Phrynops Hilarii Research Articles

High toxicity of agro-industrial wastewater on aquatic fauna of a South American stream: Mortality of aquatic turtles and amphibian tadpoles as bioindicators of environmental health.

The aim of this study was to characterize an aquatic system of Santa Fe province (Argentina) receiving wastewater from agro-industrial activities (mainly dairy) by in situ assessment (fauna mortality, physicochemical, microbiological, and pesticide residues measurement), and ecotoxicity bioassays on amphibian tadpoles. Water and sediment samples were obtained from the Los Troncos Stream (LTS), previous to the confluence with the "San Carlos" drainage channel (SCC), and from the SCC. Biological parameters (mortality and sublethal biomarkers) were used to evaluate ecotoxicity during 10-day exposure of Rhinella arenarum tadpoles to LTS and SCC samples. Nine pesticides were detected in both LTS and SCC. Chemical and biochemical oxygen demand, ammonia, and coliform count recorded in SCC greatly exceeded limits for aquatic life protection. At SCC and LTS after the confluence with SCC, numerous dying and dead aquatic turtles (Phrynops hilarii) were recorded. In the ecotoxicity assessment, no mortality of tadpoles was observed in LTS treatment, whereas total mortality (100%) was observed in SCC treatments in dilution higher than 50% of water and sediment. For SCC, median lethal concentration and the 95% confidence limits was 18.30% (14.71-22.77) at 24 h; lowest-observed and no-observed effect concentrations were 12.5% and 6.25%, respectively. Oxidative stress and neurotoxicity were observed in tadpoles exposed to 25% SCC dilution treatment. In addition, there was a large genotoxic effect (micronuclei test) in all sublethal SCC dilution treatments (6.25%, 12.5%, and 25%). These results alert about the high environmental quality deterioration and high ecotoxicity for aquatic fauna of aquatic ecosystems affected by agro-industrial wastewater. PRACTITIONER POINTS: Great mortality of turtles was observed in a basin with a high load of agro-industrial wastewater. San Carlos Channel (SCC), where effluents are spilled, is environmentally deteriorated. The water-sediment matrix of SCC caused 100% lethality in tadpoles. SCC dilutions caused neurotoxicity, oxidative stress, and genotoxicity on tadpoles.

Comparative postcranial osteohistology and bone histovariability of aquatic and terrestrial turtles: the case of the South American Phrynops hilarii, Hydromedusa tectifera (Pleurodira, Chelidae), and Chelonoidis chilensis (Cryptodira, Testudinidae).

This article presents a detailed comparative analysis of the bone microstructure of three extant species of South American turtles. The main histological characteristics of postcranial bones are identified, as well as the intraskeletal, ontogenetic and interspecific variation between aquatic and terrestrial species. For this purpose, thin sections of postcranial bones (seventh cervical vertebra, coracoid, scapula, humerus, radius, ulna, ischium, ilium, pubis, femur, tibia, and fibula) of juvenile and adult specimens of aquatic (Phrynops hilarii and Hydromedusa tectifera) and terrestrial (Chelonoidis chilensis) turtles were analyzed. Bone histology revealed an intraskeletal variation of the microanatomical and microstructural organization in these turtles. The cortical bone is composed of poorly vascularized lamellar and parallel-fibered bone tissue interrupted with lines of arrested growth (LAGs), reflecting a cyclical slow growth rate throughout these turtles' life. Although in the adult specimens a growth rate decrease was observed, none of them have reached somatic maturity. The juvenile and the adult of Chelonoidis chilensis, unlike the aquatic species studied, presented a higher vascularization in their bones, which could imply a faster growth rate in this land specie. The number of LAGs was higher in the stylopodial and zeugopodial bones, which would make these elements suitable for approximate age estimations. Pectoral and pelvic girdle bones also exhibited a good record of LAGs. The information here obtained on extant species represents a powerful tool for the interpretation of paleobiological traits present in closely related fossil forms.

Gastrointestinal helminths associated with three species of freshwater turtles in the Pampa biome, southern Brazil.

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.

New records of helminths in Chelidae freshwater turtles (Testudines) in South America

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.

