Morphological and Molecular Data Reveal Two New Species of Viannaia (Nematoda: Viannaiidae), Parasitizing Opossums (Mammalia: Didelphidae) in Mexico.

Two new species of Viannaia from the intestine of the North American opossums, Didelphis virginiana (Virginia opossum), and Philander opossum (gray four-eyed opossum), are described based on morphological and molecular data, through an integrative taxonomic approach. Maximum likelihood and Bayesian inference analyses for each dataset and the concatenated dataset were performed using a mitochondrial cytochrome c oxidase subunit 1 (COI) gene, and the nuclear ribosomal internal transcribed spacer region (ITS1-5.8S-ITS2). The phylogenetic analyses revealed 2 new species that occur in Mexico, one from the western state of Colima and another from the southern state of Chiapas. Our phylogenetic trees for both molecular markers and concatenated datasets yielded similar topologies with high bootstrap values and posterior probabilities. Viannaia is recovered as a monophyletic group, but the family Viannaiidae appears as non-monophyletic, due to the position of Travassostrongylus scheibelorum, similar to previous studies. Finally, the morphology of Viannaia and Hoineffia is discussed.

Morphological and molecular data reveal a new species of Lueheia (Acanthocephala: Plagiorhynchidae) from Turdus migratorius (Turdidae) in central Mexico and its phylogenetic implications within the family.

Members of the genus Lueheia Travassos, 1919, are endoparasites of birds, particularly passerines, throughout the Americas. Adults of Lueheia sp., (Plagiorhynchidae Golvan, 1960; Porrorchinae Golvan, 1956) were recovered from the intestine of the American robin (Turdus migratorius phillipsi Bangs) in Mexico City, and two other species of acanthocephalans identified as Porrorchis nickoli, (Plagiorhynchidae: Porrorchinae) Salgado-Maldonado and Cruz-Reyes, 2002 and Centrorhynchus microcephalus (Bravo-Hollis, 1947) Golvan, 1956 (Centrorhynchidae Van Cleave, 1916), were recovered from the Virginia opossum (Didelphis virginiana Allen) and groove-billed ani (Crotophaga sulcirostris Swainson), respectively in southeastern Mexico. Specimens of three species were sequenced at two molecular markers, the small subunit (SSU) and large subunit (LSU) of the nuclear rDNA and compared with other sequences available in GenBank. Maximum likelihood and Bayesian inference analyses of the combined (LSU + SSU) dataset and each individual dataset revealed that the specimens of Lueheia sp. formed an independent lineage, which is recognized herein as a new species, Lueheia aztecae n. sp., representing the fifth species of the genus in the Americas, and the second in the Nearctic region. The new species can be morphologically distinguished from the other five species in the genus by having a cylindrical proboscis, armed with 24-26 longitudinal rows with 9-10 hooks each. Phylogenetic inference performed with the combined dataset consisting of two genes (LSU + SSU) revealed that Lueheia aztecae n. sp. and P. nickoli belonging to subfamily Porrorchinae, formed two independent lineages, indicating that the subfamily is paraphyletic. Porrorchis nickoli and C. microcephalus formed a clade with other species of the genus Centrorhynchus, suggesting that P. nickoli should be transferred to genus Centrorhynchus, to form C. nickoli n. comb. In addition, we briefly discuss the ecological associations between the members of the families Plagiorhynchidae and Centrorhynchidae.

A New Species of Triumphalisnema (Nematoda: Coronostomatoidea) Parasite of Proculejus hirtus (Coleoptera: Passalidae) from Mexico, and the Position of the Family in the Oxyuridomorpha.

