Kuronezumia Iwamoto 1974

Genus Kuronezumia Iwamoto, 1974

[Japanese name: Suruga-nezumidara-zoku]

Kuronezumia Iwamoto, 1974:509 [type species: Nezumia (Kuronezumia) bubonis Iwamoto, 1974, by original designation].

Diagnosis. Anus separated from anal-fin origin, closer to pelvic-fin bases; periproct teardrop-shaped, moderately developed. Small dermal window of light organ between pelvic-fin bases. Infraorbital ridge not connected with preopercular ridge, separated by distinct gap. Second spinous ray of first dorsal fin finely serrated along its leading edge. Pelvic fin inserted below or anterior to pectoral-fin base. Mouth moderately large, usually subterminal. Chin barbel well developed. Teeth small, in broad bands in both jaws; premaxillary band ending anterior to posterior edge of maxillary process. Tip and lateral angles of snout lacking prominent scutes in most species. Suborbital region almost vertical, without coarsely modified scales. Head fully scaled, except for narrow naked area above upper lip. Body scales not deciduous, closely adhered to body surfaces; scale spinules needle-like, densely scattered over exposed portion or tightly packed subparallel to convergent rows; buttresses of spinules rudimentary; reticulate structure developed on posterior parts of unexposed portion. Grooved lateral line present. Cephalic sensory pores present or absent. Branchiostegal rays 7. Body dark to swarthy, lacking silvery reflection when fresh. [Modified from Sazonov & Iwamoto(1992) and Iwamoto & Graham (2001).]

Remarks. Kuronezumia was originally established as a subgenus of Nezumia Jordan in Jordan & Starks, 1904, but Sazonov & Iwamoto (1992) elevated this taxon to full generic rank. Shcherbachev et al. (1992) provided a synopsis for all the then-known species (seven species), viz., K. bubonis Iwamoto, 1974 (type species); K. dara (Gilbert & Hubbs, 1916); K. leonis (Barnard, 1925); K. macronema (Smith & Radcliffe in Radcliffe, 1912); K. paepkei Shcherbachev, Sazonov & Iwamoto, 1992; K. pallida Sazonov & Iwamoto, 1992; and Kuronezumia sp. [this undescribed species was initially recognized by Iwamoto (1974), but still remains to be described]. Two species are distributed in Japanese waters, one of which is new to science [different from the one reported by Iwamoto (1974)] and is described below.

Key to species of Kuronezumia from Japan and adjacent waters

1a Pelvic-fin rays 11–12; posterior half of mandibular rami scaled; branchiostegal membranes naked; no open pores along cephalic sensory canals; oral cavity blackish............... .................................................................................... K. dara

1b Pelvic-fin rays 15; mandibular rami almost entirely naked except for posterior margins; scaly patches present on lower portions of branchiostegal rays; cephalic sensory pores present; oral cavity pale .............................. K. endoi sp. nov.