Neoconger Girard, 1858

Smith, David G., Marceniuk, Alexandre P., Rotundo, Matheus M., Carvalho, Cintia O. & Caires, Rodrigo A., 2024, A review of the genus Neoconger (Anguilliformes: Moringuidae), with the description of a new species, Zootaxa 5492 (1), pp. 109-128 : 112-113

Genus Neoconger Girard, 1858

Neoconger Girard, 1858: 171 . Type species Neoconger mucronatus Girard, 1858 by monotypy. Masculine.

Chrinorhinus Howell Rivero, 1932 . Type species Chrinorhinus torrei Howell Rivero, 1932 by monotypy. Masculine. Characters (after Smith 1989a). Body moderately elongate, cylindrical anteriorly, strongly compressed near end of tail; anus near midlength; tip of tail soft and blunt, caudal fin well developed and not stiffened. Dorsal and anal fins low and fleshy, confluent with caudal fin; dorsal fin begins over or somewhat anterior to level of anus; pectoral fin small but not rudimentary. Gill opening crescentic and transverse, on lower half of side, upper corner touching middle to upper edge of pectoral-fin base. Lateral line incomplete, ending near level of anus, pores increasing in number with growth, up to a point; head pores present only on lower jaw.

Head conical and smoothly tapering anteriorly, tip of snout projecting slightly beyond lower jaw, rictus behind level of eye. Eye small, covered by transparent skin, larger in mature males. Anterior nostril on side of snout somewhat behind tip, without a tube in females and immatures, becoming tubular in mature males. Posterior nostril larger, immediately before eye, elongate in an anteroventral to posterodorsal direction, with a raised rim higher on anterior side, lower at posterodorsal corner. Upper lip continuous with skin of cheek; lower lip separated from skin of jaw by a slight groove. Tongue adnate.

Stomach moderate in length, ending before anus. Gas bladder very small, thin-walled, near anus.

Teeth small, smooth, pointed, recurved ( Fig. 1 ). Maxillary and dentary teeth in one or two rows (usually one). Intermaxillary teeth somewhat larger, in two or three irregular rows, not separated from maxillary and vomerine teeth. Vomerine teeth in one or two rows, reaching almost to posterior end of maxillary row.

Color gray or grayish brown with no spots, stripes, or other distinctive markings.

Maximum size about 300 mm TL.

Some sexual dimorphism is present. Like the related genus Moringua , males appear to be smaller than females. Two mature males of Neoconger mucronatus measured 107 and 159 mm in TL. Eleven confirmed females measured 187–302 mm. See further details under N. mucronatus .

Distribution. Known from tropical and subtropical waters in the western Atlantic, eastern Pacific, and western Pacific off southeastern Australia, at depths of less than 200 m.

Habits and behavior. All evidence suggests that juvenile and pre-spawning adult Neoconger spend most of their time buried in the sediment and come out only for a brief time to feed and spawn (Smith 1989: 62). Unlike Moringua , Neoconger prefers mud rather than sand ( Smith 1989a; Smith & Castle 1972). This may explain the relative rarity of specimens in collections. Their fossorial habits would render them largely inaccessible to trawl nets. Divers spend little time making rotenone collections in barren muddy habitats, and would thus be unlikely to collect them. The relative abundance of larvae compared to adults indicates that these eels are more common than they seem.

Species. Three species have previously been recognized in this genus: Neoconger mucronatus Girard, 1858 in the western Atlantic from the Gulf of Mexico to Brazil; Neoconger vermiformis Gilbert, 1890 in the eastern Pacific from the northern Gulf of California to Panama and northern Colombia; and Neoconger tuberculatus ( Castle 1965) , known only from two leptocephali collected off New South Wales, Australia. The species are all much alike in general appearance, differing only in certain meristic and morphometric characters

The record of an adult Neoconger from Fiji reported by Smith (1989a: 60) is erroneous.The specimen in question, CAS 217641, is not Neoconger but a member of the Moringua raitaborua group. These eels are characterized by low vertebral counts, relatively stout body, and jaws nearly equal in length. They differ from Neoconger in having the anus well behind midlength and the DFO behind the anus.

Etymology. From the Latin neo, new, and Conger , a genus of eels. Apparently referring to a resemblance to the Congridae .

Figures

FIGURE 1. Tooth patterns in species of Neoconger. A, teeth in one row. B, teeth in two rows.