Parapharyngodon hispidus n. sp. (Nematoda: Pharyngodonidae) in Tropidurus hispidus (Spix) (Squamata: Tropiduridae) from Caatinga Biome of the Vale do São Francisco, state of Pernambuco, Brazil with a key for the Neotropical species of the genus Parapharyngodon Chatterji.

One species of Parapharyngodon Chatterji (Nematoda: Pharyngodonidae), parasitizing the large intestine of Tropidurus hispidus (Spix) (Squamata: Tropiduridae) in Caatinga biome from Brazil is described and illustrated . This new species differs from a part of its congeners by a set of characters in males: the presence of four pairs of caudal papillae, unpaired post cloacal papilla absent, and smooth anterior cloacal lip. Among the Parapharyngodon species with four pairs caudal papillae, unpaired post clocal papilla absent, and smooth cloacal lips, only P. hispidus n. sp. and P. jairaipurii Rizvi Bursey (Oriental realm), features the same characteristics including sharp pointed tip of spicule, stout terminus or spike of tail of females, and punctate ornamentation of the eggshell. However, these two species are different by the size of spicules (spicules of P. jairaipuri are around 55% of the size spicules of P. hispidus n. sp.); and the arrangement of the caudal papillae (two pairs of adcloacal papillae in P. jaraipuri which are absent in P. hispidus n. sp.). Parapharyngodon hispidus n. sp. is the 55th species assigned to the genus and the 11th species of this genus described in Neotropical hosts.

Genetic diversity of Syphacia Seurat, 1916 (Nematoda: Oxyuridae) across the hybrid zone of their rodent hosts in Russia.

The genetic diversity of Syphacia nematodes (intestinal parasites of rodents) was studied in the hybrid zone of two sister species of common voles, Microtus arvalis and Microtus obscurus, in the Oka River valley, east of Moscow. Syphacia nematodes of other rodent species (Microtus rossiaemeridionalis, Alexandromys oeconomus, Sylvaemus uralensis, and Apodemus agrarius) that inhabit the area were also studied. Phylogenetic trees for the studied nematodes were inferred from the analysis of nuclear ITS1+5.8S+ITS2, LSU rDNA, and mitochondrial CO1 gene partial sequences. Syphacia nematodes of the studied area form three well-defined clades in the phylogenetic tree of this genus. Morphological analysis revealed similarities between the obtained sequences with those of known Syphacia species from the GenBank database, which enabled identifying these three clades up to the species level: S. montana, S. agraria, and S. frederici. Russian haplotypes of Syphacia are different from West European and East Asian haplotypes with pronounced genetic distances. A high level of specificity was reported for two of these three species (S. frederici, only in Sylvaemus uralensis; S. agraria, only in Apodemus agrarius). S. montana was found in different species of voles. Remarkably, S. montana specimens from M. arvalis and M. obscurus were genetically uniform, while S. montana, specimens from hybrids between these two species formed a separate clade distant from those originating from non-hybridised hosts.

A new species of Wellcomia (Nematoda: Oxyuridae) in the plains viscacha (Rodentia: Chinchillidae) from Argentina, an emended diagnosis and an update of the genus Wellcomia.

Wellcomia species (Oxyuridae, Syphaciinae) parasitise several families of rodents from Africa, Asia and America with diverse ecological characteristics. A new species of Wellcomia is described based on specimens obtained from the plains viscacha Lagostomus maximus (Chinchillidae) from Argentina. The description includes morphometric and ecological aspects and an emended diagnosis of the genus Wellcomia. In addition, a molecular characterisation (18S rRNA) and an exploratory analysis of the genetic distances of the species included in this genus are provided. The new species, Wellcomia hugoti n. sp., differs from other species of the genus in the morphology of the cephalic plate, the ventral rugose area in males and the vulva in females. The new species showed a low prevalence (7.7%) and a high mean abundance (73.8). The genetic distances detected do not allow a comprehensive assessment of the monophyly of the genus. This is the seventh record of this genus in rodents from the Americas, the second in rodents from Argentina and the first record for the family Chinchillidae.

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.

Oxyuricassis ekstromi n. sp. (Oxyurida: Pharyngodonidae) from Lasiancistrus saetiger (Siluriform: Loricariidae) from the Eastern Amazon.

