Identification of the Commercially Important Oreosomatid Fish (Zeiformes: Teleostei) of the Emperor Seamounts, with Comments on Diagnostic Characters of the Species

Koichi Hoshino, Kunpei Kosaka, Kota Sawada, Masashi Kiyota
2022 Species Diversity  
An oreosomatid of the genus Allocyttus McCulloch, 1914 is fished commercially on the Emperor Seamounts. However, the species' identity is uncertain, as is the taxonomy of the oreosomatid species of the seas around Japan, where the names Allocyttus verrucosus Gilchrist, 1906 (type locality: off South Africa) and A. folletti Myers, 1960 (type locality: off California) have both been used. From its anticipated susceptibility to over-exploitation, it is urgent to establish the correct taxonomic
more » ... tity to facilitate effective management measures. Meristics, morphometrics and scale characters of the specimens from the Emperor Seamounts and Japan agreed well with data of the holotype of A. folletti and differed from those of A. verrucosus, confirming that those specimens represent A. folletti. Oreosomatids reported from the western North Pacific in the literature were identified as A. folletti. From the data of the present study and historical references, A. folletti is thought to be distinguished from A. verrucosus by the following characters: more dorsal-and anal-spines+rays (36-42 vs. 33-38 and 31-35 vs. 27-33 respectively), more total vertebrae (37-41 vs. 34-38), greater numbers of enlarged scales of dorsal-(S-DFB) and anal-fin base (S-AFB) (31-42 vs. 26-31, and 29-37 vs. 25-28 respectively), more spines on the margin of S-DFB and S-AFB (up to 7-12 vs. 3-6), a shorter preanal-fin length (53.8-63.6% vs. 64.8-83.7% of SL), a longer caudal peduncle (10.4-15.6% vs. 6.1-10.2% of SL), a shorter head , and cycloid scales on the mid-side of body (vs. ctenoid). Available data indicate that A. folletti reaches up to 537 mm SL, larger than A. verrucosus (up to ca. 325 mm SL). From the anticipated slow growth and longevity, concern is raised regarding the susceptibility of A. folletti to over-exploitation.
doi:10.12782/specdiv.27.1 fatcat:zra445w2sbftzgvnungptd5aua