozoon spp. diversity on Crotalus durissus terrificus snakes using both molecular and morphological approaches. Naturally infected animals were employed. Blood was collected, blood smears were prepared and an aliquot was stored at -20°C for DNA extraction. Five specimens of C. durissus terrificus were selected, each of them infected with one gamont type. Morphological and morphometric analyses of the found gamonts led to their grouping into three populations. For molecular characterization, seven oligonucleotide pairs that amplify distinct regions of rDNA gene were tested by adopting the PCR technique. Only the oligonucleotide pairs HepF300/Hep900 and HEMO1/HEMO2 were efficient in amplifying and distinguishing different isolates of Hepatozoon spp. from snakes. The better results were obtained when both oligonucleotide pairs were used in association. Based on the molecular and morphologic differences, three new species were proposed: Hepatozoon cuestensis sp. nov.; Hepatozoon cevapii sp. nov. and Hepatozoon massardii sp. nov. This is the first description of new Hepatozoon species from snakes, based on molecular characterization and morphological data, in South America.

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 Haemocystidium (Apicomplexa: Plasmodiidae) species of the dhub lizard, Uromastyx aegyptia microlepis , in Abu Dhabi, distinguished by the absence of pigment.

The spiny-tailed lizard, Uromastyx aegyptia microlepis , in Abu Dhabi is parasitized by Haemocystidium apigmentada n. sp., and 2 species of Hepatozoon . The elongate gametocytes of H. apigmentada are 13-19 × 6-9 µm, with length × width (LW) 90-133 µm(2), and L/W ratio 1.56-3.17. Gametocyte dimensions do not differ by sex. Gametocytes are unpigmented. Hepatozoon species 1 has gamonts with a consistently terminal nucleus, with dimensions of 13-16 × 4.5-7 µm, LW of 58-104 µm(2), and L/W ratio of 2.00-3.22. Hepatozoon species 2 gamonts have a broad nucleus at the midbody, and dimensions of 13-15.5 × 5-7 µm, LW of 71-109 µm(2), and L/W ratio of 1.93-3.00.

Light and transmission electron microscopic characteristics of a novel Hepatozoon spp. in naturally infected cotton rats (Sigmodon hispidus).

A novel species of Hepatozoon was recently reported in cotton rats (Sigmodon hispidus) collected from an area of Oklahoma where American canine hepatozoonosis is endemic. In this study, the various stages of merogony of the parasite were characterized by light and electron microscopy. Meronts occurred within parasitophorous vacuoles in hepatocytes and ranged from mononucleated spherical forms to large, mature forms in vacuoles that contained approximately 50 peripherally arranged merozoites. Developing merozoites had characteristic apicomplexan organelles, including anterior and posterior polar rings, a conoid, microtubules, rhoptries, micronemes, and a trilaminar membrane. As the meronts matured, numerous curvilinear merozoites budded from a residual body. This morphologic characterization extends our understanding of this novel Hepatozoon and adds information about the hepatozoa, apicomplexan parasites that infect numerous species.

Parasitological and molecular features of the Hepatozoon species in the myocardium of Japanese Martens (Martes melampus melampus).

The Hepatozoon species in the myocardium of Japanese martens (Martes melampus melampus) was characterized by histological and molecular methods. Histologically, granulomatous nodules with Hepatozoon sp. merozoites/gametocytes, or schizonts, or both were observed in the hearts of Japanese martens. The most frequently observed forms were merozoites/gametocytes within phagocytes; each host cell included a zoite, which was not microscopically identifiable as a merozoite or gametocyte. Schizonts were oval in shape and 36.9 ± 5.7 x 28.9 ± 3.4 µm in size; each schizont had approximately 20-60 nuclei. The size of the merozoites could not be measured because no mature schizonts were observed. In the analyses of the partial 18S rRNA gene sequence, it was strongly suggested that the Hepatozoon sp. in Japanese marten and the Hepatozoon sp. in pine marten (Martes martes) in Scotland were the same species.

Hepatozoon ursi n. sp. (Apicomplexa: Hepatozoidae) in Japanese black bear (Ursus thibetanus japonicus).