ANÁLISIS DE GENOTOXICIDAD EN ERITROCITOS DE TORTUGAS (Phrynops hilarii) DE SITIOS ANTROPIZADOS Y NATURALES DE ENTRE RÍOS, ARGENTINA

The micronucleus test (MN) is a biomarker of non-destructive genotoxicity that allows chromosomal damage and other nuclear alterations (NA) to be detected. Phrynops hilarii is a freshwater chelonium that inhabits regions of central-northern Argentina. The main objective was to determine the presence of MN and other NA in erythrocytes of natural populations of P. hilarii comparing their frequencies between three sites, two anthropized and one of control (cities of Diamante and Paraná) of Entre Ríos, Argentina, during the period 2015-2016. Eighteen individuals (six per sampling site) were evaluated at the sites: 1- PD: Pre-Delta National Park (control), 2- AG: Salto Ander Egg (agroecosystem) and 3- SU: Caleta Club Náutico (urban system). Blood was obtained from the femoral vein. The samples were stained with the May Grünwald-Giemsa method and observed under a microscope with an immersion objective. Micronucleus (MNF) and nuclear alterations (NAF) frequencies were determined every 1000 erythrocytes observed. A significant difference (p<0.05) was found between the PD site and the other sites (AG and SU), both for MNF (p=0.0021) and for NAF (p=0.0011). The highest frequency values ​​corresponded to the AG site (MNF: 3.33 ± 0.62; NAF: 4.67 ± 0.56). Finally, biomonitoring with P. hilarii was useful, so it could be considered as a bioindicator species to assess the quality of Argentina’s environments. Key words: Genotoxicity biomarkers, micronucleus test, nuclear alterations

A new species of Hedruris (Nematoda: Hedruridae) from freshwater turtles, its life cycle and biogeographic distribution of the genus.

We describe Hedruris dratini n. sp. (Nematoda, Hedruridae) from Hydromedusa tectifera and Phrynops hilarii in Argentina based on morphological and molecular characters. Also, we provide information about its life cycle. The new species differs from other species of the genus by possessing the excretory pore, nerve ring and deirids at equal distance from the anterior end. Additionally, H. dratini n. sp. has mammilated eggs and males possess nine pairs of caudal papillae. The subadults and adults of H. dratini n. sp and H. orestiae were characterized by sequencing the small subunit ribosomal DNA (18S). We present for the first time a life cycle of a species of Hedruris that includes an amphipod as intermediate host and a reptile as definitive host. Furthermore, we analysed the host and geographic distribution of all Hedruris species. Although the genus has a cosmopolitan distribution and parasitizes a great host diversity, the majority of species have a Gondwanian distribution, with amphibians being the preferred hosts.

Review of chelid and emydid turtle distributions in southern South America with emphasis on extralimital populations and new records for Argentina

There are many cases of animals reported in localities away from natural areas of distribution for the species. With respect to native freshwater turtles of Argentina and bordering countries, several populations (and single specimens) were reported for areas that cast doubts about their origin, due to not only the long distance from other known localities but also the geographical barriers that are in between. The present work provides a review of localities of the native turtle species Hydromedusa tectifera, Phrynops hilarii, Acanthochelys pallidipectoris, A. spixii and Trachemys dorbigni in Argentina, Bolivia, Brasil, Paraguay and Uruguay, and adds new records for some of these species for Argentina. We also employ an analysis to recognise core and extralimital populations, and a methodology based on five criteria that must be taken into account to elucidate if one extralimital turtle record is the result of anthropogenic action or a case of natural occurrence. Finally, we discuss about the origin of extralimital reports of turtles of the mentioned species.

Osteohistological correlates of muscular attachment in terrestrial and freshwater Testudines.

Sharpey's fibers are considered the anatomical structures integrated to the muscles. Since these fibers leave marks at the microscopic level, their presence and distribution are used as evidence of muscle attachment in extinct and extant forms. In recent years, studies have been focusing on muscle-bone and tendon-bone interaction mostly on mammals. The main objective of this work is to contribute to the morphological and histological knowledge of muscle attachment in other amniotes, such as reptiles, and their variation related to different locomotor habits. In this way, a study was performed on terrestrial and aquatic turtles. The musculature related to the movement of the humerus, and pectoral girdle in Chelonoidis chilensis, Phrynops hilarii and Hydromedusa tectifera was analyzed. Dissections were performed mapping the origins and insertions of each muscle and undecalcified thin sections were performed in specific muscular attachment sites. We found some differences which were not previously reported, related to the insertion of the m.pectoralis, the m.coracobrachialis magnus and the origin of the m.tractor radii. The osteohistology revealed the presence of Sharpey's fibers in the cortex of all the bone elements analyzed. Patterns were established in relation to the orientation and density of Sharpey's fibers, which were used for the categorization of each muscle attachment site. The comparative micro-anatomical study of these areas did not reveal any important differences between terrestrial and freshwater turtles in muscles involved with the rotation, abduction and adduction of the humerus. In this way, the preliminary results suggest an absence of correlation between the distribution and density of Sharpey's fibers between different habitat forms, at least in the bones and species analyzed.

