Decarthrocerus

Perkins, Philip D., 2009, Revisions of the genera Parhydraena Orchymont, Protozantaena Perkins, Decarthrocerus Orchymont, and Parhydraenopsis nomen novum, aquatic and humicolous beetles from Africa and Madagascar, and comparative morphology of the tribe Parhydraenini (Coleoptera: Hydraenidae), Zootaxa 2038, pp. 1-119 : 14

Key to species of Decarthrocerus

1 Pronotum wide compared to length of elytra (pronotal width/elytral length ratio ca. 0.71); aedeagus as illustrated ( Figs. 89, 91) ....................................................................................................................................... mahalicus n. sp.

- Elytra longer compared to width of pronotum (pronotal width/elytral length ratio ca. 0.60–0.67) ............................ 2

2 Elytra less strongly attenuate posteriorly, serial punctures more uniformly sized; aedeagus as illustrated ( Figs. 84, 86) ................................................................................................................................................. jeanneli Orchymont

- Elytra strongly attenuate posteriorly, serial punctures larger, some confluent on sloping sides of elytra ................... 3

3 Metaventral impression circular; body size smaller (length ca. 2.17 mm); maxillary palpi slightly longer (palpus length/head width ratio ca. 0.43); aedeagus as illustrated ( Figs. 85, 87) ......................................... bambusicus n. sp.

- Metaventral impression elongate oval; body size larger (length ca. 2.29 mm); maxillary palpi slightly shorter (palpus length/head width ratio ca. 0.34) ... aedeagus as illustrated ( Figs. 88, 90) ................................................. mbizi n. sp.