Hydraena duohamata, Perkins, Philip D., 2011

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 : 16-17

Hydraena duohamata , new species

Figs. 6 (habitus), 11 (aedeagus), 148 (female abd.), 153 (spermatheca), 193 (map)

Type Material. Holotype (male): Venezuela : Territorio Federal Amazonas, Cerro de la Neblina , 1.5 km S Basecamp, in small ponds full of dead leaves; rainforest ridge, elev. 250 m, 0° 50' N, 66° 10' W, 15 ii 1985, P. J. Spangler, P. M. Spangler, R. A. Faitoute, W. E. Steiner. Deposited in the MIZA. Paratypes (25): Venezuela : Same data as holotype (21 USNM); Cerro de la Neblina , Basecamp, flight-intercept pan trap across small stream in forest, elev. 140 m, 0° 50' N, 66° 10' W, 24 ii 1985, P. J. Spangler, P. M. Spangler, R. A. Faitoute, W. E. Steiner (4 USNM).

Differential Diagnosis. Similar in dorsal habitus to H. paeminosa ( Figs. 3 , 6 ); differentiated therefrom by the smaller size (ca. 1.58 mm vs. 1.70 mm) and the serial elytral punctures near the suture. Reliable determinations will also include examination of the male genitalia ( Figs. 9, 11).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.58/0.69; head 0.23/0.38; pronotum 0.39/0.46, PA 0.38, PB 0.43; elytra 0.98/0.69. Dorsum of head with frons dark brown to piceous, clypeus brown; pronotum brown in front of and behind diffusely margined dark brown to piceous fascia, ratios of color bands, as measured in midline, ca. 8/12/6; elytra dark brown; legs brown; palpi testaceous, tip not darker.

Dorsum of head microreticulate, dull. Frons punctures small, ca. 1xef, interstices ca. 1–2xpd. Clypeus punctures obsolete. Mentum microreticulate, sparsely finely punctulate, dull; postmentum microreticulate and densely punctulate, dull. Genae posteriorly raised in low ridge, except midline lacking ridge.

Pronotum and elytra coarsely densely punctate, subscabrous, interstices microreticulate, more markely on pronotum than elytra. Pronotum with median 1/3 of anterior margin emarginate, and with narrow hyaline border; scintilla absent; PF1 absent; PF2 very shallow, almost imperceptible; PF3 and PF4 deep, confluent, separated from lateral margin by low irregular ridge. Elytra quite convex at summit of posterior declivity, slightly past midlength; lateral explanate margins narrow; punctures random except serial near suture over ca. median 1/2. Apices in dorsal aspect weakly separately rounded, in posterior aspect margins forming moderately deep angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. x/1.5/7/4. P1 slightly wider than laminate; median carina sinuate in profile. P2 narrow, tapering to sharp point, tip contiguous with low median carina of metaventrite. Plaques moderately wide, parallel, weakly raised, located at sides of shallow median depression. Metaventrite with median carina in anterior 1/2, also with very short point on each side, extended posteriorly from margin of each mesocoxal cavity. AIS width at straight posterior margin ca. equal plaque separation. All tibiae very slightly arcuate, slender. Male abdominal apex symmetrical; last tergite without apicomedian notch, posterior margin slightly upturned. Female (microslide mount, n=1): last tergite broadly rounded, without apicomedian notch, ca. 38 well hooked, sharply pointed, long, slender, moderately widely spaced setae in more or less double row; gonocoxite divided by weakly sclerotized midlongitudinal area, apical margin transverse, lacking transverse ridge; spermatheca disc type ( Fig. 153 ).

Etymology. Named in reference to the double row of hooked setae on the female last tergite.

Distribution. Currently known only from the type locality, and one site very nearby ( Fig. 193 ).

Figures

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

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

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.