Hemolivia species infecting Central American wood turtles (Rhinoclemmys pulcherrima manni) and problems with differential diagnosis within the genus Hemolivia

Blood parasites of the genus Hemolivia Petit, Landau, Baccam and Lainson, 1990 (Adeleorina: Karyolysidae) are hemogregarines of ectothermic vertebrates, such as lizards, chelonians, and toads. Only five species of Hemolivia from vertebrate hosts and one from their tick vector have been described so far. In the present study, Central American wood turtles (Rhinoclemmys pulcherrima manni) originating from Southern Nicaragua were screened for the presence of hemogregarines. Ten out of 30 specimens (33.3%) were positive for Hemolivia using both approaches - microscopy and PCR-based analyses. Phylogenetic analyses based on the 18S rRNA gene revealed the presence of two haplotypes, both placed as sister taxa in the Hemolivia clade. Their phylogenetic position was supported by high bootstrap values and high posterior probabilities, suggesting that there are at least two new distinct haplotypes corresponding to two distinct species. However, the specimens of each haplotype were microscopically indistinguishable from each other based on the gamont morphology, therefore, only a single species could be described and named, as Hemolivia pulcherrima n. sp. We consider that the uniform morphology of the most common blood stages of species of the genus Hemolivia complicates their differential diagnosis. Sequence divergence and different host spectra, therefore, remain the only differentiating tools.

Genetic diversity, phylogenetic position, and co-phylogenetic relationships of Karyolysus, a common blood parasite of lizards in the western Mediterranean

The genus Karyolysus was originally proposed to accommodate blood parasites of lacertid lizards in Western Europe. However, recent phylogenetic analyses suggested an inconclusive taxonomic position of these parasites of the order Adeleorina based on the available genetic information. Inconsistencies between molecular phylogeny, morphology, and/or life cycles can reflect lack of enough genetic information of the target group. We therefore surveyed 28 localities and collected blood samples from 828 lizards of 23 species including lacertids, skinks, and geckoes in the western Mediterranean, North Africa, and Macaronesia, where species of Karyolysus and other adeleorine parasites have been described. We combined molecular and microscopic methods to analyze the samples, including those from the host type species and the type locality of Karyolysus bicapsulatus. The phylogenetic relationship of these parasites was analyzed based on the 18S rRNA gene and the co-phylogenetic relationship with their vertebrate hosts was reconstructed. We molecularly detected adeleorine parasites in 37.9% of the blood samples and found 22 new parasite haplotypes. A phylogenetic reconstruction with 132 sequences indicated that 20 of the newly detected haplotypes clustered in a well-supported clade with another 18 sequences that included Karyolysus galloti and Karyolysus lacazei. Morphological evidence also supported that K. bicapsulatus clustered in this monophyletic clade. These results supported the taxonomic validity of the genus. In addition, we found some parasite haplotypes that infected different lizard host genera with ancient diverging histories, which suggested that Karyolysus is less host-specific than other blood parasites of lizards in the region. A co-phylogenetic analysis supported this interpretation because no significant co-speciation signal was shown between Karyolysus and lizard hosts.

Haemogregarine of Genus Dactylosoma (Adeleorina: Dactylosomatidae) in Species of Rhinella (Anura: Bufonidae) from the Brazilian Amazon

PURPOSE

The present study aims to record the occurrence of a haemogregarine of the genus Dactylosoma in anurans in the eastern Brazilian Amazon.

METHODS

Specimens of Leptodactylus macrosternum, Rhinella major, and Rhinella marina were collected in the municipality of Santarém, west of the State of Pará, in Brazil. Parasitic forms identified as Dactylosoma sp. were recorded by light microscopy, with magnification of 400 and 1000 X.

RESULTS

Aspects about the morphology and morphometry of Dactylosoma sp. are presented. The mean intensity of infection was 200,000 parasites/mL in R. major and 50,000 parasites/mL in R. marina.