A new species of the nematode Triumphalisnema Kloss, 1962 (Oxyuridomorpha), is described from the wood beetle Proculejus hirtus Truqui from the mountain mesophilic forest in Hidalgo State, Mexico. Triumphalisnema zuuei n. sp. is distinguished from the other 4 congeners species by the presence of an expanded cervical ring, well-developed lateral alae, an obtuse cauda with a short and bifurcated caudal appendage, series of cuticular folds at ventral and dorsal body surface from excretory pore level to anal region, and ellipsoidal eggs ornamented with numerous small mushroom-like structures over the surface. The phylogenetic position of the new species is inferred based on a Maximum Likelihood and Bayesian Inference analysis of partial sequences of 18S SSU rRNA. The phylogenetic analysis showed that Triumphalisnema zuuei n. sp., the only representative of the Traklosiidae in our study, is closely related to Coynema poeyi and species of Longior, Hystrignathus, and Lepidonema, all of them members of Hystrignathidae. These relationships are supported by high support values. The present study increases to 5 the number of species assigned to Triumphalisnema, all of them parasites of Passalidae. Additionally, a taxonomic key to the species of the genus is provided.

Helminth Community Structure of the Gray Four-Eyed Opossum Philander opossum (Mammalia: Didelphidae) in the Neotropical Portion of Mexico.

Studies on helminth communities associated with didelphids are scarce; the majority of works have focused at taxonomic level. To increase the ecological knowledge of these host-parasite associations, during March (dry season) of 3 consecutive years (2013-2015) a total of 49 adults of the gray four-eyed opossum (Philander opossum) was collected in the Neotropical portion of Mexico (Agua Fría, Chiapas State) and examined for helminths. The main objectives of this study were to describe the infra- and component communities of helminths associated with P. opossum and to compare the helminth fauna of the Mexican population of this host species with those studied in French Guiana and in other Mexican terrestrial didelphids. The helminthological record of this host consisted of 12 species: 7 taxa of Nematoda, 3 of Trematoda, 1 Cestoda, and 1 Acanthocephala. Eight of the 12 taxa have been previously recorded in Didelphidae and 4 represent accidental infections ( Glossocercus sp., Stomylotrema vicarium, Spirura mexicana and Acanthocephala gen. sp.). Diet of hosts is the main structuring factor of the communities (92% of the helminth species were recruited through ingestion). Forty-eight hosts were parasitized by at least 1 helminth species; Rhopalias coronatus was the most prevalent and abundant species in the hosts sampled. No significant differences were found in global prevalence among the helminth species present in all samplings, considering host sex and year. The dominance exerted by R. coronatus led to low values of evenness and diversity at both community levels. No significant differences were observed in composition of helminth species among the 3 sampling years regarding sex. The results of our study showed changes in helminth abundance at infracommunity level; during the first sampling these changes are explained by species with direct life cycle ( Viannaia sp. and Cruzia tentaculata), whereas in last 2 surveys the explanation can be attributed to species with heteroxenous life cycles (particularly R. coronatus, Duboisiella proloba, and Turgida turgida). Thirty-three percent of the helminth species recorded in P. opossum in Agua Fría is shared with the other 2 terrestrial species of didelphids sampled in different sites of Mexico: Didelphis marsupialis and Didelphis virginiana. In contrast, samples from French Guiana and Agua Fría, differ in terms of helminth fauna, confirming that the helminth communities of opossum species inhabiting the same locality show higher levels of taxonomic similarity than communities of conspecific marsupials allopatrically distributed.

Molecular data reveal a new species of Rhopalias Stiles & Hassall, 1898 (Digenea, Echinostomatidae) in the Common opossum, Didelphismarsupialis L. (Mammalia, Didelphidae) in the Yucatán Peninsula, Mexico.

