The sentinel crabs of the genus Chaenostoma (Stimpson, 1858) (Crustacea: Brachyura: Macrophthalmidae), with description of a new species and new records

The genus Chaenostoma (Stimpson, 1858) so far includes four distinct species, i.e. C. boscii (Audouin, 1826), C. lisae (Poupin and Bouchard, 2010), C. punctulatus Miers, 1884, and C. sinuspersici (Naderloo and Türkay, 2011). Chaenostoma java n. sp. is here described as a fifth species from Java (Indonesia) easily distinguished from its congeners by the features of the male first pleopod, the penultimate segment of the male abdomen, and the unique female gonopore. The new species is most similar to C. lisae, but they differ in the morphology of the male chelipeds and female gonopores. Chaenostoma lisae is redescribed and recorded from Madagascar, Mayotte I. and New Caledonia. An identification key for the genus is provided.