Allometry and sexual dimorphism of the Nile Softshell Turtle<i> (Trionyx</i><i> triunguis):</i> male-biased size and conserved body shape
Makaleler > Tam Makale · 2026
Yazarlar: Salim Can AKÇINAR, Ertan Taskavak
SALAMANDRA, SCI İndekslerine Giren Dergi, Uluslararası, Wos, 2026, cilt 62, ss 211-219
Özet
The Mediterranean subpopulation of the Nile softshell turtle (Trionyx triunguis) is critically endangered, yet fundamental demographic and morphological parameters remain unresolved. This study aimed to evaluate sexual size and shape dimorphism, and ontogenetic growth trajectories using a dataset of 264 individuals in the Dalaman population in Turkiye. We found a significant male-biased sexual size dimorphism, with adult males averaging approximately 8% larger in straight carapace length (SCL) than females. However, multivariate and size-adjusted analyses revealed a highly conserved body shape, demonstrating that despite absolute size divergence, overall somatic morphology remains functionally monomorphic across adult sexes. Furthermore, allometric growth analysis identified total tail length as the primary secondary sexual characteristic for differentiating males, characterized by a distinct rapid hyperallometric elongation between 40.8 and 48.0 cm SCL. Consequently, the specific size-class thresholds identified provide field researchers with practical, non-invasive metrics to rapidly assess population structure. While males can be identified by tail elongation that extends the cloaca beyond the posterior carapace margin (> 40.8 cm SCL), individuals lacking this trait should only be confidently assigned as female at sizes exceeding 48 cm SCL. Ultimately, providing these actionable baseline parameters will directly support accurate population assessments and targeted conservation management.