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Dorsal-fin rays 10–12, usually 11. Anal-fin rays (25) 27–31, usually 28–30. Pectoral-fin rays 9–11, usually 10. Vertebrae 43–45, including 19 anal vertebrae. Gill rakers 5 + 11,very rarely 5 + 10, 5 + 12, 6 + 10, or 6 + 11. Pyloric caeca 7–8. Peritoneum black, anal opening (vent) bordered by black ring. SL 4.2–4.8 times greater than head length, decreases with growth. Eye diameter equal to width of interorbital distance. SL 6.0–7.0 times greater than body depth, decreases with growth. Photophores: OV and VAL on same level, anterior 1–2 VAL sometimes slightly raised; VAV and VAL 8 each; 1st or 2nd or 1st and 2nd AC slightly raised; AC 22–25, including 15–17 above the anal fin.
Indo–West Pacific species. P. corythaeola is known from the Andaman Sea (type locality), from northwestern Australia, from the Maldives, from the Arabian Sea at Karachi, from the Gulf of Aden, from the islands of Socotra (Suqutra), Zanzibar, and Madagascar, from the Saya de Malha and Nazareth banks, and the shores of Mozambique and Natal. This species is found in the Pacific in the waters of Japan, East China, and South China seas, in the Philippines and Tasman Sea.
Parin N, Borodulina O. 1990. Survey of the genus Polymetme (Photichthyidae) with a description of two new species. Voprosy Ikhtiologii 30(5):733–743.
The following morphologic description of the genus is based on Parin and Borodulina (1990). Body elongate, vertebrae 42-46. Eye normal. Mouth large, two rows of premaxillary teeth. Branchiostegal rays 13–14. Gill rakers 15–19, typically 16 to 18. Dorsal-fin rays 10–13 (14), Anal-fin rays (25) 27–34. Pectoral-fin rays 9-11. Pelvic-fin rays 7. Pelvic fins far anterior to the dorsal-fin origin. Origin of anal fin below the end of the base of the dorsal fin. Adipose fin present. Photophores: ORB 1, by the anterior margin of the orbit. OP 3. SO 1. BR 9–10. IV 21, 10th slightly raised; VAV 8–9; AC 22–25, of them, 15-19 above the anal fin, anterior 2 may be slightly raised; IC 50–54. OV 9; VAL 8–9, anterior 1 or 2 may be slightly raised; OA 17–18.
Maximum length 198 mm (Matsubara, 1938)
Andaman Sea, Investigator station 115, 116 and 233, in 188–220, depth 185 and 405 fathoms.
Syntypes: ZSI F13076-7, 150/1, 314-5/01
