RESUMEN

Scaphanocephalus is a small trematode genus belonging to the family Opistorchiidae. The genus currently contains only three species associated with marine fish as intermediate hosts and fish-eating birds as definitive hosts. Here, specimens of Scaphanocephalus were collected from the Osprey, Pandion haliaetus, and the White mullet, Mugil curema in the Yucatán Peninsula, Mexico. We report for the first-time DNA sequences of adult specimens of Scaphanocephalus, particularly S. expansus, as well as a sequence of a different species sampled as metacercaria. Morphological comparisons of Scaphanocephalus expansus confirmed the identity of the adult specimens, with minor morphological variations; Scanning electron photomicrographs were included, and the species was re-described. Phylogenetic analysis based on 28S rDNA sequences showed that Scaphanocephalus is monophyletic within Opisthorchiidae and consists of three independent lineages. Sequences of adults are identical to those of S. expansus. Instead, the sequence of the metacercaria sampled from the mesentery of Mugil curema nested with specimens reported as Scaphanocephalus sp. from a labrid fish in the Mediterranean Sea, herein named it as Scaphanocephalus sp. 2.

Asunto(s)

Falconiformes , Enfermedades de los Peces , Heterophyidae , Smegmamorpha , Trematodos , Infecciones por Trematodos , Animales , México , Filogenia , ADN de Helmintos/genética , Heterophyidae/genética , Peces , Metacercarias , Infecciones por Trematodos/veterinaria

RESUMEN

Members of the genus Strigea Abildgaard, 1790 are endoparasites of birds distributed worldwide. Adults of an undescribed species of the genus Strigea were collected from the intestines of two hawk species (Rupornis magnirostris and Accipiter coperii). Other species identified as Parastrigea macrobursa that were described in Argentina were also recovered from two hawk species (Buteogallus urubitinga and Buteogallus anthracinus) in three localities along the coasts of Mexico. Specimens of the two species were sequenced for three molecular markers, the internal transcribed spacers locus (ITS1-5.8S rDNA- ITS2) and the domains D1-D3 from the large subunit from nuclear ribosomal DNA and the cytochrome c oxidase subunit 1 from mitochondrial DNA. The newly sequenced specimens were aligned with other strigeids sequences downloaded from GenBank. Maximum likelihood and Bayesian analyses inferred with each molecular marker revealed that our specimens of Strigea sp. formed an independent lineage, which is recognized herein as a new species, Strigea magnirostris n. sp., representing the first species in Mexico and the 16th in the Neotropical region. Morphologically, the new species is distinguished from other congeneric species from the Americas by having an oral sucker with several papillae around it, well-developed pseudosuckers (118-248 µm), a tegument covered with tiny spines, a larger cone genital (193-361 × 296-637) and a larger copulatory bursa (247-531 × 468-784). Our phylogenetic analyses revealed that P. macrobursa is not closely related to other members of the genus Parastrigea and is nested within Strigea, suggesting that P. macrobursa should be transferred to Strigea to form Strigea macrobursa n. comb., expanding its distribution range from Mexico to Argentina. Finally, the analyses also revealed that the taxonomy and systematics of Strigea should be re-evaluated, combining morphological and molecular characteristics.

Asunto(s)

Rapaces , Trematodos , Animales , Filogenia , Teorema de Bayes , Aves , ADN Ribosómico/genética , México , ADN de Helmintos/genética

RESUMEN

Adult specimens of Andracantha gravida (Alegret, 1941) were recorded from the intestines of the double-crested cormorant Nannopterum auritus (Lesson) (type host) and brown pelican Pelecanus occidentalis L. in two localities from Mexico: Celestún, Yucatan (south-eastern) and Punta Piedra, Tamaulipas (north-eastern). The specimens of A. gravida are morphologically characterized by having a pipe-shaped body without swellings, the absence of small trunk spines between the two fields of spines on the foretrunk and a cylindrical proboscis with 14-16 rows of 10-12 hooks per row. Newly generated partial sequences of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene were generated from adult isolates of A. gravida from Mexico and compared with one sequence of A. gravida and with sequences of other polymorphid acanthocephalans available in GenBank. Phylogenetic analyses based on maximum likelihood and Bayesian inference methods of the cox1 dataset placed all the species of Andracantha in a single clade, with weak support. The analyses of the cox1 dataset placed Andracantha sigma Presswell, García-Varela & Smales, , as sister to the clade formed by A. gravida, Andracantha phalacrocoracis (Yamaguti, 1939), Andracantha leucocarboi Presswell, García-Varela & Smales, and an unidentified species of Andracantha from Japan. The newly generated cox1 sequences of A. gravida from piscivorous birds of Mexico formed a strongly supported clade with the published sequence of A. gravida from the double-crested cormorant from the south-eastern coast of Mexico. The intraspecific genetic divergence among isolates identified as A. gravida ranged from 0.0% to 2.2%. A cox1 haplotype network inferred with 14 sequences revealed the presence of nine haplotypes, two of which were shared between the populations of piscivorous birds from the north-eastern and south-eastern coasts of Mexico and seven of which were unique. The fixation index between the populations from north-eastern and south-eastern Mexico was low (0.06949), which suggests genetic flow. This can be explained by the migration patterns of the brown pelican and the double-crested cormorant along the coasts of the Gulf of Mexico.

