The genus Geosesarma De Man, 1892 (Decapoda, Brachyura, Sesarmidae) from Sulawesi, Indonesia

Abstract Three species of Geosesarma: G. celebense, G. leprosum and G. clavicrure have been previously described from the Indonesian island of Sulawesi. To evaluate their identities, we examined type material of the three species, and they are re-described and illustrated. A short segment of 229 bp of COX1 gene from the Sulawesian Geosesarma was obtained (when available) and used for genetic comparisons. Our record of G. celebense from Selatan, South Sulawesi, and the genetic affinity between the type from North Sulawesi and the southern material indicates that G. celebense is well distributed throughout Sulawesi. The present study also describes a new species of Geosesarma from central Sulawesi. Geosesarma schubarti new species differs significantly from other Sulawesian Geosesarma in the morphology of the carapace, which is distinctly squarish in shape with a clear second anterolateral tooth. Genetic distances, using the segment of COX1 marker, showed all Sulawesian Geosesarma species, including the new one, are distant from each other. Our morphological comparisons also show that G. clavicrure is actually a junior subjective synonym of Bresedium brevipes; and the sequences of G. clavicrure grouped stably with B. brevipes in the 16S phylogenetic tree, and G. clavicrure therefore needs to be removed from the genus Geosesarma. As a consequence, with the new species, there remain three known species for Sulawesi (G. celebense, G. leprosum, G. schubarti), but based on currently available evidence it is considered likely that there exist additional species from this genus on the island.