The Influence of Environmental Conditions and Coinfection by Blood-Feeding Parasites on Red Blood Cell Physiology of an Ectothermic Host.

AbstractVector-borne blood parasites cause myriad sublethal effects and can even be deadly to endotherms, but far less is known about their impacts on ectothermic hosts. Moreover, the pathologies documented in endotherms are generally linked to infection by blood parasites rather than by their vectors. Here, we measured hematocrit, hemoglobin, and relative proportions of immature red blood cells to evaluate the physiological effects of two blood-feeding parasites and coinfection on ectothermic hosts, differentiating among pathological responses, extrinsic factors, and natural variations. We investigated a population of wild eastern hellbender salamanders (Cryptobranchus alleganiensis), which harbor leeches (Placobdella appalachiensis) that transmit blood parasites (Trypanosoma spp.) to their hosts, often resulting in coinfection. We observed seasonal changes in host hematology corresponding to water temperature and demonstrated their ability to modulate hematological parameters in response to acute stress. We reveal seasonal relationships between parasite dynamics and host physiology, in which peak parasitemia occurred when hosts had seasonally high hematocrit and hemoglobin concentrations. We found that coinfected individuals expressed symptoms of anemia, including a regenerative response to depletion of their red blood cells. We also documented a more pronounced pathological response to leech vectors than to the trypanosomes they transmit. Our research underscores the complex interactions between host physiology, multiple parasites, and environmental factors and highlights the pathologies associated with the vector in coinfections. Given the contributions of climate change and disease in the rapid global decline of ectotherms such as amphibians, our study provides timely foundational insights into multiple factors that influence their red blood cell physiology.

Two new kathlaniid species (Nematoda: Cosmocercoidea) parasitic in salamanders of the genus Andrias (Amphibia: Caudata: Cryptobranchidae).

The new nematode species, Falcaustra hanzaki n. sp. and Urodelnema takanoensis n. sp. (Cosmocercoidea: Kathlaniidae), were found from the intestine of giant salamanders in Kyoto Prefecture, Japan. The first species is featured by the number and arrangement of caudal papillae (3 pairs of precloacal papillae, 8 pairs of postcloacal papillae and a single ventral precloacal papilla), the presence of a single pseudosucker, spicules equal in size (520-638 µm long), and V-shaped gubernaculum in males; vulva situated about 3/5 of a body in females. The second species is characterized by the number and arrangement of caudal papillae (5 pairs of precloacal papillae, 6 pairs of postcloacal papillae and a single ventral precloacal papilla), spicules equal in size (403-593 µm long), V-shaped gubernaculum in males; vulva situated about 3/5 of a body in females. The molecular phylogenetic analysis was performed using the partial 18S and 28S ribosomal DNA and the internal transcribed spacers 1 region in the nuclear DNA. This phylogenetic study raised a question about the validity of Family Kathlaniidae and related families of Cosmocercoidea.

GENETIC DIVERSITY OF CYSTODISCUS SPECIES IN AMPHIBIANS IN THE SOUTHERN UNITED STATES.

Myxosporean species in the genus Cystodiscus are parasites of amphibians and have been reported from several continents. Typically used for the identification of myxozoans, the spores produced by these species are similar to one another, possessing 2 polar capsules and being ovoid. The number of transverse depressions on the spore can be useful for delineating species, but these can sometimes be difficult to distinguish. In North America, Cystodiscus serotinus and Cystodiscus melleni have been described, and for C. serotinus in particular, numerous reports and a wide range of hosts have been associated with this species. Given the challenges of identifying some of these species, we questioned whether all encounters of Cystodiscus species can be attributed to these 2 described species, or if there may be additional undescribed species or cryptic species. Over 7 yr, 383 amphibians representing 13 species of toads, frogs, and salamanders were collected from sites in Oklahoma and Arkansas. Cystodiscus infections were found in 56 individuals (14.6%). Tissues from these infected individuals were preserved in alcohol for genetic analysis. The small subunit (SSU) and large subunit (LSU) ribosomal RNA genes were partially sequenced and analyzed phylogenetically. Nine distinct SSU sequence types and 7 distinct LSU sequence types were identified. Phylogenetically, sequence types were attributable to C. serotinus, C. melleni, Cystodiscus axonis, and an undescribed species. For the previously described species, there were multiple SSU sequence types: 4 for C. serotinus and 2 for both C. melleni and C. axonis. Phylogenetic patterns were similar for the LSU sequence analysis using a shorter sequence than the SSU, and we propose that the LSU is useful for initial barcoding of Cystodiscus species in any future surveys. In our qualitative assessment of sequence types compared to geography and host species, SSU types C1 and C2 (C. axonis) were only found in Union County, Arkansas, and McCurtain County, Oklahoma, respectively. Also, salamanders were only infected with SSU types B or D (C. melleni), and type B was only found in salamanders. Our finding of C. axonis in North America is notable because this species was described in Australia and is associated with host pathology. Our work reveals that there are cryptic species of Cystodiscus in the United States, one of which may be a pathogen, highlighting the importance of genetic analysis for future surveys of these species.

