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We describe Baalemys mansillai gen. et sp. nov. a chelid turtle, based on an articulated shell from the Portezuelo Formation of the Baal locality, northern shore of Barreales lake, Neuquén Province, Argentina. Baalemys mansillai gen. et sp. nov. is distinguished from other chelids by its oval shape, moderate size, distinctive granulated ornamentation, narrow nuchal plate, first hexagonal neural with short posterolateral margins, a second neural plate that is a regular hexagon, and a posterior lobe that is longer than both the anterior lobe and the bridge. This unique combination of features supports the establishment of a new genus and species. Baalemys mansillai gen. et sp. nov was discovered in the Baal locality with sauropod dinosaurs, theropod dinosaurs, crocodiles, pelomedusoid turtles and other genera of chelids; a similar biota was identified in other localities of the Portezuelo Formation. The identification of Baalemys mansillai gen. et sp. nov. significantly adds to our knowledge of the diversity of pleurodiran turtles from the Portezuelo Formation, the Neuquén Basin, and the broader Patagonian region. [ABSTRACT FROM AUTHOR]

Abstract Phrynops geoffroanus has a wide distribution in South America, living in aquatic environments such as rivers, streams, and lakes, in natural and urban environments. In this work, the plastron formula and the diversity index associated with the allometric condition are established for the species. For the morphometric analyses, the following were calculated: standard error, class intervals, sample standard deviation, principal component analysis, and allometry. When evaluating the morphometric dependence, r = 0.85 was obtained, which allowed us to verify the allometric classification Y, the growth rate K, and the proportion of growth b for each segment that composes the length of the plastron (LP). Thus, the calculated morphometric set demonstrates that the plastron formula can serve as a diagnostic character for Phrynops geoffroanus. We inferred from this study that the plastron formula can be maintained even in conditions of high environmental degradation.

Abstract Ranacephala hogei is a South American freshwater turtle considered one of the 25 most endangered chelonian species in the world. Endemic to the Atlantic Forest hotspot of southeastern Brazil, the conservation status of R. hogei is subject to continuous assessment at various levels. However, the scarcity of data regarding this species, particularly its geographic range, challenges these evaluations. In an effort to address these gaps, we conducted a comprehensive long-term inventory using different methods to study this species. Our efforts resulted in a 144% increase in documented occurrence points, including a new hydrographic basin and protected areas. By combining historical and current records, we have observed the persistence of R. hogei in rural areas, even in locations where its extinction was previously predicted. Consequently, our data significantly contribute to supporting future conservation assessments.

Cooper Creek is one of Australia's largest unregulated river systems and one of the world's most variable large river systems. It is a dynamic environment that oscillates between booms and busts; yet, many species thrive in it. One of these species, the Cooper Creek turtle (Emydura macquarii emmotti) has received little attention, despite being one of Australia's largest freshwater turtles and living further inland than any other Australian turtle. We conducted surveys for E. m. emmotti in 2001–2004, 2019, and 2022, focussing predominantly on the Waterloo waterhole. Waterloo had a large population of E. m. emmotti (508 estimated individuals; 95% CI = 447–596) with an estimated density of 64.8 turtles/ha (95% CI = 57.0–76.2) and estimate biomass of 74.4 kg/ha (95% CI = 57.6–100.3 kg/ha). Juveniles were highly abundant in all years, representing up to 63.6% of captured individuals. It was slightly (but not significantly) male‐biased in 2001–2004 and significantly female‐biased in 2019. All sizes and sexes used the floodplain during a flooding event in 2022, but more males than females were captured on the floodplain, and there was evidence of male‐biased dispersal across the years. Compared to Murray River turtles (Emydura macquarii macquarii), E. m. emmotti exhibited megacephaly across all ages and sexes, with particularly pronounced megacephaly in adult females. Algae were present on many individuals (including on the skin and plastron) but was relatively more abundant on juveniles. Leeches were not detected on any of the 66 turtles that were examined for them. The following injuries/malformations were noted: missing or injured limbs (3.2%), missing or injured eyes (1.3%), damaged shells (8.0%), scute/shell anomalies and malformations (10.6%), and marginal scute seams extending into the costals (67.4% of adults, 1.2% of juveniles). This paper presents some of the first work on this unusual turtle and makes recommendations for future research. [ABSTRACT FROM AUTHOR]

