GENETIC AND TRAIT VARIABILITY OF GYRINICOLA REVEALS THE EXISTENCE OF AT LEAST FOUR SPECIES WITHIN THE UNITED STATES.

The tadpole-dwelling pinworm, Gyrinicola batrachiensis (Walton, 1929) Adamson, 1981 was recognized as the sole representative of the genus across Canada and the United States. However, evaluation of the morphology of these parasites across their range revealed considerable morphological variability that suggested diagnosable morphotypes. These morphotypes were associated with different species of anurans, several of which occurred in sympatry. Herein we use an extensive geographic sampling across the United States to obtain the morphotypes, screen their genetic diversity, and analyze this information using an integrative approach. We reconstructed their phylogeny using nuclear ribosomal partial genes 18S and 28S, ITS1, 5.8S, and ITS2, as well as 5 mitochondrial genes generated with Next-Generation sequencing technology. This phylogeny reveals 3 well-resolved lineages, which upon the use of a statistical approach (bPTP [Bayesian implementation of the Poisson tree processes]) supports the delimitation of 4 distinct groups equivalent to species. These putative species groups were tested using morphological characteristics paired with a MANOVA and canonical variate analysis. Results suggest that at least 4 species of Gyrinicola are present within North America, resulting in the resurrection of G. armatus (Walton, 1933) and the description of 2 new species.

MOLECULAR PHYLOGENETIC ANALYSIS OF GYRINICOLA BATRACHIENSIS (NEMATODA: OXYUROIDEA) LENDS SUPPORT TO THE MONOPHYLY OF THE GENUS AND THE RESURRECTION OF GYRINICOLINAE.

Gyrinicola Yamaguti, 1938, includes 6 species of oxyurid found within the intestinal tract of numerous, larval, anuran species in Europe, Asia, South America, and North America. The systematic placement and hierarchical treatment of the genus has shifted at least 5 times since its discovery; the group was first considered as its own family (Gyrinicolidae), then treated as a subfamily (Gyrinicolinae) of Cosmocercidae, then as a member of the Pharyngodonidae, followed by movement back to the Cosmocercidae, and finally a recent proposal suggested the resurrection of the Gyrinicolidae. Species in the genus vary widely in the morphology of the uterine tract, a characteristic often used to indicate membership in the genus, as it is tied to the reproductive mode. However, until recently very few genetic data were available to aid in the placement of this unique group of worms, and before this study to the best of our knowledge none existed for the North American species. To examine the monophyly and placement of the Gyrinicola we sampled populations of Gyrinicola batrachiensis across North America and screened them for genetic diversity using nuclear markers 18S and 28S. Phylogenies suggest at least 3 clades exist among the nematodes from North America and that these clades, alongside Gyrinicola japonica, form a well-supported group within Oxyuroidea. Further representation of Pharyngodonidae from other vertebrate classes may help clarify the relationship of this historical grouping to other members of the Oxyuroidea.

Redescription of Gyrinicola japonica, a Tadpole-Endoparasitic Nematode from Japan, with Resurrection of the Family Gyrinicolidae (Nematoda: Oxyurina).

The taxonomic account of the tadpole-parasitic nematode Gyrinicola japonica Yamaguti, 1938, which is the type species of the genus, was reassessed based on syntypes and newly-collected specimens from the type locality. Our redescription of G. japonica addresses the erroneous original description of a spicule in this nematode, and emends the diagnosis of the species. Additionally, molecular phylogenetic trees based on nuclear 18S and 28S rDNA sequences revealed that G. japonica forms a distinctive lineage within the suborder Oxyurina, and this tadpole-specialist is phylogenetically close to the lizard-parasitic nematodes that belong to the family Pharyngodonidae. The results of morphological examination with the aid of molecular phylogenetic trees highlight the systematic uniqueness of this tadpole-parasitic group within Oxyurina, and Gyrinicolidae is accordingly resurrected as a distinctive oxyurinan family, with redefinition of the family and the genus Gyrinicola.

Redescription of the nematode parasites of lizards: Strongyluris oscari Travassos, 1923 (Heterakidae) from Brazil and Pharyngodon mamillatus (Linstow, 1897) (Pharyngodonidae) from Egypt.

Strongyluris oscari Travassos, 1923, parasite of Topidurus torquatus (Wied-Neuwied, 1820) (Tropiduridae) from Brazil and Pharyngodon mamillatus (Linstow, 1897) of Chalcides ocellatus (Forskal, 1775) (Scincidae) from Egypt, were redescribed based on light and scanning electron microscopy, and re-evaluation of specimens from parasitological collections. The following features were accurately observed in S. oscari for the first time: structure of lips and pharyngeal valve, presence and distribution of somatic papillae, number and arrangement of caudal papillae, presence of inner sclerotised structures supporting the ventral sucker and the ventral region in tail of males, and structure of the posterior anal lip in females. The unpaired papilla on the inferior edge of the ventral sucker in males of S. oscari is a cuticular groove instead of a true papilla. Regarding the morphology of P. mamillatus the following features were given in details for the first time: structure of the cephalic end in both male and female, location of amphids, position of phasmids in females and the accurate morphology of caudal bursa in males, including the distribution of caudal papillae and the genital cone morphology. Strongyluris oscari and P. mamillatus have no intraspecific morphological variations, but wide range on biometric features. These variations may be accounted by host/environment attributes, since they exhibit wide host and geographical spectra. The present results increased the morphological knowledge of P. mamillatus and S. oscari, strengthening their taxonomic validity.

The diversity and evolution of nematodes (Pharyngodonidae) infecting New Zealand lizards.

Host-parasite co-evolutionary studies can shed light on diversity and the processes that shape it. Molecular methods have proven to be an indispensable tool in this task, often uncovering unseen diversity. This study used two nuclear markers (18S rRNA and 28S rRNA) and one mitochondrial (cytochrome oxidase subunit I) marker to investigate the diversity of nematodes of the family Pharyngodonidae parasitizing New Zealand (NZ) lizards (lygosomine skinks and diplodactylid geckos) and to explore their co-evolutionary history. A Bayesian approach was used to infer phylogenetic relationships of the parasitic nematodes. Analyses revealed that nematodes parasitizing skinks, currently classified as Skrjabinodon, are more closely related to Spauligodon than to Skrjabinodon infecting NZ geckos. Genetic analyses also uncovered previously undetected diversity within NZ gecko nematodes and provided evidence for several provisionally cryptic species. We also examined the level of host-parasite phylogenetic congruence using a global-fit approach. Significant congruence was detected between gecko-Skrjabinodon phylogenies, but our results indicated that strict co-speciation is not the main co-evolutionary process shaping the associations between NZ skinks and geckos and their parasitic nematodes. However, further sampling is required to fully resolve co-phylogenetic patterns of diversification in this host-parasite system.

Guide to the Parasites of Fishes of Canada Part V: Nematoda.

Keys are provided for the identification of the nematode species known to be parasites of Canadian fishes. The nematodes are described and illustrated, with a note of the site(s) they occupy in named fish host(s) and their geographical distribution. Parasite records are given by author and date, full details of which can be found in a bibliography of over 800 references. Diagnoses and keys for 22 Families, 47 genera and 88 species of nematodes are also given, together with a glossary of terms, a host-parasite list, and indices to both nematode parasites and hosts.