CONCLUSION

The present study expands the occurrence of parasites of the genus Dactylosoma in Brazil, presenting a new anuran host for this parasite in the Brazilian Amazon region.

First molecular detection of Hemolivia and Hepatozoon parasites in reptile-associated ticks on Iriomote Island, Japan

Hepatozoon and Hemolivia are members of the haemogregarines and are reported in reptiles and reptile-associated ticks. However, no studies have reported on Hepatozoon and Hemolivia in Japanese reptile-associated ticks. This study aimed to molecularly identify and to characterize Hepatozoon and Hemolivia in Japanese reptile-associated ticks, Amblyomma geoemydae (Cantor, 1847) and Amblyomma nitidum (Hirst & Hirst, 1910). A total of 41 and 75 DNA samples from A. geoemydae and A. nitidum ticks, respectively, were used for screening of Hepatozoon and Hemolivia with polymerase chain reaction targeting 18S rDNA. As a result, Hemolivia and Hepatozoon were detected in two A. geoemydae and one A. nitidum, respectively. The sequences of Hemolivia spp. showed a 99.5% (1,050/1,055 bp) identity with Hemolivia parvula (KR069083), and the Hemolivia spp. were located in the same clade as H. parvula in the phylogenetic tree. The sequences of Hepatozoon sp. showed a 98.4% (1,521/1,545 bp) identity with Hepatozoon colubri (MN723844), and the Hepatozoon sp. was distinct from validated Hepatozoon species in the tree. Our findings highlight the first molecular record of Hemolivia in Japan and present the first detection of Hepatozoon in A. nitidum. Further investigations on these tick-borne protozoa are required to understand their life cycle and pathogenicity.

Haemogregarines and Criteria for Identification

Simple Summary

Taxonomic classification of haemogregarines belonging to Apicomplexa can become difficult when the information about the life cycle stages is not available. Using a self-reporting, we record different haemogregarine species infecting various animal categories and exploring the most systematic features for each life cycle stage. The keystone in the classification of any species of haemogregarines is related to the sporogonic cycle more than other stages of schizogony and gamogony. Molecular approaches are excellent tools that enabled the identification of apicomplexan parasites by clarifying their evolutionary relationships.

Abstract

Apicomplexa is a phylum that includes all parasitic protozoa sharing unique ultrastructural features. Haemogregarines are sophisticated apicomplexan blood parasites with an obligatory heteroxenous life cycle and haplohomophasic alternation of generations. Haemogregarines are common blood parasites of fish, amphibians, lizards, snakes, turtles, tortoises, crocodilians, birds, and mammals. Haemogregarine ultrastructure has been so far examined only for stages from the vertebrate host. PCR-based assays and the sequencing of the 18S rRNA gene are helpful methods to further characterize this parasite group. The proper classification for the haemogregarine complex is available with the criteria of generic and unique diagnosis of these parasites.

Distribution modeling of Amblyomma rotundatum and Amblyomma dissimile in Brazil: estimates of environmental suitability

The number of reports of tick parasitism in amphibians and reptiles has increased over the past few years, including new host and location records for Amblyomma rotundatum and Amblyomma dissimile. However, knowledge of the geographical distribution remains incomplete, and in many regions of Brazil, the presence of these vectors has not been investigated. Several candidate models were built using a correlative maximum entropy approach, and best-fitting models were selected based on statistical significance, predictive ability, and complexity based on current climatic trends and future projected climate changes. Final models showed a good ability to discriminate A. rotundatum and A. dissimile current and future potential distributions. The entire country had higher predicted suitability for A. rotundatum while A. dissimile was mainly restricted to the Amazon and Pantanal biomes. A. rotundatum is a species with enormous potential for dissemination in the next decades, potentially through the legal and illegal transport of reptiles and amphibians. The proposed model is useful for targeting surveillance efforts increasing the efficiency and accuracy of future ecological research and tick management efforts.