Oxyuricassis ekstromi n. sp. is the third species of the genus described from the intestine of Lasiancistrus saetiger Armbruster in Brazil. This species can be easily differentiated from its congeners by the presence of a tooth-like sclerotized piece that occupies half of the stoma and absence of spine projections on the tail of both males and females. Also, males of the new species lack caudal alae present in Oxyuricassis coronatus and Oxyuricassis hexaspinatus. Additionally, we observed a different number and pattern of the distribution of cloacal papilla; males of O. coronatus and O. hexaspinatus have 1 pair of pre-cloacal and 2 pairs of post-cloacal papillae; while the new species has 1 pre-cloacal and 3 post-cloacal pairs of papillae.

Morphological description and phylogenetic assessment of 28S rRNA for Thelandros chalcidiae sp. nov. from Chalcides ocellatus.

Thelandros is a genus of oxyurid nematodes which parasitize both omnivorous and herbivorous hosts. Thelandros chalcidiae sp. nov. is a new taxa described from the large intestine of the ocellated skink, Chalcides ocellatus, from the South Sinai Desert in Egypt. The recovered parasite species was examined at both morphological and molecular levels in order to determine the exact taxonomic position within Pharyngodonidae family. The current pharyngodonid species is characterized by a mouth opening bounded by three bilobed lips; male worms are characterized by the presence of two pairs of cloacal papillae (pre- and adcloacal) and one single caudal papillae (postcloacal) and caudal alae in an auricular form and females with post-equatorial vulva, amphidelphic ovary in which anterior ovary extended to level of excretory pore and posterior ovary extended posteriorly up anal opening. The recovered nematodes were compared with other known species from different hosts and it was found to be morphologically different from them. Molecular characterization based on the partial 28S rRNA nuclear ribosomal gene sequence showed sequence identities ≥ 83.15% with taxa under family Pharyngodonidae, 74.84-87.37% with Oxyuridae, 80.54% with Heteroxynematidae, and 75.98-77.72% with Thelastomatidea. Phylogenetic analysis showed that parasite sequence in conjunction with existing data facilitate placement of this species within Oxyurida. The present species is deeply embedded in genus Thelandros with close relationships to previously described Thelandros sp. and T. galloti in same taxon. This study highlighted importance of combining morphological and genetic data with taxonomy in pharyngodonid species.

Morphological redescription and phylogenetic assessment of Spauligodon aspiculus (Oxyuroidea: Pharyngodonidae) infecting the white-spotted gecko, Tarentola annularis (Squamata: Gekkonidae).

Thirty white-spotted geckos, Tarentola annularis, from the South Sinai desert in Egypt, were examined for helminth parasites. Spauligodon aspiculus was observed to infect 19 geckos with 63.33% as a prevalence of parasitic infection. The present nematode species is separated from congeners by morphological and metrical characteristics such as lateral alae, aspinose filamentous tail, and no spicule, and three pairs of caudal papillae with posterior pair excluded from envelopment by the caudal alae in the male worms, and knobbed eggs, and postbulbar vulva in females. It compared morphometrically with other Spauligodon species described previously and showed few differences in measurements. Molecular characterization based on the partial 28S rRNA nuclear ribosomal gene sequence showed that there was a close identity, up to 72%, with other sequences retrieved from GenBank. Phylogenetic analysis showed that the parasite sequence in conjunction with existing data facilitates the investigation of the placement of this pharyngodonid species within Oxyuridae. The present species is deeply embedded in the genus Spauligodon with close relationships to previously described Spauligodon nicolauensis (gb| JN619349.1, and JF829243.1) as more related sister taxa. This study highlights the importance of combining genetic and morphological data with taxonomy in pharyngodonid species.

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.

Oxyurid nematodes of pet rodents in Slovakia - a neglected zoonotic threat / Nematódeos oxiurídeos de roedores de estimação na Eslováquia - uma ameaça zoonótica negligenciada

Abstract The role of rodents as reservoirs of helminths of public health importance is not well known. The zoonotic potential of Syphacia spp. has been confirmed; therefore, the study aimed to estimate the occurrence of oxyurid nematodes in small rodents from pet shops and breeding clubs in Slovakia. Fecal samples of 586 pet rodents kept in 133 cages were collected between 2016 and 2018 and examined by Faust´s flotation method. Four species of oxyurid nematodes, Syphacia muris, S. obvelata, Aspiculuris tetraptera and Paraspidodera uncinata were detected. A. tetraptera was found in the faecal samples of all rodent species included in this survey. The number of positive boxes varied from 5.4% in hamsters to 70.0% with mice. The prevalence of Syphacia muris was highest in Mongolian gerbils where up to 75.0% boxes were positive; S. obvelata was found in 26.7% of boxes with mice, 25.0% of boxes with Mongolian gerbils and 3.2% of boxes with rats. The high prevalence of Syphacia spp. in all animal species points out the infection risk for humans. Animals offered for sale are often in close contact with human beings; therefore they should be regularly tested for parasites and then effectively dewormed.