Asunto(s)

Acantocéfalos , Animales , Filogenia , Golfo de México , Teorema de Bayes , Aves , México

RESUMEN

Members of Forticulcitinae Blasco-Costa, Balbuena, Kostadinova & Olson, 2009 include endoparasites of mullet fishes distributed worldwide. Adult specimens were collected from the intestines of white mullet (Mugil curema) and flathead grey mullet (Mugil cephalus) from five localities in the Gulf of Mexico and a single locality in Venezuela. Photogenophores were sequenced for two nuclear molecular markers, the large subunit (LSU) and second internal transcribed spacer (ITS2) of nuclear rDNA. The new sequences were aligned with other sequences downloaded from GenBank. The maximum likelihood and Bayesian inferences were deduced using the combined dataset (LSU + ITS2). The phylogenetic analyses revealed four new lineages belonging to Forticulcitinae. Three new species are described in the present study. Ekuarhuni mexicanus n. sp. can be differentiated from its congeneric species by presenting a longer hermaphroditic sac length (136-180 µm) and a wider testis (91-123 µm). Forticulcita macropharyngis n. sp. and Forticulcita venezuelensis n. sp. are the 8th and 9th species described in Forticulcita. Both species belong to the diminutive morphotype of Forticulcita. Forticulcita macropharyngis n. sp. can be morphologically distinguished from the other congeneric species by the presence of a massive and muscular pharynx (46-110 µm long, 74-106 µm wide). Forticulcita venezuelensis n. sp. is the second species of the studied genus recorded in South America and can be differentiated from congeneric species by possessing the largest testis (138-201 µm long, 83-100 µm wide). Finally, the fourth lineage corresponds to Overstreetoides Andrade-Gómez & García-Varela, 2021; however, few specimens of this lineage were collected, precluding any description of the species. In addition, a key is proposed for differentiating the genera and species of Forticulcitinae.

Asunto(s)

Filogenia , Smegmamorpha/parasitología , Trematodos/clasificación , Américas , Animales , ADN de Helmintos/genética , ADN Ribosómico/genética , Golfo de México , Especificidad de la Especie , Trematodos/anatomía & histología , Trematodos/genética , Venezuela

RESUMEN

Two new genera and four new species from subfamily Forticulcitinae are described from the intestines of white mullet (Mugil curema) and flathead grey mullet (Mugil cephalus) collected in 27 localities across a wide geographical range on Pacific Ocean slopes comprising three countries in Middle America: Mexico, Guatemala and Costa Rica. The new genera Ekuarhuni n. gen. and Overstreetoides n. gen. had to be erected to accommodate two new species, Ekuarhuni papillatum n. sp. and Overstreetoides pacificus n. sp., with unique morphological traits that differentiate them from the two genera described previously. In addition, two new species, Forticulcita minuta n. sp. and Forticulcita isabelae n. sp., were described, which were characterized as exhibiting a small body size (< 1100 µm long). These new species were classified as the diminutive morphotype, together with three other congeneric species of Forticulcita. Forticulcita minuta n. sp. is distinguished by being the smallest species within the genus (< 305 µm). Meanwhile, Forticulcita isabelae n. sp. is distinguished by its body size and testis length. In specimens of the four new species, sequencing was performed with two molecular markers, the large subunit (LSU) and the internal transcribed spacer 2 (ITS2) of nuclear rDNA, and the results were compared with other sequences available in GenBank. Phylogenetic analyses performed with the combined dataset of the two nuclear molecular markers (LSU + ITS2) placed all the analysed species within the clade of Forticulcitinae with strong bootstrap support (100%) and a high Bayesian posterior probability (1.0). The four new species showed differences in abundance in their definitive hosts and were widely distributed along the Pacific Ocean coasts of Mexico, Guatemala and Costa Rica, in Middle America.