Batracholandros salamandrae (Oxyuroidea: Pharyngodonidae) in Endemic Salamanders (Amphibia: Plethodontidae) of the Trans-Mexican Volcanic Belt: Host Range Wide Distribution or Cryptic Species Complex?

Salamanders of the tribe Bolitoglossini Hallowell are a highly diversified group of amphibians, and their helminth parasite fauna has been scarcely studied. Some species of plethodontid salamanders distributed along the Trans-Mexican Volcanic Belt, in central Mexico, were sampled, and their helminth parasites were recovered for taxonomic identification. Specimens of a pharyngodonid nematode from 2 species of bolitoglossines of the genus Pseudoeurycea Taylor were morphologically identified as Batracholandros salamandrae (Schad, 1960) Petter and Quentin, 1976. These specimens were studied in further detail through light and scanning electron microscopy and were sequenced for 2 ribosomal genes and 1 mitochondrial gene to test the hypothesis of whether B. salamandrae is a species widely distributed in salamanders across the Nearctic biogeographic region, or if it represents a cryptic species complex. Our molecular results revealed that these specimens consisted of 2 genetic lineages in concordance with host species, although with slight morphological differences among specimens in each of them. A thorough study, including the generation of molecular data from individuals from other areas of North America, and the examination of type specimens, is required to test the reliability of these morphological differences and to corroborate the species identity of the 2 genetic lineages.

Endoparasites infecting exotic captive amphibian pet and zoo animals (Anura, Caudata) in Germany.

Alongside exotic reptiles, amphibians, such as toads, frogs, salamanders, and newts, are nowadays considered popular pets worldwide. As reported for other exotic pet animals, amphibians are known to harbor numerous gastrointestinal parasites. Nonetheless, very little data are available on captive amphibian parasitic diseases. In this study, we applied direct saline fecal smears (DSFS) to examine in total 161 stool samples from 41 different amphibian species belonging to the orders Anura and Caudata. In addition, carbolfuchsin-smear (CFS) staining (n = 74 samples) was used to detect amphibian Cryptosporidium oocysts. Also, complete dissections of deceased amphibians (n = 107) were performed to specify parasite infections and to address parasite-associated pathogenicity. Overall, examined amphibian fecal samples contained 12 different parasite taxa. The order Rhabditida with the species Rhabdias spp. and Strongyloides spp. were the most prevalent nematode species (19.3%), followed by flagellated protozoans (8.7%), Amphibiocapillaria spp./Neocapillaria spp. (7.5%), Oswaldocruzia spp. (4.3%), Blastocystis spp. (3.1%), Cosmocerca spp. (3.1%), oxyurids (Pharyngonoidae) (3.1%), spirurids (1.2%), un-sporulated coccidian oocysts (0.6%), Tritrichomonas spp. (0.6%), Karotomorpha spp. (0.6%), and Cryptosporidium spp. (0.6%). One CFS-stained fecal sample (1.4%) was positive for Cryptosporidium oocysts. Within dissected amphibians, 31 (48.4%) of the anurans and 11 (26.2%) of the salamanders were infected with gastrointestinal parasites. One cutaneous Pseudocapillaroides xenopi infection was diagnosed in an adult African clawed frog (Xenopus laevis). Etiologically, 17 (15.9%) of them died due to severe parasitic and/or bacterial infections (e.g., Chryseobacterium indologenes, Citrobacter freudii, Sphingobacterium multivorum, Klebsiella pneumoniae). High prevalence and pathological findings of several clinical amphibian parasitoses call for more detailed investigation on gastrointestinal parasite-derived molecular mechanisms associated with detrimental lesions or even death.

