Sexual dimorphism in Kinosternon scorpioides (Linnaeus, 1766) from the Brazilian Amazon

Area of Science:

• Herpetology
• Zoology
• Comparative Anatomy

Background:

• Sexual dimorphism is a common evolutionary phenomenon influencing species' phenotypes.
• Understanding sexual dimorphism in turtles is crucial for conservation efforts, especially for threatened species like Kinosternon scorpioides.

Purpose of the Study:

• To investigate and verify sexual dimorphism in the scorpion mud turtle (Kinosternon scorpioides).
• To utilize both linear and geometric morphometry techniques to analyze carapace and plastron variations between sexes.

Main Methods:

• Collected linear measurements and digital images of the carapace and plastron from adult male and female Kinosternon scorpioides.
• Applied linear morphometry to assess differences in height and width between sexes.
• Employed geometric morphometry, including Analysis of Variance (ANOVA), to evaluate variations in plastron size and carapace/plastron shape.

Main Results:

• Linear morphometry revealed statistically significant differences in carapace and plastron height and width, with females being larger.
• Geometric morphometry demonstrated significant variations in plastron size and distinct shape tendencies for carapace and plastron between males and females.
• The plastron showed particularly notable differences, confirming significant sexual dimorphism in Kinosternon scorpioides.

Conclusions:

• Sexual dimorphism is definitively present in Kinosternon scorpioides, primarily evident through plastron morphology.
• Morphometric analyses provide valuable tools for assessing phenotypic characteristics in animal populations.
• This research contributes to the broader understanding of turtle biology and aids in the conservation of threatened populations.