Morphological and genetic features of a new Hepatozoon species, Hepatozoon ursi n. sp., in Japanese black bear (Ursus thibetanus japonicus) were studied. Schizogonic developmental stages were observed in the lungs of Japanese black bears. The schizonts were sub-spherical in shape and 45.7+/-4.6 x 42.7+/-4.5 microm in size. Each mature schizont contained approximately 80-130 merozoites and 0-5 residual bodies. The merozoites were 7.0+/-0.7 x 1.8+/-0.3 microm in size. Intraleukocytic gametocytes were slightly curved, cigar-like in shape and had a beak-like protrusion at one end. The size of the gametocytes was 10.9+/-0.3 x 3.3+/-0.2 microm. The analyses of the18S rRNA gene sequences supported the hypothesis that H. ursi n. sp. is different from other Hepatozoon species. Mature Hepatozoon oocysts were detected in two species of ticks (Haemaphysalis japonica and Haemaphysalis flava) collected on the bears infected with H. ursi n. sp. Two measured oocysts were 263.2 x 234.0 microm and 331.8 x 231.7 microm, respectively. The oocysts contained approximately 40 and 50 sporocysts, respectively. The sporocysts were sub-spherical in shape and 31.2+/-2.5 x 27.0+/-2.9 microm in size. Each sporocyst contained at least 8-16 sporozoites, with the sporozoites being 12.2+/-1.4 x 3.5+/-0.5 microm in size. H. ursi n. sp. is the first Hepatozoon species recorded from the family Ursidae.

New exogenous stages of oocysts, sporocysts, and sporozoites of Goussia cichlidarum Landsberg and Paperna 1985 (Sporozoa: Coccidia) and impact of endogenous stages on the swim bladder of tilapias in Egypt.

Obviously, the present study reports the coccidian parasite so-called Goussia cichlidarum for the first time in Egypt. Altogether, 25 exogenous stages were clearly distinguished from specimens of naturally infected fishes of Oreochromis niloticus, O. auraeus, and Tilapia zillii from different locations. The total prevalence of infection was about 41%. Mostly, infected fish grossly seemed with a healthy body, although severe lesions have been detected microscopically in massive infection. Portions of thick wall swim bladder have been placed in vitro. The released parasitic stages have been photographed, sketched, measured, described, and compared with previously described species. Oocysts, sporocysts, and sporozoites have also been differentiated morphologically and morphometrically. Maturity stages of sporozoites containing sporocysts within either an oocyst or those released and sporulated outside the oocyst were considerably discernible. In addition, endogenous stages have also been investigated in histological sections included gamonts, merozoites, oocysts, and different stages of sporozoites.

Potential environmental and host gender influences on prevalence of Haemogregarina platessae (Adeleorina:Haemogregarinidae) and suspected Haemohormidium terraenovae (incertae sedis) in Brazilian flounder from the Patos Lagoon Estuary, southern Brazil.

Flounder, Paralichthys orbignyanus (Valenciennes), were captured in polluted and non-polluted sites within the Patos Lagoon Estuary, southern Brazil, over four seasons. Blood films showed a high prevalence of infection with a haemogregarine, or mixed parasitaemias of this and an organism resembling Haemohormidium terraenovae So, 1972. Haemogregarine gamont stages conformed to existing descriptions of Desseria platessae (Lebailly, 1904) Siddall, 1995 from flatfishes, but intraerythrocytic division of meronts was observed, leading to the recommendation for nomenclatural correction, placing the haemogregarine in the genus Haemogregarina (sensu lato) Danilewsky, 1885. Statistical analyses suggested that although sample sizes were small, infections with meront stages, immature and mature gamonts were all influenced by site, and possibly therefore, by pollution. Season also appeared to determine likelihood of infection with meronts and immature gamonts, but not mature gamonts, while adult fish gender apparently affected infection with immature and mature gamonts, but not meronts. The H. terraenovae-like organism exhibited unusual extracellular forms and did not match closely with the type description of H. terraenovae; precise identification was therefore difficult. Data analyses suggested that parasitism by this organism was influenced by site and fish gender, since females and males from non-polluted water were infected, but only females from the polluted site. Season was also important and significantly more adult fish of both sexes were infected with this parasite in the Brazilian summer and autumn, compared with winter and spring. Finally, these appeared to be the first observations of Haemogregarina platessae, and possibly H. terraenovae, from the southern hemisphere.

Studies on besnoitiosis bennetti in miniature donkeys.