Evaluating the ontogenetic external morphology of an ectoparasitic Torix tukubana (Hirudinida: Glossiphoniidae), with records of its new host amphibian species.

Torix is a leech genus containing freshwater proboscidate species, and several members of this taxon are ectoparasites specific to amphibians. Torix tukubana inhabits mountain streams in Japan, and only two frog species are known to be hosts. We collected this leech from two other amphibians, Onychodactylus japonicus (Japanese clawed salamander) and Rana ornativentris (montane brown frog), for the first time. This finding suggests that the host specificity of T. tukubana is low. The immature individuals of T. tukubana were also collected and identified based on DNA data. This is the first juvenile record of this species confirmed by its DNA barcode sequences. Several morphological characters known from large individuals and used as diagnostic characteristics in taxonomic keys were not observed in the juveniles, suggesting that these are ontogenetic traits.

First report of Euryhelmis parasites (Trematoda, Heterophyidae) in Africa: conservation implications for endemic amphibians.

In this study, we report, through molecular identification, the first African records of a digenean trematode parasite of the genus Euryhelmis. We recovered metacercariae encysted in an anuran, the endemic Moroccan painted frog (Discoglossus scovazzi), and a vulnerable caudate, the North African fire salamander (Salamandra algira), from four localities in North Africa (Morocco). Our records go back to the past century and have been confirmed in successive fieldwork seasons thereafter. Metacercarial stages of these parasites require amphibians as the last intermediate host, but the exact identity of the primary hosts and predators of the infected animals in Africa remain unknown. Our searches with basic local alignment search tool (BLAST) from Genbank revealed that hosts were infected by parasites of Euryhelmis costaricensis, which showed almost the same genetic identity (with only one substitution) to previous reports from Costa Rica and Japan, suggesting a recent introduction in Morocco. We proceed to discuss the likely role of introduced mustelids as the potential definitive hosts of trematode adults. Under this assumption, we conclude that the infestation of Discoglossus scovazzi and Salamandra algira might pose a risk to these threatened species.

Evidence of ectoparasite-induced endocrine disruption in an imperiled giant salamander, the eastern hellbender (Cryptobranchus alleganiensis).

Parasitic leeches and trypanosomes release chemical signals into their hosts to evade immuno-detection, but it is unknown whether these compounds manipulate host behavior or endocrine physiology. We determined whether parasitic infections with leeches and/or trypanosomes affected the immune and stress response of an imperiled giant species of amphibian, the eastern hellbender (Cryptobranchus alleganiensis Daudin). We monitored corticosterone and white blood cell counts in response to restraint and injection with adrenocorticotropin hormone (ACTH) or saline for up to 50 h. The presence of leeches dampened hellbender corticosterone responses to restraint and reduced diel patterns of plasma corticosterone. Injection with ACTH restored the normal inter-renal responses of hellbenders, suggesting that leeches, possibly through neurotransmitters in leech saliva, cause down-regulation of corticosterone release at the level of the pituitary or hypothalamus. Infection with leeches also increased the relative abundance of eosinophils, white blood cells often recruited into circulation in response to parasitic infection. Lastly, neutrophil to lymphocyte (N:L) ratios increased in all animals after 24 h of capture and remained elevated for up to 50 h, but these temporal dynamics did not differ with parasite infection. Trypanosome infection did not affect any aspect of hellbender physiology that we measured. Our findings reveal a previously undocumented host-parasite dynamic. While the functional significance to the parasite is unclear, the physiological and behavioral implications for the host are great, given the important role of glucocorticoids in regulating physiology and behavior.

Variable infection of stream salamanders in the southern Appalachians by the trematode Metagonimoides oregonensis (family: Heterophyidae).