Daily and Seasonal Basking Behavior in Two South American Freshwater Turtles,Trachemys dorbigniandPhrynops hilarii

Abstract Many species of reptiles maintain their body temperature behaviorally in a narrow range, even in the presence of considerable environmental temperature variation, by choosing microhabitats with different temperatures. In freshwater turtles, thermoregulation is generally achieved by aerial basking, even though they perform all other vital activities such as food consumption and reproduction in the water. Therefore, time budgets related to basking should be constrained and individuals should maximize the energy per unit time during basking, potentially by increasing basking frequency at noon during colder months and increasing use of basking when water temperature decreases. We analyzed basking behavior during the austral summer to study the effects of season, water temperature, and time of day in 2 South American freshwater turtles: Trachemys dorbigni (black-bellied slider) and Phrynops hilarii (Hilaire's side-necked turtle). We found that water temperature negatively affected basking frequency in...

Linderochelys rinconensis (Testudines: Pan-Chelidae) from the Upper Cretaceous of northern Patagonia: New insights from shell bone histology, morphology and diagenetic implications

The panchelid turtle Linderochelys rinconensis de la Fuente, Calvo and González Riga, 2007 was described on the basis of several postcranial elements from the Rio Neuquén Subgroup of Loma del Lindero site, near Rincon de los Sauces (Neuquén, Argentina). New preparation of the type material revealed new parts of the animal, including cervical vertebrae, parts of the carapace and a right tibia. The study of the newly recovered material herein improves our knowledge of the macroanatomy of this taxon. The first costal shows an axillary buttress similar to Australasian chelids and the cervical vertebrae morphology suggests a short-necked chelid condition. The re-examination of the type material of Linderochelys and the discovery of new material allowed new studies on microanatomy, osteohistology and diagenesis. Osteohistology suggests some similarities with Patagonian Cretaceous and Palaeocene Yaminuechelys, based on the presence of parallel-fibred bone in the external cortex and a much thinner internal cortex. Paleoecological studies on the proportions of forelimbs and microanatomy point towards aquatic or semi-aquatic habits, closely related to the condition seen in some extant South American chelids, such as Phrynops hilarii, Phrynops geoffroanus, and Mesoclemmys gibba. The fossil-diagenetic processes inferred substitution, fracturing, plastic deformation and permineralization events. Combined analyses through scanning electron microscopy with energy-dispersive X-ray spectrometry and petrographic studies revealed the substitution of hydroxyapatite by francolite. Permineralization stages include infilling of vascular canals, trabeculae and fractures with iron oxides and carbonate minerals during their burial history.

Seasonal activity and basking of the southernmost population of the freshwater turtle Phrynops hilarii (Chelidae)

This study focuses on basking behaviour of Phrynops hilarii in the southernmost population of the species’ range. The objective was to determine how environmental features affect the basking behaviour of the species. We analyzed two years of data on the seasonal activity of the species for the same stream. We detected 389 P. hilarii basking, mostly alone (76.8%), and on logs and branches (79.3%), but large turtles used shorelines more frequently than did smaller turtles. Basking peaked during late winter and early spring. We found no correlation between the number of basking turtles and air, substrate or water temperatures. P. hilarii was active through all seasons, with activity peaking in summer, when temperature is highest but basking frequency is low. Type of substrate, time of day, and season are key factors that influence the basking behaviour of P. hilarii.

