Nezumia cf. coheni, Iwamoto and Merrett, 1997

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 : 95-96

Nezumia cf. coheni [sensu Iwamoto and Merrett, 1997]

Figure 21A–C .

Nezumia coheni (not of Iwamoto and Merrett, 1997): Shao et al., 2008: table 2 (3 spec., SWT, 1305 m; first record from Taiwan).

MATERIAL EXAMINED (3 spec.).— SWT: ASIZP 63791 (3, 290+-333+ TL), CD 192, 1305 m .

DISTINGUISHING FEATURES.— 1D II,9–11; P i19–i21; V 9–10; GR-I (inner) 2+7, total GR-II (outer /inner) 8–9 / 9–10; scale rows below 2D origin 7.0–8.5, under midbase of 1D 6.5; lateral-line scales over distance equal to predorsal length 33–35. Snout conical with smoothly rounded dorsal and ventral profiles, length 31–33% HL, interorbital flat, its width 22–24%, orbit 27–32%, suborbital almost vertical, gently rounded, depth 17–19%; upper jaw 33–35%; barbel 15–20%; outer gill slit 12–16%; pre-A length 165–186%; outer V to A origin 44–50%; body depth about 77–92%; 1D-2D interspace 38–52%; height 1D 94–98%; length 1D base 24–30%; length P 51–61%; length outer V 49–54%. Underside of snout mostly naked; underside of head becoming increasingly covered with scales ventrally and posteriorly from about vertical through nasal fossa; pores and sensory papillae of cephalic lateralis system densely arrayed on underside of head, especially under snout and mandibles, producing a roughened surface texture; scales densely covered with broadly lanceolate spinules. All fins dark, blackish; dermal window of light organ relatively small and located between inner margins of V bases. Color in alcohol overall dark brownish; abdomen, gill covers, and gill membranes blackish; mouth dark but somewhat pale along outer margins; gums pale. Attains at least 333 mm TL.

DISTRIBUTION.— Known from the South China Sea off the sw. coast of Taiwan in 1305 m.

REMARKS.— Shao et al. (2008) first recorded these specimens as Nezumia coheni Iwamoto and Merrett, 1997 , but on closer examination, certain character disparities suggested that the Taiwan specimens may represent a different species. The pelvic fin-ray count of 9 or 10 contrasts with the usually 11 (rarely 9 or 10) of N. coheni . Certain proportional measurements differed slightly: suborbital depth 17–19% HL cf. 15–16% in N. coheni ; preanal length 165–186% cf 143–166%; and barbel length into orbit diameter 1.3–1.6 times cf. 1.6–2.0 times. The spinules on body scales also have rather broadly convex tips in the Taiwan specimens compared with the more attenuated and sharp tips of N. coheni . Although the three Taiwan specimens are in excellent condition, they were all collected together and are all of relatively the same size and likely do not show the range of variation in the species. The similarities in most features suggest a close relationship between N. coheni and these Taiwan specimens, if indeed they are different. We must await collection and study of more specimens of different sizes to confirm or reject the notion of their being different species.

Figures

FIGURE 21. Nezumia cf. coheni. A. ASIZP 63791, 1 of 3, 333+ mm TL, fresh. B-C.ASIZP 63791, 1 of 3, 290+ mm TK. B. lateral view. C. lateral view of left head.