Harryplax severus, a new genus and species of an unusual coral rubble-inhabiting crab from Guam (Crustacea, Brachyura, Christmaplacidae)

Abstract

Harryplax severus, a new genus and species of coral rubble-dwelling pseudozioid crab is described from the island of Guam in the western Pacific Ocean. The unusual morphological features of its carapace, thoracic sternum, eyes, antennules, pereopods and gonopods place it in the family Christmaplacidae Naruse & Ng, 2014. A suite of characters on the cephalothorax, pleon and appendages distinguishes Harryplax severus gen. & sp. n. from the previously sole representative of the family, Christmaplax mirabilis Naruse & Ng, 2014, described from Christmas Island in the eastern Indian Ocean. This represents the first record of Christmaplacidae in the Pacific Ocean. With the discovery of a second genus, a revised diagnosis for Christmaplacidae is provided.

Endemic species of Christmas Island, Indian Ocean

“…Endemism is not restricted to the species level; there are about ten endemic genera -the crab genus Christmaplax, the beetle genera Rhyncholobus and Psammorpha, the hemipteran genera Andrewsiella and Paurostauria (although the validity of the latter genus may merit further scrutiny: Fletcher (2008)), the psocid Sundapsocus, the grasshopper Nisiocatantops, the cockroach Metanocticola, a new genus of copepod (Arietellidae) (Bruce and Davie 2006) and Papasula (comprising Abbott's booby only). The crab family Christmaplacidae, originally based on one Christmas Island species, was considered endemic (Naruse and Ng 2014) until the recent discovery of another species assigned to the family, from Guam (Mendoza and Ng 2017).…”