Asunto(s)

Intestinos/parasitología , Smegmamorpha/parasitología , Trematodos/clasificación , Trematodos/genética , Animales , Teorema de Bayes , Costa Rica , ADN de Helmintos/genética , ADN Ribosómico/genética , ADN Espaciador Ribosómico/genética , Guatemala , México , Océano Pacífico , Filogenia , Alimentos Marinos/parasitología , Trematodos/aislamiento & purificación

RESUMEN

Species of the allocreadiid genus Creptotrema are parasites of freshwater fishes in the Americas. Species in the genus possess one pair of muscular oral lobes on the oral sucker. Currently, the genus contains eight species, six distributed in South America, one in Middle America and one in North America. Genetic data are only available for the North American species, Creptotrema funduli, a parasite of fundulids originally described from Oneida Lake, New York State. In this study, we obtained 28S ribosomal DNA sequences of trematodes morphologically similar to Creptotrema agonostomi from the mountain mullet, Dajaus monticola, across a wide geographical range in Middle America. Our molecular phylogenetic analyses showed that (1) the genus Creptotrema, as currently conceived, is not monophyletic; (2) the allocreadiids in mountain mullets should be re-allocated in the genus Pseudoparacreptotrema; and (3) the allocreadiid trematodes from D. monticola across Middle America represent four morphologically similar species, three of which can be distinguished genetically. These three new species are described herein using an integrative taxonomy approach. We contend that accurate estimates of species diversity and phylogenetic relationships among allocreadiids, and most likely other species of trematodes, necessarily require an integrative taxonomy approach that should consider at least DNA sequences and scanning electron microscopy.

Asunto(s)

Peces/parasitología , Lagos/parasitología , Filogenia , Trematodos/clasificación , Infecciones por Trematodos/veterinaria , Américas , Animales , ADN de Helmintos/genética , Enfermedades de los Peces/parasitología , Variación Genética , ARN Ribosómico 28S/genética , Trematodos/anatomía & histología , Trematodos/aislamiento & purificación

RESUMEN

A new species of the genus Lyperosomum Looss, 1899, from the intestine of the golden-fronted woodpecker (Melanerpes aurifrons) from northern Mexico is described. Lyperosomum cuauhxinqui sp. n. is morphologically distinguished from other congeneric species from the Americas by a higher oral/ventral sucker ratio and its body length and width. The sequences of domains D1-D3 of the large subunit (LSU) of nuclear ribosomal DNA and cytochrome c oxidase subunit 1 (cox 1) from the mitochondrial DNA of the new species were obtained and compared with available sequences from GenBank. The genetic divergence estimated between the new species and other congeneric species ranged from 2 to 6% and 13.4 to 17.3% for LSU and cox 1, respectively. Phylogenetic analyses based on the two (LSU and cox 1) molecular markers consistently showed that L. cuauhxinqui sp. n. was nested within the genus Lyperosomum, with strong bootstrap support (100%) and Bayesian posterior probabilities (1.0). In particular, the LSU tree indicated that the sequence of the new species is closely related to sequences from Zonorchis alveyi, Zonorchis delectans and Zonorchis sp. from Central America, suggesting that these sequences should be transferred to the genus Lyperosomum. The new species represents the first record from Mexico and the fifth species identified in the Americas. Our study also revealed that the taxonomy of the genus Lyperosomum should be re-examined by combining molecular, morphological and ecological characteristics.

Asunto(s)

Aves/parasitología , Dicrocoeliidae/anatomía & histología , Dicrocoeliidae/clasificación , Filogenia , Animales , Teorema de Bayes , América Central , ADN de Helmintos/genética , ADN Mitocondrial/genética , ADN Ribosómico/genética , Femenino , Variación Genética , México , Análisis de Secuencia de ADN

RESUMEN

A new species of the genus Plagiorhynchus Lühe, 1911 from the intestine of the long-billed curlew (Numenius americanus) from northern Mexico is described. Plagiorhynchus (Plagiorhynchus) aznari n. sp. is morphologically distinguished from other congeneric species from the Americas by having a trunk expanded anteriorly and a cylindrical proboscis, armed with 19 longitudinal rows of hooks, with 14-15 hooks each row. Nearly complete sequences of the small subunit and large subunit of the nuclear ribosomal DNA of the new species were determined and compared with available sequences from GenBank. Phylogenetic analyses inferred from the two molecular markers consistently showed that P. (Plagiorhynchus) aznari n. sp. is closely related to P. (Plagiorhynchus) allisonae, and this clade is sister to a clade formed by P. (Prosthorhynchus) transversus and P. (Prosthorhynchus) cylindraceus from Plagiorhynchidae. The new species represents the second record of the genus in Mexico and the fourth species in the Americas. The phylogenetic relationships among the members of the order Polymorphida in this study provide significant insights into the evolution of ecological associations between parasites and their definitive hosts. Our analyses suggest that the colonization of marine mammals, fish-eating birds and waterfowl in Polymorphidae might have occurred independently, from a common ancestor of Centrorhynchidae and Plagiorhynchidae that colonized terrestrial birds and mammals.

