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Maintenance of the life cycle of a wide diversity of helminths depends on the aquatic environment. Freshwater turtles are considered one of the main groups in these ecosystems due to their high density and biomass. However, there is little information on the infection parameters of helminths associated with the Chelidae species Hydromedusa tectifera, Phrynops hilarii, and Acanthochelys spixii that occur in the Pampa biome. Therefore, this study aimed at analyzing the gastrointestinal helminth assemblage of the three species. Analyses showed that A. spixii was associated with 11 helminth taxa while P. hilarii and H. tectifera were parasitized by eight taxa each. The gastrointestinal helminth assemblage of A. spixii and H. tectifera showed high similarity by the Morisita index. Infections suggest that the helminth fauna is directly related to the diet of the hosts, since A. spixii, P. hilarii, and H. tectifera are generalist and/or opportunistic with diets composed of various invertebrates, which, in turn, are part of the life cycles as intermediate hosts of most of the identified helminths. Thus, this study highlights not only the importance of helminthological research for the understanding of the biology of host organisms, but also the need for conservation of flooded areas characteristic of the Pampa biome, which is essential to maintain the diversity of the ecosystem.

En este estudio se recogieron registros de 135 taxones de helmintos parásitos (Nematoda, Trematoda, Cestoda, Monogenoidea y Acanthocephala) y ectosimbiontes (Temnocephalida) asociados a Testudines continentales de Sudamérica. Se identificaron 89 helmintos a nivel de especie, mientras que otros se identificaron hasta el nivel de género o familia. La mayor diversidad de helmintos asociados a los Testudines se registró en Brasil. Chelidae fue la familia con el mayor número de especies de helmintos. En cuanto al estado de conservación, 17 especies de Testudines con registros de helmintos están citadas en la Lista Roja de Especies Amenazadas de la IUCN. El conocimiento de la biodiversidad de los helmintos y de las relaciones entre estos organismos y los Testudines puede aportar datos importantes sobre la biología de los hospedadores. Por lo tanto, la información generada por los estudios de los helmintos puede contribuir a la investigación que tiene como objetivo la conservación de los organismos y sus hábitats.

Helminthological studies with Chelidae freshwater turtles in South America were conducted in Argentina, Uruguay and Brazil, where nematodes, digeneans and monogeneans were reported. In this context, the study aims to report new cases of gastrointestinal helminth parasites of Acanthochelys spixii, Hydromedusa tectifera, and Phrynops hilarii. A total of 65 hosts from the southern region of Rio Grande do Sul, Brazil, were examined. Seven taxa belonging to Nematoda, Digenea, and Monogenoidea have new cases on hosts Chelidae in South America, as well as a Nematoda and two Digenea have new host cases for Brazil. Thus, the study expands the knowledge about the diversity of helminths and the geographic distribution of taxa associated with Chelidae turtles.

Uncertainty about taxonomy and nomenclature of the Australian long-necked turtle Chelodina oblonga has ensued since its description by Gray in 1841. This has been due to the general nature of information about provenance of the lectotype specimen and the ostensible morphological similarity of the specimen to another taxon from northern Australia that confused Gray and many subsequent workers. The south-western Australian provenance of the specimen has recently been confirmed by Shea et al. (2020). The present paper provides a detailed consideration of morphology of the specimen and compares it with other specimens available to Gray and to larger series that are now available. The study elucidates morphological aspects that have underlain the history of confusion and it highlights a number of characters that consistently differentiate adults of the relevant taxa. These demonstrate that morphology of the C. oblonga lectotype conforms with the taxon from the south-west of Western Australia, as has also been confirmed by recently published investigations of mitogenomics and historical information about provenance of the lectotype.

Aquatic animals, such as freshwater turtles, are much dependent on the water bodies where they live. Here we describe the size distribution of a population of Phrynopsgeoffroanus complex that died after the total drought of the artificial water reservoir where it lived in Caatinga. Amongst the 438 animals we found dead in the Cedro water reservoir, we measured the maximum carapace length of 72 individuals. The population was mainly composed of adult individuals and dead turtles measured in areas that kept water for longer were larger than animals from areas that dried up early.

The sexing of species is an important tool for population management. In tortoises and turtles, sexing is usually done according to secondary characteristics, such as plastron morphology or phallus eversion techniques. In this paper, we present the phallus eversion method and compare its efficiency to other existing techniques. This new method aims at shortening the management time and reducing the physical aftereffects on the animals, fostering the clinical and reproductive management of Geoffroy’s side-necked turtle (Phrynops geoffroanus) and related species. A sample of fifty individuals was taken in the central region of Piauí state, Northeastern Brazil. The proposed method consisted of moving the head from its resting position. The methods achieving a success rate higher than 80% were compared to each other as for the stimulation time required for phallus eversion. The method as here proposed achieved 100% efficiency in the sex determination of specimens with a linear carapace length between 10 and 34 cm. Also, when compared to the second most efficient method, it substantially reduced the time needed for managing the specimens (91%), avoiding possible sequelae in the individuals handled. Resumo A sexagem das espécies é uma ferramenta importante para o manejo populacional. Em tartarugas, cágados e jabutis, a sexagem geralmente é feita de acordo com características secundárias, como morfologia do plastrão ou técnicas de eversão do falo. Neste artigo, apresentamos o método de eversão do falo e comparamos sua eficiência com outras técnicas existentes. Este novo método visa encurtar o tempo de manejo e reduzir os efeitos colaterais físicos nos animais, promovendo o manejo clínico e reprodutivo do cágado-de-barbicha (Phrynops geoffroanus) e espécies relacionadas. Uma amostra de cinquenta indivíduos foi coletada na região central do estado do Piauí, Nordeste do Brasil. O método proposto consiste em remover a cabeça de sua posição de repouso. Os métodos que obtiveram índice de sucesso superior a 80% foram comparados entre si quanto ao tempo de estimulação necessário para a eversão do falo. O método aqui proposto alcançou 100% de eficiência na determinação do sexo de espécimes com comprimento de carapaça linear entre 10 e 34 cm. Além disso, quando comparado ao segundo método mais eficiente, reduziu substancialmente o tempo necessário para o manejo dos espécimes (91%), evitando possíveis sequelas nos indivíduos manuseados.

