Hydraena steineri, 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 : 57

Hydraena steineri , new species

Figs. 118 (habitus), 120 (aedeagus), 202 (map)

Type Material. Holotype (male): Bolivia: Beni, 40 km E. San Borja, Estacion Biologica Beni, Palm Camp at Rio Curiraba, ex. small pool on sand bar, edge of sunlit river, 14 ix 1987, W. E. Steiner. Deposited in the USNM.

Differential Diagnosis. A coarsely, densely punctate species with an indistinct piceous pronotal fascia that is surrounded by dark brown areas. The elytral punctures are quite closely spaced, separated from one another by only about 1xpd. Similar to H. concepcionica in coarse punctation, general body outline, and plaques ( Figs. 118– 119 ); differentiated therefrom by the darker color with much less distinctive pronotal macula/fascia, the more elongate elytra, and the slightly larger size (ca. 1.52 vs. 1.49 mm). The aedeagi of the two species, while showing some general plan similarities, differ markedly in many details ( Figs. 120–121).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.52/0.63; head 0.25/0.36; pronotum 0.36/0.50, PA 0.40, PB 0.46; elytra 0.96/0.63. Dorsum of head piceous; pronotum dark brown in front of and behind very diffusely margined piceous fascia, ratios of color bands, as measured in midline, ca. 5/12/6; elytra dark brown; legs brown to dark brown; maxillary palpi light brown, tip not darker.

Frons moderately coarsely punctate, punctures ca. 1.5xef, slightly denser near eyes than medially; interstices shining, ca. 0.5xpd laterally, 1–1.5xpd medially. Clypeus microreticulate laterally, finely sparsely punctulate medially. Mentum microreticulate, very sparsely very finely punctulate, very weakly shining; postmentum very finely densely micropunctulate in median area, surrounding areas smooth, shining. Genae raised, shining, without posterior ridge.

Pronotum weakly arcuate laterally; anterior margin straight behind eyes, emarginate behind frons, scintilla absent; coarsely punctate, punctures on disc much larger and deeper than those of frons, interstices shining, 0.5– 1xpd on disc, punctures larger and denser at anterior and posterior, interstices narrow walls to 1xpd; PF1 absent; PF2 very shallow or absent; PF3 deep; PF4 absent.

Elytra weakly arcuate laterally; summit of posterior declivity at ca. midlength; lateral explanate margins moderately wide; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, punctures becoming slightly finer and more widely spaced toward posterior. Intervals not raised, shining, on basal 1/3 ca. 1xpd, as are interstices between punctures of a row, a few punctures subserial. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/1.5/6/4. P1 laminate; median carina sinuate in profile. P2 l/w ca. 2/1, sides slightly converging toward blunt apex, apex raised slightly above mesoventral intercoxal process. Plaques narrow, widest posteriorly, slightly arcuate, slightly converging toward one another anteriorly, weakly, if at all, raised, located at sides of median depression. Metaventrite with very short longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity. AIS width at straight posterior margin ca. 2x P2. Protibia straight, rather slender, widest at ca. distal 1/3 Meso- and metatibia slender, straight. Abdominal apex symmetrical; last tergite with apicomedian notch. Females not yet known.

Etymology. Named in honor of the collector, long-time friend and colleague, Warren Steiner.

Distribution. Currently known only from the type locality ( Fig. 202).

Figures

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

FIGURE 119. Hydraena concepcionica, holotype, dorsal and lateral habitus, and venter.