Grenadiers (Teleostei: Gadiformes: Macrouridae) of Japan and adjacent waters, a taxonomic monograph

Abstract

The taxonomy of the gadiform fish family Macrouridae (sensu stricto) in the northwestern Pacific off Japan and adjacent waters is critically reviewed on the basis of 7846 specimens. A total of 76 species belonging to 18 genera is recognized, including four new species of the genera Coelorinchus (2 species), Kuronezumia (1), and Nezumia (1). Coelorinchus lanceolatus sp. nov. superficially resembles Coe. anatirostris Jordan & Gilbert in Jordan & Starks, 1904, but differs most notably from that species in having a distinctly longer snout (107% of the postrostral length vs. 60–88%). Coelorinchus nox sp. nov. is closely similar to Coe. smithi Gilbert & Hubbs, 1920, but readily differs from the latter in that the occipital scales are covered with short, erect, needle-like spinules in widely divergent, comb-like rows (vs. moderately reclined, keel-like to knife-like spinules in saw-toothed rows). Kuronezumia endoi sp. nov. is a distinctive species among the genus, and is clearly diagnosed from other congeners in having the highest number of pelvic-fin rays (15 vs. ≤14). Nezumia rara sp. nov. closely resembles N. tomiyamai (Okamura, 1963), but they can be distinguished from each other by the combination of a number of morphometric characters, including the orbit-preopercle distance, interorbital width, pelvic-fin length, and length of gill slit. New and reconfirmed synonymies include: Coe. abbreviatus Chu & Lo in Chu, Chan & Chen, 1963 and Coe. intermedius Chu & Lo in Chu, Chan & Chen, 1963 with Coe. multispinulosus Katayama, 1942; Coe. productus Gilbert & Hubbs, 1916 with Coe. anatirostris; Coe. asteroides Okamura, 1963 with Coe. hige Matsubara, 1943; Coe. sparsilepis Okamura & Yatou, 1984 with Coe. parallelus (Günther, 1877); Coryphaenoides filamentosus Okamura, 1970 with Cor. cinereus (Gilbert, 1896); Cor. liocephalus (Günther, 1887) with Cor. leptolepis Günther, 1877; Cor. spinulosus (Gilbert & Burke, 1912) with Cor. acrolepis (Bean, 1884); and Ventrifossa fusca Okamura, 1982 with V. misakia (Jordan & Gilbert in Jordan & Starks, 1904). Lectotypes are designated for Coe. parallelus, Cor. asper Günther, 1877, Cor. liocephalus, and Cor. nasutus Günther, 1877. Previous records of N. burragei (Gilbert, 1905) and N. propinqua (Gilbert & Cramer, 1897) from Japan represent misidentifications, and these species are eliminated from the list of Japanese grenadiers. Coryphaenoides armatus (Hector, 1875) and Cor. leptolepis are recorded for the first time from the hadal zone. All species are illustrated, with full descriptions for 14 species. Dichotomous keys to genera and species are also provided. The distribution of each species in the study area is revised based on the specimens examined here, with re-identification of voucher specimens of most previous geographical records.