Chromis tweddlei, a new deep-water species of damselfish (Pomacentridae) from the Cargados Carajos Bank, southwestern Indian Ocean

Abstract

Chromis tweddlei, a new species of damselfish, is described from seven specimens, 88.8–111.1 mm standard length (SL), collected during a 2008 expedition by the R.V. Dr. Fridtjof Nansen at 214–219 m depth (an unusually deep occurrence for the genus) on the Cargados Carajos Bank, Mascarene Plateau, southwestern Indian Ocean. Chromis tweddlei sp. nov. closely resembles Chromis axillaris, Chromis pelloura, and Chromis woodsi, the only congeners occurring in the western Indian Ocean (WIO) that share the character of having 14 dorsal-fin spines and a dark caudal band. Chromis tweddlei sp. nov. can be distinguished from its regional congeners by having II,13–14 anal-fin rays, 19–20 pectoral-fin rays, 18–19 tubed lateral-line scales, 4 scales above lateral line to the origin of dorsal fin, 29–32 total gill rakers, and colouration, including a caudal band that tapers anteriorly the full length of the caudal peduncle. A key to the 14 dorsal-fin spine species of Chromis from the WIO is provided.