Kumba Marshall, 1973

Nakayama, Naohide, 2020, Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph, Megataxa 3 (1), pp. 1-383 : 224-225

Genus Kumba Marshall, 1973

[Japanese name: Kagamihige-zoku]

Kumba Marshall, 1973:616 (type species: Kumba dentoni Marshall, 1973 , by original designation).

Parakumba Trunov, 1981:28 (type species: Parakumba maculisquama Trunov, 1981 , by original designation).

Diagnosis. Anus separated from anal-fin origin in most species (immediately anterior to anal-fin origin in K. musorstom Merrett & Iwamoto, 2000 ); periproct narrowly developed. Small dermal window of light organ between pelvic-fin bases (no external evidence of light organ in K. musorstom ). Pelvic-fin rays 8–13, its origin below or anterior to pectoral-fin base. Second spinous ray of first dorsal fin serrated along its leading edge. No modified scales on head ridges and tip and lateral angles of snout. Chin barbel present. Teeth small, in narrow bands in both jaws. Underside of head almost completely naked, including gular and branchiostegal membranes; dorsal surface of snout broadly naked anteriorly. Body scales covered with short, erect, needle-like spinules in widely spaced, subparallel rows; scale spinules lacking buttresses; no reticulate structure. Grooved lateral line present. Cephalic sensory pores present or absent. Branchiostegal rays 7. [Modified from Iwamoto & Sazonov (1994).]

Remarks. The genus Kumba was established by Marshall (1973) for his new species K. dentoni . This genus had been represented by only the type species, until Iwamoto & Sazonov (1994) provided a systematic revision of the group. In their revised classification, Kumba was considered not only to be a senior synonym of Parakumba Trunov, 1981 , but also to include the following nine species: K. calvifrons Iwamoto & Sazonov, 1994 ; K. dentoni ; K. gymnorhynchus Iwamoto & Sazonov, 1994 ; K. hebetata ( Gilbert, 1905) ; K. japonica (Matsubara, 1943) ; K. maculisquama ( Trunov, 1981) (type species of Parakumba ); K. punctulata Iwamoto & Sazonov, 1994 ; and two undescribed species (these species were not named in their study, due to the immature state or questionable status of their materials). Of these, K. hebetata and K. japonica were previously classified under Nezumia Jordan in Jordan & Starks, 1904 and Ventrifossa Gilbert & Hubbs, 1920 respectively ( Iwamoto 1990).

Merrett & Iwamoto (2000) described K. musorstom , the latest species of the genus to be described, based on a single specimen collected from the Norfolk Ridge. This species is unique within the genus in that the anus is situated immediately anterior to the anal-fin origin, without any external evidence of the light organ anterior to the periproct. In the other species of Kumba , the anus is separated from the anal-fin origin, usually closer to the pelvic-fin bases, and a small dermal window of the light organ is present anterior to the periproct. The unique characters of K. musorstom casts doubt on the generic affiliation of this species. The position of the anus and the presence/absence of the light organ are considered to be important diagnostic characters in the generic classification of grenadiers ( Iwamoto 1990). Based on the original description given by Merrett & Iwamoto (2000), K. musorstom seems to be closely similar to Asthenomacrurus Sazonov & Shcherbachev, 1982 , with which it shares many morphological features, but they differ in the number of pelvic-fin rays (12–13 in K. musorstom vs. 7–9 in Asthenomacrurus ) and the presence/ absence of the serration along the leading edge of the first dorsal fin (absent vs. present). A further in-depth study of K. musorstom is obviously required to clarify the generic affiliation of this enigmatic species.