Relationship between oxidative stress and sexual coloration of lizards depends on thermal habitat

Sexual signals serve as an honest indicator of individual quality, reflecting either developmental and/or maintenance costs. A possible underlying physiological mechanism is oxidative stress, which could mediate energy trade-offs between sexual signals and other quality traits. In ectotherms, thermal performance acts as a key indicator of individual quality and influence signal intensity. We investigated how oxidative state is reflected in visual signals of lizards from different thermal habitats. According to our hypothesis, efficient thermoregulation requires different strategies in different thermal environments. In a habitat with predictable temperature changes, animals are less exposed to suboptimal temperature ranges and selection will, therefore, be stronger on the maximum oxidative damage at optimal body temperature. Contrarily, in a habitat with rather stochastic thermal shifts, individuals are often constricted by suboptimal thermal conditions, and oxidative damage can be limiting on a wide temperature range. We used Iberolacerta cyreni and Psammodromus algirus inhabiting stochastic and predictable thermal environments respectively. We examined two aspects of oxidative stress: the level of reactive oxygen metabolites at the preferred temperature (maximal ROM) and the temperature range in which animals produce at least 80% of the maximum level of reactive oxygen metabolites (effective ROM range). In I. cyreni, we found that duller coloration was related to a wider effective ROM range, while expression of coloration in P. algirus was negatively correlated with the maximal ROM. Our results suggest that different thermal constraints affect different aspects of oxidative damage which can indicate individual quality and are, therefore, represented in sexual ornaments.

Hemogregarine and Rickettsial infection in ticks of toads from northeastern Colombia

The toads Rhinella spp. are in constant contact with humans and domestic animals and are commonly parasitized by ticks, which are also potential vectors of pathogenic microorganisms, such as apicomplexans and rickettsia. However, little is known about microorganisms associated with toad ticks. In this work, we molecularly evaluated the presence of Rickettsia spp. and hemogregarines in ticks of Rhinella horribilis and R. humboldti in the Colombian Caribbean, finding two different species of Rickettsia: the colombianensi strain and one close to R. bellii. In the case of hemogregarines, since only 18S gene sequences are available, it is difficult to define species and place them correctly in a phylogeny, but most of our samples show a 99% identity with Hemolivia stellata, while others identical to each other seem to form another clade within this genre. All collected ticks were identified as Amblyomma dissimile, representing the first time that H. stellata was recorded in this tick. The prevalence of both microorganisms was very high, which makes it necessary to generate robust phylogenies to clarify their taxonomic diversity and to correctly define their ecological role and pathogenicity, which should be taken into account in amphibian conservation plans and veterinary medicine.

Molecular and morphological characterization of a haemogregarine in the alligator snapping turtle, Macrochelys temminckii (Testudines: Chelydridae)

A severely underweight alligator snapping turtle Macrochelys temminckii Troost in Harlan, 1835, was found near Tyler, Texas, and taken to the Caldwell Zoo. Blood films were submitted to Texas A&M University, College Station, Texas, for morphological and molecular identification of haemogregarine-like inclusions in the red blood cells. Intraerythrocytic Haemogregarina sp. forms were found on microscopic examination at a parasitemia of <1 %. The morphology and morphometric data for the forms indicate similarity to Haemogregarina macrochelysi n. sp. Telford et al., 2009, previously reported in alligator snapping turtles in Florida and Georgia, but two characteristic stage forms were not shared between H. macrochelysi n. sp. and the parasite found in this report. The haemogregarine 18S ribosomal RNA gene (1555-bp fragment) was amplified and cloned, and five clones sequenced. The sequences were deposited in the NCBI GenBank database. All five showed ∼96 % identity to Haemogregarina balli Paterson and Desser, 1976, Hepatozoon sp., and Hemolivia stellata Petit et al., 1990. A 774-bp segment shared 98-99 % identity with the corresponding Haemogregarina sp. rDNA sequence (KR006985) from Caspian turtles (Mauremys caspica McDowell, 1964) in Iran. A neighbor-joining phylogenetic tree generated from aligned sequences from the clones, 26 hematozoa, Adelina dimidiata Schneider, 1875, and Cryptosporidium serpentis Levine, 1980, revealed the cloned sequences clustered on their own branch within the Haemogregarina spp. clade. No genetic data are available for H. macrochelysi n. sp. at this time, so it remains unclear if this parasite in a Texas alligator snapping turtle is conspecific with H. macrochelysi n. sp.

