A new species of damselfish (Pomacentridae) from the Indian Ocean

Abstract

The pomacentrid fish Chromis dimidiata (Klunzinger, 1871), type locality Red Sea, formerly believed to be wide-ranging into the Indian Ocean, is restricted to the Red Sea. The Indian Ocean population is described as a new species, Chromis fieldi. It differs in having modally 17 pectoral rays and 17 lateral-line scales, compared to modally 16 pectoral rays and 15 lateral-line scales for C. dimidiata, and the demarcation of the dark brown anterior part of the body from the white posterior part is convex, compared to nearly straight in C. dimidiata, and not as sharply defined dorsally and ventrally. Phylogenetic comparisons based on mitochondrial DNA (mtDNA) cytochrome b sequences support morphological differentiation with evolutionary separation of C. dimidiata sampled in the central Red Sea and C. fieldi sampled in the Indian Ocean (d = 0.019). These two species differ from the related C. iomelas Jordan & Seale, 1906 of the western and central Pacific in having modally 12 dorsal and anal fin soft rays (vs. 13 for C. iomelas), the demarcation of dark brown and white distinctly anterior to the origin of the anal fin, and d = 0.085 to d = 0.087 for cytochrome b.