Lycenchelys Gill 1884

Genus Lycenchelys Gill, 1884

(Japanese name: Hebigenge-zoku)

Lycenchelys Gill, 1884: 180 (type species by subsequent designation: Lycodes muraena Collett, 1878).

Lycodophis Vaillant, 1888: 311 (type species by monotypy: Lycodes albus Vaillant, 1888).

Embryx Jordan & Evermann, 1898: 2458 (type species by original designation: Lycodopsis crotalinus).

Lyciscus Evermann & Goldsborough, 1907: 342 (type species by monotypy: Lycodopsis crotalinus Gilbert, 1890).

Apodolycus Andriashev, 1979: 29 (type species by original designation: Apodolycus hureaui Andriashev, 1979).

Diagnosis. Vertebrae 19–30 + 66–118 = 85–144; suborbital bones 6–10; suborbital pores 6–11; 1st dorsal-fin pterygiophores associated with vertebrae 2–21, with 0–16 free pterygiophores; palatopterygoid series weak; oral valve weak; pseudobranch, pelvic fins, and vomerine and palatine teeth usually present; scales, pyloric caeca and lateral line(s) present (Anderson, 1994; Shinohara & Matsuura, 1998; Shinohara & Anderson, 2007; this study).

Distribution. Widespread in the Pacific (mainly in northwestern and eastern), Atlantic, Arctic and Southern oceans, and around the Kerguelen Islands (Anderson, 1994, 2006; Anderson & Fedorov, 2004; Anderson & Møller, 2007; Shinohara & Anderson, 2007; Thiel et al., 2018; this study). Maximum collection depth 5320 m, in the Peru- Chile Trench (holotype of Lycenchelys atacamensis Andriashev, 1980) (Andriashev, 1980; Anderson, 1988, 1995; Anderson & Fedorov, 2004).

Remarks. The genus Lycenchelys currently includes about 60 species (Anderson & Fedorov, 2004; Anderson, 2006; Anderson & Møller, 2007; Shinohara & Anderson, 2007; Nelson et al., 2016; Thiel et al., 2018). This study recognizes 11 species of Lycenchelys in Japanese waters, in accordance with recent studies (i.e., Shinohara & Anderson, 2007; Hatooka, 2013).

The diagnosis of the genus above mainly follows Anderson (1994), except for the numbers of suborbital pores and total vertebrae, variations in which were reported by Shinohara & Matsuura (1998), Shinohara & Anderson (2007) and this study.

Keys to species of genus Lycenchelys from Japanese waters

1a. Interorbital pores absent............................................................................... 2

1b. Interorbital pores present............................................................................... 3

2a. Pelvic-fin base positioned below 7th suborbital pore; suborbital pores 7 + 1; preoperculomandibular pores 9; lateral lines 2; pectoral fin and its base having scales............................................................ L. remissaria

2b. Pelvic-fin base set posterior to suborbital pores; suborbital pores 6 + 1–2; preoperculomandibular pores 8; lateral line 1; pectoral fin and its base lacking scales............................................................. L. ryukyuensis

3a. Occipital pores absent................................................................................. 4

3b. Occipital pores present................................................................................ 5

4a. Total vertebrae 85–89; pectoral-fin rays 13–16; pectoral fin and its base lacking scales; body reddish orange when fresh.............................................................................................. L. aurantiaca

4b. Total vertebrae 91–95; pectoral-fin rays 17–19; pectoral fin and its base having scales; body dark brown when fresh................................................................................................. L. squamosa

5a. Distinct spots or blotches present on body.................................................................. 6

5b. Distinct spots or blotches absent on body.................................................................. 7

6a. Six to 10 white blotches present above upper edge of gill opening and on dorsal fin extending onto dorsal part of body; total vertebrae 122–128....................................................................... L. albomaculata

6b. Blackish irregular blotches on most portions of dorsal fin and dorsal part of body; total vertebrae 137–142...... L. maculata

7a. Pelvic fins present; suborbital bone arrangement L-shaped; a single lateral line.................................... 8

7b. Pelvic fins absent; suborbital bone arrangement semicircular; two lateral lines........................... L. tohokuensis

8a. First suborbital pore located just below nostril tube; interorbital pores 1–2, when 1 interorbital pore present, located between middle centers of eyes or slightly posteriorly................................................... L. hippopotamus

8b. First suborbital pore located behind nostril tube; interorbital pore 1, located anterior to center of eyes................... 9

9a. Occipital pore usually 1 (rarely 2 or 3), 1 pore always present on midline of occiput; preoperculomandibular pores 9–10; total vertebrae 132–139.......................................................................... L. makushok

9b. Occipital pores usually 2 (rarely 1), located on left and/or right sides of occiput; preoperculomandibular pores 7–9; total vertebrae 117–134....................................................................................... 10

10a. Opercular flap absent; distance between 2nd and 3rd postorbital pores long, 11.8–18.2% HL.................... L. rassi

10b. Opercular flap present; distance between 2nd and 3rd postorbital pores short, 4.1–9.2% HL............. L. melanostomias