Onset of morphological sexual maturity, sexual size dimorphism, relative growth, heterochely, and laterality of the endemic and potentially endangered freshwater crab Kingsleya attenboroughi (Decapoda, Pseudothelphusidae)

Abstract

Morphometric studies on freshwater crabs of the family Pseudothelphusidae are scarce, resulting in a significant gap in biological and ecological information about these crabs. Here, we evaluate the onset of morphological sexual maturity, sexual size dimorphism, relative growth, heterochely, and laterality of the endemic and potentially endangered pseudothelphusid crab Kingsleya attenboroughi. The morphometric dataset was derived from four capture–release sampling campaigns, during which morphometric measurements were made from live crabs so that it was unnecessary to euthanize or collect specimens. Females attain morphological sexual maturity at a larger size (42.1 mm carapace width) than males (34.9 mm). There is sexual size dimorphism, in which adult and juvenile females have larger carapace width and pleon width, whereas adult males have larger propodus length and propodus height. The relative growth of adult and juvenile males exhibited positive allometry of the chela, whereas juvenile females exhibited positive allometry of the pleon, with a decrease in pleon growth rate in adulthood. Juvenile males and females exhibit heterochely and laterality in the larger chela, with a tendency towards right-handedness, but these characteristics persist only in adult males. We discuss our results based on the importance of these structures in ecological and biological activities associated with each sex.