Bathycongrus castlei Smith and Ho, 2018, previously recorded only from Taiwan, is newly reported from Japan, based on two specimens (352+, 362 mm total length) collected from coastal waters in Tosa Bay, Kochi Prefecture at depths ranging from 128-315 m. Bathycongrus castlei differs from two congeners previously reported from Japan, Bathycongrus retrotinctus (Jordan and Snyder, 1901) and Bathycongrus wallacei (Castle, 1968), in having an intermediate number of total vertebrae (159-162 in B.

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... ei vs. 143-151 in B. retrotinctus and 172-181 in B. wallacei) and dark margins on the entire surface of the dorsal, anal and caudal fins (vs. only to the posterior end of the medial fins in B. retrotinctus and B. wallacei), 1 or 2 slightly enlarged teeth with a few small teeth at the front and sides and 6-9 stout or nearly granular teeth behind on the vomer [vs. 2 (sometimes 1) enlarged teeth surrounded by several smaller teeth in B. retrotinctus and 2 (rarely 1 or 3) enlarged teeth on midline, with 2 smaller teeth directly behind, side by side, and a few additional small teeth in the front and behind, no teeth laterally in B. wallacei]. A detailed description and fresh coloration are given for the specimens and a new standard Japanese name "Heri-tsumaguro-anago" is proposed for B. castlei.