Pelomedusoides constitutes the most diverse group of Mesozoic and Cenozoic side-necked turtles. However, when it originated is still being poorly known and controversial. Fossil remains from the Early Cretaceous (Valanginian) Rosa Blanca Formation of Colombia were described almost a decade ago as potentially belonging to Podocnemidoidea (a large subclade inside Pelomedusoides) and representing one of the earliest records of this group of turtles. Here, I revise this hypothesis based on a new fragmentary specimen from the Rosa Blanca Formation, represented by a right portion of the shell bridge, including the mesoplastron and most of peripherals 5 to 7. The equidimensional shape of the mesoplatron allows me to support its attribution as belonging to Pelomedusoides, a group to which the previously podocnemidoid material is also attributed here. Although the Valanginian pelomesudoid material from Colombia is still too fragmentary as to be considered the earliest indisputable record of the Pelomedusoides clade, their occurrence is at least in agreement with current molecular phylogenetic hypotheses that suggest they split from Chelidae during the Jurassic and should occur in the Late Jurassic and Early Cretaceous fossil record.

Among turtles, cases of ?gigantism? occur mostly in pleurodiran Pelomedusoides and cryptodirans, but are infrequentamong pleurodiran chelids, which are mostly small-medium sized turtles. Yaminuechelys spp. are extinct South Americanlong-necked chelids (from the Late Cretaceous?early Paleocene of Patagonia, Argentina) with caparaces almost threetimes larger than their extant sister taxon, Hydromedusa tectifera. Since evolutionary changes in size can be analyzedbased on growth dynamics, we studied growth strategies from an osteohistological point of view. We sampled bothextinct (Yaminuechelys maior) and extant (H. tectifera) species, in order to test hypotheses related to the mechanismsinvolved in the macroevolution of size within this clade. For this purpose, thin sections of long bone (humerus andfemur) shafts of specimens of different ontogenetic stages for these species were prepared. The osteohistological studyreveals a similar growth dynamic in both taxa, with a poorly vascularized cortex dominated by parallel- fibered boneand interrupted by lines of arrested growth (LAGs). The huge body size of Y. maior appears to be a consequence of theprolongation of the growth phase, suggesting that it had a longer lifespan than H. tectifera, allowing to reach greatersizes. In this way, and assuming that there is no displacement at the beginning of development (e.g., a delay in the earlieststages of growth) in H. tectifera, the acquisition of a large size in Yaminuechelys would be explained by hypomorphosisof the former or hypermorphosis of the latter, depending on the reconstruction of the ancestral condition of this clade. Fil: Pereyra, Maria Eugenia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Bona, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina Fil: Cerda, Ignacio Alejandro. Universidad Nacional de Río Negro. Sede Alto Valle. Instituto de Investigaciones en Paleobiología y Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Jannello, Juan Marcos. Universidad Tecnologica Nacional. Facultad Reg.san Rafael. Instituto de Evolucion, Ecologia Historica y Ambiente. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mendoza. Instituto de Evolucion, Ecologia Historica y Ambiente.; Argentina Fil: de la Fuente, Marcelo Saul. Universidad Tecnologica Nacional. Facultad Reg.san Rafael. Instituto de Evolucion, Ecologia Historica y Ambiente. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mendoza. Instituto de Evolucion, Ecologia Historica y Ambiente.; Argentina Fil: Desántolo, Bárbara. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Cátedra de Citología; Argentina

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Hybridization and introgression between species is remarkably common, even between distantly related taxa. This suggests that the frequency of hybridization between species has been greatly constrained, not by evolutionary divergence in isolation, but by lack of opportunity. This constraint is being relaxed by human-mediated dispersal. Here, we document a case where such dispersal of a widespread species of freshwater turtle (Emydura macquarii) into the highly restricted range of a critically endangered endemic turtle (Myuchelys georgesi) has provided opportunity for the two to hybridize. This has raised concerns about the potential impact of hybridization on the endemic species, and its continued persistence in the face of challenges brought about by habitat alteration, increased competition, disease and genetic pollution. This study serves to highlight the risks associated with human-mediated dispersal, which can bring into contact species that would otherwise never or only rarely have met, and thus provide opportunities for hybridization and introgression between even distantly related species, with uncertain consequences for already threatened species.

The matamata is one of the most charismatic turtles on earth, widely distributed in northern South America. Debates have occurred over whether or not there should be two subspecies or species recognized due to its geographic variation in morphology. Even though the matamata is universally known, its natural history, conservation status and biogeography are largely unexplored. In this study we examined the phylogeographic differentiation of the matamata based on three mitochondrial DNA fragments (2168 bp of the control region, cytochrome oxidase subunit I, and the cytochrome b gene), one nuclear genomic DNA fragment (1068 bp of the R35 intron) and 1661 Single Nucleotide Polymorphisms (SNPs). Our molecular and morphological analyses revealed the existence of two distinct, genetically deeply divergent evolutionary lineages of matamatas that separated in the late Miocene (approximately 12.7 million years ago), corresponding well to the time when the Orinoco Basin was established. As a result of our analyses, we describe the genetically and morphologically highly distinct matamata from the Orinoco and Rio Negro Basins and the Essequibo drainage as a species new to science (Chelus orinocensis sp. nov.). Chelus fimbriata sensu stricto is distributed in the Amazon Basin and the Mahury drainage. Additionally, the analyses revealed that each species displays phylogeographic differentiation. For C. orinocensis, there is moderate mitochondrial differentiation between the Orinoco and the Rio Negro. For C. fimbriata, there is more pronounced differentiation matching different river systems. One mitochondrial clade was identified from the Amazon, Ucayali, and Mahury Rivers, and another one from the Madeira and Jaci Parana Rivers. The C. orinocensis in the Essequibo and Branco Rivers have haplotypes that constitute a third clade clustering with C. fimbriata. Phylogenetic analyses of the R35 intron and SNP data link the matamatas from the Essequibo and Branco with the new species, suggesting past gene flow and old mitochondrial introgression. Chelus orinocensis is collected for the pet trade in Colombia and Venezuela. However, neither the extent of the harvest nor its impact are known. Hence, it is crucial to gather more information and to assess its exploitation throughout its distribution range to obtain a better understanding of its conservation status and to design appropriate conservation and management procedures. Resumen La matamata es una de las tortugas mas carismaticas del mundo, ampliamente distribuida en el norte de Sudamerica. Debido a su variacion morfologica geografica, se debate sobre el reconocimiento de dos subespecies o especies. A pesar de que la matamata es universalmente conocida, su historia natural, estado de conservacion y biogeografia han sido muy poco estudiados. En este estudio examinamos la diferenciacion filogeografica de las matamatas en base ​​a tres fragmentos de ADN mitocondrial (2168 pb de la region de control, la subunidad I del citocromo oxidasa y el gen del citocromo b), un fragmento de ADN genomico nuclear (1068 pb del intron R35) y 1661 polimorfismos de nucleotido unico (SNPs). Nuestros analisis moleculares y morfologicos revelaron la existencia de dos linajes evolutivos distintos de matamatas, geneticamente divergentes que se separaron en el Mioceno tardio (hace aproximadamente 12.7 millones de anos), correspondiendo al tiempo en que se establecio la cuenca del Orinoco. Como resultado de nuestros analisis, describimos las geneticamente y morfologicamente distintas matamatas de las cuencas del Orinoco, Rio Negro y Essequibo como una especie nueva para la ciencia (Chelus orinocensis sp. nov.). Chelus fimbriata sensu stricto se distribuye en la cuenca del Amazonas y en el drenaje del Mahury. Adicionalmente, los analisis revelaron que cada especie muestra diferenciacion filogeografica. Para C. orinocensis, hay una moderada diferenciacion mitocondrial entre el Orinoco y el Rio Negro. Para C. fimbriata, hay una diferenciacion mas pronunciada, concordando con los diferentes sistemas fluviales. Se identifico un clado de los rios Amazonas, Ucayali y Mahury y otro de los rios Madeira y Jaci Parana. Las C. orinocensis de los rios Essequibo y Branco tienen haplotipos que constituyen un tercer clado que se agrupa con C. fimbriata. Los analisis filogeneticos del intron R35 y los datos de SNP asocian las matamatas de Essequibo y Branco con la nueva especie, sugiriendo flujo de genes pasado ​​e introgresion mitocondrial antigua. Chelus orinocensis se colecta para el comercio de mascotas en Colombia y Venezuela. Sin embargo, ni se conoce el alcance de las colectas ni su impacto. Por lo tanto, es crucial recopilar mas informacion y evaluar su explotacion en todo su rango de distribucion, comprender mejor su estado de conservacion y para disenar acciones apropiadas de conservacion y manejo.

