Careproctus gilberti, Burke, 1912

Kai, Yoshiaki, Matsuzaki, Koji, Mori, Toshiaki, Pitruk, Dmitry L., Misawa, Ryo & Tashiro, Fumihito, 2024, Snailfishes of the genus Careproctus (Perciformes: Liparidae) with a reduced pelvic disk: three new species and new records from the western North Pacific with comments on their phenotypic diversity, Zootaxa 5492 (2), pp. 191-213 : 193-194

The Careproctus gilberti species group

Diagnosis. A species group of Careproctus with the following characters: reduced pelvic disk, less than 2.7% SL in length, usually round, sometimes incomplete (see each description of species); gill slit moderately large, extending ventrally to pectoral-fin rays 4–19, not reaching to base of lower pectoral-fin lobe; teeth simple or weakly shouldered.

Species included. In addition to C. gilberti , Careproctus barbatulus sp. nov., C. longibarbatus sp. nov., C. mederi , C. ostentum , C. parvidiscus , and C. spinulosus sp. nov.

Remarks. Among other liparids, species of Elassodiscus , which are also characterized by a reduced pelvic disk, are most similar to the above species group but can be distinguished on the basis of having a black orobranchial cavity (vs. pale orobranchial cavity), a gill slit above the pectoral fin or extending ventrally to pectoral-fin rays 1–7, 4 proximal pectoral radials with no interradial fenestrae (vs.proximal pectoral radials 3–4 with interradial fenestrae), and no pleural ribs (vs. usually 1–3 pleural ribs) ( Kido 1988; Pitruk & Fedorov 1993; Kai et al. 2020). The species group is genetically closely related to the Careproctus rastrinus and Careproctus reinhardti species groups ( Orr et al. 2019), but is differentiated from both of the latter in having a smaller pelvic disk (vs. 2.2–9.6% SL) and moderately large gill slit (vs. small gill slit, extending ventrally to pectoral-fin ray 10 at most, except for Careproctus reinhardti Krøyer, 1862 , which has a large gill slit extending ventrally to the base of the lower pectoral-fin lobe) ( Chernova 2005; Orr et al. 2015).

Key to the species of the Careproctus gilberti species group

1a. Lower part of pectoral girdle protruding anteroventrally below mandible......................................... 2

1b. Lower part of pectoral girdle not protruding anteroventrally below mandible...................................... 3

2a. Skin thin, almost naked (covered with extremely deciduous cactus-like prickles); dorsal-fin rays 50; anal-fin rays 44................................................................................................ C. parvidiscus

2b. Skin relatively thick, covered by cactus-like prickles; dorsal-fin rays> 51; anal-fin rays> 47......................... 4 3a. Skin thin, prickles absent or deciduous if present............................................................ 5

3b. Skin relatively thick, covered by cactus-like prickles......................................................... 6

4a. Body white in preservative....................................................................... C. mederi

4b. Body dark in preservative....................................................................... C. ostentum

5a. Gill slit large, extending ventrally to pectoral-fin rays 12–19................................................... 7

5b. Gill slit moderately large, extending ventrally to pectoral-fin ray 8.................................. C. sp. cf. gilberti

6a. Pectoral fin with shallow notch, lower lobe short, extending slightly posterior to anus.............. C. barbatulus sp. nov.

6b. Pectoral fin deeply notched, lower lobe long, same length as or slightly longer than upper lobe, extending to two-thirds between anus and anal fin origin............................................................... C. spinulosus sp. nov.

7a. Dorsal-fin rays 56–60; anal-fin rays 50–54; peritoneum dark brown.......................... C. longibarbatus sp. nov.

7b. Dorsal-fin rays 49–55; anal-fin rays 44–48; peritoneum pale or silvery with black dots....................... C. gilberti