Peristedion amblygenys Fowler, 1938

Ono, Makoto & Kawai, Toshio, 2014, Review of Armored Searobins of the Genus Peristedion (Teleostei: Peristediidae) in Japanese Waters, Species Diversity 19, pp. 117-131 : 125-126

Peristedion amblygenys Fowler, 1938

[New Japanese name: Tsunobuto-kihoubou] ( Figs 2C , 3C , 6 ; Table 3)

Peristedion amblygenys Fowler, 1938: 122 , fig. 58 (type locality: South China Sea , west coast of Luzon , Philippines); Richards 2000: 607 (South China Sea); Ho et al . 2013: 39, fig. 1 ( Taiwan and Philippines).

Material examined. HUMZ 188916 , 1 , 134 , East China Sea (28°29.63′N, 126°55.45′E to 28°27.45′N, 126°54.49′E), 29 February 2004 .

Non-Japanese material examined. 7 specimens, 90.9–166 mm SL. FRLM 32253 , 1 , 143 , Dong-gang Fishing Port, Taiwan, 22 May 2005; HUMZ 185190 , 185192 , 2 , 139–166 , Dong-gang Fishing Port , Taiwan, 28 August 2002; HUMZ 190243 , 1 , 123 , off Java, Indonesia (08°21.3′S, 110°07.2′E to 08°22.8′S, 110°05.3′E), 465–470 m depth, bottom trawl, 31 May 2005; HUMZ 194175 , 1 , 136 , off Sumatra, Indonesia (05°42.4′S, 102°29.6′E to 05°42.6′S, 102°31.2′E), 377–388 m depth, bottom trawl, 30 May 2005; HUMZ 194579 , 1 , 90.9 , off Java, Indonesia (08°36.0′S, 111°47.5′E to 08°35.0′S, 111°46.3′E), 438–475 m depth, bottom trawl, 23 May 2005; USNM 98870 , holotype of Peristedion amblygenys , 130, west coast of Luzon (16°30.36′N, 120°11.6′E), 81–82 m depth, 10 May 1909 .

Diagnosis. Rostral projection broadly triangular with straight margin on medial side at base, width 12.1–13.3% HL; anterior margin of fourth sensory pore anterior to anterior margin of premaxilla; perifacial rim moderately broad, laterally prominent starting at level of anterior margin of lower jaw; branches on filamentous barbel 22–34; total chin barbels 22–24.

Description. Counts and measurements provided in Table 3. Body fusiform, depth 6.7 in SL, width 7.4 in SL, covered with bony plates. Head large, depressed, length 3.3 in SL. Perifacial rim prominent laterally starting at level of anterior margin of lower jaw ( Fig. 2C ), composed of second and third infraorbitals and preopercle, gradually increasing in width posteriorly, terminating at posterior edge of preopercle with posterior margin nearly perpendicular to side of head. Rostral projections broadly triangular with straight medial margin at base ( Fig. 2C ); both projections parallel ( Fig. 3C ) with single tiny spine on base. Anterior edge of fourth sensory pore of rostral projection anterior to anterior edge of premaxilla ( Fig. 2C ). Mouth moderately large. Both jaws toothless. Upper jaw symphysis loose. Lower jaw with single mandibular ridge. Vomer and palatine toothless. Three groups of barbels on lip: first group with three barbels, second with four, and third consisting of filamentous barbel with 22 branches; filamentous barbel moderately long, reaching posterior margin of lower jaw. Six groups of barbels on chin, 22 in total: first group with three barbels, second with three, third with four, fourth with four, fifth with five, and sixth with three. Gill rakers on first arch rudimentary, comb-like with minute prominences on inner side. Gill membrane narrowly united to isthmus. Eye large. Interorbital space deeply concave, its width nearly equal to orbital diameter, 4.3 in HL. Single rudimentary spine on lateral side of second infraorbital. Single strong spine on opercle. No spines on nasal, lateral ethmoid, and mesethmoid. Single smooth ridge present laterally on fourth infraorbital. Frontal-1 spine stout, small, on dorsoposterior part of orbit. Frontal-2 spine weakly prominent. Parietal spine stout, large. Posterior edge of posttemporal ridge formed by single large, stout spine.

