Hydraena (Monomadraena) acicula, Perkins, 2017

Perkins, Philip D., 2017, Hydraenidae of Madagascar (Insecta: Coleoptera), Zootaxa 4342 (1), pp. 1-264 : 48

Hydraena (Monomadraena) acicula species group

Six species are included in this group: H. acicula , H. antsahabe ,. H. lubrica , H. casacolumna , H. goldschmidti , and H. amplexa .

Members of this group are of small to moderate size (ca. 1.22–1.93 mm), brown to dark brown, and have moderately coarse and moderately dense dorsal punctation. The pronotum lacks PF1 and PF2 and may or may not have a weakly delimited macula. The metaventrite has a strong anteromedian carina that is not contiguous with the plaques. The plaques are unusually large in several of the species. The posterior ridge of the mentum is weakly demarcated. Mesotibiae of males have a row of short stout spines on the medial margin, and the margin is notched between the spines; number of spines vary (2–3, 3–4, and 4–5). Male metatibiae are unmodified.

The aedeagi have a similar general plan: the main piece is slender, the single paramere (right side) is large, originates near the basal orifice, and extends to or slightly beyond the main piece. The gonopore is located at the end of a short to moderately long flagellum that is not coiled (e.g., Figs. 39–40).