Sternostylus new genus

(Figs. 2A, 3B)

Ptychogaster — Henderson, 1888: 170 (part).— Alcock, 1901: 279 (part). Gastroptychus— Caullery, 1896: 390 (part).— Poore, 2004: 221 (part).— Baba, 2005: 19 (part).— Macpherson & Baba, 2011: 49 (part).

Type species. Ptychogaster formosus Filhol, 1884 .

Etymology. From the Greek sternon (= breast, sternum), plus stylus (= column, style), alluding to the unique shape of the sternal plastron, which distinguishes the genus from all genera of the Chirostylidae . Gender: masculine.

Diagnosis. As for family.

Species included. Gastroptychus cavimurus Baba, 1977b (eastern Pacific); Ptychogaster defensa Benedict, 1902 (eastern Pacific); Ptychogaster formosus Filhol, 1884 (eastern and northwestern Atlantic); Gastroptychus hawaiiensis Baba, 1977a (central Pacific); Ptychogaster hendersoni Alcock & Anderson, 1899 (Indian Ocean and western Pacific); Gastroptychus iaspis Baba & Haig, 1990 (eastern Pacific); Ptychogaster investigatoris Alcock & Anderson, 1899 (Indian Ocean and western Pacific); Gastroptychus meridionalis de Melo-Filho & de Melo, 2004 (western Atlantic); Ptychogaster milneedwardsi Henderson, 1885 (eastern Pacific [Strait of Magellan]); Chirostylus perarmatus Haig, 1968 (eastern Pacific); Gastroptychus rogeri Baba, 2000 (southwestern Pacific); Gastroptychus salvadori Rice & Miller, 1991 (western Atlantic).

Remarks. At present, the single genus Sternostylus is recognized for the 12 species assigned to the

Sternostylidae .