A new genus and species of panchelid turtle (Mendozachelys wichmanni gen. et sp. nov.) from the upper Campanian–lower Maastrichtian Loncoche Formation (southern Mendoza Province, Argentina) is described here. This species is represented by only one complete and articulated large specimen (carapace length estimated in 950 mm) that was recovered from tidal flat deposits. A detailed morphological and osteohistological description is made, recognizing autapomorphic characters that allow differentiating this taxon from the rest of extant and extinct panchelids. Osteohistological characters suggest an aquatic to semi-aquatic life style for Mendozachelys wichmanni gen. et sp. nov. Phylogenetic analysis based on morphological data suggested that this new taxon is nested within crown Chelidae. Both phylogenetic signals (morphological and molecular) about the assessment of long-necked chelids monophyly or polyphyly are discussed. Fil: de la Fuente, Marcelo Saul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla; Argentina Fil: Maniel, Ignacio Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla; Argentina Fil: Jannello, Juan Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla | Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Museo de Historia Natural de San Rafael - Ianigla; Argentina Fil: Sterli, Juliana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Museo Paleontológico Egidio Feruglio; Argentina Fil: Gonzalez Riga, Bernardo Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina Fil: Novas, Fernando Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina

Body size is an important parameter for ecology, reproduction, evolution, and development of animal species, besides understanding their taxonomic relationships and to establishing the relationships between individual size and shape. We evaluated the variation in body size traits, sexual dimorphism in populations of a turtle species Acanthochelys spixii across its distribution in Brazil and we described sex ratio in those populations. Description of the size-classes on these populations was also provided. We sampled 86 adults (16 in Minas Gerais (MG) and 70 in Rio Grande do Sul (RS)). The sex ratio was 1:1 in both sampling areas. Females were larger than males, and specimens from RS were larger than those from MG. The posterior-lobe width (PLW) was deemed the most significant sexing variable in a linear discriminant analysis of specimens within each state. Two variables, PLW and maximum carapace width, together distinguished the four groups (males and females in MG and RS) with 77% accuracy. Overall, most...

Freshwater turtles from 28 species representing 6 families, categorized as “wild,” “captive,” or “wild-caught, captive-raised,” were analyzed for the presence of intraerythrocytic, parasitic protozoa. Microscopic analyses of blood smears from 327 individual turtles revealed parasites in the blood of 29% of these individuals (n = 96), with levels of parasitemia ranging from 0.003% to 2.1%. SYBR ® Green–based quantitative polymerase chain reaction confirmed these results with 29% overall prevalence (94 of 324), with 66% prevalence in the Geoemydidae, 26% prevalence in the Emydidae, and 23% prevalence in the Kinosternidae. No infections were detected in members of the Chelidae, Pelomedusidae, and Trionychidae. Prevalence was highest in wild turtles with 67%–100% from 7 locations, followed by wild-caught, captive-raised turtles with 4%–26% from 2 locations, while detections in captive turtles were zero in 2 locations and 3% in the remaining third location. Comparative sequence analyses of 583-bp amplicons of 18S rRNA gene fragments allowed us to identify 80 Haemogregarina infections and one Hemolivia infection. Parasites representing the genus Hepatozoon were not detected. Because parasites were generally detected in wild turtles and only rarely in captive turtles, captive breeding with subsequent release of turtles would seem to pose little risk to free-ranging turtles with regard to the spread of these parasites. On the contrary, wild turtles would be more likely sources of parasite transmission to captive populations if used in breeding programs.

Studying how different variables influence the size and shape of animals’ home ranges helps our understanding of the ecology of individuals and populations. This study aims to assess the effects of sex and body mass on home range size and the sexual differences in the use of terrestrial habitats of a population of aquatic turtles Phrynops geoffroanus from an urban area in Mato Grosso do Sul, Brazil. Turtles were captured along a river by active search, occasional encounter and hoop traps. Using individual VHF radio transmitters, 13 individuals (7 females and 6 males) were radio-tracked by homing in on the signal strength of the transmitter. Home ranges were estimated by 95% and 50% core one-dimensional fixed kernel and linear distance method. Home ranges were similar for both sexes (t = -0.50, DF = 12, p = 0.62) and independent of body mass (t = -0.53, DF = 12, p = 0.60). However, females seemed to use terrestrial habitats more than males (females = six recorded locations out of 767 points; males = none), probably to nest. To gain insight on how males and females use their space, it would be useful to focus future studies on the influence of sex in microhabitat selection of Phrynops geoffroanus. Finally, as sex did not influence home range, studying the contribution of other variables – both intrinsic, as age or personality, and extrinsic, as habitat composition or distribution of trophic resources – shaping the home ranges of the species is proposed.