Many factors contribute to parasites varying in host specificity and distribution among potential hosts. Metagonimoides oregonensis is a digenetic trematode that uses stream-dwelling plethodontid salamanders as second intermediate hosts in the Eastern US. We completed a field survey to identify which stream salamander species, at a regional level, are most likely to be important for transmission to raccoon definitive hosts. We surveyed six plethodontid species (N = 289 salamanders) from 23 Appalachian headwater sites in North Carolina: Desmognathus quadramaculatus (n = 69), Eurycea wilderae (n = 160), Desmognathus ocoee (n = 31), Desmognathus monticola (n = 3), Eurycea guttolineata (n = 7), and Gyrinophilus porphyriticus (n = 19). We found infection in all species except D. monticola. Further analysis focused on comparing infection in the two most abundant species, D. quadramaculatus and E. wilderae. We found that D. quadramaculatus had significantly higher infection prevalence and intensity, probably due to a longer aquatic larval period and larger body sizes and thus greater cumulative exposure to the parasite.

Phyllodistomum kanae sp. nov. (Trematoda: Gorgoderidae), a bladder fluke from the Ezo salamander Hynobius retardatus.

The Ezo salamander, Hynobius retardatus, is endemic only to Hokkaido, the northernmost island of Japan. Gravid flukes of the family Gorgoderidae were discovered from the urinary bladder of H. retardatus. The parasites were identified as a new species named Phyllodistomum kanae sp. nov. In the neighboring Honshu island another bladder fluke, Phyllodistomum patellare, has already been found from the Japanese newt. The new species clearly differs from P. patellare in having a spherical ovary and very weakly lobed testes. The discovery of species of Phyllodistomum from urodelan amphibians is very uncommon in Eurasia. A molecular phylogeny based on 28S ribosomal DNA suggests that sphaeriid bivalves may serve as the first intermediate host for the new species.

Morphology, ultrastructure and molecular characterisation of Spiroxys japonica Morishita, 1926 (Spirurida: Gnathostomatidae) from Pelophylax nigromaculatus (Hallowell) (Amphibia: Ranidae).

Gnathostomatid nematodes identified morphologically as Spiroxys japonica Morishita, 1926 were collected from the dark-spotted frog Pelophylax nigromaculatus (Hallowell) (Amphibia: Ranidae) in China. Light and scanning electron microscopy were used to study the morphology of this species in detail. Previously unreported morphological features are revealed and others corrected. In addition, adult nematodes of S. japonica collected from P. nigromaculatus and Spiroxys hanzaki Hasegawa, Miyata & Doi, 1998 collected from Andrias japonicus (Temminck) (Caudata: Cryptobranchidae) in China and Japan, respectively, and the third-stage larva of S. japonica collected from Lithobates catesbeianus (Shaw) (Anura: Ranidae) in Japan, were characterised using molecular methods by sequencing and analysing ribosomal [large ribosomal DNA (18S) and internal transcribed space] and mitochondrial [cytochrome c oxidase subunit 1] target regions, respectively. The new morphological and genetic data contributes to a more accurate diagnosis of this hitherto little known nematode genus.

Experimental exposure of adult San Marcos salamanders and larval leopard frogs to the cercariae of Centrocestus formosanus.

The gill parasite Centrocestus formosanus (Trematoda: Heterophyidae) is an exotic parasite of concern in Texas because it has been shown to infect multiple threatened and endangered fish species. The purpose of this study was to determine if C. formosanus could present a threat to larval anurans, as well as threatened neotenic salamanders endemic to the spring-fed systems of Texas. We exposed adults of the San Marcos salamander Eurycea nana (Caudata: Plethodontidae) and tadpoles of the Rio Grande leopard frog Lithobates berlandieri (Anura: Ranidae) to the cercariae of C. formosanus . The San Marcos salamander showed no signs of metacercarial infection, suggesting that E. nana may be refractory to C. formosanus cercariae. Centrocestus formosanus readily infects the gills of leopard frog tadpoles, but the metacercariae apparently died prior to reaching maturity in our tadpoles.

Widespread trypanosome infections in a population of eastern hellbenders (Cryptobranchus alleganiensis alleganiensis) in Virginia, USA.

