9. Eurumetopos johnstonii Morton.
The Australian Museum, Sydney, possesses a mounted example of Eurumetopos johnstonii, sent from Tasmania by the late Alexander Morton, the author of the genus and species. He thought it was a Serranid, stating that “it bears in many respects a close resemblance to the Oligorus.” I examined the specimen referred to, many years ago, and came to the conclusion that it was referable to the Stromateidae. It is, however, only quite recently that I have been able to satisfy myself on this point, and to ascertain more closely its systematic position and affinities.
Last month (August 1911) Messrs. Dennis Brothers, of Christchurch, sent a fish to me for determination. with the remark that, notwithstanding their long experience in the New Zealand fish trade, they had never seen one like it before. On making inquiries I found that the specimen was one of five which the firm had secured, and that other fish-merchants had also obtained examples of the same kind, but had readily disposed of them before I became aware of the fact. Somewhat later the daily newspapers contained an announcement that some large fishes were being obtained at the Chatham Islands, and, though no one was able to give them a name, they proved to be excellent eating, and it was proposed to put them on the market as a regular commodity. From the popular description supplied I strongly suspected that the Chatham Island fishes would be found to be of the same species as those sent to Christchurch, and therefore enlisted the kind aid of Mr. A. Hamilton, Director of the Dominion Museum, as the fish companies operating at the Chatham Islands ship their catches
direct to Wellington. Mr. Hamilton was fortunate in being able to secure a specimen for me, which confirmed my supposition, and it is this larger specimen which forms the basis of the subjoined description.
I understand that the occurrence of the fishes at the Chatham Islands was of short duration only, and that, though they were quite plentiful at the period of their appearance, they are not now to be obtained.
During a subsequent visit to Sydney I was permitted to re-examine the specimen of Eurumetopos johnstonii, and compared with it a cast of the smaller of our two examples. I found them to be specifically identical.
The Tasmanian specimen exhibits the following characters:—B. VII; D. VIII, I, 20; A. III, 15.
The length of the head equals the depth of the body, and the pectoral is as long as the head.
The radial formula, as given by Morton* in his original description, appears to have been slightly mutilated by the printer, producing a very misleading result, which in all probability accounts for the non-recognition of the affinities of the species for such a long period. The figures D, 9 1–9, were intended for D. 9, 19, or, as now more usually written, D. VIII, I, 19. The anal formula is III, 13.
The following is a description of the Chatham Island specimen: B. VII; D. VIII, I, 20; A. III, 15; V. I, 5; P. 20; C. 24+6. L. lat. 84; L. tr 18+34. Vert. 10+12=22.
Length of head, 3.0; height of body, 2.7; and length of caudal, 5.5 in the length; diameter of eye, 5.2; interorbital space, 2.7; and length of snout, 4.0 in the head.
Head rounded, compressed, naked and porous above, tumid over the nostrils; the latter are close together, the anterior being circular, while the posterior one is an oblique slit lying midway between the end of the snout and the eye; snout truncate; the interorbital is broad and convex; the eye is relatively low in the head and is somewhat overhung by an obtuse ridge. The cleft of the mouth is horizontal, and the maxilla, which has a supplemental bone, extends to below the second third of the orbit; its distal portion is rounded and its width nearly half the diameter of the eye. The opercular bones are thin and entire, and the angle of the preopercle is greatly, though roundly, produced. Gill-membranes united far forward, not attached to the isthmus; gill-rakers long, 21 in number on the first arch, of which 16 are on the lower limb; pseudobranchiae present, but ill-developed.
Teeth.—The teeth are confined' to the jaws, the rest of the mouth being edentulous; they are small, set close together, and form a single series along the whole margins of both jaws.
Fins.—The dorsal fin commences over the edge of the operculum; the fourth and fifth spines are the longest, three-fourths the diameter of the eye; the last spine is continuous with the rays, the anterior of which is the longest and twice the diameter of the eye. The anal commences beneath the eighth dorsal ray, and is similar in character to the dorsal, terminating more posteriorly, however. The pectoral is falcate, and its seventh ray is as long as the head. The ventral spine is long and slender, its length one-half more than the diameter of the eye; the length of the first ray is twice the orbital diameter; the fin lies below the pectoral. Caudal emarginate;
[Footnote] * Morton, Proc. Roy. Soc. Tasm., 1888, p. 76, with plate.
the peduncle long and narrow, its depth one-fourth more than the diameter of the eye.
Scales.—Head generally naked, but with scales on the opercles; upper part of head with a spongy porous integument. The body-scales are not markedly deciduous, are of moderate size, and finely denticulated; they extend on to all the vertical fins. The lateral line does not follow the curve of the back, excepting for its anterior half, the hinder part being almost straight.
Length, 945mm. The type was 990mm., doubtless measured to the end of the longest caudal ray.
Colours.—Steel-blue above, silvery beneath.
The genus Eurumetopos, of which E. johnstonii is the type and only known species, may be thus defined: Body oblong, compressed; snout obtuse; mouth large; tooth present only in the jaws. Premaxillaries slightly protractile, maxillaries with supplemental bone; they are not entirely concealed by the preorbitals when the mouth is closed. Opercular bones thin, entire; branchiostegals 7; gill-membranes united far forward, not attached to the isthmus, pseudobranchiae developed; gill-rakers long; scales of moderate size, fairly adherent, lateral line not concurrent with the dorsal profile. A single dorsal fin with about IX, 20 rays; anal with about III, 15 rays; pectoral pointed, with 20 rays; ventrals below the pectorals. Vertebrae 22.
The genus appears to be sufficiently established, and finds its nearest ally in Psenopsis Gill, differing in the larger mouth, the character of the maxillaries, the more adherent scales of relatively smaller size and their development on to the bases of the dorsal and anal fins. The lateral line is not concurrent with the dorsal profilc, and the number of rays in the vertical fins is noticeably smaller.
The following notes are supplied for the convenience of those wishing to make a further comparison: In 1802 Gill* crected the genus Psenopsis for Trachynotus anomalus Schlegel, a species taken in Japanese scas.† The affinities of the fish were previously recognized by Bleeker (1853),‡ who placed it in the genus Psenes. Regan§ has more recently added Bathyseriola eyanea Alcock,∥ from Indian seas, to the genus Psenopsis, remarking, “There can be no question that these two species belong to the same genus, although their relationship has not hitherto been suspected, and the two species are very closely allied.”
[Footnote] * Gill, Proc. Acad. Phil., 1802, p. 157.
[Footnote] † Schlegel, Fauna Japan, Poiss., 1850, p. 104.
[Footnote] ‡ Blecker, Verh. Bat. Gen., vol 26 1853, p. 104
[Footnote] § Regan, Ann. Mag. Nat. Hist. (7), vol. 10, 1002, p. 130 (also see for further references.).
[Footnote] ∥ Alcock, Cat. Indian Deep-sca Fishes, 1800, p. 48, pl. 17, fig. 1.