The Australian freshwater turtle fauna is dominated by species in the family Chelidae. The extant fauna comprises a series of distinct lineages, each of considerable antiquity, relicts of a more extensive and perhaps diverse fauna that existed when wetter climes prevailed. Several phylogenetically distinctive species are restricted to single, often small, drainage basins, which presents challenges for their conservation. Specific threats include water resource development, which alters the magnitude, frequency, and timing of flows and converts lentic to lotic habitat via dams and weirs, fragmentation of habitat, sedimentation, nutrification, and a reduction in the frequency and extent of floodplain flooding. Drainage of wetlands and altered land use are of particular concern for some species that are now very restricted in range and critically endangered. The introduced European red fox is a devastatingly efficient predator of turtle nests and can have a major impact on recruitment. In the north, species such as the northern snake‐necked turtle are heavily depredated by feral pigs. Other invasive animals and aquatic weeds dramatically alter freshwater habitats, with consequential impacts on freshwater turtles. Novel pathogens such as viruses have brought at least one species to the brink of extinction. Species that routinely migrate across land are impacted by structural simplification of habitat, reduction in availability of terrestrial refugia, fencing (including conservation fencing), and in some areas, by high levels of road mortality. We report on the listing process and challenges for listing freshwater turtles under the Australian Environment Protection and Biodiversity Conservation Act, summarize the state of knowledge relevant to listing decisions, identify the key threatening processes impacting turtles, and identify key knowledge gaps that impede the setting of priorities. We also focus on how to best incorporate First Nations Knowledge into decisions on listing and discuss opportunities to engage Indigenous communities in on‐ground work to achieve conservation outcomes. [ABSTRACT FROM AUTHOR]

Turtles exhibit a wide range of courtship behaviours, but there are still many knowledge gaps, and the courtship and mating behaviours of many species are poorly known. Here, I present an observation of heterosexual courtship behaviour in wild saw‐shelled turtles (Myucheyls latisternum), as well as an observation of a male M. latisternum attempting to mount another male. The heterosexual courtship was characterized by the male repeatedly waving his feet at the female, scratching her face, pushing her chin with his nose (often moving her backwards) and attempting to align his snout with hers while facing her. A particularly strong emphasis seemed to be placed on aligning the snouts, and when they were aligned, the male would blow water out of his nose across her face (or into her nose). The female appeared indifferent to the male, and they swam away together before any copulation was observed. In the observation of apparent homosexual behaviour, a large male sat submerged and partially buried in a pile of leaves, while a smaller male repeatedly tried to mount him. It appeared that the smaller male was trying to align their posteriors in a typical turtle mating position. The large male eventually swam away. These observations expand our understanding of the courtship behaviour of Australian turtles and present the first documented case of same‐sex mounting in M. latisternum as well as one of the few reported observations of same‐sex mounting in wild turtles. [ABSTRACT FROM AUTHOR]

Matamata turtles (Chelus Duméril, 1806) are composed of two extant species, Chelus fimbriata Schneider, 1783 and Chelus orinocensis Vargas-Ramírez, Caballero, Morales-Betancourt, Lasso, Amaya, Martínez, Silva-Viana, Vogt, Farias, Hrbek, Campbell & Fritz, 2020, inhabitants of the main freshwater drainages of northern South America. The systematics and palaeobiogeography of Chelus is still unresolved. Here, we describe several new fossil specimens from the Late Miocene of Urumaco (Venezuela) and Tatacoa (Colombia). The fossils are mostly complete, articulated shells that allow reestablishing validity of two extinct taxa, Chelus colombiana Wood, 1976 and Chelus lewisi Wood, 1976. One of the specimens of C. lewisi from Urumaco represents the first record within the genus for which autopodial bones (a left manus) and additional limb bones are preserved together with ashell, demonstrating evolutionary conservatism in limb anatomy for the genus. The specimen comes from the Socorro Formation, representing the earliest so far known record of Chelus for the Urumaco sequence. Additionally, one specimen from Tatacoa is the first fossil for which cervical and pectoral girdle elements are preserved. Phylogenetic analysis supports the existence of two separate clades inside of Chelus, one formed by the extinct species and the other by the extant ones. [ABSTRACT FROM AUTHOR]