Spiroxys contortus (Rudolphi, 1819) and Hedruris orestiae (Moniez, 1889) in Argentine turtles

Knowledge of parasites in turtles is scarce, particularly with regard to freshwater turtles of South America. Here, we describe the association of Spiroxys contortus (Rudolphi, 1819)in Phrynops hilarii (Duméril & Bibron, 1835) and S. contortus and Hedruris orestiae (Moniez, 1889) in Hydromedusa tectifera (Cope, 1870). The presence of S. contortus in P. hilarii represents a new host record and also the southernmost geographic record for this species. More interestingly, the presence of H. orestiae in H. tectifera represents the first record of this helminth species from a reptilian host.

Intestinal digeneans of freshwater turtles Phrynops hilarii and Acanthochelys spixii (Testudines: Chelidae) from southern Brazil

The work was aimed to increase knowledge on the diversity of parasitic digeneans in freshwater turtles from southern Brazil. Phrynops hilarii and Acanthochelys spixii are common turtle species of the Rio Grande do Sul fauna; however, little is known about the helminths parasitizing these hosts. In this context, 14 A. spixii and 5 P. hilarii were necropsied and helminthologically examined. The digenean species Cheloniodiplostomum sp. (Proterodiplostomidae), and Telorchis platensis (Telorchiidae) were reported for the first time in A. spixii. This is the first report of Cheloniodiplostomum testudinis, and Telorchis birabeni in P. hilarii from Brazil.

Basal frequency of micronuclei and hematological parameters in the side-necked turtle, Phrynops hilarii (Duméril & Bibron, 1835).

The present study aimed to evaluate basal frequency of micronuclei (MN) and hematological values in adult Phrynops hilarii in order to propose this aquatic turtle, broadly distributed in our region, as a biological monitor for future studies of environmental pollution assessment. Thirty-two adult turtles from a semi-natural environment located at the Zoological Experimental Station (Santa Fe, Argentina) were used. Blood samples were taken and the following parameters were determined: basal frequency of MN (BFMN), total red blood cells (RBC) count, hematocrit (Ht), hemoglobin (Hb), total and differential white blood cells (WBC). The BFMN determined for the species was 3.56 ± 1.39, while hematological parameters showed the following reference values: 0.937 ± 0.12 x10 6 RBC/µl, 27062.50 ± 4565.43 WBC/mm 3 , hematocrit 18 ± 1.81% and Hb concentration 4.80 ± 0.45 g/dl. Differential WBC counts were: 76 ± 2.90% for lymphocytes, 20.12 ± 2.56% for heterophils, 1.5 ± 0.19% for monocytes, and 2.12 ± 0.61% for eosinophils, while no basophils were observed in any of the samples analyzed. No differences were observed between males and females in any of the variables analyzed. Data provided in this work could be useful as reference values for future studies of natural regions where P. hilarii occurs, employing this species as a sentinel organism for genotoxic and immunotoxic evaluation of environmental pollutants.

How Far from Water? Terrestrial Dispersal and Nesting Sites of the Freshwater TurtlePhrynops hilariiin the Floodplain of the Paraná River (Argentina)

Terrestrial environments surrounding aquatic resources are important and intensively used by semi-aquatic species. In the present work, terrestrial dispersal and nesting sites of the freshwater turtle Phrynops hilarii were analyzed in the floodplain of the Paraná River, using field data and variables obtained from remote sensing. A total of 112 turtles and 44 nests were recorded during road sampling for one year (covered a total of 786 km in 30 surveys). Individuals were at a mean distance of 171.45 m from water, with a negative correlation between number of turtles and distance from water bodies. No significant differences in distance of turtles from water were observed among seasons. Phrynops hilarii nested at a mean distance of 136.51 m from water, showing a negative correlation between number of nests and distance from water bodies. Mean elevation of nests relative to maximum level of water body nearest each record was 1.13 m. The correlation between number of nests and elevation of the nearest water body was positive and significant. The landscape surrounding wetlands is important for P. hilarii to complete the life cycle, as nesting is done in this environment. Our results show that the habitat selected for nesting and terrestrial dispersal was proportionally different from that available in the entire study area, with a higher proportion of wetlands, grasslands and forests.

