Key to the australiensis species group

1 Central ocellus placed at 42–50% SL, its spot covering 5–11 dorsal-fin rays and 0 or exceptionally 1 vertical scal rows on body below dorsal fin, anal-fin rays 73–81, vertebrae 52–57, and developed gill rakers 8–12.............................. 2

- Central ocellus placed at 51–54% SL, its spot covering 14–18 dorsal-fin rays and 5 to 7 vertical scale rows on body below dorsal fin, anal-fin rays 85–88, vertebrae 58–60, and developed gill rakers 14–15..................... N. superocellatus

2 Abdomen with or without black-speckled pigmentation, dorsal-fin rays 90–99, pseudobranchial filaments 8–11, and dorsal-fin rays covered by central-ocellus spot 9–13.................................................................. 3

- Abdomen without black-speckled pigmentation, dorsal-fin rays 88–92, pseudobranchial filaments 4–8, and dorsal-fin rays covered by central-ocellus spot 5–11......................................................... N. australiensis

3 Abdomen with black-speckled pigmentation, pectoral-fin rays 23–26, otolith ostium height 64–69% sulcus length, and 11–15 ostium length............................................................................. N. nigriventris

- Abdomen without black-speckled pigmentation, pectoral-fin rays 27–30, otolith ostium height 67–75% sulcus length and 14– 18 ostium length........................................................................ N. unimaculatus