ABSTRACT We analyzed the influence of the season, the environment, and the sex, as well as the relation of body mass (BM) in the serum albumin (ALB), aspartate aminotransferase (AST), creatinine (C), creatine kinase (CK), phosphorus (P), total calcium (tCa), total protein (TP), urea (U), uric acid (UA), calcium:phosphorus ratio (Ca:P), and the globulin value (GV) of thirty individuals of Phrynops geoffroanus of the urban area of Cuiabá, Mato Grosso, Brazil. The modeling of biochemical parameters was performed using the Generalized Additive Models for Location, Scale and Shape (GAMLSS) to verify the influence of variables considered in this study on each of the biochemical parameters analyzed. The season influenced AST, CK, C, tCa, Ca:P and UA. The environment influenced tCa, Ca:P, U and UA. On the other hand, CK, tCa, P, Ca:P and U differed significantly between males and females. Regarding the BM, a relationship of this variable was observed with CK, C, tCa, P, U, UA and Ca:P. We concluded that the season, environment, sex, and body mass can influence the biochemical parameters of P. geoffroanus, and these factors should be routinely considered in the interpretation of laboratory results.

The fossil record of Cretaceous turtles in Santa Cruz Province is scarce. Turtles have been reported from the Mata Amarilla Formation (Cenomanian), the Cerro Fortaleza Formation (Campanian–Maastrichtian), and the Chorrillo Formation (early Maastrichtian). In this contribution, we examined all the turtle remains recovered from six localities in the Mata Amarilla Formation, nearby Mata Amarilla farm (Santa Cruz Province, Argentina). These fossils are housed at the “Padre Molina” Museum in Río Gallegos, Santa Cruz. Most of the carapace and plastral remains are conferred to an indeterminate small species of cf. Prochelidella sp., while the remaining fragments are attributed to a mid-sized species of an indeterminate Chelidae. Prochelidella spp. is a group of turtles distributed in Chubut, Río Negro, Neuquén, and Mendoza provinces, ranging from the Aptian to the Maastrichtian, with two main gaps (late Albian and Coniacian–Santonian). The recognition of cf. Prochelidella sp. in the Austral-Magallanes Basin extends the geographic range of this group more than 500 km south to the previously known southernmost record of Prochelidella, Pr. argentinae, from the Golfo San Jorge Basin (Chubut, Argentina).

Invasive red foxes (Vulpes vulpes) are a serious conservation issue for Australia's freshwater turtle species, including the endangered Bell's turtle (Myuchelys bellii). As many as 96% of Australian freshwater turtle nests may be depredated in a season by foxes. Current methods of turtle nest protection rely on early detection of nesting activity, followed by nest-specific structures to prevent predation. An alternative method to provide protection against fox raiding was tested: nesting refuge structures based on a design successfully used in the United States to protect diamondback terrapin (Malaclemys terrapin) nests. Six wood and chicken wire structures were placed at different sites beside large riverine pools on the Macdonald and Gwydir rivers, northeastern New South Wales, Australia, in the summers of 2019–2020 and 2020–2021. Sites were chosen for known previous nesting activity or presence of mature females, and each structure was placed in typical Bell's turtle nesting habitat at known nesting sites. Prior to placement, the soil was tilled with a rotary hoe to make the interior of the structure more enticing as nesting habitat, because Bell's turtles had been previously seen to nest in disturbed soils. Although females did approach the structures and in one case entered, no females were recorded nesting inside. Further, severe flooding in both years damaged and/or displaced 4 of the 6 structures. Rigid nest protection structures were therefore not shown to be an effective nest protection method for this species, despite their success in other regions for other species. Negative results such as these are important for conservation studies because they guide conservation efforts away from expending limited resources on ineffective methods and strategies. [ABSTRACT FROM AUTHOR]

