Nettenchelys Alcock 1898

Smith, David G., Lin, James, Chen, Hong-Ming & Pogonoski, John J., 2015, The eels of the genus Nettenchelys, with description of a new species from Taiwan (Teleostei: Anguilliformes: Nettastomatidae), Zootaxa 4060 (1), pp. 105-120 : 106-107

Genus Nettenchelys Alcock 1898

Nettenchelys Alcock 1898:149 . Type species Nettenchelys taylori Alcock 1898 , by monotypy. Feminine.

Diagnosis. Body elongate, round anteriorly, compressed posteriorly, deepest in middle and tapering at both ends, tail slender and attenuate, its tip delicate and frequently broken. Dorsal fin begins over gill opening or slightly behind, anal fin begins immediately behind anus, the fins confluent with caudal fin. Pectoral fin absent. Head and snout slender, elongate, and slightly depressed, snout projecting beyond tip of lower jaw. Anterior nostril tubular, near tip of snout; posterior nostril located on dorsal surface of head or body, from a point just posterior to eye to dorsal surface of body well behind dorsal origin ( Fig. 1 ). Lateral line on body complete; 5 SO pores, 8–10 + 2–4 IO pores, 11–16 POM pores. Teeth small, conical, in narrow bands on jaws and vomer; vomerine tooth patch elongate, sometimes with a median series of enlarged teeth anteriorly.

Species. Nettenchelys contains nine known adult species: N. dionisi Brito 1989 ; N. erroriensis Karmovskaya 1994 ; N. exoria Böhlke & Smith in Smith et al. 1981; N. gephyra Castle & Smith in Smith et al. 1981; N. inion Smith & Böhlke in Smith et al. 1981; N. paxtoni Karmovskaya 1999 ; N. proxima n. sp.; N. pygmaea Smith & Böhlke in Smith et al. 1981; and N. taylori Alcock 1898 . They are distinguished by the position of the posterior nostril ( Figure 1 ), the presence or absence of the median supratemporal pore, infraorbital pore counts, and the form of the vomerine teeth ( Table 1 ). A tenth species, Nettenchelys belottii (D’Ancona 1928) , is known only from a larva.

Distribution. Tropical Atlantic and Indo-West Pacific, rarely collected as adults.

Remarks. All of the known specimens have regenerated tails. As a result, the total number of vertebrae, an important character in eels, is unknown for any of the species, except by inference from the number of myomeres in larvae.

Character N. dionisi N. erroriensis N. exoria N. gephyra N. inion N. paxtoni N. proxima n. sp. N. pygmaea N. taylori

single row of enlarged vomerine teeth anteriorly Yes No No Yes No No Yes Yes No

Figures

FIGURE 1. Position of the posterior nostrils in nine species of the genus Nettenchelys (modified after Karmovskaya, 1999). (a) N. pygmaea, N. proxima; (b) N. gephyra and N. dionisi; (c) N. inion; (d) N. paxtoni; (e) N. exoria; (f) N. erroriensis; and (g) N. taylori.