Johngarthia lagostoma (H. Milne Edwards, 1837) is a land crab of family Gecarcinidae, endemic to oceanic islands, and considered a key species of great ecological relevance. Currently, its distribution is restricted to four islands in the Atlantic Ocean: Fernando de Noronha, Atol das Rocas, Ascensão, and Trindade. Recent evaluations have indicated the species is under threat of extinction, due to its restricted distribution and anthropic impacts. In Trindade island, there is a peculiar relevance for studies on the biology and distribution of J. lagostoma: genetic isolation in a pristine environment. The present project aims to evaluate the physiological sexual maturity of J. lagostoma, in the Trindade island, comparing the maturity sizes obtained with other studies on land crabs of the Gecarcinidae family. The animals were previously collected (Universal CNPq Project n. 404224/2016) in different environments on the island, with five individuals being considered per size class (LC, cephalothoracic width) of 10mm for each sex. Each specimen was submitted to biometry (LC) with caliper and, after dissection, the stage of gonadal macroscopic development will be established, as follow: immature (IM), in maturation (EM), and mature (MA). Those identified as adults (EM + MA), for each sex, will be displayed cumulatively over the size classes (LC), fitted to the sigmoid curve, and obtaining the size at the onset of sexual maturity (LC50%). The results of this study will assist in the management of the species, as it is under threat of extinction, which requires a greater number of bioecological studies aimed at better conservation and management.
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