Pterygotrigla (Parapterygotrigla) megalops ( Fowler 1938 )

Richards, William J. & Yato, Takuji, 2014, Revision of the subgenus Parapterygotrigla (Pisces: Triglidae: Pterygotrigla), Zootaxa 3768 (1), pp. 23-42 : 31-32

Pterygotrigla (Parapterygotrigla) megalops ( Fowler 1938)

Large Eye Gurnard

( Figures 4 A –D, Tables 1 & 2 )

Dixiphistops megalops Fowler 1938:116 , Fig. 55 (original description, Luzon, Philippines); Holotype (unique). Parapterygotrigla megalops del Cerro & Lloris 1997:114 (distribution, meristics).

Pterygotrigla megalops Richards 1999:2377 (illustration, characters, distribution), Richards in Randall & Lim 2000:607 (listed); Myers & Donaldson 2003:619.

Parapterygotrigla sp. Yatou in Okamura et al. 1982:282 (color photo), 283, 398 (description in Japanese and English respectively).

Parapterygotrigla sp. B in various Australian reports.

Material examined. Holotype (unique): USNM 98879, 1 (96 mm SL), Off San Fernando Pt. Light, W coast of Luzon I., Philippines, 16°38'N, 119°57'18"E, Albatross sta. D.5441, 10 May 1909, 340 m. USNM 393319, 4 (33– 78 mm SL), FRV Townsend Cromwell Cr. 53, St. 94, 15 o10’N, 145o40’E, near Saipan, 30 April 1974, 366– 379 m (40 mm SL specimen cleared & stained).

Australian waters: CSIRO H1183.05, 1 (85 mm SL), Australia, Queensland Plateau, 17o32’S, 149o34.8’E, FRV Soela 6/85/62, 12 Mar. 1985, 454 m; CSIRO 11882, 1 (80 mm SL), Australia, Queensland, east of Flinders Reefs, 17o28.3’S, 149o41.2’E, FRV Soela, sta. 6/85/63, 12 Mar. 1985, 400 m. CSIRO H720-08, 3 (93–115 mm SL), Australia, Queensland, S of Saumarez Reef, 18o16’S, 118o12’E, RV Soela, sta. 2/82/36,37,38, 10 Apr. 1982, bottom temp. 10.0–12.4o C, 405 m.

Additional Material from Japanese waters (not examined): FUMT P- 3310, 1 (172 mm SL), Japan, Kyushu- Palau Ridge, summit Minami-Koho Seamount, ca. 26o08’N, 135o47’E, 28 Dec.1979, 360– 380 m. HUMZ 74906, 1 (200 mm SL), collected with FUMT P- 3310.

Diagnosis. Antrorse AIO spine absent, AIO long (20–28%SL), P1 fin reaches just beyond A fin origin (32– 36% SL), large eye (11–15% SL), pterygiophores exposed along base of D1 (large plates including one in advance of first D1 spine) and D2 fins with small spines at ray bases that are directed anteriorly.

Description. Specimens <78 mm SL not included in the description.

D 1 VII–VIII, D2 12, A 12(11), P 1 13–15 + 3 moderate reaching just beyond A fin origin (32–42% SL), GR long (2–5% SL) & slender (11–16 + rudiments), vert. 10–11 + 16–17 = 27 (holotype 10 + 17), llsc 57–68, nape with scales, breast with patch of scales, few, or naked, belly with scales, trunk scales strongly ossified, large eye (11– 15% SL), pterygiophores exposed along base of D1 (large plates including one in advance of first D1 spine) and D2 fins (small anteriorly directed spines), cleithral spine long (8–18% SL), swimbladder thin-walled, AIO spines long (20–28% SL), nasal spine present, postocular spine present in small specimens <10 cm SL, nuchal spine strong, opercular spine small, preopercular ridge present with small terminal spine, D1 fin spines serrate, vomer with few teeth in one specimen none in others, snout length 13–23% SL, snout angle 18–40o, body depth 21–26% SL, least depth caudal peduncle 6–7% SL, cheek height 8–11% SL, premaxillary length 15–17% SL, 1st P1 free fin ray 27– 35% SL, length D2 fin base 24–26% SL, length A fin base 23–25% SL, P2 fin length 24–29% SL, head length 36– 43% SL, orbital width 10–15% SL, interorbital width 9–12% SL, 1st D1 fin spine length 7–10% SL, 2nd D1 fin spine length 14–16% SL, 3rd D1 fin spine length 14–15% SL. Pterygiophore interdigitation pattern: //1/2/1/1/1/1/1/1/1/1/ 1/2/1/1/1/1/1/1/1/1/1/.

Coloration. Reddish on head and dorsally on trunk with some mottling, belly pale, D1 spines reddish with pale membranes and black spot on 1st three spines, D2 and A fins pale, P1 fin reddish base and upper ray, external surface pale, internal surface black, edges clear, iris yellow.

Distribution. Western Pacific Ocean, Philippines, Saipan, southern Japan, Australia off Queensland, in deep water, 340– 454 m.

Discussion. The two specimens (FUMT P-3310 & HUMZ 74906) from the Kyushu-Palau Ridge were thought to be an undescribed species by T. Yatou and K. Mochizuki (1982). The forms were distinguished on the basis of P. megalops lacking exposed pterygiophores along the base of the D2 fin, a shorter cleithral spine, and the first free P1 fin ray extending to the posterior tip of the P1 fin (vs. not reaching). In comparing the specimens, P. megalops has exposed pterygiophores along the base of the D2 fin, the 1st free P1 fin ray ranges from 27–31% SL in the Japanese specimens vs. 31–35% SL in the holotype, Saipan, and Australian specimens which are considerably smaller (> 172 mm SL Japan, <95.7 mm SL holotype and others). The cleithral spine is very similar in length in both forms (Japanese specimens 16–18% SL, vs 13–17% SL for the holotype, Saipan and Australian specimens). In any event the small differences observed could be due to size. This is a very rarely collected species that is widely distributed in the western Pacific.

Figures

FIGURE 4 A. Pterygotrigla megalops lateral and dorsal head views, CSIRO 1183.05, 85.5 mm SL, Australia, Queensland Plateau. B. Lateral view of Pterygotrigla megalops holotype, USNM 98879, 95.7 mm SL, Philippines. C. Dorsal view of head of Pterygotrigla megalops holotype, USNM 98879, 95.7 mm SL, Philippines. D. Lateral color photo of Pterygotrigla megalops FUMT P- 3310, 172 mm SL, Japan, Kyushu-Palau Ridge from Yatou in Okamura et al. 1982: 282.