Besnoitia tissue cysts associated with the skin lesions recovered from the naturally-infected miniature donkeys (Equus asinus) during clinical examination were studied by the light and electron microscopy, as well as histochemically to elucidate the specific morphologic features of the cyst causing this disease. The cyst was differentiated phenotypically from those of other Besnoitia spp. The interpretation of results showed that morphometric attributes of the tissue cysts and the associated pathological changes in these donkeys were due to B. bennetti infection. The findings were confirmed by the phylogenetic analysis based on DNA sequences of the first internal transcribed spacer of nuclear rDNA. The cluster analysis showed that B. bennetti was distinct from all other Besnoitia spp. and positioned B. bennetti with parasites described from Besnoitia besnoiti of cattle and B. tarandi of reindeer. The genetic attributes complemented the morphological criteria and verified the accurate delimitation of the Besnoitia cysts isolated from these donkeys.

Klossiella quimrensis (Apicomplexa: Klossiellidae) causes renal coccidiosis in western barred bandicoots Perameles bougainville (Marsupialia: Peramelidae) in Western Australia.

Previous studies have described a range of Klossiella species parasitic in marsupial hosts. Klossiella quimrensis is the etiologic agent of renal coccidiosis in the peramelid marsupial hosts Isoodon obesulus and Perameles gunnii in Eastern Australia, but there is no previous report of klossiellosis in Western Australian peramelids. This study describes klossiellosis diagnosed by histology of renal tissue sections collected during necropsy of 20 Perameles bougainville between 2000 and 2005. Sporonts, sporoblasts, and macrogametes were identified within parasitophorous vacuoles of epithelial cells located near the renal corticomedullary junction. The prevalence of renal coccidiosis in P. bougainville diagnosed by renal histology is estimated at 30%. Only a single unsporulated sporocyst was detected by examination of cystocentesis-collected urine, indicating that microscopic evaluation of urine samples is an insensitive diagnostic test for detection of K. quimrensis in P. bougainville. This infection in P. bougainville is indirectly associated with mild multifocal interstitial lymphohistiocytic nephritis and is likely to be only minimally pathogenic in otherwise healthy individuals. Our study also extends the host and geographic range of K. quimrensis to include P. bougainville and Western Australia.

Morphological and ultrastructural redescription of Calyptospora serrasalmi Cheung, Nicrelli & Ruggieri, 1986 (Apicomplexa: Calyptosporidae), a parasite found in two new host species of the genus Serrasalmus

Coccidians are pathogenic protoparasites found in various fish species. In this report, we used light and electron microscopy to study the morphological and ultrastructural features of Calyptospora serrasalmi, a coccidian parasite found to parasitize two additional species of the teleostean genus Serrasalmus, S. striolatus and S. rhombeus, from the Amazon river and the lagoonal region of Recife, Brazil, respectively. Infection involved only the liver parenchyma, with the coccidians occurring as isolated oocysts or in clusters of up to 40-50 oocysts encapsulated by a layer of connective tissue. Several life cycle stages were observed in the same section, with oocysts being the most evident. Each spherical oocyst (~25.5 um in diameter) contained four sporocysts, each surrounded by a thin membranous veil. The sporocysts were pear-shaped (11.8x6.0 um) with an attached apical sporopodium that had several small lateral projections (up to 0.5 um long). These small projections were formed by the same material as the sporocyst wall and were distributed over the basal portion of the wall in 10-12 longitudinal series. The sporocysts lacked a Stieda body and contained two vermiform sporozoites. Calyptospora serrasalmi was distinguishable from previously described species on the basis of sporocyst morphology.

Light and transmission electron microscopic studies of a haemogregarine in naturally infected fan-footed gecko (Ptyodactylus hasselquistii).

The present study focuses on and describes the developmental stages of a haemogregarine species in the blood and tissues of the gecko Ptyodactylus hasselquistii. The blood stages were differentiated into two forms: a short gamont measuring 11.87 x 6.42 microm and a banana-shaped mature gamont measuring 14.13 x 10.03 microm in length and width, respectively. Both erythrocytes and leucocytes had been invaded. The parasitaemia level is up to 410 per 10,000 erythrocytes counted. The gamont has a karyolytic effect on the host cell nucleus. Merogony occurred in the parenchyma cells of liver and the endothelial cells of the lung. The meronts in the lung were found in two forms: the micromeront measured 14.93x13.14 microm and produced a few numbers (average 4) of macromerozoites. The macromeront measured 26.3 x 16 microm and produced more small-sized merozoites (average 11.5), or micromerozoites. On the ultrastructural level, merozoites have a pellicle, which consists of an outer and inner membrane. The merozoites are nearly identical to the blood stages of the parasite.