Key to the species of Tritonus Mulsant 1 Size smaller, less than 8.0 mm. Elytra not broadly flattened laterally; at most very slightly explanate. Ground punctation variable.........................................................................................................................2 - Size larger, greater than 8.0 mm. Elytra broadly flattened and explanate along margins. Ground punctation very fine to appearing absent ....................................................................................... T. complanatus sp.n. 2 Ground punctation on elytra irregular in size, including very coarse punctures that are of similar size to the pronotal and elytral systematic punctures. Prosternum with distinct median carina.............................3 - Ground punctation on elytra fine to very fine, easily distinguished from the larger systematic (setiferous) punctures. Prosternum without a distinct median carina; at most slightly elevated anteriorly...................4 3 Carina of the mesoventrite raised anteriorly such that the carinal surface is not in a uniform plane............ ........................................................................................................................................... T. riambavy sp.n. - Carina of the mesoventrite low and even; not raised anteriorly ........................................... T. steineri sp.n. 4 Glabrous region on abdominal ventrite 1 narrow, extending distinctly less than half the length of the ventrite. Lateral margins of elytra parallel sided. Posterior margins of abdominal ventrites 2 and 3 never strongly crenulate (e.g. Fig. 11)...................................................................................................................6 - Glabrous region on abdominal ventrite 1 broad and distinct, extending towards the thorax at least half the length of the ventrite. Lateral margins of elytra slightly rounded, giving the habitus a more evenly ovoid appearance. Posterior margins of abdominal ventrites 2 and 3 sometimes strongly crenulate (e.g. Fig. 12).....................................................................................................................................................................5 5 Anterior margins of abdominal ventrites 2 and 3 indistinctly crenulate. Size smaller (6.6–7.1 mm)........... ................................................................................................................................................. T. riana sp.n. - Anterior margins of abdominal ventrites 2 and 3 coarsely crenulate (Fig. 12). Size larger (7.1–7.6 mm) ... ......................................................................................................................................... T. crenulatus sp.n. 6 Lateral angles of clypeus evenly rounded, not quadrate. Carina of the mesoventrite forming a high, linear, glabrous ridge. Metafemora with sparse, inconspicuous microreticulation. Madagascar ............................. .............................................................................................................................. T. madagascarensis sp.n. - Lateral angles of clypeus smoothly quadrate. Carina of the mesoventrite forming a low, glabrous ridge. Metafemora with very distinct microreticulation covering the entire surface. Mauritius ............................. ................................................................................................................................... T. cribratus (Mulsant)

Published as part of Short, Andrew Edward Z., 2008, Revision of the Afrotropical genus Tritonus Mulsant (Coleoptera: Hydrophilidae), pp. 41-55 in Zootaxa 1855 on pages 44-45, DOI: 10.5281/zenodo.183532