Hydraena tridigita, 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 : 31-32

Hydraena tridigita , new species

Figs. 45 (habitus), 47 (aedeagus), 197 (map)

Type Material. Holotype (male): Peru : Cajamarca, Celendin area, 6° 52' S, 78° 8' W, 25 v – 11 vi 1936, F. Woytkowski. Deposited in the SEMC. Paratypes: Same data as holotype (14 SEMC).

Differential Diagnosis. A darkly colored species with a very indistinct pronotal macula. The elytra are not as convex as most species, and the elytral apices are rather sharply, separately rounded. The plaques are ovals, only about 1/3 as wide as the mesoventral intercoxal process. Similar in dorsal habitus to H. scintillamima ( Figs. 35 , 45 ); differing therefrom in the smaller size (ca. 1.54 mm vs. 1.71 mm), the less densely punctate pronotal disc, the more gradually declivous elytra, and the smaller metaventral plaques. The pronotal scintilla is very small, and the head does not have a stridulatory file. The aedeagi of the two species markedly differ ( Figs. 37, 47).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.54/0.67; head 0.25/0.37; pronotum 0.36/0.48, PA 0.38, PB 0.45; elytra 0.96/0.67. Dorsum of head dark brown to piceous; pronotum brown to dark brown except piceous on disc; elytra dark brown; legs brown; maxillary palpi testaceous, tip not darker.

Frons punctures ca. 1xef, slightly larger and denser near eyes than medially; interstices laterally microreticulate, dull, ca. 0.5–1xpd, medially shining, ca. 1–4xpd. Clypeus microreticulate, dull laterally, very finely sparsely punctulate and shining medially. Mentum microreticulate and very sparsely very finely punctulate, dull; postmentum very finely densely micropunctulate and dull in median concavity, surrounding areas smooth, shining. Genae raised, shining, without posterior ridge.

Pronotum weakly arcuate laterally; anterior margin straight behind eyes, emarginate behind frons except slightly produced at distinct but small scintilla; punctures on disc slightly larger and deeper than largest punctures on frons, interstices shining, 1–5xpd on disc, punctures larger and denser at anterior and posterior, sparser above and to sides of PF2; PF1 shallow; PF2 moderately deep; PF3 deep; PF4 shallow; PF3 and PF4 shallowly confluent.

Elytra weakly arcuate laterally; summit of posterior declivity at about midlength; lateral explanate margins moderately wide; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, punctures becoming slightly smaller and more widely spaced toward posterior. Intervals not raised, shining, on basal 1/3 ca. 1–2xpd, as are interstices between punctures of a row, a few punctures subserial. Apices in dorsal aspect rather sharply, weakly separately rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 3/1/3/4. P1 laminate; median carina sinuate in profile. P2 l/ w ca. 5/3, sides straight, apex blunt, raised slightly above mesoventral intercoxal process. Plaques very small ovals, located at posterior sides of median depression. Metaventrite with very small point on each side, extended posteriorly from margin of each mesocoxal cavity. AIS width at straight posterior margin very slightly greater than 1x P2. Protibia slightly arcuate, medial margin very slightly widened over distal 1/2. Meso- and metatibia slender, straight. Male abdominal apex asymmetrical; last tergite with marginal notch, offset to left side. Female (microslide mount, n=1): last tergite sharply rounded, with very small apicomedian notch, ca. 13 slender, widely separated hooked setae, apicomedian gap wide; gonocoxite not midlongitudinally divided, apical margin broadly rounded, low transverse ridge evident at border of microreticulation; spermatheca type C2.

Etymology. Named in reference to the three processes of the aedeagus.

Distribution. Currently known only from the type locality ( Fig. 197).

Figures

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

FIGURE 45. Hydraena tridigita, holotype, dorsal and lateral habitus, and venter.