Morphological and molecular characterisation of Haemogregarina sp. (Apicomplexa: Adeleina: Haemogregarinidae) from the blood of the Caspian freshwater turtle Mauremys caspica (Gmelin) (Geoemydidae) in Iran

To date, a number of species of Haemogregarina have been described from different turtle hosts, mainly based on the morphology of the developmental stages detected in the host erythrocytes. The diversity and overlapping morphological features in the old and recent descriptions has led to considerable complications in the taxonomy of Haemogregarina spp. In this study, different stages of maturity and developing gamonts of a putative new species of Haemogregarina were detected in erythrocytes of the Caspian turtle Mauremys caspica (Gmelin) (Geoemydidae) originating from a southern province in Iran. Although some of the morphological characteristics were consistent with Haemogregarina stepanowi Danilewsky, 1885, some new observations were made, particularly in the gamont stage. The phylogenetic analysis based on 18S rDNA sequences revealed that the present isolate appears as basal to a large clade of Haemogregarina spp. with sequences available in the GenBank database. In accordance with the phylogenetic results, the present Iranian isolate showed a higher degree of interspecific divergence (up to 3.3%) compared to the data for the taxa available in the GenBank database. Thus, molecular data indicate that this isolate may represent a new species. However, further genetic analyses are needed as a complementary tool to the morphological characterisation in order to elucidate the phylogenetic relationships of Haemogregarina spp.

Systematic revision of the adeleid haemogregarines, with creation of Bartazoon n. g., reassignment of Hepatozoon argantis Garnham, 1954 to Hemolivia, and molecular data on Hemolivia stellata

Life cycles and molecular data for terrestrial haemogregarines are reviewed in this article. Collection material was re-examined: Hepatozoon argantis Garnham, 1954 in Argas brumpti was reassigned to Hemolivia as Hemolivia argantis (Garnham, 1954) n. comb.; parasite DNA was extracted from a tick crush on smear of an archived slide of Hemolivia stellata in Amblyomma rotondatum, then the 18S ssrRNA gene was amplified by PCR. A systematic revision of the group is proposed, based on biological life cycles and phylogenetic reconstruction. Four types of life cycles, based on parasite vector, vertebrate host and the characteristics of their development, are defined. We propose combining species, based on their biology, into four groups (types I, II, III and IV). The characters of each type are defined and associated with a type genus and a type species. The biological characters of each type are associated with a different genus and a type species. The phylogenetic reconstruction with sequences deposited in the databases and our own new sequence of Hemolivia stellata is consistent with this classification. The classification is as follows: Type I, Hepatozoon Miller, 1908, type species H. perniciosum Miller, 1908; Type II, Karyolysus Labbé, 1894, type species K. lacertae (Danilewsky, 1886) Reichenow, 1913; Type III Hemolivia Petit et al., 1990, type species H. stellata, Petit et al., 1990; and Type IV: Bartazoon n. g., type species B. breinli (Mackerras, 1960).