Eastern hellbender salamanders (Cryptobranchus alleganiensis alleganiensis) are declining in North America and because of this the health status of individuals in several populations is closely monitored by researchers. During a health survey of hellbenders from a stream in Smyth County, VA, USA, we examined Giemsa-stained blood smears of 71 animals captured during 2011 for the presence of blood parasites. We discovered an unknown species of trypanosome that was apparently widespread within this population; 40 of the 71 individuals (56.3 %) were infected. There are seven known trypanosome species of caudate amphibians; based on microscopic examination, the parasite we observed appeared most similar to Trypanosoma cryptobranchi, which was reported in this species only once before, 76 years ago, from a single animal apparently captured in Iowa. Given that some trypanosomes can adversely affect the health of their hosts, we recommend further monitoring be done in this and other hellbender populations to determine the geographic extent of the parasite and its effects on its increasingly rare host.

Metagonimoides oregonensis (Heterophyidae: Digenea) infection in Pleurocerid snails and Desmognathus quadramaculatus salamander larvae in Southern Appalachian streams.

Metagonimoides oregonensis (Heterophyidae) is a little-known digenetic trematode that uses raccoons and possibly mink as definitive hosts, and stream snails and amphibians as intermediate hosts. Some variation in the life cycle and adult morphology in western and eastern populations has been previously noted. In the southern Appalachians, Pleurocera snails and stream salamanders, e.g., Desmognathus spp., are used as intermediate hosts in the life cycle. We completed a series of studies in this system examining some aspects of larval trematode morphology and first and second intermediate host use. Molecular sequencing of the 28S rDNA of cercariae in our survey placed them clearly within the heterophyid family. However, light and scanning electron microscopy revealed both lateral and dorso-ventral finfolds on the cercariae in our region, whereas original descriptions of M. oregonensis cercariae from the west coast indicate only a dorso-ventral finfold, so further work on the systematics of this group may be warranted. A survey of first intermediate host, Pleurocera proxima, from 7 streams in the region identified only M. oregonensis, virgulate-type cercariae, and cotylomicrocercous-type cercariae in the streams, with M. oregonensis having the highest prevalence, and the only type present that use amphibians as second intermediate hosts. Based on clearing and staining of 6 Desmognathus quadramaculatus salamander larvae, we found that individual salamanders could have over 600 metacercariae, which form between muscle fibers throughout the body. Histological observations suggest that the metacercariae do not cause excessive tissue damage or inflammation, and likely persist through metamorphosis, thereby transmitting potentially large numbers of worms to definitive host raccoons foraging along streams.

Distribution, abundance, and genetic diversity of Clinostomum spp. metacercariae (Trematoda:Digenea) in a modified Ozark stream system.

Land-use alterations can have profound influences on faunal distributions, including host-parasite relationships. Yellow grub trematodes ( Clinostomum spp.) have complex life cycles involving 3 hosts: a snail, a fish or amphibian, and a bird. Here, we analyze the distribution, prevalence, intensity, abundance, and genetic diversity of encysting metacercariae of Clinostomum spp. in salamanders and fishes throughout an aquatic system that includes a natural Ozark stream and man-made ponds. We found Clinostomum sp. infecting permanently aquatic Oklahoma salamanders ( Eurycea tynerensis ; 56% prevalence) and larval grotto salamanders ( Eurycea spelaea ) immediately downstream from a man-made pond. However, Clinostomum sp. did not infect any salamanders in the spring that supplies this pond, or in sections farther downstream (~0.5 and 2 km). Metacercariae of Clinostomum sp. were present in ~90% of introduced largemouth bass ( Micropterus salmoides ) in the man-made pond adjunct to the stream. Morphological examination and phylogenetic analyses based on the mitochondrial gene cytochrome oxidase 1 ( Co1 ) and the nuclear ribosomal gene 18S show that fishes and salamanders at this site are primarily infected with Clinostomum marginatum . There is a relatively high degree of mitochondrial haplotype diversity in C. marginatum at this site but no consistent genetic difference between parasites in largemouth bass from the man-made pond and those in salamanders from the stream. Based on the microgeographic distribution and relationships of metacercariae of C. marginatum at this site, we hypothesize that the adjunct man-made pond has created an ecological situation that brings the cercariae of this parasite into contact with novel stream salamander hosts.

New species of Oswaldocruzia (Nematoda: Molineidae) and other helminths in Bolitoglossa subpalmata (Caudata:Plethodontidae) from Costa Rica.

