Hydraena nanoscintilla, 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 : 30

Hydraena nanoscintilla , new species

Figs. 39 (habitus), 43 (aedeagus), 195 (map)

Type Material. Holotype (male): Brazil: Matto Grosso, Cuiabá, 66 km E Serra, MT, 19 iv 1976, S. A. Vanin. Deposited in the MSP.

Differential Diagnosis. A small species with rather dense but not especially coarse dorsal punctation, and having the pronotum and elytra the same dark brown color ( Fig. 39 ). The pronotum has a small scintilla, and rather deep foveae PF2; on the disc the interstices are small, ca. 0.5–1xpd. The metaventral plaques are very small, almost absent. The dorsal habitus can perhaps in some vague way be compared to that of H. scintillamima ( Fig. 35 ), but the two species differ markedly in size, microreticulation, plaques and other characters. The male genitalia of the two species markedly differ ( Figs. 37, 43).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.19/0.50; head 0.17/0.31; pronotum 0.29/0.38, PA 0.32, PB 0.37; elytra 0.73/0.50. Dorsum of head dark brown to piceous; pronotum and elytra dark brown; legs brown; maxillary palpi testaceous, tip slightly darker.

Frons punctures ca. 1xef, interstices microreticulate, dull, ca. 0.5–2xpd. Clypeus microreticulate, dull, finely rather densely punctulate medially. Mentum and postmentum very sparsely very finely punctulate, microreticulate, dull. Genae raised, shining, without posterior ridge.

Pronotum weakly arcuate laterally; anterior margin straight behind eyes, emarginate behind frons except very slightly produced at small scintilla; punctures on disc much larger and deeper than those on frons, interstices weakly shining, 0.5–1xpd on disc, punctures slightly denser at anterior and posterior; PF1 shallow; PF2 moderately deep; PF3 very deep; PF4 shallow; PF3 and PF4 shallowly confluent.

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

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1.5/0.5/2.5/3. P1 laminate; median carina sinuate in profile. P2 l/w ca. 2.5/1, sides parallel, apex blunt, raised slightly above mesoventral intercoxal process. Plaques very small, almost absent, not raised, located at sides of median depression. Metaventrite with sharp point on each side, extended posteriorly from margin of each mesocoxal cavity. AIS width at straight posterior margin ca. 2x P2. Protibia very slightly, if at all, arcuate, widest at ca. midlength, medial margin in distal 1/2 with row of short setae. Meso- and metatibia straight, mesotibia slightly wider than metatibia. Abdominal apex very slightly asymmetrical; last tergite with small apicomedian notch.

Etymology. Named in reference to the small size, of body, aedeagus, and scintilla.

Distribution. Currently known only from the type locality ( Fig. 195 ).

Figures

FIGURE 35. Hydraena scintillamima, holotype, dorsal and lateral habitus, and venter.

FIGURE 39. Hydraena nanoscintilla, holotype, dorsal and lateral habitus, and venter.

FIGURE 195. Geographical distributions of Hydraena species in the Costiniceps Complex.