Asunto(s)

Acantocéfalos/anatomía & histología , Acantocéfalos/clasificación , Aves/parasitología , Helmintiasis Animal/parasitología , Filogenia , Acantocéfalos/aislamiento & purificación , Animales , ADN de Helmintos/genética , ADN Ribosómico/genética , Femenino , Intestinos/parasitología , Masculino , México

RESUMEN

The family Clinostomidae Lühe, 1901 contains 29 species allocated to seven genera, of which Clinostomum Leidy, 1856 is the most diverse, with c. 14 valid species. The diversity of Clinostomum has been assessed, combining morphological and molecular data. The genetic library for species in this genus has increased steadily, although there is little or no information for the other genera included in the family. Molecular phylogenetic relationships among the genera of clinostomids have not been assessed, and their classification is still based on morphological traits. The monotypic Ithyoclinostomum was described from a fish-eating bird in Brazil, and its metacercariae have been found in several locations in South America, parasitizing erythrinid freshwater fishes. We collected unusually large metacercariae from the body cavity of cichlids in several locations across Middle America. These metacercariae exhibited some resemblance to Ithyoclinostomum, although several differences prevent their inclusion in Ithyoclinostomum dimorphum, casting doubt on their taxonomic identification. The main objective of this paper was to characterize the metacercariae collected in cichlids using both morphology and molecular data from three molecular markers, and to assess the molecular phylogenetic relationships among the genera of Clinostomidae to establish the position of the newly generated sequences. We took a conservative position and tentatively placed the metacercariae as belonging to Ithyoclinostomum.

Asunto(s)

Cíclidos/parasitología , Trematodos/anatomía & histología , Trematodos/clasificación , Animales , América Central , Agua Dulce/parasitología , Metacercarias , Filogenia

RESUMEN

Tapeworms of the family Gryporhynchidae are endoparasites of fish-eating birds distributed worldwide. Currently the family contains 16 genera classified on the basis of the morphology of the rostellar apparatus, rostellar hooks and strobilar anatomy. However, the phylogenetic relationships among the genera are still unknown. In this study, sequences of the near complete 18S (SSU) and 28S (LSU) from rDNA of 13 species of gryporhynchids (adult specimens) representing eight genera (Cyclustera, Dendrouterina, Glossocercus, Gryporhynchidae gen. sp., Neovalipora, Paradilepis, Parvitaenia, Valipora) and one species of metacestode from fish (Neovalipora) were generated. Additionally, sequences of metacestodes of the genera Amirthalingamia, Neogryporhynchus, Paradilepis, Parvitaenia and Valipora from Africa recently added to the GenBank database were analysed. Phylogenetic relationships were inferred using maximum-likelihood (ML) and Bayesian inference of each (SSU and LSU) dataset. The phylogenetic analyses indicated that the family Gryporhynchidae is a well-supported monophyletic group within the Cyclophyllidea. The trees inferred with SSU and LSU datasets had similar topologies and suggested that the genera Glossocercus (two species sequenced) and Paradilepis (four spp.) are monophyletic. In contrast, Dendrouterina, Parvitaenia and Valipora are paraphyletic, suggesting that the species composition of these genera should be critically reviewed. Interestingly, species of the genera that use the same groups of definitive hosts such as herons (Ardeidae), cormorants (Phalacrocoracidae) and ibis (Threskiornithidae) are together in the phylogenetic tree, even though they differ markedly from each other in some morphological characters, especially shape and size of rostellar hooks.

Asunto(s)

Cestodos/genética , Cestodos/aislamiento & purificación , ADN Ribosómico/genética , Filogenia , Ribosomas/genética , África , Animales , Enfermedades de las Aves/parasitología , Aves/parasitología , Cestodos/clasificación , Infecciones por Cestodos/parasitología , Infecciones por Cestodos/veterinaria , ADN de Helmintos/genética , Enfermedades de los Peces/parasitología , Peces/parasitología

RESUMEN

Members of the genus Neoechinorhynchus Stiles & Hassall, 1905 are endoparasites of freshwater fishes, brackish water fishes, and freshwater turtles distributed worldwide. In North America, 33 species have been described. One of the most widely distributed species in the eastern United States and Canada is Neoechinorhynchus (Neoechinorhynchus) cylindratus, a common acanthocephalan that infects centrarchid fishes. In the current study, adult specimens of N. (N) cylindratus were collected from largemouth bass (Micropterus salmoides) from the Purificación River in northern Mexico. In the same freshwater system, two additional congeneric species (Neoechinorhynchus (Neoechinorhynchus) emyditoides and Neoechinorhynchus (Neoechinorhynchus) panucensis) were collected and analysed. Sequences of the large subunit, internal transcribed spacers ITS1 and ITS2, 5.8S from nuclear DNA, and sequences of the cytochrome c oxidase subunit I (cox 1) from mitochondrial DNA were generated and aligned with other sequences obtained from GenBank. Maximum likelihood and Bayesian inference analyses inferred for each dataset showed that N. (N) panucensis, N. (N) emyditoides and N. (N) cylindratus were nested within several clades, indicating that these species do not share a common ancestor. Our phylogenies also revealed that the genus Neoechinorhynchus is paraphyletic, requiring further taxonomic revision using phylogenetic systematics and re-examination of morphological and ecological data. The presence of several N. (N) cylindratus adults in northern Mexico allowed us to typify this species for the first time using a combination of morphological and molecular characteristics. The current record shows a wide distribution range of N. (N) cylindratus across Canada, the United States and Mexico in the Nearctic region.

