Makoto Okamoto

Epigonus cavaticus (Teleostei: Perciformes), a new epigonid fish from Palau, western Central Pacific

A new epigonid fish, Epigonus cavaticus, is described on the basis of eight specimens (59.2–69.5 in standard length: SL) collected from a cave at depth 20 m, southern fringing reef of Ngemelis Island, Palau. The species differs from other congeners by having minute teeth on both jaws, no opercular spine, pyloric caeca 7–8, gill rakers 25–27, total pored lateral line scales 48–50, dorsal fin rays VII-I, 10–11 (mode VII-I, 10), pectoral fin rays 16, vertebrae 10 + 15, body depth 21.4–25.0% SL, pectoral fin length 22.7–24.6% SL, eye diameter 44.4–47.5% head length: HL, upper jaw length 40.2–42.5% HL. Four paratypes (63.7–66.8 mm SL) of the new species are female with mature gonads, it is the smallest in size at sexual maturity among the congeners.

Development and distribution of the early life stages of the longfin pearleye Benthalbella linguidens (Aulopiformes: Scopelarchidae) in the western North Pacific

The early life history and development of the scopelarchid Benthalbella linguidens was studied, based on 203 specimens (from 5.3 to 89.7 mm in body length: BL) collected from Kuroshio, Oyashio waters and transition waters of the western North Pacific. The early life stages of B. linguidens are distinguished from those of other species of Benthalbella that inhabit the North Pacific by the characters of 62–64 myomeres in the larval stage and 26–28 anal fin rays in juvenile and transforming specimen. Larvae are elongate; notochord flexion begins at ca. 12 mm BL and is completed at ca. 15 mm BL. The fin ray complements are established at ca. 40 mm BL. The single transforming specimen (89.7 mm BL) that has peritoneal pigment was collected from transition waters. All larvae were collected from Kuroshio and transition waters from winter to early summer; however, the size of larvae in Kuroshio waters was apparently smaller than that in transition waters, with ranges of 5.3–32.4 mm BL (mean 17.1) and 15.3–35.3 mm BL (mean 27.5), respectively. Juveniles were distributed in transition and Oyashio waters and were absent in Kuroshio waters, where adults are commonly distributed. These occurrences of larvae and juveniles in the western North Pacific indicate that B. linguidens spawns in Kuroshio waters in winter and uses transition waters as nursery grounds.

Description of a new species of threadfin (Teleostei: Perciformes: Polynemidae), Polydactylus longipes, from Mindanao Island, Philippines

Abstract Polydactylus longipes n. sp. is described on the basis of three specimens collected from Mindanao Island, Philippines. The species is uniquely distinguished from other Polydactylus species with six pectoral filaments by the length of the latter, the uppermost two extending beyond the midpoint of the caudal peduncle. The new species is further distinguished from other Polydactylus species by the following combination of characters: 13 unbranched pectoral fin rays, six pectoral filaments, 54 or 55 pored lateral line scales, six and 11 scale rows above and below the lateral line, respectively, 31 or 32 gill rakers, vomerine teeth present and grayish-black body.

Larval and juvenile development of Lestidiops sphyraenopsis Hubbs, 1916 (Aulopiformes: Paralepididae) in the western North Pacific, with a reexamination of the holotype of Stemonosudis molesta (Marshall, 1955)

The early life stages of Lestidiops sphyraenopsis (Paralepididae) are described on the basis of 14 specimens [7.8 mm in notochord length (NL)–88.6 mm in standard length (SL)] collected from the western North Pacific, and the holotype of Stemonosudis molesta is reexamined. Larval L. sphyraenopsis occurred in the Kuroshio waters, and juveniles were taken in the Kuroshio–Oyashio transition waters. Diagnostic characters of larval and juvenile L. sphyraenopsis are 96–101 myomeres; 27–31 anal fin rays; 4–9 peritoneal pigment sections in larvae (7.8 mm NL–27.3 mm SL); dorsal and anal pigment patches present; and anus located anterior to a vertical through dorsal fin origin. Stemonosudis molesta, known only from the holotype from the South Pacific, is similar to immature specimens of L. sphyraenopsis, but can be clearly distinguished from the latter by having higher vertebral counts (105 vs. 96–101) and by morphometric and pigment differences. Consequently, S. molesta is a valid species, and the distribution of L. sphyraenopsis is restricted to the North Pacific.