Resumo O papel dos roedores como reservatórios de helmintos de importância para a saúde pública não é bem conhecido. O potencial zoonótico de Syphacia spp. foi confirmado; portanto, o estudo teve como objetivo estimar a ocorrência de nematóides oxiurídeos em pequenos roedores de pet shops e clubes de reprodução na Eslováquia. Amostras fecais de 586 roedores mantidos em 133 gaiolas foram coletadas entre 2016 e 2018 e examinadas pelo método de flotação de Faust. Foram detectadas quatro espécies de nematódeos oxiurídeos, Syphacia muris, S. obvelata, Aspiculuris tetraptera e Paraspidodera uncinata, A. tetraptera foi encontrado nas amostras fecais de todas as espécies de roedores incluídas nesta pesquisa. O número de gaiolas positivas variou de 5,4% em hamsters a 70,0% em camundongos. A prevalência de Syphacia muris foi maior nos gerbilos da Mongólia, onde até 75,0% das gaiolas foram positivas; S. obvelata foi encontrada em 26,7% das gaiolas com camundongos, 25,0% das gaiolas com gerbilos da Mongólia e 3,2% das gaiolas com ratos. A alta prevalência de Syphacia spp. em todas as espécies animais aponta o risco de infecção para os seres humanos. Animais oferecidos para venda estão frequentemente em contato próximo com seres humanos; portanto, eles devem ser regularmente testados quanto a parasitas e, então, efetivamente desparasitados.

Oxyurid nematodes of pet rodents in Slovakia - a neglected zoonotic threat.

The role of rodents as reservoirs of helminths of public health importance is not well known. The zoonotic potential of Syphacia spp. has been confirmed; therefore, the study aimed to estimate the occurrence of oxyurid nematodes in small rodents from pet shops and breeding clubs in Slovakia. Fecal samples of 586 pet rodents kept in 133 cages were collected between 2016 and 2018 and examined by Faust´s flotation method. Four species of oxyurid nematodes, Syphacia muris, S. obvelata, Aspiculuris tetraptera and Paraspidodera uncinata were detected. A. tetraptera was found in the faecal samples of all rodent species included in this survey. The number of positive boxes varied from 5.4% in hamsters to 70.0% with mice. The prevalence of Syphacia muris was highest in Mongolian gerbils where up to 75.0% boxes were positive; S. obvelata was found in 26.7% of boxes with mice, 25.0% of boxes with Mongolian gerbils and 3.2% of boxes with rats. The high prevalence of Syphacia spp. in all animal species points out the infection risk for humans. Animals offered for sale are often in close contact with human beings; therefore they should be regularly tested for parasites and then effectively dewormed.

The importance of integrative approaches in nematode taxonomy: the validity of Parapharyngodon and Thelandros as distinct genera.

Despite the advances of molecular tools, new nematode species are still described mainly based on morphological characters. Parapharyngodon and Thelandros are two genera of oxyurids with unclear related taxonomic histories. Here we use morphological characters (linear measurements and categorical variables) and genetic information (18S rRNA, 28S rRNA and COI partial gene sequences) to confirm the relationships between representatives of these two genera and to determine whether they can be discriminated morphologically. Genetic results confirm the existence of two main clades, mostly congruent with Parapharyngodon and Thelandros genera but with several discordances. Thelandros is polyphyletic, with two of the species analysed (T. filiformis and T. tinerfensis) being part of the Thelandros clade, but with a third one (T. galloti) falling within the Parapharyngodon clade. Regarding the Parapharyngodon clade, P. cubensis, P. scleratus and Parapharyngodon sp. from Mexico form congruent lineages, while most P. echinatus samples cluster in another group, with one exception. Interestingly, P. micipsae samples are scattered across the Parapharyngodon clade, suggesting that they were misidentified or rather represent alternative morphotypes of other species. Morphological analysis identified the length of the tail, number of caudal papillae, position of the nerve ring, presence of caudal alae and length of the lateral alae as reliable characters to distinguish between Parapharyngodon and Thelandros genetic clades. Our study highlights the current taxonomic inconsistency in these groups, mainly derived from the exclusive use of morphological data. As such, we advocate for the routine implementation of molecular data in nematode taxonomic studies.

