Ventrifossa divergens Gilbert and Hubbs, 1920

Iwamoto, Tomio, Nakayama, Naohide, Shao, Kwang-Tsao & Table, Hsuan-Ching Ho, 2015, Synopsis of the Grenadier Fishes (Gadiformes; Teleostei) of Taiwan, Proceedings of the California Academy of Sciences 62 (3), pp. 31-126 : 107-108

Ventrifossa divergens Gilbert and Hubbs, 1920

Figure 27 .

Ventrifossa divergens Gilbert and Hubbs, 1920:549 (holotype, USNM 78230, Celebes Sea near Sibuko Bay, Borneo, 4°12ʹ44ʺN, 118°27ʹ44ʺE, Albatross sta. 5592, 305 fm [558 m]; 59 paratypes).— Iwamoto, 1990: 299–300, fig. 676–677 (descr.) .

MATERIAL EXAMINED (21 spec.).— SWT: ASIZP 66928 (1, 62 HL, 320+ TL), PCP 339, 846 m ; ASIZP 66255 (1, 67 TL), OCP 303, 807 m. SCS: ASIZP 66781 (4, 59–64 HL, 297+-330+ TL), and ASIZP 66782 (2, 58–59 HL, 275+-310+ TL), CD 320, 731 m ; ASIZP 66784 (2, 41–47 HL, 205+-217+ TL), OCP 317, 515 m. Other specimens (all from Albatross Philippines Expedition of 1907–1909): Indonesia: USNM 78230 (holotype, 48.4 mm HL, 271 mm TL) . USNM 122917 (paratypes, 3, 34.2–40.3 HL), Molucca Sea , 545 m, sta. 5621. Philippines: USNM 122916 (paratypes, 2, 142+-469+ TL), off ne. tip of Luzon , 410 m, sta. 5325 ; USNM 122919 (41.5 HL, 222 TL), off ne. Mindoro, 623 m. USNM 148988 (paratype, 53.0 HL, 281 TL), off Balayan Bay , Batangas, sw. Luzon, sta. 5116 or 5115. USNM 149361 (paratype, 24.7 HL, 140 TL), off sw. Luzon, 315 m, sta. 5289. USNM 149363 (paratype, 53.2 HL, 250 TL) and USNM 150400 (paratype, 19.5 HL, 105 TL), off sw. Luzon, 391 m, sta. 5290 .

DISTINGUISHING FEATURES (from 11 USNM specimens, holotype data with asterisk*).— 1D II,9–11(10*); P i18–i25 (21–22*); V 8*–9; total GR-I (mesial) (12*)15–18, GR-II (lat.) 14*–15(17); scale rows below 1D 10–12, below midbase 1D (10*), below 2D 8–9* (11); lateral line scales over distance equal to predorsal length (48*). Snout length (29*) 26–31% HL; preoral length (15*) 14–19%; internasal 19*–25%; interorbital (24*) 30–37%; orbit (31*) 30–38%; suborbital (11*) 13–15%; postorbital (44*) (38) 41–47%; orbit to preopercle (45*) 40–46%; upper jaw 43*–49%; barbel (28*) 26–35%; outer gill slit (19*) 24–28%. Color in alcohol silvery on sides, brown dorsally but darker anteriorly, blackish ventrally on head and trunk; lips, lower jaw and gill membranes black; leading edge of snout blackish; mouth and gill cavity as in others of genus; 1D dusky proximally, paler distally; V dusky to black; base and axil of P black. Attains more than 47 cm TL.

DISTRIBUTION.— From South China Sea off Taiwan and Hong Kong; Philippines (e., n. and w. Luzon , off n. Mindoro , Sulu Sea off Panay ); Celebes Sea off e. Borneo ; Molucca Sea off Halmahera. Depth range about 183 to 807 m. Records of the species from s. Africa were misidentifications of a species that was subsequently described as V. mystax Iwamoto and Anderson, 1994 .

REMARKS.— Chiou et al., (2004b:46, fig. 19) recorded this species from Taiwan based on two specimens, ASIZP 61309 and 61310, which we re-identified as V. saikaiensis . However, new specimens were collected off Taiwan at depths of 515– 807 m. Based on examination (by TI) of many USNM specimens, there may actually be more than one species represented in the type series. The holotype ( USNM 78230) had several characters that appeared to be outside the normal range of other specimens. These characters include a low GR-I count of 12 total (mesial side) cf. 15–18 in others examined, narrower interorbital (24% cf. 26–32%), narrower suborbital (11% cf. 13–15%); shorter upper jaw (43% cf. 43–49%); and shorter outer gill slit (19% cf. 24–28%). Other measurements appear to be at one or another extreme in the range. The relatively sharply pointed snout and high anterior dorsal profile also differ in degree with other specimens. Among other Ventrifossa species from Taiwan, the one most similar is V. longibarbata , and so far as our limited study material allow, the two species overlap or are essentially identical in their counts and measurements. The snout in V. divergens appears to be slightly more pointed and protruding, and the broad black stripe across the 1D in V. longibarbata is generally prominent, compared to the difuse duskiness of that fin in V. divergens . A more in-depth study may reveal other distinguishing characters. The overall brownish color of V. saikaiensis , its longer postorbital length (44–49% HL), and fewer scale rows below the 2D (6.0–6.5 cf. 8–9 in V. divergens ), among other characters, distinguish that species from V. divergens . Compared with V. rhipidodorsalis , V. divergens has a longer preoral (15–19% cf. 11–15% of HL), somewhat broader interorbital (26–32% cf. 21–26%), somewhat larger orbits (with overlap, 29–38% cf. 27–32%), and somewhat shorter postorbital (with overlap, 38–44% cf. 43–48%); V. rhipidodorsalis also has a somewhat higher average number of V rays (9–10) and more prominent black blotches on 1D.

Figures

FIGURE 27. Valtrifossa divergens Gilbert and Hubbs, 1920. ASIZP 66928, 320+ mm TL, fresh. B. ASIZP 66781, 292+ mm TL, preserved, photo reserved laterally.