Bony plates in four rows on trunk. Dorsal row: single backward-directed spine on each plate; these spines decreasing in size posteriorly, reduced to low ridge on caudal peduncle, except for single strong spine with serrated edge on last two plates. Upper lateral row: first to third plates small, lined obliquely downward to sixth plate; successive bony plates formed by seventh and eighth, and ninth and 10th plates; each plate with backward-directed spine; 25th to 36th in upper lateral row with forward-directed smooth spine, except for posteriormost plate with serrate spine. Lower lateral row: first plate largest; each plate with backward-direct- ed spine; row of plates ending at caudal peduncle. Ventral row: each plate with backward-directed spine; these spines decreasing in size posteriorly, except for last two plates; last two plates having serrate edge; row of plates absent at caudal peduncle. Bony plates in front of anus two, with low ridge and no spines; contralateral pairs of plates sutured along ventral midline raggedly.

Dorsal fin originating between first and second bony plates in dorsal row, second and third fin spines situated on second bony plate. Almost all soft rays originating between bony plates. Dorsal spines and soft rays connected by fin membrane. Anal fin originating between second and third bony plates in ventral row, remaining soft rays originating on bony plates. Last dorsal spine and last dorsal and anal soft rays small, scarcely visible. Joined pectoral fin rays reaching to 10th bony plate in upper lateral row. Fourth pectoral fin ray longest. Two detached pectoral fin rays thick; upper one based anterior to base of lowest joined fin ray (12th fin ray), longer than joined fin rays, barely reaching first anal fin ray; lower detached fin ray originating anterior to base of upper one, reaching anus. Pelvic fin soft rays gradually elongated from anterior to posterior, reaching anus. Caudal fin emarginate.

Color in alcohol. Head and body light brown. Dorsal fin spine region with black margin; soft ray region with black submarginal band. Joined pectoral fin with three blotches located basally on upper half, in middle of fin, and posteriorly. Both upper and lower detached pectoral fin rays and anal fin clear. Pelvic fin clear. Caudal fin with black dorsal margin.

Distribution. Known from the East China Sea, South China Sea, and Indian Ocean off Indonesia on bottoms of 81–475 m depth.

Remarks. Peristedion amblygenys was previously known from Taiwan ( Ho et al. 2013), the Philippines ( Fowler 1938; Ho et al. 2013), and the South China Sea ( Richards 2000). A single specimen collected from the East China Sea (HUMZ 188916) is the first record around Japan. In addition, two specimens from off Java (HUMZ 190243) and Sumatra (HUMZ 194175) in Indonesia are the first records from the Indian Ocean.

Figures

Fig. 2. Ventral view of head of Japanese species of Peristedion. A, Peristedion orientale, HUMZ 188920, 143mm SL; B, Peristedion liorhynchus, HUMZ 80306, 187mm SL; C, Peristedion amblygenys, HUMZ 188916, 134mm SL; D, Peristedion nierstraszi, BSKU 689, 133mm SL. Solid triangle points to rounded margin. Open triangle points to straight margin. Shaded areas indicate prominent perifacial rim. Barbels omitted.

Fig. 3. Dorsal view of head of Japanese species of Peristedion. A, Peristedion orientale, HUMZ 188920, 143mm SL; B, Peristedion liorhynchus, HUMZ 80306, 187mm SL; C, Peristedion amblygenys, HUMZ 188916, 134mm SL; D, Peristedion nierstraszi, BSKU 689, 133mm SL.

Fig. 6. Peristedion amblygenys, lateral view, HUMZ 188916, 134mm SL.