Twenty-seven new specimens recovered from lower levels of the Sarmiento Formation (Casamayoran SALMA, middle Eocene) in the ‘Cañadón Hondo’ area, Chubut (Argentina), bring new information on the Palaeogene long-necked chelid Hydromedusa casamayorensis. The discovery of cranial and postcranial remains allows a complete description of the only known extinct species of the genus Hydromedusa recognizing diagnostic characters that revalidate the taxonomic status of this species. Hydromedusa casamayorensis is incorporated into a cladistic framework of chelid turtles. The unconstrained and constrained phylogenetic analyses recovered H. casamayorensis as a sister taxon of Hydromedusa maximiliani plus H. tectifera. A Danian age is proposed at least for the origin of the Hydromedusa clade, while a Late Cretaceous age is suggested for the split from the Yaminuechelys clade. Great differences in size are documented for H. casamayorensis based on the various specimens recovered from this study. The osteohistological study in H. casamayorensis and H. tectifera shows similarities in the internal cortex and cancellous bone of both taxa, but some differences are observed in the external cortex of H. casamayorensis (e.g. a parallel fibred bone on the more external surface of this cortex). Fil: Maniel, Ignacio Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina Fil: de la Fuente, Marcelo Saul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina Fil: Sterli, Juliana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Museo Paleontológico Egidio Feruglio; Argentina Fil: Jannello, Juan Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentina Fil: Krause, Javier Marcelo. Museo Paleontológico Egidio Feruglio; Argentina. Universidad Nacional de Río Negro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

To investigate the movement patterns and activity ofHydromedusa maximilianiin southeastern Brazil, sixteen adult freshwater turtles (eight males and eight females) were monitored with radio-transmitters from October 2009 to November 2010. An additional 22 turtles (11 males and 11 females) were monitored with thread-bobbins over a 3-day period.Hydromedusa maximilianishowed strong tendency to remain close to the river course. The distance moved each day varied from 0 to 179 m/day (radio-tracking) and 1.5 to 201 m/day (thread-bobbins). Males moved greater distances than females during the mating season (August to November), while females exhibited pronounced movements associated with egg-laying (December to February). Male and female movements did not differ significantly. Straight line distance measurements, usually obtained by radio-tracking, underestimate actual movement distances, since the nonlinearity of movements is not captured by radio-tracking as opposed to spool tracking, even when long distances are travelled. Results from this study are important for establishing conservation strategies for this vulnerable species.

A new coccidian species of the genus Isospora Schneider 1881 (Apicomplexa, Eimeriidae) is reported from a single specimen of chelid turtle, Platemys platycephala (Schneider, 1792), obtained in a flooded area of the Amazonian municipality of Altamira, in Para State, northern Brazil. The oocysts of Isospora platemysi n. sp. are subspheroidal, 19.0-24.0 × 22.5-18.5 (22.6 × 20.8) µm in size [length/width ratio 1.0-1.1 (1.1)], with a colourless wall, 1.0-1.9 (1.4) wide, with two smooth layers; polar granule is present, oocyst residuum and micropyle are both absent. The sporocyst is ovoidal, 10.0-12.1 × 8.0-10.0 (11.0 × 9.1) µm [length/width ratio 1.1-1.3 (1.2), with a knob-like Stieda body. Sub-Stieda body is present, rounded irregular-trapezoidal; para-Stieda body is absent. Sporocyst residuum is dispersed and composed of granules of differing sizes. This is only the fifth record of Isospora in chelonians, and the first report of a coccidian parasite of the genus Platemys.

Knowledge of blood parasites in Brazilian chelonians is limited, since they have been recorded in only six species. Mesoclemmys vanderhaegei (Bour) is a freshwater turtle with a wide geographic distribution in Brazil, but there is little information about its natural history. This paper reports on a study of the prevalence and infection intensity of a haemogregarine in two subpopulations of M. vanderhaegei. The study was conducted in two areas of Cerrado in the Upper Paraguay River basin in the state of Mato Grosso, Brazil, between November 2010 and August 2013. Ninety-five (53%) of the 179 turtles captured were positive for haemogregarine parasites. The parasitic forms observed were two morphotypes of intraerythrocytic gametocytes. The prevalence differed between size classes, increasing significantly according to the animals' body size. There was no significant difference between prevalence and sex, or between sampling periods. The mean parasite intensity was 9 parasites/2,000 erythrocytes (0.45%) and the parasite population presented an aggregated distribution, with an aggregation index of 19 and discrepancy of 0.772. This is the first record of a hemoparasite in the freshwater turtle M. vanderhaegei.

Hydromedusa maximiliani is a freshwater turtle endemic to the mountainous regions of the Brazilian Atlantic rainforest. Using X-rays techniques, we provide the first substantial records of the species' reproductive biology in the wild. Twenty-six of 42 X-rayed females from 2007 to 2009 were ovigerous between September and December and 9 had eggs each year during the 3-yr period. Clutch size varied from 1 to 3, with 55% of females having 2 eggs. The smallest reproductive female was 100.2 mm in plastron length, corresponding to an age of about 13 yrs old. Significant positive correlation was verified between female body size and both egg size and clutch volume. Nesting was inferred to occur from late spring to early summer (November and December). These findings are important for management programs since this vulnerable species inhabits a threatened biodiversity hotspot.

Mesoclemmys raniceps is a medium-sized aquatic turtle widely distributed throughout the northern Amazon Basin in South America. Little information has been published about its reproductive...

Two new genera and species of freshwater turtle blood flukes (TBFs) are described herein based on specimens infecting the nephritic and mesenteric blood vessels of “matamatas” (a side-necked turtle, Chelus fimbriata [Schneider, 1783] [Pleurodira: Chelidae]) from the Amazon River Basin, Peru. These taxa comprise the first-named species and the first-proposed genera of freshwater TBFs from the continent of South America. A new comparison of all TBF genera produced 6 morphologically diagnosed groups that are discussed in light of previous TBF classification schemes and a novel phylogenetic hypothesis based on the nuclear large subunit ribosomal DNA (28S). Considering external and internal anatomical features, species of the new genera (Atamatam Bullard and Roberts n. gen., Paratamatam Bullard and Roberts n. gen.) are most similar to each other and are together most similar to those of several marine TBF genera. The 28S phylogenetic analysis supported the monophyly of all 6 morphologically diagnosed groups of genera. Most notably, the freshwater TBFs of South America comprise a derived group nested within the clade that includes the paraphyletic marine TBFs. Not surprisingly in light of morphology, another marine TBF lineage (Neospirorchis Price, 1934) clustered with the freshwater TBFs of Baracktrema Roberts, Platt, and Bullard, 2016 and Unicaecum Stunkard, 1925. Our results, including an ancestral state reconstruction, indicated that (1) freshwater TBFs have colonized marine turtles twice independently and that (2) the South American freshwater TBFs comprise a marine-derived lineage. This is the first evidence that TBFs have twice independently transitioned from a marine to freshwater definitive host. Marine incursion is considered as a possible mechanism affecting the natural history of marine-derived freshwater TBFs in South America. A dichotomous key to accepted TBF genera is provided.

