Geosesarma hednon, a new species of terrestrial crab (Crustacea: Decapoda: Brachyura: Sesarmidae) from Taiwan and the Philippines

Abstract

A new species of Geosesarma, G. hednon, is described from Taiwan and the Philippines. The new species represents the northernmost record of this genus. Geosesarma hednon is morphologically closest to G. maculatum (De Man, 1892) and G. ternatenese (Serène, 1968) (both from Indonesia), but can be distinguished from them by outer margin of the external orbital tooth being subparallel to the rest of the lateral carapace margin, a short flagellum of the third maxilliped, the shape of the male abdomen, and the structure of the male first pleopods. Geosesarma hednon has small eggs and marine planktonic larval development, which distinguishes it from many other species of Geosesarma that are known to have abbreviated or direct development. This supports current doubts about the homogeneity and monophyly of the genus Geosesarma.