Coryphaenoides asper Günther, 1877

Iwamoto, Tomio, Ho, Hsuan-Ching & Shao, Kwang-Tsao, 2009, Description of a new Coelorinchus (Macrouridae, Gadiformes, Teleostei) from Ta i w a n, with notable new records of grenadiers from the South China Sea, Zootaxa 2326, pp. 39-50 : 45-47

Coryphaenoides asper Günther, 1877

Fig 3 A–C

Coryphaenoides asper Günther, 1877:440 (holotype BMNH, 13 inches; off Tokyo, Japan; 34°37’N, 140°32’E, 1875 fm [3,429 m]; Challenger sta. 237, 17 June 1875).

Macrurus asper: Günther, 1887:137 , pl. 36, fig. A (description, figure)

Specimen examined. ASIZP 66107 (92.3 mm HL, 432+ mm TL), R/V Ocean Researcher I, sta. CD325, South China Sea; 20°40’N, 118°03’E, 1982 m, 20 Aug 2005.

Counts. 1D II,11; P i19 /i21; V 10; gillrakers first arch (outer/inner) 0+4 / 2+ 5, gillrakers second arch (outer/inner) 1+6 / 1+ 8; scales below 1D origin 7.5, below 2D origin 5.5, below mid-base 1D 5, lateral line scales over distance equal to predorsal length 37.

Measurements (in mm, percent of head length in parentheses). Snout length 26.8 (29); preoral length 14.6 (16); internasal width 21.7 (24); interorbital width 26 (28); orbit diameter 17.4 (19); suborbital height 12.8 (14); postorbital length 48.7 (53); distance orbit to preopercle angle 44.3 (48); length upper jaw 30.2 (33); length barbel 12.8 (14); length outer gill slit 6.8 (7); preanal length 153 (166); length isthmus to A 80 (87); length V origin to A origin 45 (49); greatest body depth 75 (81); depth at A origin 61 (66); body width 53 (57); head width 54 (59); 1D–2D interspace 19 (21); height 1D 84 (91); length base 1D 24 (26); length P – [damaged]; length outer V ray 77 (83).

Description of ASIZ P66107. Head broad, with overall shape much like those in C. rudis Günther, 1878 and C. marshalli Iwamoto, 1970 , but scales cover entire snout and suborbital regions. Interorbital space broad, about equal to snout length, much greater than orbit diameter ( Fig. 3 B). Snout slightly protruding beyond mouth; terminal snout scute stout and prominent. Orbit about 2.7 times into postorbital length of head. Upper jaw about one-third head length, extending posteriorly about to vertical through middle of orbit. Suborbital region smoothly curved, without an acute ridge, but scales along ridge prominent and slightly modified, as are scales over orbit and median nasal ridge. Posterior margin of preopercle slightly angulate forming a shallow lobe; interopercle slightly protruding at posterior end, where it is blackish and without scales. Chin barbel short, slender, about equal to least depth of suborbital. Gill membrane broadly attached to isthmus without a free fold. Tip of isthmus approximately under posterior angle of preopercular ridge.

Head and body uniformly covered with scales except on gill and gular membranes, fins, and lips. Scales on dorsum densely covered with greatly reclined conical spinules in irregularly parallel to slightly convergent rows; larger scales with 15 or 16 rows of spinules ( Fig. 3 C). The last spinule in middle of scale often longer than others and projects farther beyond scale margin; this enlarged spinule not prominent, however, and together do not render surface of fish with a striated appearance. Stomach everted and clogging mouth; inner surfaces of stomach beset with numerous nematodes, hanging from stomach wall.

Premaxillary dentition consists of small conical teeth in broad tapered band with the outer series slightly enlarged and spaced; dentary band with small teeth in broad band at symphysis but band narrows rapidly laterally and posteriorly.

First dorsal fin with moderately elongated second spinous ray; second dorsal fin rudimentary anteriorly, interspace between first and second dorsal fins short, about equal to orbit diameter, less than length of base of first dorsal; pectoral fins damaged, with broken tips; outer pelvic ray considerably prolonged, reaching well beyond anal-fin origin to 9th or 10th anal fin ray.

Body overall grayish-brown; abdomen and chest more swarthy gray-brown. Head much darker than (and contrasts with) body; most of head swarthy gray to black, especially over the opercle and suborbital. Gular and branchiostegal membranes entirely black, barbel dusky, lips black, but gums pale, and mouth dark gray. Sensory papillae prominent under and atop head and on mandibular rami. First dorsal and pectoral fins black, but bases somewhat paler; pelvic fins dark dusky to blackish with outer prolonged ray pale.

Remarks. This nicely preserved Taiwan specimen of C. asper is only the second one captured of this rare deepwater grenadier. It agrees rather well with the short original description by Günther (1877) and the fine, detailed drawing in the Challenger Reports ( Günther 1887: pl. 26, fig. A). One difference of note lies in the spinulation of the scales; those depicted in the holotype have spinules in rather few slightly divergent rows, whereas those in the Taiwan specimen are arranged in many (15–16 in larger scales, Fig. 3 C) subparallel to slightly convergent rows. We cannot evaluate the significance of this difference without additional specimens for comparisons.

The recent acquisition of a specimen of Coryphaenoides asper is a good example of how little we still know of the fauna of the greater depths of the oceans, even in an area as well explored as the waters off Japan, where the holotype was taken 134 years ago. The recent captures in more than 3,000 m off Japan of two undescribed species of Coryphaenoides (one of which will be described by Nakayama and Endo of Kochi University, the second to be reported on in a separate work by Nakayama, Endo, and Iwamoto) are additional examples of this lack of adequate collecting at greater ocean depths.

Figures

FIGURE 3. Corphaenoides asper, ASIZP 66107, 92.3 mm HL, South China Sea, preserved specimen. A. Lateral view of body. B. Dorsal view of head. C. SEM of scale, taken from lateral body posterior to pectoral fin.