Asunto(s)

Acantocéfalos/genética , Enfermedades de los Peces/parasitología , Helmintiasis Animal/parasitología , Acantocéfalos/clasificación , Acantocéfalos/aislamiento & purificación , Animales , Lubina/parasitología , ADN de Helmintos/genética , ADN Intergénico/genética , Agua Dulce/parasitología , México , Filogenia

RESUMEN

Neoechinorhynchus is one of the most speciose genera of acanthocephalans, with approximately 116 described species. A recent study, aimed at establishing the genetic diversity of Neoechinorhynchus in Middle American freshwater fishes, validated nine species molecularly and morphologically and revealed the existence of 10 putative candidate species. Neoechinorhynchus golvani, a parasite commonly found in cichlids throughout Middle America with an allegedly large intraspecific morphological variability, was found to represent a species complex; species delimitation methods uncovered three additional genetic lineages. Here, we re-analyse the morphological and molecular data for N. golvani species complex infecting cichlids in that geographical area. A multivariate analysis of variance (MANOVA) was conducted particularly for the length of apical, middle and posterior hooks of the species/lineages of Neoechinorhynchus in cichlids, revealing morphological variation in the length of apical hooks for Lineage 8, although no morphological distinction was observed for Lineages 9 and 10. A new concatenated phylogenetic analysis of one mitochondrial and two ribosomal DNA genes was used to further corroborate the species delimitation among lineages; Neoechinorhynchus Lineage 8 was found to be morphologically and genetically distinct from its sister taxa, N. golvani and other two undescribed genetic lineages, and is formally described as a new species. Neoechinorhynchus costarricense n. sp. is described from the intestines of eight species of cichlids in Costa Rica. The new species is distinguished from the other species/lineages of Neoechinorhynchus in cichlids mainly by the size of the apical hooks of the proboscis.

Asunto(s)

Acantocéfalos/crecimiento & desarrollo , Acantocéfalos/genética , Enfermedades de los Peces/parasitología , Helmintiasis Animal/parasitología , Acantocéfalos/clasificación , Acantocéfalos/aislamiento & purificación , Animales , Cíclidos/parasitología , Costa Rica , ADN de Helmintos/genética , ADN Ribosómico/genética , Agua Dulce/parasitología , Intestinos/parasitología , Filogenia

RESUMEN

The phylogenetic position of Clinostomum heluans Braun, 1899 within the genus Clinostomum Leidy, 1856 is reported in this study based on sequences of the barcoding region of the mitochondrial cytochrome c oxidase subunit 1 gene ( COX1). Additionally, molecular data are used to link the adult and the metacercariae of the species. The metacercariae of C. heluans were found encysted infecting the cichlid fish Australoheros sp. in Minas Gerais, Brazil, whereas the adults were obtained from the mouth cavity of the Great White Egret, Ardea alba, in Campeche, Mexico. The COX1 sequences obtained for the Mexican clinostomes and the Brazilian metacercaria were almost identical (0.2% molecular divergence), indicating conspecificity. Similar molecular divergence (0.2-0.4%) was found between sequences of C. heluans reported here and Clinostomum sp. 6 previously obtained from a metacercaria recovered from the cichlid Cichlasoma boliviense in Santa Cruz, Bolivia. Both maximum likelihood and Bayesian inference analyses unequivocally showed the conspecificity between C. heluans and Clinostomum sp. 6, which form a monophyletic clade with high nodal support and very low genetic divergence. Moreover, tree topology reveals that C. heluans occupies a basal position with respect to New World species of Clinostomum, although a denser taxon sampling of species within the genus is further required. The metacercaria of C. heluans seems to be specific to cichlid fish because both samples from South America were recovered from species of this fish family, although not closely related.

