Abstract
A new species of anthiine fish, Plectranthias alcocki n. sp. is described and illustrated based on two specimens, (63.7–72.5 mm SL), recently collected from deep-waters of the Arabian Sea, off Kollam, Kerala, India. The following combination of characters distinguishes it from all other congeners: Dorsal-fin rays X, 15; anal-fin rays III, 7; pectoral-fin rays 14, all unbranched; pelvic-fin rays I, 5; lateral-line complete, the pored lateral-line scales 28; scales above lateral line to origin of dorsal fin 1; scales dorsally on head extending to posterior nostrils; no scales on maxilla or chin; gill rakers 5 + 11 (2 + 7 developed); circumpeduncular scales 10; fourth dorsal spine longest, 2.8 (2.6) in head length (HL), longest dorsal-fin soft ray (second) 2.4 (2.7) in head length; body depth 34.4 (35)% SL; head length 46 (49.8)% SL; orbital length 8.6 in SL; margin of preopercle finely serrate, the serrae 33 (28), ventral edge without antrorse spines; dorsal fin continuous and notched; first anal-fin spine 4.9 (5.6) in HL, second anal-fin spine 2.2 (2.6) in HL; pelvic fins relatively short, 4.0–4.3 in SL; the dorsal fin with a black blotch at base of fourth to eighth spines, one at base of the last three spines, and two at base of soft portion of fin, the dark pigment extending onto adjacent body.