Deep-Water Eels from Cook Strait, New Zealand
Naked deep-sea eels with the body extremely slender and jaws excessively attenuated; snout much more than half length of head; teeth small with backwardly-directed, curving lips, numerous, set in curving bands and quincunxial rows; two pairs of large nostrils, the anterior with a short tube, close in front of eye; nuchal constriction present; gill-openings well developed, convergent forward, anus far in advance of middle of length; pectorals and vertical fins well developed; fin membranes thin, not enveloping rays; lateral line pores present or absent; caudal filament present or absent.—Beebe and Crane, 1937b, p. 350.
The members of this widely distributed family are delicate, attenuated eels living the major part of their lives in mid-water depths. Roule and Bertin (1929, pp. 1–113) and Beebe and Crane (1937b, pp. 349–383) have added greatly to the knowledge of this family and in particular Nemichthys scolopaceus Richardson, 1848 and Borodinula infans (Günther, 1878). Less frequently recorded species of these genera, especially those from the Pacific region, are not well known.
Previous to this account the Nemichthyidae has been recorded only once from New Zealand waters; this was the occurrence of a damaged specimen of Nemichthys on a baleen plate of a humpback whale killed near Tory Channel, Cook Strait, in July, 1952. The specimen retained sufficient character in spite of its damaged condition to be referrable to N. scolopaceus. In their description of the specimen, Richardson and Garrick (1953, p. 467) are of the opinion that the eel had been page 4taken by the whale at a depth between 50 and 100 fathoms. The genera of the family are well characterized. Günther (1878, p. 251) originally included all known snipe-eels in the genus Nemichthys but Gill and Ryder (1883, p. 26) later divided this genus into two sections, Nemichthys and Labichthys, mainly on the nature of the lateral line—a triple row of pores in the former and a single row in the latter. It was further recognised by Jordan and Davis (1891, p. 655) that Labichthys could be divided into those forms in which the "ano-pectoral length" is very short, equal to only about 0.7 of the postorbital length, and those in which this was much greater, equal to five times the postorbital length. The forms so recognised were named Labichthys and Avocettina respectively. Whitley (1931, p. 334) has rejected the generic name Avocettina, this being preoccupied by Avocettina (pro- nus Bonaparte, 1850), Mulsant and Verreaux, 1866, Aves, in favour of Borodinula, and this is accepted in the following account.