Asunto(s)

Enfermedades de las Aves/parasitología , ADN de Helmintos/química , Enfermedades de los Peces/parasitología , Filogenia , Trematodos/clasificación , Infecciones por Trematodos/veterinaria , Animales , Secuencia de Bases , Aves , Brasil , Cíclidos/parasitología , Código de Barras del ADN Taxonómico/veterinaria , ADN de Helmintos/genética , Complejo IV de Transporte de Electrones/química , Complejo IV de Transporte de Electrones/genética , Metacercarias/clasificación , Metacercarias/genética , México , Mitocondrias/enzimología , Mitocondrias/genética , Trematodos/genética , Trematodos/crecimiento & desarrollo , Infecciones por Trematodos/parasitología

RESUMEN

Members of the genus Uvulifer are distributed worldwide and infect aquatic snails and freshwater fishes as first and second intermediate hosts, respectively, and fish-eating birds (kingfishers) as definitive hosts. Metacercariae of Uvulifer spp. were collected from the fins and skin of 20 species of freshwater fishes in Mexico, Guatemala, Honduras, Nicaragua and Costa Rica, and the adults were recovered from the intestine of kingfishers in four localities of Mexico. The genetic divergence among 76 samples (64 metacercariae and 12 adults) was estimated by sequencing the 28S and 5.8S nuclear genes, as well as the internal transcribed spacers ITS1 and ITS2, and one mitochondrial gene (cox1). Maximum likelihood and Bayesian inference analyses inferred with each dataset showed a high genetic diversity within the genus Uvulifer across Middle America, revealing the existence of four genetic lineages that exhibit some level of host specificity to their second intermediate hosts. The metacercariae of lineage 1 were associated with characids and cyprinids in central and northern Mexico. Metacercariae of lineages 2 and 3 were associated with cichlids distributed widely across Middle America. The lack of adults of these lineages in kingfishers, in lineages 2 and 3, or the fact that just a few adult specimens were recovered, as in lineage 1, prevented a formal description of these species. The metacercariae of lineage 4 were found in poeciliids, across a distribution range comprising Mexico, Guatemala, Honduras and Nicaragua, and the adult was found in the green kingfisher in Mexico. The number of specimens sampled for lineage 4, for both gravid adults and metacercariae, allowed us to describe a new species, Uvulifer spinatus n. sp. We describe the new species herein and we discuss briefly the genetic diversity in Uvulifer spp. and the importance of using DNA sequences to properly characterize parasite diversity.

Asunto(s)

Peces/parasitología , Variación Genética , Metacercarias/clasificación , Metacercarias/aislamiento & purificación , Trematodos/clasificación , Trematodos/aislamiento & purificación , Aletas de Animales/parasitología , Animales , América Central , Análisis por Conglomerados , ADN de Helmintos/química , ADN de Helmintos/genética , ADN Ribosómico/química , ADN Ribosómico/genética , ADN Espaciador Ribosómico/química , ADN Espaciador Ribosómico/genética , Complejo IV de Transporte de Electrones/genética , Especificidad del Huésped , Metacercarias/anatomía & histología , Metacercarias/genética , Microscopía , Filogenia , ARN Ribosómico 28S/genética , ARN Ribosómico 5.8S/genética , Análisis de Secuencia de ADN , Trematodos/anatomía & histología , Trematodos/genética

RESUMEN

Saccocoelioides olmecae n. sp. is described from specimens recovered from the intestine of the fat sleeper Dormitator maculatus (Bloch) (Perciformes: Eleotridae) collected in six localities along the coast of the Gulf of Mexico. The new species is mainly distinguished from the other three described species of Saccocoelioides Szidat, 1954 from North and Middle America (i.e. S. sogandaresi Lumsden, 1963, S. chauhani Lamothe-Argumedo, 1974 and S. lamothei Aguirre-Macedo & Violante-González, 2008) by having an elongated body, a sac-like caecum, a uterus that extends to the first third of body and by having vitelline follicles longitudinally elongated reaching the posterior end of the body. Sequences of the large subunit (LSU) of the ribosomal DNA, including the domain D1-D3, and the internal transcribed spacer 2 (ITS2) were used independently and concatenated to corroborate the morphological distinction among S. olmecae n. sp., S. chauhani and S. lamothei from freshwater and brackish-water fish from Middle America. The genetic divergence estimated among the three species of Saccocoelioides was very low: 1% for LSU and from 1 to 4% for ITS2. Maximum likelihood and Bayesian inference analyses for each dataset and both datasets combined revealed that S. olmecae n. sp. represents an independent clade with moderate bootstrap support and posterior probabilities. This is the third species of Saccocoelioides described in Mexico, and the 17th species from the Americas.

