Molting behavior, gastrolith formation, and mandibles of Enoplometopus debelius Holthuis, 1983 (Decapoda: Astacidea: Enoplometopidae) in an evolutionary context

Molting, gastrolith formation, and mandibular morphology are key features associated with growth, calcium regulation, and feeding ecology in decapod crustaceans. These aspects remain poorly understood in the reef lobster Enoplometopus debelius Holthuis, 1983. We investigated molting behavior, gastrolith structure, and mandibular sclerotization in E. debelius to evaluate their evolutionary significance within Astacidea. Molting occurred predominantly at night, and freshly molted individuals delayed consumption of exuviae for approximately two days. X-ray imaging revealed the presence of two pairs of gastroliths, in contrast to the single pair typically observed in other astacideans. Mandibular morphology showed strong mineralization of the incisor ridge, consistent with adaptations to marine feeding conditions. These findings suggest that E. debelius retains distinct morphological and functional traits that provide insight into the evolutionary diversification of Astacidea.