Hydraena clavulata, Perkins, 2017

Perkins, Philip D., 2017, Hydraenidae of Madagascar (Insecta: Coleoptera), Zootaxa 4342 (1), pp. 1-264 : 137-138

Hydraena clavulata , new species

Figs. 123 (habitus), 125 (aedeagus), 287 (map)

Type Material. Holotype (male): Fianarantsoa, Ranomafana, Talatakely, R. Fopognina, elev. 967 m, 21° 16' S, 47° 25' E, 1 xi–20 xii 2004, M. Balke & M. Monaghan (MD 027) ( ZSMC). Paratypes: Same data as holotype (4 ZSMC).

Differential Diagnosis. Somewhat similar to H. orchisa in size (ca. 1.48 vs. 1.52 mm), color, arcuate lateral margins of pronotum and elytra, and dorsal sculpture; differing therefrom in having proportionally smaller elytra that are acuminate apically, presence of metaventral plaques that are widely separated, and having non-arcuate metatibiae. The aedeagi of the two species are roughly similar in size and placement of the parameres, and shape of the basal orifice; however, the shapes of the distal pieces differ markedly ( Figs. 125, 126).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.48/0.66; head width 0.36; pronotum 0.38/0.53, PA 0.40, PB 0.48; elytra 0.88/0.66.

Dorsum of head with frons and clypeus dark brown to piceous; pronotum with dark brown macula, diffusely margined, borders light brown to testaceous, wide; elytra brown; legs light brown; maxillary palpi testaceous, distal 0.5 of last palpomere not darker.

Frons punctures ca. 1–1.5xef, larger and denser near eyes than medially; interstices shining, 0.5–1xpd laterally, 1–3xpd medially. Clypeus very finely sparsely punctate, interstices shining medially, microreticulate laterally. Mentum very sparsely very finely punctulate, strongly shining. Postmentum finely punctulate and effacedly microreticulate, no median depression. Genae raised, shining, without posterior ridge.

Pronotum with lateral margins rather markedly arcuate, posterior angles obtuse; anterior margin straight behind eyes, emarginate in middle; punctures on disc distinctly larger and deeper than those of frons, interstices strongly shining, 1–2xpd, punctures larger and denser at anterior and posterior; PF1 absent; PF2 very shallow; PF3 deep; PF4 absent or very shallow.

Elytra arcuate laterally, subacuminate posteriorly; summit of posterior declivity slightly before midlength; lateral explanate margins narrow; serial punctures on disc slightly smaller than largest pronotal punctures. Intervals not raised, strongly shining, ca. 2–3xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly sharply 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 parallel or very slightly converging toward blunt apex, apex raised slightly above metaventral intercoxal process. Plaques moderately narrow, widely separated posteriorly, converging but not confluent anteriorly, very weakly if at all raised, separated posteriorly by ca. 4x plaque width, located at sides of median depression. Metaventrite with very short point 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, other tibiae straight, slender. Abdominal apex with large, slightly off-center asymmetrical notch.

Etymology. Named in reference to the club-shaped distal process of the aedeagus.