Asunto(s)

Enfermedades de los Peces/parasitología , Perciformes , Trematodos/clasificación , Trematodos/aislamiento & purificación , Animales , Análisis por Conglomerados , ADN de Helmintos/química , ADN de Helmintos/genética , ADN Ribosómico/química , ADN Ribosómico/genética , ADN Espaciador Ribosómico/química , ADN Espaciador Ribosómico/genética , Golfo de México , Intestinos/parasitología , Microscopía , Filogenia , ARN Ribosómico/genética , Análisis de Secuencia de ADN , Trematodos/anatomía & histología , Trematodos/genética

RESUMEN

Tylodelphys aztecae n. sp. (Digenea: Diplostomidae) is described from adult specimens obtained from the intestine of the pied-billed grebe (Podilymbus podiceps) and the metacercariae found in the body cavity of freshwater fishes of the families Goodeidae and Cyprinidae in eight localities across central and northern Mexico. The new species is mainly distinguished from the other four described species of Tylodelphys from the Americas (T. adulta, T. americana, T. elongata and T. brevis) by having a forebody slightly concave, a larger ventral sucker, two larger pseudosuckers and by having between 2 and 7 eggs in the uterus. Partial DNA sequences of the mitochondrial gene cytochrome c oxidase subunit I (cox1), and the internal transcribed spacers (ITS1+5.8S+ ITS2) of the ribosomal DNA, were generated for both developmental stages and compared with available sequences in GenBank of other congeners. The genetic divergence estimated among Tylodelphys aztecae n. sp. and other congeneric species varied from 12 to 15% for cox1, and from 3 to 11% for ITS. In contrast, the genetic divergence among metacercariae and adults of the new species was very low, ranging between 0 and 1% for cox1 and between 0 and 0.3% for ITS. Phylogenetic analyses inferred with both molecular markers using maximum likelihood and Bayesian inference placed the adults and their metacercariae in a single clade, confirming that both stages are conspecific. The morphological evidence and the genetic divergence, in combination with the reciprocal monophyly in both phylogenetic trees, support the hypothesis that the diplostomids found in the intestines of the pied-billed grebe bird and the body cavity from goodeid and cyprinid fishes in central and northern Mexico represent a new species.

Asunto(s)

Aves/parasitología , Peces/parasitología , Trematodos/clasificación , Trematodos/aislamiento & purificación , Estructuras Animales/anatomía & histología , Animales , Análisis por Conglomerados , ADN de Helmintos/química , ADN de Helmintos/genética , ADN Ribosómico/química , ADN Ribosómico/genética , ADN Espaciador Ribosómico/química , ADN Espaciador Ribosómico/genética , Complejo IV de Transporte de Electrones/genética , México , Microscopía , Filogenia , ARN Ribosómico 5.8S/genética , Análisis de Secuencia de ADN , Trematodos/anatomía & histología , Trematodos/genética

RESUMEN

The diplostomid genus Austrodiplostomum currently contains two species, i.e. A. mordax and A. ostrowskiae. Adults of these species inhabit the intestine of cormorants of the genus Nannopterum, whereas larval forms (metacercariae) are found in the eyes (vitreous humor) of freshwater fishes. Records of both species have been established across a wide geographic range in the Americas. Diplostomid adults and metacercariae were collected from a wide geographical range that spans from south-eastern Mexico, southwards to Central and South America. Even though the diplostomid has been largely reported in Mexico as Diplostomum (Austrodiplostomum) compactum, our specimens were identified morphologically as A. ostrowskiae. Sequences of the mitochondrial gene cytochrome c oxidase (cox 1) were obtained for 86 individuals, including 15 adults recovered from the intestine of Nannopterum brasilianus, in five localities, and 71 metacercariae from the eyes of ten fish species, in 13 localities. Sequences were used to evaluate the genetic diversity, and to test conspecificity of these specimens with the available sequence of A. ostrowskiae. Sequences were aligned with another 12 taxa representing five genera of Diplostomatidae, forming a dataset of 104 taxa with 478 nucleotides. The genetic divergence estimated among the 86 sequenced individuals, and that of A. ostrowskiae from the double-crested cormorant, Nannopterum auritus, in the USA, was very low, ranging from 0 to 0.8%. The maximum likelihood (ML) and Bayesian consensus trees showed that all sequences nested within a monophyletic lineage, with strong bootstrap and Bayesian posterior probability support values (100/1.0). In conclusion, a link between the metacercariae in fish and the adults in cormorants was established, indicating also that a single species is found in the distribution range comprising southern USA, southwards to Venezuela. Previous records of this species, particularly from Mexico, need to be corrected.

