A Revision of the Triggerfish Genus Xanthichthys, with Description of a New Species

The balistid genus Xanthichthys is characterized by: convex dorsal and ventral profiles of head, a projecting lower jaw, three to six longitudinal grooves on side of head, a groove running anteriorly from eye, no osseous plates behind gill opening, a narrow caudal peduncle, and second dorsal and anal fins elevated anteriorly. It consists of five species: the Atlantic X. ringens (Linnaeus), the Indo-West-Pacific X. lineopunctatus (Hollard), X. auromarginatus (Bennett), and X. caeruleolineatus new species, and the Pacific X. mento (Jordan and Gilbert). X. caeruleolineatus is distinctive in its low dorsal soft-ray count (26 to 28), low anal-ray count (23 to 25), high number of head-scale rows (21 to 24), large size (attains more than 300 mm SL), and color pattern which features an irregular blue longitudinal line along the side of the body. X. mento and X. auromarginatus are sexually dichromatic.