Anatomy of the fully formed chondrocranium of Podocnemis unifilis (Pleurodira: Podocnemididae)

AbstractThis study describes the anatomy of the chondrocranium of Podocnemis unifilis (Pleurodira, Podocnemididae), based on recently hatched specimens, and cleared and double‐stained specimens. The orbitotemporal region is dramatically different from those observed for other species of turtles in that the: (1) planum supraseptale is greatly reduced and present only as tiny projections on the posterodorsal margin of the interorbital septum, (2) pila metoptica is free from all neighbouring structures and bifurcates distally, (3) pila antotica is greatly reduced, (4) foramina for optic nerve, ophthalmic artery and oculomotor nerves are open dorsally by virtue of this species lacking the taenia marginalis and taenia medialis, and (5) tectum synoticum is present and invested dorsally by the supraoccipital, despite the fact that this bone forms by replacement of the supraoccipital. The unique morphology of the pila metoptica is explained either as de novo formation of processes on the terminus of this cartilage or by retention of portions of the taenia medialis (anteriorly) and pila antotica or pila accessoria (posteriorly). Variation in the orbitotemporal region presented here is discussed for two other pleurodiran turtles (Phrynops hilarii and Emydura subglobosa) and briefly compared with the anatomy observed in Cryptodira.

Plasma B-esterase and Glutathione S-transferase Activities in the South American Reptiles Caiman latirostris (Crocodylia, Alligatoridae) and Phrynops hilarii (Testudines, Chelidae)

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.

Dating cryptodiran nodes: Origin and diversification of the turtle superfamily Testudinoidea

The superfamily Testudinoidea is the most diverse and widely distributed clade of extant turtles. Surprisingly, despite an extensive fossil record, and increasing amount of molecular data available, the temporal origin of this group is still largely unknown. To address this issue, we used a comprehensive molecular dataset to perform phylogenetic and molecular dating analyses, as well as seven fossil constraints to calibrate the ages of the nodes in the phylogeny. The molecular dataset includes the complete mitochondrial genomes of 37 turtle species, including newly sequenced mitochondrial genomes of Phrynops hilarii, Emys orbicularis, Rhinoclemmys punctularia, and Chelonoidis nigra, and four nuclear markers. Our results revealed that the earliest divergences within crown testudinoids occurred around 95.0Mya, in the early Late Cretaceous, earlier than previously reported, raising new questions about the historical biogeography of this group.

Estimation of Core Terrestrial Habitats for Freshwater Turtles in Southern Brazil Based on Nesting Areas

Nesting sites of three species of turtles, Trachemys dorbignyi, Phrynops hilarii, and Hydromedusa tectifera, were analyzed from 1997 to 2002 at the Taim Ecological Station, in the southern Brazil. Our objective was to evaluate the size of the core habitat necessary to protect nesting sites of these species and to relate this information to Brazilian environmental legislation. Trachemys dorbignyi and P. hilarii have similar width of their nesting sites, 49.6 ± 36.3 m and 50.5 ± 30.4 m, respectively. Hydromedusa tectifera lays its eggs closer to the edge of waterbodies, on average at 12.6 ± 10.0 m. Curves were constructed to define the widths of the core habitats needed to protect 90% of the nests of each species. Trachemys dorbignyi requires 94 m of terrestrial habitat from the edge of waterbodies, P. hilarii requires 79 m and H. tectifera 24 m. In the study area, Brazilian legislation establishes a core habitat that is sufficient to protect the nests of these species around large waterbodies. However, because the protection areas are prescribed according to the width of the aquatic environments, this provision is insufficient for the majority of the aquatic environments in the region.

Feeding in Syntopy: Diet of Hydromedusa tectifera and Phrynops hilarii (Chelidae)

Abstract Stomach contents were obtained from 25 Hydromedusa tectifera and 47 Phrynops hilarii that live in syntopy in a pampasic stream in Buenos Aires province, Argentina. Both species are arthropod consumers. Copepods, ostracods, and hemipterans are the preferred items for P. hilarii, and H. tectifera prefers copepods, ostracods, immature dipterans (mainly chironomids), and ephemeropteran larvae. Items that most contribute to the diet of both species are immature chironomids, corixids, and belostomatids. Available food varies little among seasons, being slightly lower in winter months and part of the summer. Diet diversity changes by seasonal variation of prey item abundance in the diet of both species. Diet diversity is higher for P. hilarii (more generalist and broader trophic niche) than in H. tectifera, but there is no niche overlap between them. No significant correlation between the size of turtles and length of prey items was found. There is no evidence that the long neck of H. tectifera relates ...