Multispina Group

Two species comprise the Multispina Group: H. multispina and H. cordispina . These species are very unusual, having a spinose labrum and spinose elytra, and the elytra have only five series of punctures between the suture and the humeral umbo (Figs. 21–22). The coxae are rather widely separated by P1 and P2, and the plaques are unusually shaped. The genae are carinate laterally. The aedeagus of H. multispina is also very unusual (Fig. 41).

Only females are known for H. cordispina; it is possible that this species is parthenogenetic (20 specimens in type series, all female). The female gonocoxite in both species is "divided", having a weakly sclerotized midlongitudinal area (Fig. 150). The spermatheca (Figs. 158–159) is more similar to that of members of the Leechi and Marginicollis Groups than to that of the Paeminosa and Curvosa Groups. In H. cordispina the proximal end of the spermatheca, where the duct joins, is very constricted, and may be closed (Fig. 159).

H. cordispina was collected from leaf litter, and is probably humicolous. The microhabitat of H. multispina is not known, but characters of the female abdomen, specifically the patch of setae on each side of the fifth ventrite (Fig. 150), suggest less than fully aquatic habits (in fully aquatic Hydraena these setae are in a transverse band that forms the posterior border of the ventral respiratory bubble).