Larvae and juveniles of two Brotula species (Ophidiiformes: Ophidiidae) collected from the Northwest Pacific Ocean

Abstract

Larva and juveniles belonging to two ophidiid species of the genus Brotula Cuvier 1829, Brotula sp. 1 [3 specimens, 14.2, 50.7, and 55.7 mm in standard length (SL)] and Brotula sp. 2 (1 specimen, 47.8 mm SL), were collected from the Northwest Pacific Ocean off the Okinawa, Izu (Aoga-shima Island and Miyake-jima Island), and Ogasawara Islands, Japan. Although the counts and proportions of both species agree with the documented ranges of Brotula multibarbata Temminck and Schlegel 1846 known from Japan, the larva and juveniles are clearly different from each other by the following combination of characters: counts of dorsal-fin rays [Brotula sp. 1, 122–126 (about 130 in the larva) vs. Brotula sp. 2, 118], anal-fin rays [94–101 (106) vs. 85], caudal-fin rays (11 vs. 9), and vertebrae (14 + 45–46 = 59–60 vs. 16 + 42 = 58); position of dorsal-fin origin [above or posterior to pectoral-fin base (above 6th vertebra) vs. anterior to pectoral-fin base (above 3rd vertebra)]; predorsal length (56.5–59.8% vs. 51.0% of preanal-fin length); blackish spots behind eye (present vs. absent); brown spots on body and vertical fins (present vs. absent); size of pectoral fin [small, not reaching anus (13.5–13.7% of SL) vs. large, reaching anus (28.3% of SL)]; and length between dorsal- and anal-fin origins (22.7–24.6% vs. 31.3% of SL). The occurrence of the larva and juveniles suggests that “B. multibarbata” known from Japan represents two species: Brotula sp. 1 and Brotula sp. 2 are probably B. multibarbata and Brotula formosae Jordan and Evermann 1902, respectively; the former is currently regarded as the senior synonym of the latter. In addition, this study describes for the first time the living coloration of Brotula larva.