The extant pig‐nosed turtle (Carettochelys insculpta), persisting in far northern Australia and southern New Guinea, is the last surviving member of Carettochelyidae and the only non‐Gondwanan freshwater turtle lineage in Australia. Despite having a global fossil record dating to the Cretaceous, the absence of carettochelyid fossils from Australia has implied a relatively recent colonization of this landmass. Here we report an upper Miocene to lower Pliocene carettochelyid fossil from Beaumaris, Victoria, in south‐eastern Australia. This record is the most southerly occurrence of the clade Carettochelyidae. The presence of carettochelyids in southern Australia, and a discontinuous record of trionychids (soft‐shell turtles) in the Cenozoic of Queensland, suggests at least two colonizations of Australia by Trionychia, pre‐dating the extant pig‐nosed turtle. This cryptic southern history of tropical soft‐shell and pig‐nosed turtles ended before the recent aridification of Australia, leaving the Gondwanan side‐necked turtles as the dominant turtle group in Australian freshwater ecosystems. Therefore, this singular fossil reveals a previously unknown shift in the diversity and evolutionary history of freshwater turtles in Australia. [ABSTRACT FROM AUTHOR]

In this work we focus on the fossil record of turtles and tortoises from the Chubut Province, in Patagonia, Argentina. This record is the richest, most diverse, the longest and continuous in the country and one of the most important in the continent. In this work, we present and study new fossils from all known clades of turtles from the province, coming from targeted field campaigns, as well as from past investigations, placed in a comprehensive and detailed chronostratigraphic context. In Chubut, more than 241 occurrences of turtles from at least 223 collection points are known, spanning from the Toarcian (Jurassic) to the Tortonian (Miocene). we manage to fill some of the gaps in the fossil record, complete the anatomical knowledge of many taxa, explore new geographical areas, and present some important highlights. Among these, the record of the oldest pan-chelid turtles indicates the significant potential of the sedimentary deposits of Chubut. Furthermore, we discuss the changes in the diversity and faunal turnovers of the various turtle clades in this region during the last 180 Ma and across important events during the Cretaceous/Paleocene and Oligocene/Miocene boundaries.

The matamatas (Chelus fimbriata and the recently described Chelus orinocensis) are the largest species in the family Chelidae, easily identified by their distinct morphological characteristics. The matamatas have a wide distribution in South America, occurring in Bolivia, Brazil, Colombia, Ecuador, Guyana, French Guiana, Peru, and Venezuela, as well as Trinidad and Tobago. However, there are many gaps in the knowledge of its distribution. The objective of this study was to present new records of occurrence for the C. fimbriata species complex and describe the area of distribution. We compiled data from published papers, databases in museums and other scientific collections, and research institutes and conservation organizations. From these data we mapped the species distribution, considering 3 types of river drainages based on water color in the Amazon Basin. We added 182 new records in Brazil, Venezuela, Colombia, Bolivia, and Peru, demonstrating that the C. fimbriata species complex has a wide distribution, totaling 6,907,551 km2 across all 3 river types. Most records were concentrated in areas lower than 200 m above sea level. [ABSTRACT FROM AUTHOR]

