Hydraena paeminosa

Perkins, Philip D., 2011, New records and description of fifty-four new species of aquatic beetles in the genus Hydraena Kugelann from South America (Coleoptera: Hydraenidae), Zootaxa 3074, pp. 1-198 : 14

Paeminosa Group

( Perkins 1980: 210)

Six species are included in the Paeminosa Group: H. paeminosa ( Guyana, Suriname), H. boliviana ( Bolivia) , H. xingu ( Brazil) , H. duohamata ( Venezuela) , H. punctilata ( Brazil) , and H. neblina ( Venezuela) . Species in this group are moderately large to large (ca. 1.60–1.96 mm), coarsely punctate, and have a characteristic habitus ( Figs. 3–8 ). Ventrally, the gena has a posterior ridge, and the mesoventral intercoxal process (P2) tapers to a sharp point that is contiguous with a median carina of the metaventrite.

The male genitalia are usually quite tubular, and have a basic plan similarity; the parameres are characteristic, the left paramere is very small, and located toward the distal end of the main piece, whereas the right paramere has been lost, the paramere setae having their sockets on the main piece (e.g., Figs. 9–11).

Perkins (1980) established this group based on the dorsal and ventral morphology, and aedeagal structure of H. paeminosa , the only species known at that time. The validity of this group is strongly corroborated by the female genital structure. The female gonocoxite is "divided", having a weakly sclerotized midlongitudinal area, and is similarly shaped in all females of species in the group ( Fig. 148 ; females are not yet known for H. punctilata ). The spermatheca is circular, somewhat disc-shaped (e.g., Figs. 153, 154 ) in all species except H. paeminosa , in which the spermatheca has additional lateral lobes ( Fig. 155). The spermatheca differs markedly from that of all other American Hydraena , except members of the Curvosa Group. Externally and male genitalically the two groups are quite different.

Species in this group have been collected primarily from pool habitats. The following habitat information is present in the locality data: small pool on sand bar, edge of sunlit river ( H. boliviana ); waterholes from drying up forest stream with gravelly bottom; detrital pools forest; forest creek; pooled detrital creek ( H. paeminosa ); stream, pond ( H. xingu ); in small ponds full of dead leaves, rainforest ridge; flight-intercept pan trap across small stream in forest ( H. duohamata ); along small whitewater stream; pools of dead leaves & sticks; flight-intercept pan trap along open weedy river bank; flight-intercept pan trap in rainforest; flight-intercept pan trap across small stream in forest ( H. neblina ).

Five of the species are rather closely related, based on the male genitalia and general habitus. H. neblina is quite divergent in both the aedeagus and habitus.

Based on the known distributions, this group appears to be restricted to a circum-Amazonian pattern ( Fig. 193 ). The Amazon basin appears to be a "black hole" for Hydraena , but this could simply reflect a lack of specialized collecting in that huge area.

Figures

FIGURE 3. Hydraena paeminosa, holotype, dorsal and lateral habitus, and venter.

FIGURE 4. Hydraena boliviana, holotype, dorsal and lateral habitus, and venter.

FIGURE 5. Hydraena xingu, holotype, dorsal and lateral habitus, and venter.

FIGURE 6. Hydraena duohamata, holotype, dorsal and lateral habitus, and venter.

FIGURE 7. Hydraena punctilata, holotype, dorsal and lateral habitus, and venter.

FIGURE 8. Hydraena neblina, holotype, dorsal and lateral habitus, and venter.

FIGURES 148 – 150. Female terminal abdominal segments of Hydraena species.

FIGURES 151 – 154. Spermathecae of Hydraena species.

FIGURES 193 – 194. 193. Geographical distributions of species in the Paeminosa Group. 194. Geographical distributions of species in the Curvosa and Multispina Groups.