The Central Chiapas Mud Turtle (Kinosternon abaxillare) is one of the least-studied turtles in Mexico. It is considered a microendemic, with a limited distribution in the Central Depression of Chiapas. In this article, we summarize its population ecology and provide a new assessment of its morphology from Villa Hidalgo, Chiapas, Mexico. We captured 168 individuals with 64 recaptures (232 total captures), and we report a population size of 231 individuals with a density of 700 turtles/ha (189 kg/ha standing crop biomass). The population showed a female-biased sex ratio (1:1.5) and the population structure was largely composed of adults. Finally, we provide a set of morphological measurements for all size classes and sexes of K. abaxillare for the first time. The plastral formula (relative lengths of midline plastral seams) was identical in all size classes and sexes (Ab > An > Gu > Hu > Fe > Pe). Females and males reached similar carapace length but not body mass. Further studies are needed to determine the overall conservation status of this range-restricted species.