Feral populations of Chelodina longicollis (Shaw, 1794) have established in Tasmania but many aspects of their biology in the wild remain unknown. A number of C. longicollis specimens were available for examination for parasites. Two species of digenean parasites were found in three of the 11 turtles examined: a Choanocotyle sp. and Thrinascotrema brisbanica Jue Sue & Platt, 1999. This is the first report of parasites from feral turtles in Tasmania. Due to the lack of native populations of freshwater turtles in Tasmania, these parasites must also have been introduced to Tasmania and have established life cycles in the new environments. The implications of such introductions, without suitable definitive hosts available to assist in establishing parasite infections, is discussed. An updated list of digenean parasites reported from Australian freshwater turtles is presented. [ABSTRACT FROM AUTHOR]

Among turtles, cases of “gigantism” occur mostly in pleurodiran Pelomedusoides and cryptodirans, but are infrequent among pleurodiran chelids, which are mostly small-medium sized turtles. Yaminuechelys spp. are extinct South American long-necked chelids (from the Late Cretaceous–early Paleocene of Patagonia, Argentina) with caparaces almost three times larger than their extant sister taxon, Hydromedusa tectifera. Since evolutionary changes in size can be analyzed based on growth dynamics, we studied growth strategies from an osteohistological point of view. We sampled both extinct (Yaminuechelys maior) and extant (H. tectifera) species, in order to test hypotheses related to the mechanisms involved in the macroevolution of size within this clade. For this purpose, thin sections of long bone (humerus and femur) shafts of specimens of different ontogenetic stages for these species were prepared. The osteohistological study reveals a similar growth dynamic in both taxa, with a poorly vascularized cortex dominated by parallel- fibered bone and interrupted by lines of arrested growth (LAGs). The huge body size of Y. maior appears to be a consequence of the prolongation of the growth phase, suggesting that it had a longer lifespan than H. tectifera, allowing to reach greater sizes. In this way, and assuming that there is no displacement at the beginning of development (e.g., a delay in the earliest stages of growth) in H. tectifera, the acquisition of a large size in Yaminuechelys would be explained by hypomorphosis of the former or hypermorphosis of the latter, depending on the reconstruction of the ancestral condition of this clade. [ABSTRACT FROM AUTHOR]

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 biology. Because there is a significant problem identifying juveniles of this species found in the wild, and a controversy concerning the taxonomic status of the Mesoclemmys nasuta group, we incubated eggs from known females from known localities at controlled and ambient temperatures. We describe the hatchlings produced. The eggs hatched after an incubation period of 249 d at 28°C. Incubation experiments found both M. raniceps and Mesoclemmys heliostemma phenotypes hatching from the same clutch of eggs, suggesting that these taxa are conspecific. Mesoclemmys wermuthi had been incorrectly synonymized with M. nasuta and later absorbed by M. raniceps when M. raniceps was elevated to species status, resulting in the confusion of M. raniceps being different from M. heliostemma. Mesolemmys wermuthi is a distinct species separate from M. raniceps; however, M. wermuthi is preceded by Hydraspis maculata, which was synonymized with M. raniceps and is available for this species as Mesoclemmys maculata. [ABSTRACT FROM AUTHOR]

The Amazonian red side-necked turtle Rhynemis rufipes is an endemic Amazonian Chelidae species that occurs in small streams throughout Colombia and Brazil river basins. Little is known about various biological aspects of this species, including its sex determination strategies. Among chelids, the greatest karyotype diversity is found in the Neotropical species, with several 2n configurations, including cases of triploidy. Here, we investigate the karyotype of Rhinemys rufipes by applying combined conventional and molecular cytogenetic procedures. This allowed us to discover a genetic sex-determining mechanism that shares an ancestral micro XY sex chromosome system. This ancient micro XY system recruited distinct repeat motifs before it diverged from several South America and Australasian species. We propose that such a system dates back to the earliest lineages of the chelid species before the split of South America and Australasian lineages.

