Nannobrachium fernae (Wisner 1971)

13-16 AO photophores; 8-9.5 tooth patches on the lower limb of the second gill arch; 37-38 lateral line organs (Ref. 36121). Pectoral fin relatively well developed and robust (Ref. 36121).

Dorsal spines (total): 0; Dorsal soft rays (total): 12 - 14; Analspines: 0; Analsoft rays: 15 - 18; Vertebrae: 37 - 39

Nannobrachium fernae (Wisner, 1971)

Lampanyctus fernae Wisner, 1971:50 [original description, North Pacific]; 1976: 172–173 [description, distribution, figure].—Paxton, 1979:14 [holotype and paratypes].—Willis et al., 1988:87 [distribution].

Lampanyctus (Lampanyctus) fernae.—Bekker, 1983:85, 86, 193, 198 [key, description, distribution].

COMPARATIVE DIAGNOSIS.—Nannobrachium fernae (Figure 13) can be distinguished from all other species in the Regale group primarily by the higher number of scales in its infracaudal luminous gland (Table A9), which is higher than in any other species of Nannobrachium. In addition, it can be separated from all other species of Nannobrachium by the combination of characters in Table 1.

DESCRIPTION.—Counts are based on up to 30 specimens from the North Pacific Ocean and are given in Tables A2–A9.

Proportions: Given in Table 11.

Fins: Anal-fin origin behind vertical from middle of base of dorsal fin. Pectoral fin reaching to or beyond pelvic-fin insertion, its rays relatively well developed and robust. Origin of adipose fin usually above end of anal-fin base.

Luminous Organs: PLO ;–2 photophore diameters below lateral line. PO4 usually slightly higher than, but occasionally at, level of PVO2 and behind vertical from PO3. VLO well below lateral line, typically slightly closer to lateral line than to pelvic-fin base. SAO1 variably above VO3; SAO2 closer to VO4 than to AOa1 level of SAO1–2 rather low on body, closer to ventral profile than to lateral line. SAO3 on or before vertical from AOa1; AOa1 slightly depressed; AOa1–2 interspace slightly enlarged. AOp1 above end of anal-fin base. Pol2 well before vertical from origin of adipose fin. Pre frequently not continuous with AOp. Prc3 on vertical line approximately midway between Prc2 and Prc4 but much closer to Prc2. Supracaudal and infracaudal luminous gland scales well developed; no separated scales preceding solid glands.

Size: Wisner (1976) records the species as reaching a size of about 90 mm in length, which corresponds to the maximum length of 91 mm examined in this study.

Material: 62 (38–91 mm) specimens were examined.

DISTRIBUTION AND GEOGRAPHIC VARIATION.—Nannobrachium fernae appears to have the most restricted distribution of any species of Nannobrachium (Figure 10). It is known only from an area of the North Pacific between 40°N–45°N and 135°W–165°W, with a depth of capture as shallow as 200 m at night (Wisner, 1976). Additional material I have examined comes from the same general region, so apparently this species is truly so restricted. No geographic variation was found in material examined.