NEW SPECIES OF RHABDIAS (NEMATODA: RHABDIASIDAE) AND OTHER HELMINTHS FROM NOROPS CAPITO (SAURIA: POLYCHROTIDAE) FROM NICARAGUA

Morphology, complete mitochondrial genome, and molecular phylogeny of Rhabdias macrocephalum n. sp. (Nematoda: Rhabdiasidae) from Diploderma splendidum (Reptilia: Agamidae)

Species of the genus Rhabdias Stiles & Hassall, 1905 are common parasitic nematodes occurring in the lungs of amphibians and reptiles worldwide. In the present study, Rhabdias macrocephalum n. sp. is described using integrated morphological methods (light and scanning electron microscopy) and molecular approaches (sequencing of the nuclear 28S and ITS regions, and mitochondrial cox1, cox2, and 12S genes) based on specimens collected from the green striped tree dragon Diploderma splendidum (Barbour & Dunn) (Reptilia: Agamidae) in China. The complete mitochondrial genome of R. macrocephalum n. sp. was sequenced and annotated: it is 14,819 bp in length, including 12 protein coding genes (missing atp8), 22 tRNA genes, 2 rRNA genes and three non-coding regions. The gene arrangement of R. macrocephalum n. sp. is different from all of the currently available mitogenomes of nematodes and represents a novel type of mitochondrial gene arrangement reported in Nematoda. Molecular phylogenetic results based on the ITS + 28S data support the monophyly of Entomelas, Pneumonema, Serpentirhabdias, and Rhabdias, and showed R. macrocephalum n. sp. forming a most basal lineage in Rhabdias.

Integrative taxonomy in the genus Rhabdias Stiles et Hassall, 1905 from anuran in Brazil, description of two new species and phylogenetic analyses

About 20 valid species of the genus Rhabdias are known in the Neotropical region. The present study aimed to describe two new species of Rhabdias parasitizing the lungs of Leptodactylus macrosternum and Leptodactylus podicipinus from Brazil. Distinctive characteristics between these species are numerous and based on body size, size of the buccal capsule, shape and size of the oesophagus, and position of the vulva. Molecular data based on ribosomal genes 28S and ITS region and mitochondrial COI of the two species are presented. Molecular analysis and comparison of the partial mitochondrial COI sequence of Rhabdias matogrossensis n. sp. and Rhabdias guaianensis n. sp. revealed a genetic divergence between these new species and the sequences of Rhabdias spp. previously deposited in GenBank. In the phylogenetic analysis, R. matogrossensis n. sp. was grouped with R. breviensis species complex, and R. guaianensis n. sp. was grouped as a sister group of R. cf. stenochepala. This study contributes to improving the diversity of known species of Rhabdias described in Brazilian anurans.

Infection Patterns of Helminths in Norops Brasiliensis (Squamata, Dactyloidae) from a Humid Forest, Northeastern Brazil and their Relation with Body Mass, Sex, Host Size, and Season

Climatic and ecological factors can influence the parasite load of a host. Variation in rainfall, body size, and sex of the hosts may be related to the abundance of parasites. This study investigated the helminth fauna associated with a population of Norops brasiliensis, together with the effect of host biology (sex, body size, and mass) and variation in rainfall regime on the abundance of helminths. Species of three groups of endoparasites were found (Nematoda, Cestoda, and Trematoda), with nematodes as the most representative taxa with eight species, prevalence of 63.2 %, mean intensity of 4.0 ± 0.58 (1 – 25), and mean abundance of 2.66 ± 0.44 (0 – 25). Nine helminth species are new host records for N. brasiliensis. The nematode Rhabdias sp. had the highest prevalence (53.3 %). There was no signifi cant relationship between abundance of the trematode Mesocoelium monas and host sex or season, although the abundance of this parasite increased significantly with host body size and mass, while abundance of nematodes was related to season and host mass. This study increases the knowledge about the diversity of helminth fauna associated with N. brasiliensis, revealing infection levels of hosts from northeastern Brazil.

Molecular insight into systematics, host associations, life cycles and geographic distribution of the nematode family Rhabdiasidae

Rhabdiasidae Railliet, 1915 is a globally distributed group of up to 100 known species of nematodes parasitic in amphibians and reptiles. This work presents the results of a molecular phylogenetic analysis of 36 species of Rhabdiasidae from reptiles and amphibians from six continents. New DNA sequences encompassing partial 18S rDNA, ITS1, 5.8S rDNA, ITS2 and partial 28S rDNA regions of nuclear ribosomal DNA were obtained from 27 species and pre-existing sequences for nine species were incorporated. The broad taxonomic, host and geographical coverage of the specimens allowed us to address long-standing questions in rhabdiasid systematics, evolution, geographic distribution, and patterns of host association. Our analysis demonstrated that rhabdiasids parasitic in snakes are an independent genus sister to the rest of the Rhabdiasidae, a status supported by life cycle data. Based on the combined evidence of molecular phylogeny, morphology and life cycle characteristics, a new genus Serpentirhabdias gen. nov. with the type species Serpentirhabdias elaphe (Sharpilo, 1976) comb. nov. is established. The phylogeny supports the monophyly of Entomelas Travassos, 1930, Pneumonema Johnston, 1916 and the largest genus of the family, Rhabdias Stiles and Hassall, 1905. DNA sequence comparisons demonstrate the presence of more than one species in the previously monotypic Pneumonema from Australian scincid lizards. The distribution of some morphological characters in the genus Rhabdias shows little consistency within the phylogenetic tree topology, in particular the apical structures widely used in rhabdiasid systematics. Our data suggest that some of the characters, while valuable for species differentiation, are not appropriate for differentiation among higher taxa and are of limited phylogenetic utility. Rhabdias is the only genus with a cosmopolitan distribution, but some of the lineages within Rhabdias are distributed on a single continent or a group of adjacent zoogeographical regions. Serpentirhabdias, Entomelas and Pneumonema show rather strict specificity to their host groups. The evolution of the Rhabdiasidae clearly included multiple host switching events among different orders and families of amphibians as well as switching between amphibians and squamatan reptiles. Only a few smaller lineages of Rhabdias demonstrate relatively strict associations with a certain group of hosts.

A new species of Rhabdias (Nematoda: Rhabdiasidae) from agamid lizards on Luzon Island, Philippines

Rhabdias odilebaini n. sp. is described on the basis of specimens found in the lungs of 2 species of agamid lizards: the Philippine flying lizard Draco spilopterus and the marbled bloodsucker Bronchocela marmorata . Specimens were collected in Aurora Province, Luzon Island, Philippines. The new species of Rhabdias is characterized by presence of 4 submedian lips, inconspicuous lateral lips, rounded cross-shaped oral opening, and tail end bent dorsally. This species is morphologically distinct from other Rhabdias spp. that parasitize reptilian and amphibian hosts, including 3 other species known to parasitize lizards of the Agamidae.

Rhabdias lacertae n. sp. (Nematoda: Rhabdiasidae), the first rhabdiasid species parasitising lizards in Europe

A new nematode species, Rhabdias lacertae n. sp. (Rhabdiasidae), is described from the body-cavity of the common lizard Lacerta vivipara Jacquin (Lacertidae) from the Ridge of Malá Fatra (Sokolie Hill), north-western Slovakia. The new species differs from its congeners mainly in possessing 3 min cuticular spikes at the tail tip and some other features. This is the first species of Rhabdias Stiles & Hassall, 1905 described from lizards in Europe and the first species of this genus parasitising hosts belonging to the Lacertidae.