Phylogenetic relationships and taxonomy of the short-necked turtles of the genera Elseya , Myuchelys , and Emydura in Australia and New Guinea have long been debated as a result of conflicting hypotheses supported by different data sets and phylogenetic analyses. To resolve this contentious issue, we analyzed sequences from two mitochondrial genes ( cytochrome b and ND4 ) and one nuclear intron gene ( R35 ) from all species of the genera Elseya , Myuchelys , Emydura , and their relatives. Phylogenetic analyses using three methods (maximum parsimony, maximum likelihood, and Bayesian inference) produce a single, well resolved, and strongly corroborated hypothesis, which provides support for the three genera, with the exception that the genus Myuchelys is paraphyletic – Myuchelys purvisi is the sister taxon to the remaining Elseya , Myuchelys and Emydura . A new genus is proposed for the species Myuchelys purvisi to address this paraphyletic relationship. Time-calibration analysis suggests that diversification of the group in Australia coincides with periods of aridification in the late Eocene and between the mid-Miocene and early Pliocene. Other speciation events occurred during the faunal exchange between Australia and the island of New Guinea during the late Miocene and early Pliocene. Lineages distributed in New Guinea are likely influenced by the complex geologic history of the island, and include cryptic species diversity.

Understanding of evolutionary history and speciation events to inform phylogeography of extant species can be gleaned from the fossil record. However, the fossil record for Australian freshwater turtles contains many gaps and interpretation of the fossils that are known is difficult because of poor knowledge of the morphology of extant forms. There are no fossils currently assigned to short-necked turtles in the genus Myuchelys. In an alternative approach, morphological characters of the extant species Myuchelys bellii, Myuchelys georgesi, Myuchelys latisternum, and Myuchelys purvisi were mapped against their current molecular phylogeny. The cryptic species pair, M. georgesi and M. purvisi, are morphologically very similar, but distant phylogenetically, and their common ancestor includes M. latisternum and M. bellii in its decendents. This suggests that current shared morphology of M. georgesi and M. purvisi represents a suite of symplesiomorphies (shared primitive characters). These characters i...

1Centro de Estudos de Quelonios, Departamento de Biologia, Instituto de Biociencias, Letras e Ciencias Exatas, Universidade Estadual Paulista “Julio de Mesquita Filho”, Sao Jose do Rio Preto, SP, Brasil 2Laboratorio de Hemoglobinas e Genetica das Doencas Hematologicas, Departamento de Biologia, Instituto de Biociencias, Letras e Ciencias Exatas, Universidade Estadual Paulista “Julio de Mesquita Filho”, Sao Jose do Rio Preto, SP, Brasil 3Centro de Ciencias Biologicas e da Saude, Universidade Federal do Oeste da Bahia, Barreiras, BA, Brasil

Turtles of the total Clade Pan-Chelidae have a relatively poor fossil record, which is completely restricted from the Early Cretaceous to Recent of South America and Australasia. The clade is expected to have formerly inhabited Antarctica as well. The phylogenetic relationships of extant pan-chelids remain poorly resolved, notably because there are conflicting signals between morphological and molecular data. The ecology of fossil pan-chelids appears to have been similar to that of their extant relatives. A taxonomic review of the group concluded that of 45 named taxa, 22 are nomina valida, 6 are nomina invalida and 15 are nomina dubia, whereas the final 2 are rendered non-testudinate through the designation of lectotypes. Fil: Maniel, Ignacio Jorge. Museo Municipal de Historia Natural San Rafael - Unidad Asociada al CCT Mendoza; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina Fil: de la Fuente, Marcelo Saul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Museo Municipal de Historia Natural San Rafael - Unidad Asociada al CCT Mendoza; Argentina

The matamata (Chelus fimbriatus) is a highly aquatic chelid turtle known exclusively from northern South America. Due to its extremely modified morphology, it is well circumscribed among living taxa, but that is not the case of the two extinct species ascribed to the taxon, Chelus colombianus and Chelus lewisi. These were originally described for the Miocene of Colombia and Venezuela, respectively, and are known mostly from post-cranial material. Few traits have been considered diagnostic for these fossil taxa, and their shared geographic and temporal distributions raise doubts about their distinctiveness. Here, we describe new turtle remains from the early Miocene Castillo Formation, at Cerro la Cruz, northwestern Venezuela, assigning them to C. colombianus. We also review the taxonomy and diagnostic features of the fossil species of Chelus, comparing them with the variation recognized within C. fimbriatus. All alleged differences between the fossil Chelus species were found in our sample of the extant species, and may represent intraspecific variation of a single fossil species. Further, we reviewed the fossil record of Chelus spp. and proposed a paleobiogeographic hypothesis to explain its present geographic range.

We determined normal plasma butyrylcholinesterase (BChE), carboxylesterase (CbE using α-NA substrate), and glutathione S-transferase (GST) activities in Caiman latirostris and Phrynops hilarii to obtain reference values for organophosphorus (OP) pesticide monitoring. BChE and CbE sensitivity to malaoxon was also evaluated. C. latirostris (N = 12; six males and six females) and P. hilarii (N = 12; seven males and five females) were obtained from the programs Yacare (Entre Rios Province, Argentina) and Zoo of Cordoba (Cordoba Province, Argentina). Mean total (female and male) plasma BChE activity was significantly different between reptile species, ranging between 0.337 ± 0.085 μmol min−1 ml−1 of plasma for C. latirostris and 0.251 ± 0.070 μmol min−1 ml−1 of plasma for P. hilarii. However, plasma CbE (α-NA) and GST activities were significantly higher in P. hilarii (4.81 ± 1.00 and 0.145 ± 0.045 μmol min−1 ml−1 of plasma, respectively) than in C. latirostris (0.57 ± 0.20 and 0.059 ± 0.013 μmol min−1 ml−1 of plasma, respectively). No significant differences in B-esterase and GST activities were detected between sexes, except CbE (α-NA) for C. latirostris. IC50 values for BChE and CbE (α-NA) suggested different sensitivity levels between species and between sexes. The results demonstrate that plasma esterase activity varied between species, but not between sexes (except CbE for C. latirostris). The in vitro inhibition tests indicated that CbE (α-NA) is more sensitive to inhibition than BChE. C. latirostris may be the reptile species most vulnerable to field pesticide exposure because this reptile presents the lowest CbE activity levels and its B-esterase levels seem more sensitive to OP.

