Tritonus Mulsant

Short, Andrew Edward Z., 2008, Revision of the Afrotropical genus Tritonus Mulsant (Coleoptera: Hydrophilidae), Zootaxa 1855, pp. 41-55 : 44-45

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)

Figures

FIGURES 11 – 12. Abdomen of Tritonus spp.; 11) T. riambavy; 12) T. crenulatus. Scale bars = 1 mm.