Sexual dimorphism and morphometric study of Caspian pond turtle, Mauremyscaspica, (Testudines: Geoemydidae) in Golestan Province, southeast of the Caspian Sea

The Caspian pond turtle, Mauremyscaspica, is a terrapin belonging to family Geoemydidae. Totally ۱۳۰ specimens (۶۷ males and ۶۳ females) were collected manually and by net from different aquatic habitats in Golestan Province from ۲۰۱۶ through ۲۰۱۷. Morphometric characteristics such as length were measured using digital caliper and weight by electronic weighting scale. Skin of this turtle was dark olive green in color and had rows of longitudinal yellow stripes around the head and neck. Their carapace was relatively flat, the bridges between the dorsal and ventral shells were bony, and the ends of anal scutes were found to be pointed. Fingers and toes had swimming membranes. Sexes were identified using the location of vent on the tail. Sex ratios of males to females were nearly ۱:۱. The maximum straight carapace length (SCL۲) was ۸۰.۶۶- ۲۳۰.۱۶ (۱۵۶.۷۲ ± ۴۲.۹۳) and ۵۶.۹۶ - ۲۳۶.۸۴ (۱۴۷.۰۲ ± ۵۰.۷۶) in males and females respectively. Ratios of SCL۲ to maximum plastron length (PL۲) were found to be ۱.۰۱۳ - ۱.۳۲ (۱.۱۵ ± ۰.۰۴) in males and ۱.۰۱ - ۱.۱۵ (۱.۰۸ ± ۰.۰۳) in females; ratios of SCL۲ to straight carapace width (SCW) were ۱.۲۴ - ۲.۶۰ (۱.۴۰ ± ۰.۱۶) in males and ۱.۲۰ -۱.۴۷ (۱.۳۵ ± ۰.۰۷) in females; ratios of SCL۲ to carapace height (CH) were ۲.۲۸ - ۳.۵۵ (۲.۷۹ ± ۰.۲۲) in males and ۲.۰۵ - ۸.۷۸ (۲.۸۷ ± ۱.۱۱) in females; ratios of SCL۲ to tail length۲ (TL۲) were ۲.۳۳ - ۷.۵۹ (۳.۷۶ ± ۰.۹۱) in males and ۲.۳۴ - ۴.۷۸ (۳.۰۶ ± ۰.۶۲) in females. Ratios of straight width of femuro-anal suture (FASW) to anal seam length (AnSL) were ۲.۹۵ – ۵.۸۹ (۳.۷۸ ± ۰.۵۴) in males and ۲.۶۵ - ۴.۱۳ (۳.۲۳ ± ۰.۴۰) in females. The ratio of TL۲ to TL۱ and TL۱ to RBrL are found to be the fast and simple grouping index to determine sex of the specimens.

Keywords:

Caspian pond turtle , Golestan Province , Morphometric , Sexual dimorphism