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 Phrynops geoffroanus 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. [ABSTRACT FROM AUTHOR]

Understanding the evolutionary history of diversifying lineages and the delineation of evolutionarily significant units and species remains major challenges for evolutionary biology. Low‐cost representational sampling of the genome for single nucleotide polymorphisms shows great potential at the temporal scales that are typically the focus of species delimitation and phylogeography. We apply these markers to a case study of a freshwater turtle, Emydura macquarii, whose systematics has so far defied resolution, to bring to light a dynamic system of substantive allopatric lineages diverging on independent evolutionary trajectories, but held back in the process of speciation by low level and episodic exchange of alleles across drainage divides on various timescales. In the context of low‐level episodic gene flow, speciation is often reticulate, rather than a bifurcating process. We argue that species delimitation needs to take into account the pattern of ancestry and descent of diverging lineages in allopatry together with the recent and contemporary processes of dispersal and gene flow that retard and obscure that divergence. Underpinned by a strong focus on lineage diagnosability, this combined approach provides a means for addressing the challenges of incompletely isolated populations with uncommon, but recurrent gene flow in studies of species delimitation, a situation likely to be frequently encountered. Taxonomic decisions in cases of allopatry often require subjective judgements. Our strategy, which adds an additional level of objectivity before that subjectivity is applied, reduces the risk of taxonomic inflation that can accompany lineage approaches to species delimitation. [ABSTRACT FROM AUTHOR]

Twenty-seven new specimens recovered from lower levels of the Sarmiento Formation (Casamayoran SALMA, middle Eocene) in the 'Ca~nadón 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). [ABSTRACT FROM AUTHOR]

Vertebrate ichnological associations recorded in Middle Miocene successions were unknown in South America. During that time, South America was isolated from other continents and had a unique endemic fauna and flora. The lower Vinchina succession occurred between 15.6 and 12.7 Ma and records the footprints of highly specialized mammals, reptiles, and birds for the first time. To identify all footprint producers, we focused on anatomical traits of the appendicular skeleton represented on the footprints together with body size estimations of the producers as body mass and the apparent trunk length (GAD). Carnivoripeda sudamericana nov. isp. reveals a weasel-like producer of ∼1 kg and a trunk length of 19–26 cm most likely attributed to metatherian carnivores (Sparassodonta). They represent the oldest carnivore footprints in South America. Small bipedal rodent-like mammals of ∼280 g using a jumping gait (Morphotype A) are interpreted as produced by highly specialized South American marsupials, argyrolagids, whose footprints were unknown until now. Other mammalian footprints recorded are Tacheria troyana most likely produced by dinomyid caviomorph rodents. They represent animals of ∼16 kg and a trunk length of 48–55 cm, like living dinomyids. Subcircular to oval structures (Morphotype B) seems to be produced by medium-sized ungulates, while stepping in cohesive and plastic soupy sediments. cf. Chelonipus torquatus suggests small freshwater turtles (Chelidae or Podocnemididae), of ∼400 g consistent with a trackmaker of carapace size of ∼9 cm. Aviadactyla vialovi was most likely produced by a small shorebird (Scopolacidae) of ∼40 g. All footprints are preserved on crevasse splay deposits of anastomosing fluvial systems together with meniscate feeding (Taenidium barretti) and simple dwelling trace fossils (Palaeophycus tubularis) produced by insects and are an example of the Scoyenia Ichnofacies. [Display omitted] • C. sudamericana nov. isp. may represent the first sparassodont footprints ever found. • C. sudamericana nov. isp. are the oldest carnivore footprints in South America. • First footprints found of highly specialized South American marsupials, argyrolagids • The lower Vinchina succession records South Americas's only well constrained Middle Miocene (15.6–12.7 Ma) ichnoassociation i • The ichnoassociation is dominated by small-sized mammals (sparassodonts and argyrolagids), reptiles (freshwater turtles), and birds (shorebirds), followed by medium-sized, dinomyid rodents and ungulates. [ABSTRACT FROM AUTHOR]