Mesoclemmys dahli and M. zuliae are two endangered, little-known toad-headed turtles with small distribution ranges in Colombia and Venezuela, respectively. Using the mitochondrial cytochrome b gene as a marker, we investigate their phylogeographic differentiation. Furthermore, based on 2341 bp of mtDNA and 2109 bp of nDNA of M. dahli, M. zuliae and allied chelid turtles, we infer their divergence time using a fossil-calibrated relaxed molecular clock approach. Mesoclemmys dahli and M. zuliae are closely related species, with an estimated mean divergence time of 10.6 million years. This estimate correlates with the uplift of the Serranía de Perijá, an Andean mountain chain separating their distribution ranges, suggesting that this event could have caused the evolution of the two species. Haplotype and nucleotide diversities of M. dahli are markedly higher than in Podocnemis lewyana, another endemic turtle species of Colombia. This pronounced dissimilarity may reflect differences in the phylogeographies and demographic histories of the two species, but also different habitat preferences.

Population monitoring and evaluation of spatial requirements of species are key actions for the conservation of wild populations, especially for endemic and threatened species. We estimated the abundance of the endemic species Mesoclemmys dahli in 2 streams in Cesar, Colombia, from February 2008 to February 2009, by using aquatic sampling. We monitored fluctuations in abundance through the year and used mark–recapture sampling and the Jolly–Seber model to estimate population size and density. Home ranges and movement patterns were studied by using very high frequency (VHF) radio telemetry. We calculated home ranges for the year and for the wet and dry season independently. Estimated population size for the 2 streams varied during the year from 16 (95% CI, 7–30) to 175 (95% CI, 32–298) turtles. Densities ranged from 16 turtles/ha in April to approximately 170 turtles/ha in June, which is lower than other populations of M. dahli in Colombia as well as other South American chelids. Individuals captu...

Nine microsatellite DNA loci for the Australian broad-shelled freshwater turtle (Chelodina expansa) are presented. Markers were tailed with 20-mer oligonucleotides for use in four-colour fluorescent multiplex PCRs. The markers show high allelic richness (mean N(A)=10.9, range 2-38) and expected heretozygosity (mean H(E)=0.643; range 0.161-0.963) indicating that they will be valuable for population genetics studies in C. expansa. Cross-species amplification in three Australian freshwater turtle species further highlights the potential utility of these markers, particularly in the side-neck species C. longicollis and C. rugosa.

454 shotgun sequencing was used to identify thousands of in silico microsatellite loci from two Australian freshwater turtle species (Pleurodira, Chelidae), Elseya albagula and Emydura macquarii krefftii. Twenty-nine polymorphic microsatellites were subsequently developed and tested as markers, 15 for E. m. krefftii and 14 for E. albagula. The former marker set showed greater allelic richness (mean N A = 7.7, range 3–15) than the latter (mean N A = 4.4, range 2–8). Levels of expected heterozygosity were high for both marker suites (mean H E = 0.718, range 0.177–0.875; and mean H E = 0.567, range 0.317–0.827, respectively), indicating both are suitable for studies of population genetic structure, connectivity and mating systems in these taxa. Cross-species amplification in 12 other short-necked freshwater turtle taxa highlighted the potential utility of these markers in other species, notably Emydura spp., Rheodytes leukops and Elusor macrurus.

Few studies have described the natural history of Phrynops geoffroanus in anthropogenic environments. We analyzed the stomach contents of 39 P. geoffroanus from the Anhanduizinho River, Campo Grande, Mato Grosso do Sul, Brazil, from September 2004 to April 2005. We verified the presence of invertebrates (Odonata larvae and mollusks), fish, and plant material. The primary food item ingested all year by the P. geoffroanus examined was the larval stage of Chironomus sp.

Morphological variation in size and shape of organisms has physiological, ecological, and evolutionary relevance. In this context, an important step in the identification of evolutionary units is to identify groups of populations occupying a continuous geographic space, at both genetic and morphological levels. The freshwater turtle Hydromedusa is endemic to the Neotropical region and inhabits water bodies of the Parana–La Plata basin of Argentina and coastal streams of Brazil and Uruguay. The genus is present in the fossil record since the Paleocene (56 mya) and currently consists of only 2 extant species. Hydromedusa tectifera has the widest distribution, from Santiago del Estero in Argentina to the State of Sao Paulo in Brazil. The goal of this work was to study the patterns of morphological variation of H. tectifera through most of its geographical range. Herein, we report morphological variation of carapace shape in this species associated with developmental and historical parameters. Our re...

Phrynops geoffroanus (Schweigger, 1812) is the freshwater turtle with the widest geographical distribution in South America. During 2006, physical examination and hematological evaluation were performed on free-ranging turtles from two polluted rivers, the Piracicaba River (n = 51) and its tributary Piracicamirim (n = 42), in southeastern Brazil. Red blood cell and thrombocyte counts, mean corpuscular volume and mean corpuscular hemoglobin levels differed in turtles from the two water courses. Although free-ranging turtles showed ectoparasites and boat propeler lesions, animals apparently had no signs of clinical disease. In spite of our results, further monitoring of the demography and health status of Phrynops geoffroanus in anthropogenically altered environments is recommended. Fil: Ferronato, Bruno O.. Universidade de Sao Paulo; Brasil Fil: Genoy Puerto, Alexander. Universidade de Sao Paulo; Brasil Fil: Piña, Carlos Ignacio. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentina Fil: Souza, Franco L.. Universidade Federal do Mato Grosso do Sul; Brasil Fil: Verdade, Luciano Martins. Universidade de Sao Paulo; Brasil Fil: Matushima, Eliana R.. Universidade de Sao Paulo; Brasil

Camallanus tuckeri n. sp. is described from specimens found in the intestine of the side-necked turtles Emydura australis and Chelodina burrungandjii collected from several localities in the Kimberley region of Western Australia. The new species differs from Camallanus chelonius, a parasite of African turtles, in the shape of the buccal capsule ridges, the number of precloacal papillae in males (7 pairs in the new species vs. 6 pairs in C. chelonius) and spicule shape. Camallanus tuckeri n. sp. differs from Camallanus waelhreow in the shape of buccal capsule ridges and the inflation of vulva lips in females. The new species differs from Camallanus nithoggi by possessing a smaller number of incomplete buccal capsule ridges (up to 2 in C. tuckeri n. sp. vs. 4 or 5 in C. nithoggi), larger spicules, and the inflation of a posterior vulva lip that is lacking in C. nithoggi. Camallanus tuckeri n. sp. is the first nematode reported from Em. australis and the first endoparasite reported from Ch. burrungandjii.