A new species of Parapharyngodon Chatterji, 1933 (Oxyuroidea: Pharyngodonidae), parasitic in Osteocephalus taurinus (Anura: Hylidae) from Brazil.

Parapharyngodon politoedi n. sp. is described here, based on specimens found in the large intestines of Osteocephalus taurinus from the Caxiuanã National Forest, State of Pará, Brazil. The new species is assigned to Parapharyngodon based on the presence of non-embryonated eggs with sub-terminal opercula, when in the ovijector. Parapharyngodon politoedi belongs to a group of species with three pairs of cloacal papillae and differs from its congeners by morphometric aspects, such as the length of the spicule, and the combination of the following morphological characters: ovaries never encircling the oesophagus, tail shape in females, cloacal lips, sharply pointed spicule and presence of genital cone. This is the second species of nematode reported to parasitize O. taurinus and the eleventh species of Parapharyngodon from hylids in the Neotropical region.

Integrative approach on Pharyngodonidae (Nematoda: Oxyuroidea) parasitic in reptiles: Relationship among its genera, importance of their diagnostic features, and new data on Parapharyngodon bainae.

The first integrative approach using sequences of two genes (18S and 28S rRNA) plus morphological and life history traits, was explored in Pharyngodonidae nematodes parasitic in reptiles. Additionally, first genetic characterization of Parapharyngodon bainae and new data on its morphology are given. This approach evaluated the phylogenetic relationships among genera within Pharyngodonidae, as well as the importance of their diagnostic morphological features. Specimens of P. bainae were collected from faecal pellets of the lizard Tropidurus torquatus in the State of Minas Gerais, Brazil. Nematodes were fixed for scanning electron microscopy and molecular procedures. Morphological observations revealed the accurate structures of cephalic end, of cloacal region in males, of vulva and eggs. Phylogenetic reconstructions were based upon four datasets: aligned sequences of the 18S, of the 28S, of both concatenated genes and of combined morphological and molecular datasets. Bayesian inference and maximum likelihood were performed to infer the phylogenies of molecular datasets and maximum parsimony to infer that of all-combined data. Pharyngodonid parasites of reptiles seem to configure two general monophyletic lineages, as previously assertions. Results also showed the monophyly of Spauligodon, Skrjabinodon and Parapharyngodon, as well as the clear separation between the latter and Thelandros. Combination of datasets improved nodal supports. Analysis of the all-combined datasets revealed the importance of vulval position and egg morphology as phylogenetic informative traits. However, characters of male caudal morphology appear as are highly homoplastic, and seem to be product of convergent evolution or multiple losses of ancestral traits. The closely-related Thelandros and Parapharyngodon are kept valid and their diagnosis should be based upon the position of the operculum in eggs (terminal or subterminal, respectively). Some inconsistencies in the scarce molecular and morphological databases were noted. Thus, new genetic data is required for further conclusions and current database must be evaluated with attention.

Molecular characterization of cosmopolitan and potentially co-invasive helminths of commensal, murid rodents in Gauteng Province, South Africa.

Concurrent studies of helminth parasites of introduced and native rodent species are few and miss the opportunity to identify potential co-invasive parasite species. This study employed molecular tools to infer the phylogeny and elucidate the origin of potentially co-invasive parasites of commensal, murid rodents by assessing introduced Rattus norvegicus, Rattus rattus, Rattus tanezumi, and native Mastomys coucha in Gauteng Province, South Africa. Genotypes of Nippostrongylus brasiliensis recovered from R. norvegicus are nearly identical to those recovered from elsewhere in the world. The pinworms, Aspiculurus tetraptera, recovered from introduced R. tanezumi and R. rattus, Syphacia muris recovered from R. tanezumi, and Syphacia obvelata recovered from indigenous M. coucha have affiliations to those recovered of laboratory rodents from the USA and China. Syphacia obvelata was previously only known as a commensal endoparasite of laboratory rodents, and the S. muris genotype recovered from R. tanezumi in this study shows an affiliation to a genotype recovered from the same host species in Indonesia which is part of the native range. The study emphasizes the need for surveillance of potential co-invasive species and contributes in documenting genetic diversity of endoparasites of well-known hosts.

