Hydraena stellula, 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 : 50-51

Hydraena stellula , new species

Figs. 97 (habitus), 100 (aedeagus), 200 (map)

Type Material. Holotype (male): Ecuador: Pichincha, Santo Domingo (79.6 km E), elev. 2545 m, 0° 26' S, 78° 42' W, 30 vii 1976, J. Cohen. Deposited in the USNM.

Differential Diagnosis. A relatively sparsely punctate species, with interstices on the frons and pronotal disc ca. 2–8xpd, and strongly shining ( Fig. 97 ). The pronotum has a relatively large fascia, with color band ratios ca. 5/ 13/5. Although the frons has a slight indentation in the middle of the posterior margin, there is no obvious scintilla on the pronotum behind this indentation. The aedeagus shows some similarity to that of H. delvasi ( Figs. 99–100 ), but the two species differ markedly in many details.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.30/0.58; head 0.24/0.34; pronotum 0.33/0.45, PA 0.36, PB 0.39; elytra 0.80/0.58. Dorsum of head piceous; pronotum testaceous in front of and behind piceous fascia, ratios of color bands, as measured in midline, ca. 5/13/5, fascia smaller and lighter in color laterally; elytra dark brown; legs brown; maxillary palpi testaceous, tip not darker.

Frons punctures ca. 0.5–1xef, larger and denser near eyes than medially; interstices laterally shining ca. 1xpd, medially strongly shining, ca. 2–8xpd, nearly impunctate in midline. Clypeus microreticulate laterally, very finely sparsely punctulate and strongly shining medially. Mentum very sparsely very finely punctulate, shining; postmentum very finely densely micropunctulate, weakly shining. Genae raised, shining, without posterior ridge.

Pronotum moderately arcuate laterally; anterior margin straight behind eyes, scintilla absent; punctures on disc ca. 1xpd of largest punctures on frons, interstices strongly shining, 2–8xpd on disc, punctures larger and denser at anterior and posterior; PF1, PF2, and PF4 absent; PF3 moderately deep.

Elytra moderately arcuate laterally; summit of posterior declivity slightly before 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, rather sharply rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/1/5/4. P1 laminate; median carina sinuate in profile. P2 l/ w ca. 2/1, sides parallel, apex blunt, raised slightly above mesoventral intercoxal process. Plaques narrow, very slightly converging toward one another anteriorly, weakly raised, located at sides of deep 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. Legs simple. Abdominal apex symmetrical. Females not yet known.

Etymology. Named in reference to the unusual, small, multi-spined star-shaped structure on the dorsal surface of the aedeagus.

Distribution. Currently known only from the type locality ( Fig. 200).

Figures

FIGURE 97. Hydraena stellula, holotype, dorsal and lateral habitus, and venter.

FIGURES 99 – 101. Aedeagi of holotypes, and aedeagus of H. delvasi non-type from Venezuela.