Key to world species of Lophiomus

1. Floor of mouth without conspicuous dark marking (Fig. 12D); dorsal-fin spines 5; OPSOP less than 30% of HW ............................................................................................ Lm. immaculioralis sp. nov.

– Floor of mouth with conspicuous dark markings (Figs 8D, H, 9C, G, 10C, 11D, H, 13D, H, 14D); dorsal-fin spines 6; OPSOP more than 30% of HW ......................................................................... 2

2. Body color brown (Fig. 8A, C, E, G); floor of mouth with irregular or circular pale pattern on dark background (Fig. 8D, H); pectoral-fin rays 21–23 (mostly 22, rarely 21 and 23) (Table 6) .............. .................................................................................................................. Lm. setigerus (Vahl, 1797)

– Body color brown or pale khaki (Figs 10–11, 13); the floor of mouth not as above; pectoral-fin rays not less than 23 ................................................................................................................................. 3

3. Peritoneum light (Fig. 9); floor of mouth with anastomosing dark patterns in the middle (Figs 10C, 11D, H); pectoral-fin rays 24–25; pelvic-fin rays 7 .................. Lm. laticeps (Ogilby, 1910) stat. rev.

– Peritoneum black (at least in adults) (Figs 13B, 14B); floor of mouth with reticulate pattern (Figs 13D, H, 14D); pectoral-fin rays 23–24; pelvic-fin rays 6 or 7 ................................................................... 4

4. Body color pale khaki (Fig. 13A, C, E, G); esca pennant-like flap without cirri (Fig. 16C); pelvic-fin rays 6; DS4 8.4–17.3% of the SL; SNW 31.8–39.5%, ISP 40.6–45.4%, OPSOP 47.3–53.6% of the HL ............................................................................................................... Lm. nigriventris sp. nov.

– Body color brown (Fig. 14A–B); esca tassel-like or pennant-like flap with moderately long cirri (Fig. 16E–F); pelvic-fin rays 7; DS4 16.7–24.0% of the SL; SNW 41.9–55.7%, ISP 48.6–56.7%, OPSOP 55.5–65.7% of the HL .......................................................................... Lm. carusoi sp. nov.