Oswaldocruzia cartagoensis n. sp. (Strongylida: Molineidae) from the intestines of Bolitoglossa subpalmata (Caudata: Plethodontidae) is described and illustrated. Oswaldocruzia cartagoensis n. sp. represents the 86 th species assigned to the genus and the 39th species from the Neotropical region. It is most similar to the Neotropical species of the genus that possess type I bursa, i.e., Oswaldocruzia bonsi , Oswaldocruzia brasiliensis , Oswaldocruzia lopesi , Oswaldocruzia neghmei , and Oswaldocruzia vitti . Of these, O. bonsi, O. brasiliensis, and O. neghmei lack cervical alae, rib 4 in individuals of O. vitti reaches the edge of the bursal membrane, species of O. lopesi and O. cartagoensis can be separated on the basis of spicule structure, the blade in O. lopesi is bifurcate, and that of O. cartagoensis terminates in 6-8 fine points. In addition to the new species of Oswaldocruzia, Cosmocera parva, Cosmocera podicipinus, and acanthocephalan cystacanths were also found.

Distribution and reproductive strategies of Gyrinicola batrachiensis (Oxyuroidea: Pharyngodonidae) in larvae of eight species of amphibians from Nebraska.

In total, 462 tadpoles and salamander larvae of 8 species were examined for the presence of Gyrinicola batrachiensis from 5 locations in Nebraska. Infection by G. batrachiensis occurred in tadpoles of Rana blairi , Rana catesbeiana, Rana pipiens, and Bufo woodhousii. Tadpoles of Hyla chrysoscelis , Spea bombifrons, and Pseudacris maculata and larvae of Ambystoma mavortium were not infected with G. batrachiensis. Population structure, defined as prevalence, mean abundance, and mean intensity of G. batrachiensis, varied among tadpoles of different amphibian species and was determined by collection locality, developmental period of tadpole hosts, amphibian species co-occurrence, and different reproductive strategies of G. batrachiensis , or a combination. Gyrinicola batrachiensis observed in all ranid tadpoles and B. woodhousii tadpoles from where bufonids were the only anuran species present, confirmed to the didelphic haplodiploidy and monodelphic parthenogenetic reproductive strategies, respectively. However, tadpoles of B. woodhousii that co-occurred with tadpoles of R. pipiens at Cedar Creek were inconsistent with these predictions and contained both male and didelphic female nematodes, but at a low mean intensity (1.61 ± 0.70). Didelphic female nematodes from B. woodhousii tadpoles at Cedar Creek only produced thick-shelled eggs, whereas nematodes in R. pipiens tadpoles had a high mean intensity (14.88 ± 23.83) from this location and contained both thick-shelled and thin-shelled eggs in their respective uteri. More importantly, adult female nematodes from tadpoles of R. pipiens and B. woodhousii from Cedar Creek were morphologically more similar to each other than to female nematodes recovered from tadpoles of other anuran species, other locations, or both. These data suggest that when strains of G. batrachiensis are shared by tadpoles of different amphibian species that differ in developmental period, the nematodes have an intermediate reproductive strategy in amphibian species, with tadpoles having short development.

Liolope copulans (Trematoda: Digenea: Liolopidae) parasitic in Andrias japonicus (Amphibia: Caudata: Cryptobranchidae) in Japan: Life cycle and systematic position inferred from morphological and molecular evidence.

The life cycle of Liolope copulans Cohn, 1902 (Trematoda: Digenea: Liolopidae), an intestinal parasite of the Japanese giant salamander Andrias japonicus (Temminck) (Amphibia: Caudata: Cryptobranchidae), was studied in the field and laboratory in Japan. This is the first description of mother sporocyst, daughter sporocyst and cercariae of a liolopid species. Non-oculate longifurcate pharyngeate cercariae were formed in lanceolate-cylindrical daughter sporocysts in Semisulcospira libertina (Gould) (Gastropoda: Sorbeoconcha: Pleuroceridae). They successfully developed to encapsulated metacercariae in cyprinid fishes, Nipponocypris sieboldii (Temminck and Schlegel) and Rhynchocypris lagowskii (Dybowski), by experimental infection. Cercariae had a V-shaped excretory vesicle with two looped arms, as in metacercariae and adults. Developmental stages from mother sporocyst to adult are described and illustrated. DNA sequencing was conducted for 28S and 18S rDNA of mother and daughter sporocysts, cercariae, and an adult. The result of molecular phylogenetic analysis suggests that L. copulans may be one of the basal taxa of the order Diplostomida Olson, Cribb, Tkach, Bray, and Littlewood, 2003, but its systematic position is still unclear because of the topological inconsistence between the 28S and 18S trees. Therefore, we tentatively place the family Liolopidae in the superfamily Diplostomoidea, mainly based on the morphology of sporocysts and cercariae.

