Hydraena lilianae, 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 : 37-38

Hydraena lilianae , new species

Figs. 57 (habitus), 59 (aedeagus), 167 (spermatheca), 197 (map)

Type Material. Holotype (male): Argentina: Buenos Aires Province, Punta Lara, permanent pond located within gallery forest of Punta Lara; berlese of aquatic vegetation, primarily Salvinia rotundifolia , 34° 47' S, 58° 1' W, 24 xi 1989, Liliana A. Fernández. Deposited in the AMNS. Paratypes (34): Argentina: Buenos Aires Province, Same data as holotype (15 AMNS); same locality, 34° 47' S, 58° 1' W, 20 xii 1989, Liliana A. Fernandez (9 AMNS); same locality, 34° 47' S, 58° 1' W, 17 i 1990, Liliana A. Fernandez (2 AMNS); same locality, 34° 47' S, 58° 1' W, 16 ii 1990, Liliana A. Fernandez (2 AMNS); Punta Lara, 34° 47' S, 58° 1' W, 23 ii 1972, L. Herman (2 MCZ); Misiones, Foz Iguazu, 12 xi 1915, (no collector on label) (1 NMW); Paraguay: Dep. Guaira, Mainumby Ob. Tacuara- Bach, elev. 450 m, 13 ix 1995, Drechsel (1 NMW).

Differential Diagnosis. A moderately flat, rather elongate species with coarse and dense dorsal punctation ( Fig. 57 ). The pronotum is brown, without a macula, the sides are rather sharply arcuate, the foveae PF2 are very shallow, and the discal punctation is quite regular in density, with interstices about 1–2xpd. The pronotal scintilla is small. The metaventral plaques are as wide as P2, an unusual comparative size, and are located at the sides of the deep, inverted V-shaped median depression. The aedeagus ( Fig. 59) stands alone among South American Hydraena , but the basic plan could perhaps be compared to that of H. peckorum and H. atroscintilla ( Figs. 55, 58).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.64/0.64; head 0.25/0.36; pronotum 0.40/0.53, PA 0.39, PB 0.47; elytra 1.02/0.64. Dorsum of head dark brown; pronotum brown, disc slightly darker than surrounding areas; elytra dark brown; legs brown; maxillary palpi testaceous, tip not darker.

Frons punctures ca. 1xef, denser near eyes than medially; interstices laterally microreticulate, dull, ca. 0.5– 1xpd, medially weakly shining, ca. 0.5–2xpd. Clypeus microreticulate, dull, rather densely coarsely punctate medially. Mentum and postmentum sparsely finely punctulate, effacedly microreticulate, dull. Genae raised, shining, without posterior ridge.

Pronotum rather sharply arcuate laterally; anterior margin straight behind eyes, emarginate behind frons except slightly produced at small scintilla; punctures on disc much larger and deeper than those on frons, interstices weakly shining, 1–2xpd on disc, punctures denser at anterior and posterior, many separated by narrow walls; PF1 absent; PF2 very shallow, obsolete; PF3 moderately deep; PF4 absent.

Elytra weakly arcuate laterally; summit of posterior declivity slightly behind 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, shining, on basal 1/3 ca. 1–2xpd, as are interstices between punctures of a row, a few punctures subserial. Apices in dorsal aspect conjointly sharply rounded, in posterior aspect margins forming rather deep angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/2/6/3. P1 laminate; median carina sinuate in profile. P2 narrow, l/w ca. 3/1, sides parallel, apex blunt, raised slightly above mesoventral intercoxal process. Plaques as wide as P2, slightly arcuate, becoming obsolete and converging toward one another anteriorly, weakly raised, located at sides of deep inverted V-shaped 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 gradually slightly widened from base to ca. distal 3/4, then narrowed to apex. Meso- and metatibia simple. Male abdominal apex slightly asymmetrical; last tergite vertical, with small apicomedian notch. Female (microslide mount, n=1): last tergite sharply rounded, with apicomedian notch, ca. 21 short, moderately separated, hooked setae; gonocoxite not midlongitudinally divided, apical margin sharply rounded, low transverse ridge evident at border of microreticulation; spermatheca type C2.

Etymology. Named in honor of the collector, Liliana A. Fernández.

Distribution. Currently known from Argentina and Paraguay ( Fig. 197).

Notes. The following information on the type locality was kindly provided by Liliana A. Fernández: "The study site was a permanent water body, located in Punta Lara, Ensenada district, Buenos Aires Province, Argentina (34° 47‚ S, 58° 01‚ W). This area represents the southern end of a gallery forest and has a subtropical and tropical floristic composition. The water level in the selected pond is partially influenced by the tides of the Río de La Plata river, which is approximately 200 m from it. The aquatic vegetation in the pond studied included Salvinia rotundifolia Willd. , Hydrocotyle ranunculoides L., Spirodela intermedia W. Koch , and Lemna sp. The first two species were predominant during the study. The specimens of this species were sampled during the months of December, January, February and March."

The male specimens from Paraguay and "Foz Iguazu" (one specimen from each) differ slightly from the other specimens: the main-piece of the aedeagus is narrower and slightly more pointed at the tip. However, the complex basal part that surrounds the gonopore bearing process does not differ significantly from that of the holotype, and the other males from that locality. They are therefore being treated as aedeagal variants of H. lilianae .

Figures

FIGURE 57. Hydraena lilianae, holotype, dorsal and lateral habitus, venter, and abdominal apex.