Hydraena elementaria, Perkins, 2017

Perkins, Philip D., 2017, Hydraenidae of Madagascar (Insecta: Coleoptera), Zootaxa 4342 (1), pp. 1-264 : 151-154

Hydraena elementaria , new species

Figs. 139 (habitus), 25 (aedeagus), 302 (map)

Type Material. Holotype (male): Antananarivo, Tamatave, Coastal lagoon, 15 km E of Brickaville , CL 2260, 18° 49' S, 49° 4' E, 5 xi 1986, J. T. & D. A. Polhemus (1 USNM) . Paratypes (12): Antananarivo, nr. Anjiro , ex. forest litter, 18° 53' S, 47° 58' E, 21 x 1970, P. Hammond (1 BMNH) ; Toliara, F. Dauphin (Tulear), Mandena (QMM area), ditch at right border of Riv. Amendano , 23.4°C, 0.158 mS/cm, elev. 10 m, 25° 2' S, 46° 59' E, 13 ix 2001, Gerecke & Goldschmidt (MD 77) (2 NMW) ; F. Dauphin (Tulear), Mandena (QMM area), pond at right border of Riv. Amendano , elev. 10 m, 25° 2' S, 46° 59' E, 13 ix 2001, Gerecke & Goldschmidt (MD 76) (5 NMW) ; F. Dauphin (Tulear), Mandena (QMM area), swamp with Sphagnum at left border of Riv. Amendano (1 km downstream road bridge), elev. 10 m, 17° 35' S, 45° 47' E, 13 ix 2001, Gerecke & Goldschmidt (MD 79) (4 NMW) .

Differential Diagnosis. The aedeagus of H. elementaria clearly indicates a relationship with H. randriamihajai , but the two differ in details of the main piece, the paramere, and the distal piece ( Figs. 25, 138). Externally, the two species differ in habitus, color, dorsal punctation and, in males, form of the metatibiae (nonmodified in H. elementaria ). Also refer to the diagnosis of H. ranarilalatiana . In all three species the only pronotal fovea present is PF3.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.55/0.66; head width 0.37; pronotum 0.39/0.51, PA 0.41, PB 0.46; elytra 0.92/0.66.

Dorsum of head with frons and clypeus dark brown to piceous; pronotum with dark brown macula, diffusely margined, borders lighter brown; elytra brown; legs light brown; maxillary palpi testaceous, distal 0.5 of last palpomere slightly darker.

Frons punctures ca. 1–1.5xef, larger and denser near eyes than medially; interstices shining, 0.5–1xpd laterally, 2–5xpd medially. Clypeus very finely sparsely punctate, interstices shining medially, microreticulate laterally. Mentum very sparsely very finely punctulate, shining. Postmentum punctulate in median depression. Genae raised, shining, without posterior ridge.

Pronotum with lateral margins slightly sinuate, posterior angles nearly right angles; anterior margin straight behind eyes, emarginate in middle; punctures on disc slightly larger and deeper than those of frons, interstices strongly shining, 1–6xpd, punctures larger and denser at anterior and posterior; PF1 and PF2 absent; PF3 moderately deep; PF4 absent.

Elytra weakly arcuate laterally; posterior declivity slightly before midlength; lateral explanate margins narrow; serial punctures on disc ca. 1xpd largest pronotal punctures. Intervals not raised, strongly shining, ca. 1xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming moderately deep angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.5/2/1.5. P1 laminate; median carina sinuate in profile. P2 l/w ca. 2/1, sides slightly converging toward blunt apex, apex raised slightly above metaventral intercoxal process. Plaques moderately narrow, converging very slightly anteriorly, very 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 slightly arcuate posterior margin ca. 1.5x P2. Protibia very slightly arcuate, slightly widened in distal 0.5, other tibiae straight, slender. Abdominal apex with apicomedian asymmetrical notch.

Etymology. Named in reference to the unmodified male metatibiae.