Family Nettastomatidae 87duckbill eels Marine Atlantic Indian and Pacific

Head and snout elongate and narrow; mouth enlarged; tail greatly attenuated; pectoral fin usually absent in adults (present only in Hoplunnis); vertebrae usually 190-280. Maximum length about 1 m. This family of tropical and warm temperate waters is poorly known; it is thought to be most closely related to the Uroconger line of congrids.

Six genera, Facciolella, Hoplunnis, Nettastoma,, Nettenchelys, Saurenchelys, and Venefica, with about 38 species (e.g., D. G. Smith in Bohlke, 1989:568-612; Karmovskaya, 1999).

Family SERRIVOMERIDAE (88)—sawtooth eels. Marine; midwater (pelagic) tropical to temperate, Atlantic, Indian, and Pacific.

Jaws extremely elongate and slender; vomerine teeth in two or more rows; gill openings connected ventrally; branchiostegal rays 6 or 7; color usually blackish with silvery sides; vertebrae 137-170.

Two genera, Serrivomer (about nine species, dorsal-fin origin slightly posterior to anus) and the monotypic Stemonidium (dorsal-fin origin over or slightly anterior to anus), with about 10 species (K. A. Tighe in Böhlke, 1989:613-27).

Order SACCOPHARYNGIFORMES (26)—sackpharynx fishes. Highly aberrant fishes, lacking symplectic bone, opercular bones, branchiostegal rays, scales, pelvic fins, ribs, pyloric caeca, and swim bladder; caudal fin absent or rudimentary; gill openings ventral; dorsal and anal fins long; jaws and hyomandibular greatly elongate, attached to neurocranium by only one condyle; leptocephalus larvae deep-bodied with myomeres V-shaped and not W-shaped. Like anguilliforms, they may spawn once and die.

C. R. Robins, in Böhlke (1989:9-23), gave reasons for including Cyematidae in this order rather than in the anguilliforms, where it was previously placed (see also D. G. Smith in Böhlke, 1989:629-35). Four families, five genera, and 28 species.

Suborder Cyematoidei

Family CYEMATIDAE (89)—bobtail snipe eels. Marine (bathypelagic); Atlantic, Indian, and Pacific.

Body relatively short, compressed; lateral line pores absent; eye small to vestigial; maxillae present; caudal fin present, tip of tail blunt. This family shows less reduction in characters than do the other saccopharyngiforms. Maximum length about 15 cm.

Nettastomatidae Australia Deep

Two monotypic genera—Cyema (body black; long, nonocclusible upper and lower jaws) and Neocyema (body bright red; pectoral skeleton absent, although a rayless fin is present—probably neotenic).

Suborder Saccopharyngoidei (Lyomeri). Quadrate greatly elongate; pharynx highly distensible (accommodating extremely large prey).

The species of this suborder are perhaps the most anatomically modified of all vertebrate species. Some earlier authors (e.g., V. V. Tchernavin) have questioned whether they are true bony fishes at all.

Three families, three genera, and 26 species (e.g., E. Bertelsen, J. G. Nielsen, and D. G. Smith in Bohlke, 1989:636-55, and references below).

Family SACCOPHARYNGIDAE (90)—swallowers. Marine; Atlantic, Indian, and Pacific.

Gill openings closer to end of snout than to anus; mouth large; jaws with curved teeth; pectoral fins well developed; vomer and parasphenoid absent; vertebrae about 150-300. Maximum length about 2 m, including the long slender tail. One genus, Saccopharynx, with about10 species (Tighe and Nielsen, 2000).

Family EURYPHARYNGIDAE (91)—gulpers or pelican eels. Marine; tropical and temperate, Atlantic, Indian, and Pacific.

Gill openings small, closer to anus than to end of snout; only teleost with five gill arches and six visceral clefts; mouth enormous; jaws with numerous minute teeth; pectoral fins minute; vertebrae 100-125. Maximum length about 75 cm.

One species, Eurypharynx pelecanoides (Nielsen et al., 1989).

Family MONOGNATHIDAE (92)—onejaw gulpers. Marine; Atlantic and Pacific.

Upperjaw absent (i.e., no maxilla or premaxilla); pectoral fins absent; dorsal and anal fins without skeletal supports; rostral fang with connected glands. Maximum length 15.9 cm. Most of the 70 known specimens were taken below 2,000 m. One genus, Monognathus, with about 15 species (Nielsen and Hartel, 1996).

CLUPEOCEPHALANS. The remaining two subdivisions, the Ostarioclupeomorpha (= Otocephala) and Euteleostei, are placed together as sister groups in the taxon Clupeocephala following Patterson and Rosen (1977). However, the Clupeocephala are not given formal rank here.

fOrder CROSSOGNATHIFORMES. Position uncertain. Taverne (1989) established this taxon for the Crossognathidae and Pachyrhizodontoidei, two groups previously thought to have differing affinities with the Elopomorpha. However, Taverne (1989) considered this order to be the primitive sister group of the clupeomorphs and euteleosts within the Clupeocephala.

This is a marine group, known from the Cretaceous (Lower and Upper) with one genus extending to the middle Eocene. Fossils are found primarily in Europe, North America, South America, and Australia. The following classification is based on Taverne (1989) and his other works.

Suborder Crossognathoidei. Premaxillae very small; palate without teeth and jaw teeth small; palatine very elongate.

Family CROSSOGNATHIDAE Two genera, Apsopelix and Crossognathus.

Suborder Pachyrhizodontoidei. Antorbital lost or completely fused with the first infraorbital; never more than six hypurals.

Family NOTELOPIDAE One genus, Notelops.

Family PACHYRHIZONTIDAE Six genera, Elopopsis, Greenwoodella, Pachyrhizodontus, Pachyrhizodus, Platinx (the only crossognathiform from Paleocene-Eocene), and Rhacolepis

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