Hydraena (Monomadraena) pentarubra, Perkins, 2017

Perkins, Philip D., 2017, Hydraenidae of Madagascar (Insecta: Coleoptera), Zootaxa 4342 (1), pp. 1-264 : 95

Hydraena (Monomadraena) pentarubra species group

Seven species are included in this group: H. pentarubra , H. epipleurata , H. marojejy , H. gereckei , H. manjakatompo , H. ravoandrina , and H. ambohitantely .

Members of this group are broad species, moderately large to large (ca. 1.48–2.21 mm), usually reddish brown, without a pronotal macula. The body width/length ratio varies from 0.54 ( H. epipleurata , the broadest) to 0.44 ( H. gereckei ). The genae have a posterior ridge. The prosternal intercoxal process (P1) is as wide as P2, or only very slightly narrower. Males do not have modified metatibiae, but the medial margin of the mesotibia has a row of short sharp spines, with the margin notched between the spines (spine number varying, some species with 3–4, others 4– 5). The metaventrite has an anteromedian carina, but it does not join with the plaques. The plaques vary in size and position according to the species, but not markedly so.

The aedeagi have a similar general plan: the distal part of the main piece (ventral view) is slightly produced on the right side, the distal piece is not greatly enlarged, and the gonopore is located at the end of a flagellum, which is usually not greatly elongate, and is not coiled.