Key to species of Drilonereis recorded from the Australian coast*:

1 MxI basally smooth.................................................. D. quadrioculata Hartmann-Schröder, 1979

– MxI basally dentate, teeth conspicuous or inconspicuous (Figs 7 F, 8K)........................................... 2

2. (1) Mandible absent............................................................... D. cf. logani Crossland, 1924

– Mandible present, reduced.............................................................................. 3

3. (2) Single plate mandible similar to an upside down heart of spade......................... D. australiensis Augener, 1922

– Two plate subtriangular mandible, round anterior end, plates diverging posteriorly (Fig. 8 F)............ D. orensanzi n. sp.