A new genus and species of Brachycoeliidae (Digenea) from Chiropterotriton sp. (Caudata: Plethodontidae) in Mexico and its phylogenetic position within the Plagiorchiida based on partial sequences of the 28S ribosomal RNA gene.

Parabrachycoelium longicaecum n. gen., n. sp. (Digenea: Brachycoeliidae) is described from the intestine of a plethodontid salamander Chiropterotriton sp. Hosts were collected in bromeliads at the cloud forest of Tlaquilpa, Veracruz, Mexico. Members of the Brachycoeliidae Looss, 1899 (sensu Yamaguti, 1971) are characterized by having a spined tegument; ceca usually short, not passing level of gonads, but longer in some species; gonads posterior to, or in region of, acetabulum, with ovary anterior to testes; a well developed cirrus pouch containing a bipartite seminal vesicle; and uterus occupying entire hind-body posterior to testes. However, this combination of morphological traits prevents the inclusion of the new taxon in any of the genera in that family; a new genus was, therefore, erected to accommodate the new species. The new taxon is readily distinguished from members belonging to Brachycoelium Dujardin, 1845, Mesocoelium Odhner, 1910, and Tremiorchis Mehra and Negi, 1925, by having long ceca extending into the posterior third of the body, slightly surpassing the testes, and vitellaria extending along the body. The new species morphologically resembles Caudouterina rhyacotritoni Martin, 1966, a digenean parasitizing a plethodontid salamander; however, the latter species lacks spines in the tegument and is actually placed within the Allocreadiidae. To demonstrate further the phylogenetic position of the new taxon, we sequenced the D1-D3 regions of 28S rRNA gene and conducted a phylogenetic analysis of available sequences for the order to which brachycoeliids belong (Plagiorchiida). Sequence divergence of the partial 28S rRNA gene confirms its distinction from the aforementioned brachycoeliids, and the phylogenetic position within the Plagiorchiida places the new species as closely related to a clade formed by Brachycoelium + Mesocoelium. Divergence levels and phylogenetic position within the Plagiorchiida verifies the validity of the new genus and its inclusion in Brachycoeliidae.

Heavy metals, hematology, plasma chemistry, and parasites in adult hellbenders (Cryptobranchus alleganiensis).

Ozark (Cryptobranchus alleganiensis bishopi) and eastern hellbenders (C. a. alleganiensis) from seven rivers in Missouri, USA, were collected to investigate essential information on hematology, parasites, and plasma chemistry and levels of select heavy metals (Hg, Pb, Cd, Cr, and Co) in the animals' blood. The body masses of Ozark hellbenders were much smaller than those of eastern hellbenders. Blood parasites were detected in Ozark hellbenders, but not eastern hellbenders. The higher frequency in occurrence of eosinophils in Ozark hellbenders (8.8-16.8%) than in eastern hellbenders (highest at 6.6%) might result from the infection of parasites. Seven of the 18 hematology and plasma parameters (hematocrit, basophils, eosinophils, K, P, Ca, and chloride) showed significant differences between subspecies. The blood levels of heavy metals Co, Hg, and Pb differed significantly between subspecies. Ozark hellbenders had higher blood levels of Co (p<0.001), while blood levels of Hg and Pb were higher in eastern hellbenders. The levels of chromium (Cr) and cadmium (Cd) were not different between subspecies and among rivers. The eastern hellbenders at Niangua River and the Ozark hellbenders at the North Fork of the White River had lower Hg levels compared to eastern and Ozark hellbenders at other sites. All together, our findings provide important baseline information for managing this endangered species.