Asunto(s)

Enfermedades de las Aves/parasitología , Trematodos/anatomía & histología , Trematodos/genética , Animales , Aves , Parasitosis Intestinales/epidemiología , Parasitosis Intestinales/parasitología , Parasitosis Intestinales/veterinaria , México/epidemiología

RESUMEN

In central Mexico, populations of the freshwater snail Physella cubensis were infected with metacercariae from a species of Echinoparyphium (Digenea: Echinostomatidae). In the current study, we describe both larval and adult stages of this species obtained from experimental and natural infections. A total 180 snails were collected from Patzcuaro Lake, Michoacan state in central Mexico in July 2012. In the laboratory snails were placed in individual vials and exposed to light with the aim of observing emergence of cercariae. To obtain metacercariae, uninfected snails (P. cubensis) were exposed to cercariae. Chicks were infected with metacercariae to obtain adults. Nine days post-infection, eggs were recovered and incubated in tap water at room temperature to observe miracidia. Adults obtained from natural and experimentally infected hosts possess a head collar with 45 spines in two alternating rows, confirming the identification as Echinoparyphium recurvatum von Linstow 1873. To test the conspecificity of all stages, sequences of nuclear internal transcribed spacer 1 (ITS1), 5.8S and ITS2 rDNA were obtained from two adult worms recovered from chicks and also a natural avian host, the shoveler duck Anas clypeata, together with five cercarial and four metacercarial isolates from nine snails. The genetic divergence estimated among the 13 isolates was very low, ranging from 0 to 0.6%. Phylogenetic analyses inferred by maximum likelihood and Bayesian methods showed that all isolates of E. recurvatum form a single clade with strong support. The presence of E. recurvatum in P. cubensis and A. clypeata from central Mexico represents new host reports, and extends the distribution range in the Americas.

Asunto(s)

Caracoles/parasitología , Trematodos/clasificación , Animales , ADN de Helmintos/genética , ADN Espaciador Ribosómico/genética , Larva , México , Filogenia , Trematodos/anatomía & histología , Trematodos/genética

RESUMEN

In parasitic organisms, particularly helminths, the usage of the mitochondrial cytochrome c oxidase subunit I gene as the standard DNA barcoding region for species identification and discovery has been very limited. Here, we present an integrated study, based on both DNA barcoding and morphological analyses, for acanthocephalans belonging to the genus Polymorphus, whose larvae (cystacanths) are commonly found in the mesentery of freshwater fishes, while adults are found in the intestine of fish-eating birds. The alpha taxonomy of parasitic helminths is based on adult morphological traits, and because of that larval forms cannot be identified to species level based on morphology alone. DNA barcoding offers an alternative tool for linking larval stages of parasitic organisms to known adults. We sequenced cystacanths collected from freshwater fishes in localities across central Mexico and adults obtained from fish-eating birds, to determine whether they were conspecific. To corroborate the molecular results, we conducted a morphometric analysis with 'Proboscis profiler', which is a software tool developed to detect heterogeneity in morphologically similar acanthocephalans based on the multivariate statistical analysis of proboscis hook dimensions. Both sources of information indicate that cystacanths infecting freshwater fishes in central Mexico belong to a single species, Polymorphus brevis.

Asunto(s)

Acantocéfalos/genética , Código de Barras del ADN Taxonómico , Acantocéfalos/anatomía & histología , Acantocéfalos/clasificación , Acantocéfalos/crecimiento & desarrollo , Animales , Larva/anatomía & histología , Larva/clasificación , Larva/genética , México , Datos de Secuencia Molecular , Alineación de Secuencia

RESUMEN

To explore the bacterial microbiota in Chilean oyster (Tiostrea chilensis), a molecular approach that permits detection of different bacteria, independently of their capacity to grow in culture media, was used. Bacterial diversity was assessed by analysis of both the 16S rDNA and the 16S-23S intergenic region, obtained by PCR amplifications of DNA extracted from depurated oysters. RFLP of the PCR amplified 16S rDNA showed a prevailing pattern in most of the individuals analyzed, indicating that a few bacterial species were relatively abundant and common in oysters. Cloning and sequencing of the 16S rDNA with the prevailing RFLP pattern indicated that this rRNA was most closely related to Arcobacter spp. However, analysis by the size of the amplified 16S-23S rRNA intergenic regions revealed not Arcobacter spp. but Staphylococcus spp. related bacteria as a major and common component in oyster. These different results may be caused by the absence of target for one of the primers employed for amplification of the intergenic region. Neither of the two bacteria species found in large abundance was recovered after culturing under aerobic, anaerobic, or microaerophilic conditions. This result, however, is expected because the number of bacteria recovered after cultivation was less than 0.01% of the total. All together, these observations suggest that Arcobacter-related strains are probably abundant and common in the Chilean oyster bacterial microbiota.

Asunto(s)

Arcobacter/genética , Ostreidae/microbiología , ARN Ribosómico 16S/genética , Animales , Arcobacter/fisiología , Clasificación , ADN Bacteriano/análisis , ADN Bacteriano/genética , Reacción en Cadena de la Polimerasa , Dinámica Poblacional , ARN Ribosómico 16S/análisis