Sixteen adult specimens (six males and ten females) of Acantochelys radiolata from different regions of the state of Rio de Janeiro, Brazil, were monitored in captivity from 1996 to 2000 in order to obtain data on species reproductive biology including breeding season, egg laying, egg incubation, and hatchlings. Mating behaviour was observed between November and March and showed a regular pattern constituted by three conspicuous phases: approximation, persecution, and copulation. Sixteen clutches were found between March and July and twelve eggs were found in natural conditions. Hatches occurred between September and November. Hatchlings showed gular region, anterior and posterior members, tail, and edges of carapace and plastron with reddish blotches resting on a black background. This pattern was modified to an orange tonality in the third month of life.

Aptorchis glandularis n. sp. is described from the intestine of the northwestern red-faced turtle, Emydura australis (Pleurodira: Chelidae), in the Kimberley, Western Australia. This digenean is morphologically most similar to Aptorchis aequalis but can be differentiated readily from the latter species by the presence of ventral glands arranged in 3 rows. This feature is unique among plagiorhioidean digeneans and resembles the glands observed in some monostome digeneans in Notocotylidae and Microscaphidiidae. Comparison of approximately 2,600 bases of ribosomal DNA (partial 18S, complete ITS1+5.8S+ITS2, partial 28S), obtained from all 5 known Aptorchis species, strongly supports the status of Aptorchis glandularis n. sp. as a new species. Phylogenetic analysis of these sequence data demonstrates 2 strongly supported clades (A. pearsoni + A. megacetabulus) and (A. aequalis + A. glandularis n. sp.), with A. megapharynx representing a separate lineage. This is the first report of an endoparasite from Emydura australis.

The following is a study of the trophic niche of Phrynops rufipes revealed by an investigation of stomach flushing and fecal samplings. We successfully stomach flushed all 31 adult turtles captured and collected feces from ten of the flushed turtles. Our results show that only an integrated approach using both techniques is able to provide a comprehensive picture of P. rufipes diet. Trichoptera larvae were the most eaten item in numeric terms and in frequency of occurrence, but shrimp contributed the greatest volume of invertebrates. The seeds of most kinds of palm trees common around streams in the area were eaten. Due to the limitations of stomach-flushing technique, palm fruits were underestimated, but they still contributed the highest volume of material flushed from the stomachs and found in the feces. Our findings alter the conclusions concerning the food habits of P. rufipes: it is an omnivore species that feeds in an opportunistic way on a greater quantity of benthonic macro-invertebrates...

Carpal and tarsal anatomy was documented based on the observation of dry skeletons of adult specimens representing 25 species in 15 genera and on data taken from the literature. In addition, histological sections and cleared and double-stained autopodia of recently hatched and juvenile specimens representing seven chelid and pelomedusoid species were studied. There is much more morphological diversity in the manus than in the pes. Variation in autopodial skeletons includes: the astragalus and calcaneum are either separated or fused; fusion of distal carpals 3–4−5 or just 4–5; number of centralia in the carpus; and presence/absence of a pisiform and of an accessory radial element. The widespread and probably basal phalangeal formula for Pleurodira is 2.3.3.3.3. Deviations are Pelomedusa subrufa, exhibiting a reduction to 2.2.2.2.2, Pelusios spp. with one phalanx less in digit I and for one species in digit V as well, and Acanthochelys pallidipectoris with an additional phalanx in the fourth finger. Six discrete characters itemizing some of the morphological variation observed were plotted on a composite pleurodire phylogeny, revealing not only homoplastic patterns but also the utility of some characters in supporting the monophyly of several clades. The pisiform is the last carpal element to ossify in Chelus fimbriatus. We hypothesize that the so-called fifth hooked metatarsal represents the fusion of distal tarsal 5 with metatarsal V. The accessory radial element that was occasionally present in the turtles examined may represent an atavism of the otherwise lost radiale of turtles.

Aptorchis megacetabulus n. sp. is described from the intestine of the northern long-necked turtle, Chelodina rugosa (Pleurodira: Chelidae), in Northern Territory, Australia. This is the first helminth species reported from C. rugosa. This plagiorchioidean digenean differs from the 3 previously known species of Aptorchis in the relative size of the ventral sucker, overall body proportions, nature of the cirrus sac, and egg size. Comparison of approximately 2,700 bases of ribosomal DNA obtained from all known Aptorchis species strongly supports the status of Aptorchis megacetabulus n. sp. as a new species.

Existem poucos dados na literatura sobre a reprodução de Hydromedusa tectifera (Chelidae), e estes se referem a indivíduos de cativeiro. A ecologia reprodutiva da espécie foi verificada através de monitoramentos não sistemáticos entre 1996 e 2002 na Estação Ecológica do Taim, no extremo sul do Brasil, com a intenção de reunir informações sobre a reprodução da espécie em ambiente natural. Foram encontrados 46 ninhos da espécie, entre intactos e predados. As ninhadas tiveram, em média, 11,6 ovos que apresentaram um tamanho médio de 36,5 x 23,9 mm. A média do peso dos ovos foi de 11,1 g e o seu volume individual resultou em uma média de 10148,31 mm³. Os ninhos alcançaram uma profundidade média de 11,1 e 5,8 cm da superfície ao primeiro ovo. A variação do volume dos ovos de um mesmo ninho foi menor (CV = 4,71%) do que entre diferentes ninhos (CV = 12,32%). A largura dos ovos foi positivamente dependente do seu comprimento. Já em uma mesma ninhada, o número de ovos não dependeu do seu tamanho e do seu volume. Foram observadas desovas nos meses de novembro e dezembro, mas a maioria delas ocorreu na segunda quinzena de novembro. A espécie desovou com maior freqüência no período das 18 às 20 horas, e em áreas com certa inclinação do substrato, entre 20° e 30° de declividade. A maior abundância de ninhos foi observada até 5 m de distância da lagoa. Os resultados encontrados demonstram congruência entre os dados obtidos para H. tectifera e aqueles existentes para cágados-de-pescoço-comprido da Austrália e para as espécies de Chelidae do extremo sul do Brasil.