Patterns of parasitism by Amblyomma rotundatum (Ixodidae) on Rhinella schneideri (Bufonidae) in islands of São Francisco River, Minas Gerais, Brazil

Abstract: We sampled ticks from specimens of the rococo toad Rhinella schneideriby flannel dragging on two Islands located in the São Francisco River near the Três Marias hydroelectric dam, southeastern Brazil. A total of 120 toads was examined, of which 63 (52.5%) were parasitized only by Amblyomma rotundatumtotaling 96 larvae, 163 nymphs and 134 females. The burden of parasitism ranged from one to 43 ticks, with a mean intensity of infestation of 6.2±5.5 ticks per host. The tick A. rotundatumexhibited highly aggregated distribution. Peak abundance of larvae and nymphs occurred in the dry season (May to September), whereas peak abundance of females occurred in the wet season (October to April). We collected most ticks near the head and hind limbs of R. schneideri. The finding of two engorged A. rotundatumnymphs in the same resting places of two toads and the absence of this species in the dragged areas suggest a nidicolous behavior at the studied site.

Reassignment of the land tortoise haemogregarine Haemogregarina fitzsimonsi Dias 1953 (Adeleorina: Haemogregarinidae) to the genus Hepatozoon Miller 1908 (Adeleorina: Hepatozoidae) based on parasite morphology, life cycle and phylogenetic analysis of 18S rDNA sequence fragments

SUMMARY Research was undertaken to clarify the true taxonomic position of the terrestrial tortoise apicomplexan, Haemogregarina fitzsimonsi (Dias, 1953). Thin blood films were screened from 275 wild and captive South African tortoises of 6 genera and 10 species between 2009-2011. Apicomplexan parasites within films were identified, with a focus on H. fitzsimonsi. Ticks from wild tortoises, especially Amblyomma sylvaticum and Amblyomma marmoreum were also screened, and sporogonic stages were identified on dissection of adult ticks of both species taken from H. fitzsimonsi infected and apparently non-infected tortoises. Parasite DNA was extracted from fixed, Giemsa-stained tortoise blood films and from both fresh and fixed ticks, and PCR was undertaken with two primer sets, HEMO1/HEMO2, and HepF300/HepR900, to amplify parasite 18S rDNA. Results indicated that apicomplexan DNA extracted from tortoise blood films and both species of tick had been amplified by one or both primer sets. Haemogregarina  fitzsimonsi 18S rDNA sequences from tortoise blood aligned with those of species of Hepatozoon, rather than those of species of Haemogregarina or Hemolivia. It is recommended therefore that this haemogregarine be re-assigned to the genus Hepatozoon, making Hepatozoon fitzsimonsi (Dias, 1953) the only Hepatozoon known currently from any terrestrial chelonian. Ticks are its likely vectors.

New host records for Amblyomma rotundatum (Acari: Ixodidae) from Grussaí restinga, Rio de Janeiro, Brazil

Amblyomma rotundatum Koch is a parthenogenetic tick usually associated with reptiles and amphibians. However, relatively few studies on occurrences of ticks in wild reptile populations in Brazil have been produced. The aim of this study was to analyze the presence of ticks associated with reptile species in the Grussaí restinga, in the municipality of São João da Barra, state of Rio de Janeiro, Brazil. Between December 2010 and January 2011, 131 individuals belonging to nine species of reptiles of the order Squamata were sampled: the lizards Tropidurus torquatus (n = 51), Hemidactylus mabouia (n = 25), Mabuya agilis (n = 30), Mabuya macrorhyncha (n = 6), Cnemidophorus littoralis (n = 5) and Ameiva ameiva (n = 10); and the snakes Philodryas olfersii (n = 2), Oxyrhopus rhombifer (n = 1) and Micrurus corallinus (n = 1). The only tick species found to be associated with any of the reptiles sampled was A. rotundatum. One adult female was detected on one individual of the lizard A. ameiva, one nymph on one individual of the lizard T. torquatus and four nymphs on one individual of the snake P. olfersii. This study is the first record of parasitism of A. rotundatum involving the reptiles T. torquatus and P. olfersii as hosts. Our results suggest that in the Grussaí restinga habitat, A. rotundatum may use different species of reptiles to complete its life cycle.