Hatchlings of several species of freshwater turtles have been reported to remain in subterranean nests for extended periods following hatching from the egg. It has been suggested that this delayed emergence, including overwintering in the nest in populations at temperate latitudes, is an evolved adaptation that enables hatchlings to enter the aquatic environment at the most propitious time for survival and growth. I monitored nests of a temperate-zone population of the freshwater Australian eastern long-necked turtle (Chelodina longicollis) for up to a year after nest construction in fine-grained soils adjacent to oxbow lakes and farm ponds. An estimated 84% of nests were preyed on, probably mainly by non-native red foxes (Vulpes vulpes), whereas hatchlings emerged from autumn to spring from an estimated 5% of nests. The remaining 11% of nests were neither preyed on nor had emergence by a year after nest construction. Live hatchlings were present in some nests with no emergence up to 10 months after nest construction, but substantial numbers of dead hatchlings were present beyond nine months. It therefore seems unlikely that emergence occurs more than a year after nest construction. Delayed emergence of this species in this environment appears less likely to be an adaptive strategy than to be a consequence of imprisonment in the nest by hard soil that is difficult for hatchlings to excavate. Delayed nest emergence of freshwater turtle hatchlings is considered an adaptation whereby hatchlings enter the aquatic environment at the best time for survival and growth. However, delayed emergence in a population of the Australian turtle, Chelodina longicollis , appeared to be mainly due to imprisonment in the nest by hard soil. Photo by Bruce Chessman. [ABSTRACT FROM AUTHOR]

Rionegrochelys caldieroi de la Fuente, Maniel, and Jannello gen. et sp. nov. is a Late Cretaceous turtle from Rio Negro Province, Argentina. The holotype and the referred specimens of this new species show an unusual shell morphology and microanatomy. The proportion between the carapace and plastron and the peculiar morphology of the shell such as the heart shaped carapace, a very deep nuchal notch, peripheral bones 2-11 with strongly gutter, the first vertebral scute twice as wide as long and subrectangular in shape, the posterior margin of vertebral scute 5 is three lobe shaped, and the unexpected osteohistology characterized by a massive structure, with higher compactness (80.6%) than other chelids, suggests beyond doubt that this turtle may be considered a new taxon. A semi-aquatic habitat with tendency towards terrestrial environments is inferred for Rionegrochelys caldieroi similar to that of the extant pelomedusid Pelomedusa subrufa among the extant pleurodires. Rionegrochelys caldieroi is recovered as a stem chelid. This new species seems to be closely related to Bonapartemys bajobarrealis and the clade formed by Lomalatachelys neuquina plus Mendozachelys wichmanni. [ABSTRACT FROM AUTHOR]

Mesoclemmys tuberculata is a turtle species that is distributed in northeastern Brazil, recorded mainly in the Caatinga and at some localities in the Atlantic Forest and Cerrado. In this paper we report the first species record in an area of Cerrado of Minas Gerais state, and it is the only known state record in a specific location. During field sampling, a specimen of M. tuberculata was collected in the municipality of João Pinheiro, northwest state, in a Cerrado nuclear area in the São Francisco river basin. The locality of this record is the southern and western limits of M. tuberculata’s known distribution, as well as the most inland locality of species record in the Cerrado biome.

During 2006 and 2007, we collected free-ranging Phrynops geoffroanus, from two anthropogenically altered rivers in southeastern Brazil. Oral microbiological samples were taken for isolation of aerobic and facultative anaerobic bacteria; a physical examination was performed;and we evaluated possible effects on the turtles’ health. Twenty-nine species of bacteria were isolated in Piracicaba River turtles (n=10), and twenty-four species in Piracicamirim stream turtles (n=8), most of them gram-negative. In both sites, potential pathogens for reptiles were: Escherichia coli, Klebsiella pneumoniae, Enterobacter agglomerans, Citrobacter freundii, and Bacillus sp. Although boatpropeller lesions were common on the carapace of the turtles, we have not found turtles with signs of clinical diseases. The oral bacterial microbiota of P. geoffroanus inhabiting the Piracicaba River basin are composed of a diverse microbe spectrum, and long-term studies of the effects of pollution and traumatic injuries on this population and its microbial flora are warranted.