Bathycongrus, Ogilby, 1898

Smith, David G. & Ho, Hsuan-Ching, 2018, The congrid eel genus Bathycongrus of Taiwan, with descriptions of three new species (Anguilliformes: Congridae), Zootaxa 4454 (1), pp. 118-146 : 120

Key to species of Bathycongrus in Taiwan

1A. Posterior nostril above level of upper margin of eye............................................... B. macroporis

1B. Posterior nostril near or slightly above level of mid-eye....................................................... 2

2A. Teeth on vomer uniformly small, subequal in size, none enlarged................................................ 3

2B. Usually 2 (some with 1 or 3) enlarged teeth on vomer, surrounded by small teeth................................... 6

3A. Trunk rounded in cross section; preanal lateral-line pores>39; total vertebrae>163; total length more than 30 cm in adults.. 4

3B. Trunk relatively compressed in cross section; preanal lateral-line pores 25–29; total vertebrae 107–113; total length not exceeding 20 cm ...................................................................................... 5

4A. Head large and broad; trunk length 1.5 times HL; total vertebrae 174+................................... B. brunneus

4B. Head small and narrowly pointed; trunk length 2.0–2.1 times HL; total vertebrae 163............... B. graciliceps sp. nov. 5A. Two black patches on anterior portion of dorsal fin; preanal lateral-line pores 27–29............... B. bimaculatus sp. nov. 5B. No black patch on vertical fin; preanal lateral-line pores 25–26......................................... B. bleekeri 6A. Pores present behind eye; POM 11, ST 3; total vertebrae 195–201................................. B. albimarginatus 6B. No pores behind eye; POM 9 or 10, ST 1; total vertebrae fewer than 181.......................................... 7 7A. Enlarged median vomerine teeth followed by 2 or 3 (rarely 1) small teeth, none on side...................... B. wallacei 7B. Enlarged vomerine teeth surrounded by several small teeth on side.............................................. 8 8A. Vomerine teeth forming an elongate patch, 6–9 moderately large teeth behind the enlarged vomerine teeth. B. castlei sp. nov. 8B. Vomerine teeth forming a small triangular patch, several small teeth surrounding 2 (some with 1 or 3) enlarged teeth....... 9 9A. Trunk short, 1.3–1.6 times HL; tail less slender; preanal lateral-line pores 30–35; total vertebrae 143–151..... B. retrotinctus 9B. Trunk long, 1.6–1.9 times HL; tail more slender; preanal lateral-line pores 35–39; total vertebrae 155–162...... B. guttulatus