Negative correlation between nuptial throat colour and blood parasite load in male European green lizards supports the Hamilton-Zuk hypothesis

During female mate choice, conspicuous male sexual signals are used to infer male quality and choose the best sire for the offspring. The theory of parasite-mediated sexual selection (Hamilton-Zuk hypothesis) presumes that parasite infection can influence the elaboration of sexual signals: resistant individuals can invest more energy into signal expression and thus advertise their individual quality through signal intensity. By preferring these males, females can provide resistance genes for their offspring. Previous research showed that nuptial throat colour of male European green lizard, Lacerta viridis, plays a role in both inter- and intrasexual selections as a condition-dependent multiple signalling system. The aim of this study was to test the predictions of the Hamilton-Zuk hypothesis on male European green lizards. By blood sampling 30 adult males during the reproductive season, we found members of the Haemogregarinidae family in all but one individual (prevalence = 96%). The infection intensity showed strong negative correlation with the throat and belly colour brightness in line with the predictions of the Hamilton-Zuk hypothesis. In addition, we found other correlations between infection intensity and other fitness-related traits, suggesting that parasite load has a remarkable effect on individual fitness. This study shows that throat patch colour of the European green lizards not only is a multiple signalling system but also possibly acts as an honest sexual signal of health state in accordance with the Hamilton-Zuk hypothesis.

Life cycle and behavior of Amblyomma rotundatum (Acari: Ixodidae) under laboratory conditions and remarks on parasitism of toads in Brazil

The life cycle and behavior of Amblyomma rotundatum were evaluated under laboratory conditions. The experiment started with four engorged females collected from toads (Rhinella schneideri) naturally infested at the Pirapitinga Ecological Station in the state of Minas Gerais, Brazil. Developmental periods of free-living stages were assessed in an incubator at 27 ± 1 °C, >80 % RH and darkness. The complete life cycle, including pre-attachment periods for each parasitic stage, ranged from 126 to 228 days. The pre-attachment, feeding and molting periods increased as the life cycle progressed from larva to adult female. Oviposition lasted about 20 days, with the peak occurring on days 4 and 5. Longevity of nymphs and adult females was quite similar (approximately 250 and 240 days, respectively) and slightly longer than that of larvae. Lesions caused by tick feeding are discussed and a list of known hosts, including new host records for A. rotundatum, is offered.

The impact of ticks on Bufo marinus from native habitats

We analysed the patterns of tick distribution on 2274 adult toads from Venezuela and Brazil, to explore whether these ectoparasites have any impact on the survival of Bufo marinus. A maximum-likelihood analysis showed that aggregation levels of ticks decreased significantly with the mean intensity of infection. This decline could be attributed to a density-dependent reduction of ticks within toads, density-dependent tick-induced toad mortality and/or density-dependent tick-induced changes in toad susceptibility. However, the relationship between the rate of change in tick loads and tick burdens from recaptured toads indicated that neither the loss of ticks within toads nor the toad susceptibility to further infection were dependent upon tick burdens. Therefore, we can indirectly infer that density-dependent tick-induced toad mortality is responsible for the observed decline in aggregation levels with tick age and burdens. On the other hand, a significant negative relationship between tick burdens and the size-specific weight of toads suggested that ticks may also have a significant impact on the patterns of weight deposition of adult toads. This evidence suggests that these ectoparasites may play an important role in regulating the densities of B. marinus in native habitats.

