Hydraena (incertae sedis): Monikae Group

Four species are placed in this group; members distinctively differ from other southern African Hydraena in some basic morphological characters of the venter: 1) the genae are raised and have a posterior ridge; 2) the mesoventral intercoxal process has the sides tapering to a narrow apex; 3) the abdominal intercoxal sternite is subtriangular and deeply concave; and 4) females have the gonocoxite midlongitudinally divided. In addition, the male genitalia have a distinctive form, tubular and markedly arcuate, with a terminal flagellum and with short parameres. These species appear not to be members of Hydraena (Hydraenopsis), and perhaps represent an undescribed subgenus that may be related to some South American groups, namely the Paeminosa, Curvosa, and Multispina Groups, which have some similar characters (Perkins 2011).