PCR Testing of IVC Filter Tops as a Method for Detecting Murine Pinworms and Fur Mites.

We evaluated PCR testing of filter tops from cages maintained on an IVC system through which exhaust air is filtered at the cage level as a method for detecting parasite-infected and -infested cages. Cages containing 4 naïve Swiss Webster mice received 360 mL of uncontaminated aspen chip or α-cellulose bedding (n = 18 cages each) and 60 mL of the same type of bedding weekly from each of the following 4 groups of cages housing mice infected or infested with Syphacia obvelata (SO), Aspiculuris tetraptera (AT), Myocoptes musculinus (MC), or Myobia musculi (MB) and Radfordia affinis (RA; 240 mL bedding total). Detection rates were compared at 30, 60, and 90 d after initiating bedding exposure, by using PCR analysis of filter tops (media extract and swabs) and testing of mouse samples (fur swab [direct] PCR testing, fecal flotation, anal tape test, direct examination of intestinal contents, and skin scrape). PCR testing of filter media extract detected 100% of all parasites at 30 d (both bedding types) except for AT (α-cellulose bedding, 67% detection rate); identified more cages with fur mites (MB and MC) than direct PCR when cellulose bedding was used; and was better at detecting parasites than all nonmolecular methods evaluated. PCR analysis of filter media extract was superior to swab and direct PCR for all parasites cumulatively for each bedding type. Direct PCR more effectively detected MC and all parasites combined for aspen chip compared with cellulose bedding. PCR analysis of filter media extract for IVC systems in which exhaust air is filtered at the cage level was shown to be a highly effective environmental testing method.

A new species of Spauligodon (Nematoda; Oxyuroidea; Pharyngodonidae) and other Nematodes in Cyrtodactylus epiroticus (Squamata; Gekkonidae) from Papua New Guinea.

Spauligodon papuensis sp. nov. from the large intestines of Cyrtodactylus epiroticus (Gekkonidae) from Papua New Guinea is described and illustrated. Spauligodon papuensis sp. nov. represents the 54th species assigned to the genus and the second species from the Oceanic Region. The new species is separated from congeners by the unique combination of aspinose filamentous tail and no spicule in the male; and spinose filamentous tail, fusiform, flanged eggs, and postbulbar vulva in the female. Four additional species of nematodes were also found in C. epiroticus: mature specimens of Cosmocerca zugi, Falcaustra papuensis, Physalopteroides milnensis and larvae of Abbreviata sp.

Evaluation of Anthelmintic Resistance and Exhaust Air Dust PCR as a Diagnostic Tool in Mice Enzootically Infected with Aspiculuris tetraptera.

The entry of infectious agents in rodent colonies occurs despite robust sentinel monitoring programs, strict quarantine measures, and stringent biosecurity practices. In light of several outbreaks with Aspiculuris tetraptera in our facilities, we investigated the presence of anthelmintic resistance and the use of exhaust air dust (EAD) PCR for early detection of A. tetraptera infection. To determine anthelmintic resistance, C57BL/6, DBA/2, and NCr nude mice were experimentally inoculated with embryonated A. tetraptera ova harvested from enzootically infected mice, followed by treatment with 150 ppm fenbendazole in feed, 150 ppm fenbendazole plus 5 ppm piperazine in feed, or 2.1 mg/mL piperazine in water for 4 or 8 wk. Regardless of the mouse strain or treatment, no A. tetraptera were recovered at necropsy, indicating the lack of resistance in the worms to anthelmintic treatment. In addition, 10 of 12 DBA/2 positive-control mice cleared the A. tetraptera infection without treatment. To evaluate the feasibility of EAD PCR for A. tetraptera, 69 cages of breeder mice enzootically infected with A. tetraptera were housed on a Tecniplast IVC rack as a field study. On day 0, 56% to 58% of the cages on this rack tested positive for A. tetraptera by PCR and fecal centrifugation flotation (FCF). PCR from EAD swabs became positive for A. tetraptera DNA within 1 wk of placing the above cages on the rack. When these mice were treated with 150 ppm fenbendazole in feed, EAD PCR reverted to pinworm-negative after 1 mo of treatment and remained negative for an additional 8 wk. The ability of EAD PCR to detect few A. tetraptera positive mice was investigated by housing only 6 infected mice on another IVC rack as a field study. The EAD PCR from this rack was positive for A. tetraptera DNA within 1 wk of placing the positive mice on it. These findings demonstrate that fenbendazole is still an effective anthelmintic and that EAD PCR is a rapid, noninvasive assay that may be a useful diagnostic tool for antemortem detection of A. tetraptera infection, in conjunction with fecal PCR and FCF.