Haematozoan parasites of the lizard Ameiva ameiva (Teiidae) from Amazonian Brazil: a preliminary note

Three different haematozoan parasites are described in the blood of the teiid lizard Ameiva ameiva Linn. from North Brazil: one in the monocytes and the other two in erythrocytes. The leucocytic parasite is probably a species of Lainsonia Landau, 1973 (Lankesterellidae) as suggested by the presence of sporogonic stages in the internal organs, morphology of the blood forms (sporozoites), and their survival and accumulation in macrophages of the liver. One of the erythrocytic parasites produces encapsulated, stain-resistant forms in the peripheral blood, very similar to gametocytes of Hemolivia Petit et al., 1990. The other is morphologically very different and characteristically adheres to the host-cell nucleus. None of the parasites underwent development in the mosquitoes Culex quinquefasciatus and Aedes aegypti and their behaviour in other haematophagous hosts is under investigation. Mixed infections of the parasites commonly occur and this often creates difficulties in relating the tissue stages in the internal organs to the forms seen in the blood. Concomitant infections with a Plasmodium tropiduri-like malaria parasite were seen and were sometimes extremely heavy.

Ultrastructure of Hepatozoon boigae (Mackerras, 1961) nov. comb. from brown tree snakes, Boiga irregularis, from northern Australia

Intraerythrocytic bodies identified as haemogregarine gamonts were found in 29% of 97 brown tree snakes (Boiga irregularis) examined during a haematological survey of reptiles in Australasia during 1994-1998. The morphological characteristics of the parasites were consistent with those of Haemogregarina boigae Mackerras, 1961, although the gamonts were slightly larger and lacked red caps but contained distinctive polar grey capsules. Gamonts did not distend host cells but laterally displaced their nuclei. They were contained within parasitophorous vacuoles and possessed typical apicomplexan organelles, including a conoid, polar rings, rhoptries and micronemes. Schizonts producing up to 30 merozoites were detected in endothelial cells of the lungs of 11 snakes. The absence of erythrocytic schizogony suggests the parasites belong to the genus Hepatozoon. Electron microscopy also revealed the presence of curious encapsulated organisms in degenerating erythrocytes. These stages did not possess apical complex organelles and were surrounded by thick walls containing circumferential junctions and interposed strips reminiscent of oocyst sutures.

Exotic ticks introduced into the United States on imported reptiles from 1962 to 2001 and their potential roles in international dissemination of diseases

Since 1962, a total of 29 species of exotic ticks have been introduced into the United States on imported reptiles, with 17 species from the genus Amblyomma, 11 from the genus Aponomma and one from the genus Hyalomma. In the absence of measures to control introduction of these importations, some exotic tick species will develop breeding colonies and become established as indigenous species and some tickborne diseases may be introduced to wreak havoc among susceptible native populations. However, formulation of risk assessments and rational control measures have been hampered by a lack of knowledge of these exotic ticks, with much of the available data published in older and relatively obscure publications. This report is an attempt to collate information for all 29 exotic tick species, including previously unpublished data from our laboratory, with particular reference to their geographical distribution, hosts, life cycles and vector potential, and to review methods to minimize their global dissemination.

The life cycle of haemogregarina bigemina (Adeleina: Haemogregarinidae) in South African hosts

Haemogregarina bigemina Laveran et Mesnil, 1901 was examined in marine fishes and the gnathiid isopod, Gnathia africana Barnard, 1914 in South Africa. Its development in fishes was similar to that described previously for this species. Gnathiids taken from fishes with H. bigemina, and prepared sequentially over 28 days post feeding (d.p.f.), contained stages of syzygy, immature and mature oocysts, sporozoites and merozoites of at least three types. Sporozoites, often five in number, formed from each oocyst from 9 d.p.f. First-generation merozoites appeared in small numbers at 11 d.p.f., arising from small, rounded meronts. Mature, second-generation merozoites appeared in large clusters within gut tissue at 18 d.p.f. They were presumed to arise from fan-shaped meronts, first observed at 11 d.p.f. Third-generation merozoites were the shortest, and resulted from binary fission of meronts, derived from second-generation merozoites. Gnathiids taken from sponges within rock pools contained only gamonts and immature oocysts. It is concluded that the development of H. bigemina in its arthropod host illustrates an affinity with Hemolivia and one species of Hepatozoon. However, the absence of sporokinctes and sporocysts also distances it from these genera, and from Karyolysus. Furthermore, H. bigemina produces fewer sporozoites than Cyrilia and Desseria, although, as in Desseria, Haemogregarina (sensu stricto) and Babesiosoma, post-sporogonic production of merozoites occurs in the invertebrate host. The presence of intraerythrocytic binary fission in its fish host means that H. bigemina is not a Desseria. Overall it most closely resembles Haemogregarina (sensu stricto) in its development, although the match is not exact.

