Lucigadus borealis, Iwamoto & Okamoto, 2015

Iwamoto, Tomio & Okamoto, Makoto, 2015, A New Grenadier Fish of the Genus Lucigadus (Macrouridae, Gadiformes, Teleostei) from the Emperor Seamounts, Northwestern Pacific, Proceedings of the California Academy of Sciences 62 (13), pp. 369-380 : 372

Key to the species of Lucigadus

1a. Pelvic-fin rays 7–12, rarely 13, if 12 or 13 the body with broad darkish bands that extend onto margins of anal fin.......................................................... 2

1b. Pelvic-fin rays usually 12–18, if 12 or 13, body lacking broad darkish bands and anal fin lacking alternate stretches of dark and light margins................................... 5

2a. Pelvic-fin rays 7 or 8; inner gill rakers on first arch 7–9; interorbital width 36–40% HL............................................ Lucigadus lucifer Smith and Radcliffe, 1912

2b. Pelvic-fin rays 9–12; inner gill rakers on first arch 9–12; interorbital width 22–35% HL... 3

3a. Pelvic-fin rays 11–12, rarely 13; body crossed by broad bands, with bands extending onto dorsal- and anal-fin rays............................. Lucigadus microlepis Alcock, 1894

3b. Pelvic-fin rays 9–11; body lacking bands, anal and second dorsal fins relatively uniformly pigmented along their lengths.................................................... 4

4a. Snout length 24–28% HL; height of first dorsal fin 92–107% HL; distal tip of first dorsal fin blackish; anterior rays of anal fin with blackish distal margin........................................................ Lucigadus nigromarginatus Smith and Radcliffe, 1912

4b. Snout length 28–32% HL; height of first dorsal fin 108–129% HL; inter-radial membranes of anterior third of first dorsal fin blackish; anal fin lacking blackish distal margin............................................. Lucigadus acrolophus Iwamoto and Merrett, 1997

5a. Length upper jaw 29–33% HL; length barbel 13–18% HL (rarely longer); length outer gill slit 13–17% HL; number of lateral-line scales from origin over distance equal to predorsal length 35–42; pyloric caeca 11–17.............................. Lucigadus borealis sp. nov.

5b. Length upper jaw 33–45% HL; length barbel 18–26% HL; length outer gill slit 18–31% HL; number of lateral-line scales from origin over distance equal to predorsal length 42–53; pyloric caeca 30–60............................................................... 6

6a. Pelvic-fin rays 15–18 (rarely 13); length outer gill slit 18–21% (rarely 24%) HL; length upper jaw 33–39% HL; maximum size about 22 cm TL............. Lucigadus ori Smith, 1939

6b. Pelvic-fin rays 13–15 (rarely 12); length outer gill slit 23–31% HL; length upper jaw 39–45% HL; maximum size attained more than 26 cm TL.......................................................................... Lucigadus nigromaculatus McCulloch, 1907