Parapharyngodon hugoi n. sp., a new nematode (Oxyuroidea: Pharyngodonidae) of the tree frog Trachycephalus typhonius (Linnaeus) from the Brazilian Pantanal, including a key to the congeners from amphibians of the American continent.

A new nematode Parapharyngodon hugoi n. sp. (Oxyuroidea: Pharyngodonidae) is described parasitising the large intestine of the tree frog Trachycephalus typhonius (Linnaeus) (Anura: Hylidae) from the wetlands of Pantanal, State of Mato Grosso do Sul, Brazil. The new species exhibits a unique structure of the posterior cloacal lip in males, which is supported by a rigid V-shaped structure. Parapharyngodon hylidae parasitic in hylid frogs, including T. typhonius, from Mexico, is the most similar congener to P. hugoi n. sp. but is distinguished from the new species by the presence of a gubernaculum (vs absence), by the lateral alae in males ending far anterior to cloacal opening (vs near to it) and because in gravid females the ovaries encircle the oesophageal corpus. Additionally, the new species differs from its congeners as well as from species of Thelandros Wedl, 1862, a very closely related genus, by the combination of features such as spicule length, number of caudal papillae, morphology of the anterior cloacal lip, which is echinate, and position of ovaries. The geographical distribution of hosts seems to play an important role in the speciation process of Parapharyngodon spp.; however, due the lack of molecular data this issue along with the validity of both Thelandros and Parapharyngodon are still questions to be solved in the future, after improvement of the genetic database. A key to the species of Parapharyngodon parasitic in amphibians from the American continent is provided.

Oxyuricassis coronatus n. gen. n. sp. and O. hexaspinatus n. sp. (Oxyurida: Pharyngodonidae): Parasites of Lasiancistrus saetiger (Siluriformes: Loricariidae) in Freshwater Rivers of the Brazilian Amazon.

A new nematode genus is described from intestines of Lasiancistrus saetiger Ambruster from freshwater rivers in the Brazilian Amazon. Oxyuricassis n. gen. is characterized by a cephalic cone, small buccal cavity, long esophagus with a well-developed isthmus, and a conical tail with spines. Two new species are described: Oxyuricassis coronatus n. sp. is characterized by the absence of lateral alae, a conical tail with truncated extremity with spine-like sclerotized projections around the tail tip, and caudal alae in males expanded. Oxyuricassis hexaspinatus n. sp. is characterized by lateral alae, a conical tail with tapered extremity, with 2 pairs of proximal spines at the posterior extremity of the tail, 1 dorsal pair and 1 ventral pair, plus a pair of lateral spines that vary in position between sexes, and male of O. hexaspinatus has narrow caudal alae. Both species were found co-parasitizing all of the analyzed host specimens.

The Missing Fellow: First Description of the Trypanoxyuris pigrae Male (Nematoda: Oxyuridae), a Parasite of the Black Howler Monkey (Alouatta pigra) in Mexico.

The first morphological description of the male of Trypanoxyuris pigrae Solórzano-García, Nadler, and Pérez-Ponce de León, 2016 , is presented in this study. Morphological data are supported by molecular data. Specimens of T. pigrae were recovered after the necropsy of a roadkill black howler monkey (Alouatta pigra) in southeastern Mexico. Males of T. pigrae are characterized by having 3 notched lips and a long esophagus with a posterior bulb; they also show a single crested lateral alae, a single spicule, and 4 caudal papillae. Morphological features coincide with those of the previously described T. pigrae females, and molecular profiles confirmed species identification. Males of T. pigrae are very similar to those of Trypanoxyuris minutus, another species of pinworm that also parasitizes the black howler monkey, A. pigra; however, the shape of the lips represents a very reliable diagnostic feature. Because of this, detailed en face observations are recommended to discriminate between these pinworm species.