Key to species of Lestrolepis and Lestidium in Taiwan

1A. A light organ in front of eye; luminescent duct divided into 2 branches; dorsal-fin rays 9.................... Lestrolepis 2

1B. No light organ in front of eye; luminescent duct unbranched; dorsal-fin rays mainly 10...................... Lestidium 3

2A. DFO clearly in front of midline of V–A; anal-fin rays 36–40; lateral-line scales 65–72; total vertebrae 82–88; narrow band of chromatophores above the abdominal ridge........................................................ Ll. Japonica

2B. DFO at or slightly in front of middle of V–A; anal-fin rays 41–43; lateral-line scales 75–81; total vertebrae 94–98; abdomen ridge with broad black margin....................................................... Ll. nigroventralis sp. nov.

3A. Luminescent duct extending beyond anterior margin of eye; DFO at about same level of VFO; total vertebrae 79–86...... 4

3B. Luminescent duct extending to below opercle; DFO clearly behind VFO; total vertebrae 86–93....................... 5

4A. Total vertebrae 79–83; total lateral-line scales 109–126; predorsal vertebrae 33–36; predorsal lateral-line scales 34–36......................................................................................... Lt. orientale sp. nov.

4B. Total vertebrae 85–86; total lateral-line scales 130–134; predorsal vertebrae 38–40; predorsal lateral-line scales 38–39.................................................................................. Lestidium sp.1 ( cf. atlanticum)

5A. DFO above or slightly behind tip of appressed pelvic fin; total lateral-line scales 145–158; scales between VFO and DFO 3–5.......................................................................................... Lt. prolixium

5B. DFO close, but clearly behind tip of appressed pelvic fin; total lateral-line scales 123–139; scales between VFO and DFO 5–7............................................................................. Lestidium sp.2 ( cf. prolixum)