The biology of some intraerythrocytic parasites of fishes, amphibia and reptiles

Fishes, amphibia and reptiles, the ectothermic vertebrates, are hosts for a variety of intraerythrocytic parasites including protists, prokaryotes, viruses and structures of uncertain status. These parasites may experience host temperature fluctuations, host reproductive strategies, population genetics, host habitat and migratory behaviour quite unlike those of endothermic hosts. Few blood infections of fishes, amphibia and reptiles have proven pathogenicity, in contrast to the many intraerythrocytic parasites of mammals and some birds which harm their hosts. Although not given the attention afforded to intraerythrocytic parasites of endotherms, those of ectotherms have been studied for more than a century. This review reports on the diversity, general biology and phylogeny of intraerythrocytic parasites of ectotherms. The existence of taxonomic confusion is emphasized and the main taxonomic features of most of the 23 better characterized genera, particularly the kinetoplastid and apicomplexan protists, are summarized. Transmission of protistan infections of aquatic ectotherms is also discussed. Leeches can transfer sporozoties or merozoites to the vertebrate host during feeding. Dormant sporozoites of Lankesterella may permit transmission of species of this genus between vertebrates by predation. The fish haemogregarine, Haemogregarina bigemina, probably has gnathiid isopods, rather than leeches, as its definitive hosts. Hepatozoon spp. in aquatic hosts, and Progarnia of caiman, may also use invertebrate hosts other than leeches. Protistan infections of terrestrial or semi-terrestrial hosts are transmitted by a variety of arthropods, or, in some cases, leeches, contaminated paratenic hosts, or sporocysts free in water. Transfer of protists between vertebrates by predation and congenitally may also occur. The biology of the host cells of these infections, the red blood cells of ectotherm vertebrates, is summarized and compared with that of mammalian erythrocytes. Erythropoiesis, the nature of the surface molecules (especially the possible existence of a major histocompatibility complex), the haemoglobins, and the shape and size of erythrocytes are discussed. The exoerythrocytic sites in which protists, prokaryotes, viruses and structures of uncertain status exist before erythrocyte entry are described. Tissue merogony, tissue cysts and invasion of the white cell series occur in a variety of protistan infections. Intraerythrocytic stages of protistan infections are also discussed, including modes of entry to erythrocytes, survival mechanisms, and multiplication. The impact of infection on host populations is difficult to assess, in part because there is no agreement in the literature on the criteria used to evaluate parasite-induced cost to the host. Almost all studies have been on haemogregarine and Plasmodium infections in, mainly, lizards, but also fishes and snakes. Some infections may be responsible for mortality in their hosts, but hosts themselves may be short-lived, or have a limited ability to recover from infection.

Phylogeny of adeleid blood parasites with a partial systematic revision of the haemogregarine complex

The phylogenetic relationships of taxa representative of blood parasitic adeleids were investigated in a cladistic analysis. Two phylogenetic analyses were performed. Monophyly of species of Haemogregarina (sensu lato) of some marine fishes with species of Haemogregarina (sensu stricto) was not supported in either analysis. A new genus, Desseria n.g., was created to accommodate these species. The historical burden placed on the genus Haemogregarina Danilewsky, 1885 as a repository for poorly known and inadequately described species is partially relieved through taxonomic revisions involving the genera Haemogregarina, and Desseria n.g.