A new species of Rhopalias Stiles & Hassall, 1898 is described from the small intestine of the Common opossum, Didelphismarsupialis Linnaeus from the Yucatán Peninsula, Mexico. Rhopaliasoochi sp. nov. is morphologically very similar to the type species of the genus, Rhopaliascoronatus (Rudolphi, 1819) Stiles & Hassall 1898, a species widely distributed in opossums across Mexico. A molecular phylogenetic analysis using a mitochondrial gene (cox1), and the nuclear ribosomal internal transcribed spacer region (ITS1-5.8S-ITS2), of specimens of R.coronatus collected in several localities of Mexico revealed that those from the Yucatán Peninsula, originally recorded on morphological grounds as R.coronatus actually represented an independent genetic lineage. Maximum Likelihood and Bayesian Inference analyses were performed for each data set independently, and for the concatenated data set (ITS1-5.8S-ITS2 + cox1). All phylogenetic analyses showed that the specimens from Yucatán represented a monophyletic lineage, with high bootstrap support and Bayesian posterior probabilities. In addition, the genetic divergence estimated between R.oochi sp. nov. and two species of Rhopalias, R.coronatus, and R.macracanthus Chandler, 1932 that also occur in Mexican marsupials ranged between 7-8% and 16-17%, for cox1, and between 0.1-0.2% and 7% for the ITS region, respectively. The molecular evidence gathered in this study (reciprocal monophyly in both phylogenetic analyses, and estimated genetic divergence) suggested that the specimens found in the intestine of D.marsupialis originally reported as R.coronatus from Yucatán, actually represent a new species. Morphological evidence was found through light and scanning electron microscopy to support the species distinction based on molecular data.

New records of helminths of Sceloporus pyrocephalus Cope (Squamata, Phrynosomatidae) from Guerrero and Michoacán, Mexico, with the description of a new species of Thubunaea Seurat, 1914 (Nematoda, Physalopteridae).

A total of 61 specimens of the Red-headed Spiny Lizard Sceloporus pyrocephalus Cope (Phrynosomatidae) collected during the breeding season (June/July 2003, 2004 and 2005) from Western Mexico were examined for helminths. The morphological characterization of the helminths found was made through light microscopy and scanning electron microscopy. Nine taxa of helminths were identified, two cestodes: Mesocestoides sp. and Oochoristica sp., and seven nematodes: Parapharyngodon ayotzinapaensis Garduño-Montes de Oca, Mata-López & León-Règagnon, 2016, Parapharyngodon tikuinii Garduño-Montes de Oca, Mata-López & León-Règagnon, 2016, Parapharyngodon sp., Physalopterinae gen. sp., Skrjabinoptera scelopori Caballero-Rodríguez, 1971, Strongyluris similis Caballero, 1938 and a new species of Thubunaea Seurat, 1914. Larvae of Mesocestoides sp. and Physalopterinae gen. sp. were found in the body cavity and digestive tract, respectively. Excluding the species of Parapharyngodon Chatterji, 1933, S. pyrocephalus is recorded for the first time as a host of the remaining seven taxa of helminths. Additionally, Thubunaealeonregagnonae sp. n. is described and illustrated as a new nematode species, parasite of S. pyrocephalus from Mexico. This new species can be differentiated from the majority of its congeners by the absence of spicules, the particular pattern of caudal papillae in males and the small ratio of oesophagus length:male total body length (0.1-0.16).

Two new species of Parapharyngodon parasites of Sceloporus pyrocephalus, with a key to the species found in Mexico (Nematoda, Pharyngodonidae).

Two new species of Parapharyngodon collected from the intestine of the Mexican boulder spiny lizard Sceloporus pyrocephalus are described. This study increases to 49 the number of valid species assigned to Parapharyngodon worldwide, 11 of them distributed in Mexico. Males of the two new species share the presence of four pairs of caudal papillae, an anterior echinate cloacal lip and the presence of lateral alae; however, both differ from each other in lateral alae extension and echinate cloacal anterior lip morphology. Females of both species have a prebulbar uterus and eggs shell punctuate with pores, characteristics shared with few other species of Parapharyngodon. Both new species differ from other congeneric species in the papillar arrangement, the anterior cloacal lip morphology, the lateral alae extension and total length/spicule ratio. A taxonomic key for the species of Parapharyngodon distributed in Mexico is provided.