Background. Phrynops present four valid species, including P. geoffroanus that might represents a complex of cryptic species. Here, we provide a preliminary analysis of the taxonomy and phylogenetic affinities within Phrynops, with special reference to the taxonomic status of populations of P. geoffroanus and P. tuberosus, and the recognition of a new species from Southern Brazil. Methods. We studied populations from ten Brazilian river basins. A linear morphometric analysis was performed in order to define taxonomically distinct populations. Also, a phylogenetic analysis using morphology and molecular data (sequenced for the genes R35, RAG2, c-mos, cytb, ND4, and 12S) were carried out. Three distinct sets of phylogenetic analyses were performed: parsimony to morphological and combined data, and maximum likelihood to molecular data. Results. The combined analysis shows that Phrynops represents a well supported clade. The set of skeletal data supports Mesoclemmys as the sister group of Phrynops, whereas the molecular and combined data sets show Phrynops as the sister group of a clade composed by all the remaining genera of Chelidae, except Hydromedusa. Our morphological analyses suggest that P. hilarii is the sister group of P. geoffroanus, but in both molecular and combined analyses, P. hilarii appears nested within the clade formed by the populations of P. geoffroanus. Futhermore, P. tuberosus and P. geoffroanus are not distinguishable by the set of osteological and morphometric data. On the other hand, both morphometric and osteological data show that the population of P. geoffroanus from the Paraná river basin is a distinct species. Discussion. The sister group relationships of Phrynops could not be clearly defined due to the different topologies achieved. Phrynops hilarii is included within of P. geoffroanus in both molecular and combined data, but this position has little statistical support and therefore does not express a clear position of P. hilarii within the genus Phrynops. Besides, we were not able to distinguish P. geoffroanus and P. tuberosus. However, a sampling of specific locations are still needed to objectively define the taxonomic status of P. tuberosus. Finally, the population of P. geoffroanus from the Paraná basin is clearly distinct from the remaining populations of this species. Qualitative osteological characters and morphometric results seem to demonstrate that this population is a new species of Phrynops.

Background. The clade Chelidae (Testudines, Pleurodira) is a group of fresh water turtles with representatives in Australasia and South America. Its diversity of extant and fossil species is characterized by two recognized morphotypes: the long-necked and the short-necked chelids. So far, the phylogenies constructed over Chelidae differ depending on the information source. While morphology recovers one monophyletic group of long-necked chelids (with South American and Australasian species), the molecular data split the group into South American and Australasian chelids, both as monophyletic sister groups and containing long-necked species. The consequences of this conflict imply the emergence of long-necked chelids (i) one time before the final breakup of Southern Gondwana (≅ 35 Mya) or (ii) independently after this event. Methods. Using BEAST, a set of molecular clock analyses was performed. Seven of these analyses correspond to the molecular hypothesis and thirteen to the morphological hypothesis. So, ten fossils were used as calibration points in different combinations for each hypothesis. The results were statistically compared performing ANOVA and the global similarity was inspected by a hierarchical cluster analysis (HCA). Results. Molecular hypothesis: all the analyses produced an age of the origin of Chelidae, and rising of long neck, older than 35 Mys. Divergence times in the South American clade were generally older than the observed in the Australasian clade. The result of the HCA was: analyses 2, 4 and 5 form a group and the analyses 3, 6 and 7 form another group; the analysis 1 is close related to this last. Morphological hypothesis: the origin of the clade of long-necked chelids predated the 35 Mys in all the analyses except one; however the Chelodina group resulted younger than this age in all the analyses. The HCA yielded two main groups of molecular clock analyses (1, 3, 7, 8, 9, 13 and 2, 4, 6, 10, 11, 12) and one analysis (5) clearly separated of these two. The ANOVA resulted in significant differences for all estimated nodes in both phylogenetic hypotheses. Discussion. Our set of molecular clock analyses suggests an early diversification of the chelid turtles and the raising of the long-necked chelids before the final breakup of Southern Gondwana. However, the appearance of this trait one time or as evolutionary convergence still depends on which phylogenetic scenario is taken into account. Furthermore, our results indicate that the number of calibration points not necessarily improve the precision of estimated nodes. Instead the “quality” of the fossils used as calibrations and its position in the phylogeny, have appreciable impact not only over this parameter, but also over the global evolutionary rate along the tree.

Background. Studies on the geographic variation of the matamata, Chelus fimbriatus, have previously demonstrated differences between carapace shape, plastral pigmentation and the ventral coloration of the neck between populations from the Amazon and Orinoco river basins, but did not discuss whether these populations should be considered different species. The aim of this study is to evaluate the taxonomic status of C. fimbriatus and to describe its intraspecific and ontogenetic variability and sexual dimorphism based on morphology and osteology. Methods. We analyzed 277 morphological characters and 138 osteological characters of the skull and shell of 82 matamatas from the four known populations (Amazon, Orinoco, Guyana and Tocantins) and performed the Population Aggregation Analysis (PAA) species delimitation test in searching for character states that are exclusive to and fixed between populations. The t Student test was also performed in order to observe sexual dimorphism. Results. Considerable overlap in character states between different populations prevents the recognition of these populations as independent species. Chelus fimbriatus has a high level of polymorphism, particularly among morphological and color pattern characters. Unlike what have been stated on previous studies, we recognise four different carapace shapes, of which the anteriorly larger oval shape is the most common one. Two coloration patterns can be found both for the plastron and the carapace that are strongly correlated with one another, but no such correlation was observed with geographic distribution. We furthermore recognise three states of neck coloration pattern. Ontogenetic variability was observed in the coloration of the carapace, plastron, and the underside of the neck, in that juveniles have a stronger pigmentation than adults. Sexual dimorphism was established for six morphometric variables of the shell and 20 variables of the skull. As expected, females are significant larger than males for all these variables, such as carapace, plastron and skull length. New osteological characters, such as the presence of a serrated medial process in the palatine and a pair of anterolateral tubercles in the basioccipital were observed. Discussion. This is the first study to confirm the presence of sexual dimorphism in C. fimbriatus using morphological and morphometric variables and to document infraspecific variation in detail. The possible presence of two subspecies has been discussed since the 19th century based on alleged geographic variation in coloration patterns. However, this hypothesis could not be confirmed in the context of this study and the matamata should therefore still be considered a single species with a wide distribution range.

Paradeuterobaris victoriae n. sp. (Digenea: Microscaphidiidae) and Buckarootrema minuta n. sp. (Digenea: Pronocephalidae) are described from the Victoria River red-faced turtle, Emydura victoriae (Pleurodira: Chelidae), from the Victoria River, Northern Territory, Australia. Each of the new species is the second known member of a previously monotypic genus. Paradeuterobaris victoriae n. sp. differs from Paradeuterobaris novaguineae in the extent of the vitellarium and ventral glands, the position of the testes, and the presence of numerous uterine loops between the anterior testis and seminal vesicle, among other characters. Buckarootrema minuta n. sp. differs from Buckarootrema goodmani in the relative length of the ceca, the relative position of the gonads and testes, the position of uterine loops, the number of eggs, and overall body size. This work is the first report of any parasite from the Victoria River red-faced turtle and the first report of endohelminths from turtles of Northern Territory.