Morphological variation in the Brazilian Radiated Swamp Turtle Acanthochelys radiolata (Mikan, 1820) (Testudines: Chelidae) (original) (raw)
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Iheringia. Série Zoologia, 2022
As commonly observed in turtles, sexual size dimorphism (SSD) is pronounced in the Neotropical freshwater turtle Mesoclemmys vanderhaegei (Bour, 1973), a species in which females are usually larger than males. We studied SSD in two populations of M. vanderhaegei from the Brazilian Cerrado savannah, based on 245 specimens captured between November 2010 and August 2013. The carapace length of the largest male was 201 mm (9.15% shorter than that of the largest female, 220 mm). The mean sizes of males and females did not differ in the two populations. However, a comparison of eight selected morphological variables revealed that the size distribution pattern differed between the populations. Using model selection, seven out of 34 morphometric variables - from the head, plastron, bridge, and tail - were selected as the most suitable ones to distinguish between males and females. The pattern of SSD found in M. vanderhaegei is similar to that found in other chelonian species and may be the ...
Chelonian Conservation and Biology, 2010
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 Paraná-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 results support the hypothesis that at least part of the morphological variation found is associated with population variation among basins, possibly as a result of reduced gene flow among their populations. This variation is shown in both linear and geometric morphometry analyses. Sea level fluctuations that occurred in the region during the last 15 million years could have caused the current differentiation.
Revista De Biologia Tropical, 2021
Introduction: Morphometrics analysis is an efficient and low-cost technique used in studies of sexual dimorphism in turtles. Kinosternon scorpioides scorpioides, scorpion mud turtle, has a wide phenotypic variation, depending on the area of its occurrence. Objective: The objective of this work was to identify the anatomical sexual difference of K. s. scorpioides, adults and hatchlings, through morphometric analysis; and relate the weights of adult animals to environmental factors (temperature and rainfall) in Marajo Island, Brazil. Methods: The sample collection was carried out from March to September 2018, covering both the rainy season (January to July) and the dry season (August to December). For the biometric analysis, 95 adults and 21 hatchlings were used, in which the length and width of the carapace and plastron, height of the shell, and weight were measured (adults only). For the geometric morphometry analysis, 21 adults and 13 hatchlings were used, in which 27 coordinates o...
Morphology and sexual dimorphism ofAcanthochelys spixii(Testudines, Chelidae) in Brazil
Tropical Zoology, 2016
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 body measures were larger for both males and females in the southernmost population, inhabiting higher latitudes and lower temperatures. Regarding sexual size dimorphism, females had larger PLW than males in MG, and all variables were dimorphic in RS, in general females being larger than males.
South American Journal …, 2008
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.
Chelonian Conservation and Biology, 2014
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.
Thesis Abstract Morphological and phylogeographic analysis of Brazilian tortoises (Testudinidae)
Genetics and Molecular Research, 2015
The discriminative potentials of biogeography, vocalization, morphology, cytogenetics, hemoglobin, and molecular profiling of cytochrome b as taxonomic techniques for differentiating Brazilian tortoises were evaluated in this study. In Brazil, two species of tortoises are described, Chelonoidis carbonarius and Chelonoidis denticulatus. However, in the present study, some animals that were initially recognized based on morphological characters and coloring did not correspond to the typical pattern of C. carbonarius; these animals were classified as morphotypes