Hydraena

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 : 13

Key to Groups of New World Hydraena

1 Posterior ridge of genae present, at least laterally (e.g., Figs. 2 c, 2d); abdominal intercoxal ventrite various; scintilla absent ... 2

1' Posterior ridge of genae absent (e.g., Figs. 44 , 126 ) or nearly imperceptible; abdominal intercoxal ventrite flat, with posterior margin straight or weakly arcuate; scintilla ( Fig. 2 b) present or absent........................................... 5

2 Elytra and labrum with spines ( Figs. 21 , 22 ); elytron with five rows of punctures between suture and humerous; two species from South America...................................................................... Multispina Group

2' Elytra and labrum without spines; elytron with more than five rows, or with many random punctures................... 3

3 Abdominal intercoxal ventrite concave, with posterior margin markedly arcuate; elytral punctures serial or, in few adults, with few random punctures on disc; spermatheca C-shaped; female gonocoxite not divided; Canada and the United States............................................................................................... Circulata Group

3' Abdominal intercoxal ventrite flat, with posterior margin straight or weakly arcuate; elytral punctures random, at least near base; spermatheca disc-shaped (e.g. Figs. 151–154 ) or (in H. paeminosa ) trilobed ( Fig. 155); female gonocoxite divided ( Figs. 148–150 ); South America.............................................................................. 4

4. Elytral punctures coarse and very random (e.g., Fig. 3 ); pronotum more elongate; mesoventral intercoxal process (P2) very narrow, tapering to sharp point that is contiguous with midlongitudinal carina of metaventrite (e.g., Fig. 2 c).................................................................................................... Paeminosa Group

4'. Elytral punctures serial except in small area at base ( Figs. 16–18 ); pronotum less elongate, sides more sinuate; mesoventral intercoxal process (P2) wide, apex blunt (e.g., Fig. 2 d)............................................ Curvosa Group

5 Pronotal scintilla ( Fig. 2 b) present or absent; pronotum always with posteromedial foveae (PF2; Fig. 2 a)...... Leechi Group

5' Pronotum never with scintilla; pronotum without posteromedial foveae, or if present very shallow and pronotum coarsely punctate (e.g., Figs. 110 , 118 )........................................................... Marginicollis Group

Figures

FIGURE 2. Pronotal sculpture and measurements, and metavental structures and measurements.

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

FIGURE 16. Hydraena curvosa, holotype, dorsal and lateral habitus, and venter.

FIGURE 17. Hydraena takutu, holotype, dorsal and lateral habitus, and venter.

FIGURE 18. Hydraena hintoni, holotype, dorsal and lateral habitus, and venter.

FIGURE 21. Hydraena multispina, holotype, dorsal and lateral habitus, and venter.

FIGURE 22. Hydraena cordispina, holotype female, dorsal and lateral habitus, and venter.

FIGURE 44. Hydraena scintillabella, holotype, dorsal and lateral habitus, and venter.

FIGURE 110. Hydraena loripes, holotype, dorsal and lateral habitus, and venter.

FIGURE 118. Hydraena steineri, holotype, dorsal and lateral habitus, and venter.

FIGURE 126. Hydraena ampla, holotype, dorsal and lateral habitus, and venter.

FIGURES 151 – 154. Spermathecae of Hydraena species.

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