Art. XXIII. — An apparently New Species of Regalecus (B. parkeri).

Transactions and Proceedings of the Royal Society of New Zealand, Volume 36, 1903, Page 198

Art. XXIII. — An apparently New Species of Regalecus (B. parkeri). By W. B. Benham, D.Sc., M.A., F.Z.S., Professor of Biology in the University of Otago. [Read before the Otago Institute, 9th June, 1903.] Plate IX. In November, 1902,1 received a silvery Oar-fish, which was washed ashore in Deborah Bay, near Port Chalmers, in Otago Harbour. It was observed with its head downward and the tail flapping above water in the air. The colour was silver, without—so my informant states—any other coloration. The long nuchal fin-rays were broken off at the base, as also were the pelvic fin and the tail, so that it is possible that the two former fins may have had the bright-red colouring known in R. glesne. The silver was marked by 14 dark transverse bands set at fairly regular intervals from the back of the head to the end of the body. Each band extends over the entire depth of the body, and is separated from its neighbours by a space about equal to its own length, which varies from 1 ½ in. to 2 in. (30mm. to 50 mm.), the latter being the length of the bands near the

middle of the body. These colour-bands are not black, but extremely pale grey, and could only be recognised by reflection in certain lights, the grey being due to minute pigment-cells below the silver. The fish is remarkable for its very great length as compared with its vertical height, being much more ribbon-like than other ribbon-fishes. Its total length (without the caudal fin) is 45 in. (1,144 mm.); it greatest height (at the level of anus) is only 0.75 in. (18.75 mm.); its thickness at this point is 9/32in. (7.3 mm.). This brings the ratio of length to height to about 60. The head measures. 2 ⅛ in. in length (53 mm.), and 7/8in. in height (21mm.). Diameter of eye ½in. (12mm.; distance from anterior margin to tip of retracted snout is ¾in. (18 mm.). Anus, 13 ¼ in. (337 mm.) from snout. Fin-formula: D., 7/390; P., 10; V. (?). Height of body, 1/60 of the total length; length of head, ½1 of the total length; pre-anal region to total length is 1 to 3–3. The dorsal fin is about half the height of the body, and there are 9 fin-rays to the inch anteriorly—or, roughly, about 390 fin-rays altogether. The anterior rays measured along their length are ⅝ in. (15 mm.); in the hinder part they are about ½ in. (12 mm.) long. The membrane reaches nearly to tips of the rays. The anterior or nuchal portion of the fin was damaged, but the bases of 7 rays remain, which are stouter than the usual rays, and no doubt were elongated, as in R. glesne. The pectoral fin is 7/16 in. long, with 10 rays; the pelvic (broken) are represented by a pair of minute knobs just behind the level of the pectorals on the throat. No doubt they were elongated in life. Teeth absent in the upper jaw, but there are two pairs of delicate conical teeth far forward in the lower jaw, and on the palate a small median tooth. The lateral line has a characteristic course: starting from the upper part of the back of the head, it passes rapidly downwards behind the pectoral fin to gain the lower part of the side, about 1 ⅛ in. (28 mm.) behind the bead. Thence the right and left lateral lines run backwards parallel, one on each side of the narrow belly close to the ventral mid-line and separated by a distance of ⅛ in. (3mm.). The head has black (not dark-blue, as in R. glesne) pigment bordering the lips, and a curved band of the same colour across the forehead, concentric with but slightly removed from the hinder border of the maxillary bone. The top of the head is black. The iris is also partially black, so arranged that the silver portion is a vertical oval, there being a greater width of pigment anteriorly to the pupil than posteriorly.

There are black pigment-spots along the base of dorsal fin and along side of body at posterior end. The gonad is 7 in. long. From the above it will be seen that the present fish does not agree with any of those enumerated by Dr. Gunther in the British Museum Catalogue (“Fishes,” iii., p. 300, et seq.), but it most nearly approaches the Indian species R. russelii, Shaw, which is figured in Day's “Fishes of India,” pl. 79, fig. 2. This is 2ft. 8 in. in length—i.e., 816mm. For this species Günther (p. 311) gives the following diagnosis:- D., 4–5/320; C., (?); P., 11; V., 1. The height of the body is one-twentieth of the total length. Teeth none. Caudal rays distinct.” The figure given by Day is 193 mm.—i.e., about a quarter the natural size. The greatest height is at the head; thence the dorsal surface slopes rather rapidly at first and then more gradually to the end of the body (a little more rapidly apparently than in our specimen). Height at level of pectoral is 8 mm. on figure (i.e., 32 mm. in the fish); height at middle of body, 4: mm. on figure (i.e., 16 mm. in the fish); length of head, 10mm. on figure (i.e., 40mm. in the fish); diameter of eye, 2mm. on figure (i.e., 8mm. in the fish); anterior margin to snout, 2 mm. on figure (i.e., 8 mm. in the fish); height of dorsal fin in mid-body, 2–5 mm. on figure (i.e., 10 mm. in the fish). Thus the ratio of heigbc to length is ¼7 contra (Günther). Day states of the dorsal-fin rays that the “central rays are the longest.” This fish is evidently different from Day's, and I propose the name R. parkeri, in memory of my predecessor, who made a careful study of the anatomy of R. glesne. At the same time it is possible that the present fish is the young of some known species, but it is convenient to record the occurrence under a distinctive name*. * Since writing this article I have received a second specimen of this fish, captured at Stewart; Island by Mr. Traill, and given to me by Mr. G. M. Thomson. This individual is much longer than the one described above, its measurements being as follows: Total length, 75 in.; greatest height (exclusive of fin), 1.75 in. The ratio of length to height) is about 43 (the fish is proportionately higher than the above); length of head, 3 in.; distance of anus from tip of snout, 22 in. There are, on the average, some 7 fin-rays to the inch, which gives a total of 525 fin-rays. The tail, though without the caudal fin, is uninjured, so that we may supplement the above account. At the hinder end of the body, about 3/16 from extreme tip, the dorsal fin ceases, and the ventral body-wall suddenly curves upward and backward to meet the dorsal line in a sharp point. On the upper surface, close to the point, are the broken stumps of three or four fin-ray.