Helminths of three species of opossums (Mammalia, Didelphidae) from Mexico.

From August 2011 to November 2013, 68 opossums (8 Didelphis sp., 40 Didelphisvirginiana, 15 Didelphismarsupialis, and 5 Philanderopossum) were collected in 18 localities from 12 Mexican states. A total of 12,188 helminths representing 21 taxa were identified (6 trematodes, 2 cestodes, 3 acanthocephalans and 10 nematodes). Sixty-six new locality records, 9 new host records, and one species, the trematode Brachylaimadidelphus, is added to the composition of the helminth fauna of the opossums in Mexico. These data, in conjunction with previous records, bring the number of taxa parasitizing the Mexican terrestrial marsupials to 41. Among these species, we recognized a group of helminths typical of didelphids in other parts of the Americas. This group is constituted by the trematode Rhopaliascoronatus, the acanthocephalan Oligacanthorhynchusmicrocephalus and the nematodes Cruziatentaculata, Gnathostomaturgidum, and Turgidaturgida. In general, the helminth fauna of each didelphid species showed a stable taxonomic composition with respect to previously sampled sites. This situation suggests that the rate of accumulation of helminth species in the inventory of these 3 species of terrestrial marsupials in the Neotropical portion of Mexico is decreasing; however, new samplings in the Nearctic portion of this country will probably increase the richness of the helminthological inventory of this group of mammals.

Parapharyngodon n. spp. (Nematoda: Pharyngodonidae) parasites of hylid frogs from Mexico and review of species included in the genus.

Two new species of Parapharyngodon Chatterji, 1933 , parasitizing 3 species of hylid frogs (Diaglena spatulata, Triprion petasatus, and Trachycephalus typhonius) from Mexico are described. The 2 new species share the presence of a gubernaculum with Parapharyngodon lamothei and belong to the group of those species with short spicule; both differ from the remaining species of the genus in the papillar pattern on ventrolateral and dorsal lips and in the thickness of cuticular annulations and cuticular ornamentation in the female specimens. These are the third and fourth reports of Parapharyngodon spp. parasitizing hylid frogs. In addition to the egg characteristics, we propose that length of the lateral alae is also a taxonomically relevant feature to differentiate species of the genus. A bibliographic review of all species historically assigned to Parapharyngodon is given, including those that have been declared species inquirenda, or transferred to other genera and those that are considered valid.

Helminth infracommunity structure of Leptodactylus melanonotus (Anura) in Tres Palos, Guerrero, and other records for this host species in Mexico.

The amphibian genus Leptodactylus includes around 50 species, of which only 2 are distributed in Mexico; the helminth fauna of these 2 species is poorly known. As part of a research program on amphibian parasites in Mexico from 1997 to 2005, 281 sabinal frogs Leptodactylus melanonotus from 42 localities in 11 Mexican states were examined from a helminthological perspective. A total of 20 taxa of helminths-7 digeneans (5 adults, 2 larvae) and 13 nematodes (8 adults, 5 larvae)-was found to infect this amphibian host species. These data represent 105 new locality records, and 11 taxa are recorded in L. melanonotus for the first time. Infracommunity analyses of the sabinal frogs from Tres Palos indicated that these hosts are depauperate. The helminth community is dominated by specialist species, with Cosmocerca podicipinus the most common in almost 50% of the infracommunities. Percutaneous infection and predator-prey interactions were the 2 most common infection routes by helminths in frogs from Tres Palos, with 79% of the parasites recruited via skin penetration. Finally, our results show that the helminth fauna parasitizing L. melanonotus throughout Mexico has low similarity with the helminth fauna of leptodactylids studied comprehensively in South America, with only 2 digeneans and 3 nematodes being shared by hosts from both regions. As a result of our survey, the number of helminth species parasitizing L. melanonotus increased to 34. Considering its native distribution range, this number is now 36 with the inclusion of the nematodes Oswaldocruzia costaricensis and Cruzia empera in Costa Rica.

