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Sexual dimorphism in the species Pelusios castanoides
With Pelusios castanoides sexual
differences are easy to spot. Size can be an indicator with adult
specimens, as females can reach a carapacial length of 230 mm. while
males mostly will reach typical carapace lengths of 190 to 200 mm. Notably, males have a narrower carapace and plastron than females.
Also, males have a long, thick tail which is quite notable.
The cloacal vent is at the tip of the tail, far outside the posterior
marginal border of the carapace. Females, on the other hand, have a
short blunt tail with the cloacal opening at the base of the tail. The anal notch is deep and V-formed in males while the anal notch is U-formed in females.
The posterior lobe and abdominal scutes are shorter and smaller in
males, causing the anal scutes to barely reach the posterior marginal
scutes. With females the anal scutes reach to the posterior marginal
border of the carapace, the abdominal scutes are longer and the
posterior lobe is broader. Overall the male has a less broad shell and the plastron is also clearly less broad than the plastron of the female.
From left to right: male, female, female.
Males of Pelusios castanoides have a clearly visible concave plastron. In contrary, the females have a flat plastron.
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