Gorgoderina festoni n. sp. (Digenea: Gorgoderidae) in Anurans (Amphibia) from Mexico.

Gorgoderina festoni n. sp. is described from the urinary bladder of Gastrophryne usta, Leptodactylus labialis, L. melanonotus and Bufo marinus from localities at low altitude in the states of Veracruz, Oaxaca, Guerrero and Colima, Mexico. This species differs from most other species of the genus by a combination of the following characters: lobed vitelline masses, body size 3.45-4.26 (mean 3.75) mm and sucker-ratio 1:1.3-1.52 (mean 1:1.44). The new species shares these three features with G. bilobata Rankin, 1937, G. schistorchis Steelman, 1938, G. tenua Rankin, 1937, G. vitelliloba (Olsson, 1876) and G. cryptorchis Travassos, 1924, but it differs from the first four in having gonads with entire margins. G. festoni most closely resembles G. cryptorchis, but differs from this species in body width at the level of the ventral sucker and in the absence of oesophageal glands. The autapomorphy that distinguishes G. festoni from all other members of the genus is the presence of a tegumental extension (festoon) on the external margin of the ventral sucker.

Species of Gorgoderina (Digenea: Gorgoderidae) in Rana vaillanti and Rana cf. forreri (Anura: Ranidae) from Guanacaste, Costa Rica, including a description of a new species.

Gorgoderina parvicava, G. diaster, and G. megacetabularis n. sp. are reported inhabiting the urinary bladders of Rana vaillanti and R. cf. forreri from northwestern Costa Rica. Gorgoderina megacetabularis n. sp. differs from all other species of the genus by the combination of the following characters: small body size (2.78-3.17, mean 2.92 mm), sucker ratio (1:3.1-3.7), and by the presence of 2 compact, oval, unlobed vitelline masses. Redescription of G. diaster including previously undescribed details on the reproductive apparatus and morphometric data is provided. This is the first record of the 3 species of Gorgoderina in Costa Rica and is the first record of G. diaster in R. vaillanti and R. cf. forreri.

[Infracommunity of parasite helminths of Ambystoma lernaensis (Caudata: Ambystomatidae) in Lerma, Mexico]. / Infracomunidades de helmintos parásitos de Ambystoma lermaensis (Caudata: Ambystomatidae) en Lerma, México.

The helminth infracommunity structure was analyzed in 48 salamanders (Ambystoma lermaensis) from San Pedro Tlaltizapán, Lerma, Estado de Mexico (June 1997 to March 1999). Richness (2.46 +/- 1.8), abundance (29.5 +/- 42.3), and diversity (0.64 +/- 0.58) levels characterize these communities as depauperate, similar to other amphibian helminth communities worldwide. Apparently, the main forces determining infracommunity structure are ectothermy (as regulator of the ingestion rate), and the opportunistic feeding habits of the hosts, because 80% of the helminth taxa enter the host by ingestion of intermediate hosts.

Infracomunidades de helmintos parásitos de Ambystoma lermaensis (Caudata: Ambystomatidae) en Lerma, México / Infracommunity of parasite helminths of Ambystoma lernaensis (Caudata: Ambystomatidae) in Lerma, Mexico

The helminth infracommunity structure was analyzed in 48 salamanders (Ambystoma lermaensis) from San Pedro Tlaltizapßn, Lerma, Estado de Mexico (June 1997 to March 1999). Richness (2.46 +/- 1.8), abundance (29.5 +/- 42.3), and diversity (0.64 +/- 0.58) levels characterize these communities as depauperate, similar to other amphibian helminth communities worldwide. Apparently, the main forces determining infracommunity structure are ectothermy (as regulator of the ingestion rate), and the opportunistic feeding habits of the hosts, because 80 of the helminth taxa enter the host by ingestion of intermediate hosts.