Hydraena randriamihajai, Perkins, 2017

Perkins, Philip D., 2017, Hydraenidae of Madagascar (Insecta: Coleoptera), Zootaxa 4342 (1), pp. 1-264 : 150-151

Hydraena randriamihajai , new species

Figs. 136 (habitus), 138 (aedeagus), 294 (map)

Type Material. Holotype (male): Antsiranana, Diana : Montagne d'Ambre NP: marsh by the entrance of the park, S12.511389 E49.18315, GB nets, sieves and stepping: marsh with zebu, elev. 967 m, 15 xii 2012, J. Bergsten, R. Bukontaite, J.H. Randriamihaja & T. Ranarilalatiana ( MAD12-47 ) ( NHRS) . Paratypes (22): Same data as holotype (18); Antsiranana, Diana : Montagne d'Ambre NP: marsh by the entrance of the park, S12.511389 E49.18315, sieves: open marsh with zebu, elev. 967 m, 12° 31' S, 49° 11' E, 7 xii 2012, J. Bergsten, R. Bukontaite, J.H. Randriamihaja & T. Ranarilalatiana ( MAD12-54 ) (4 NHRS) .

Differential Diagnosis. Similar to H. fulgidicollis in size (ca. 1.65 vs. 1.68 mm), general habitus, and male metatibiae having a small brush of setae; differing therefrom in being less finely sparsely punctate and less shining dorsally, having very shallow pronotal foveae PF3, having longer plaques, and having a patch of long setae on the prosternum. The aedeagi of the two species differ markedly ( Figs. 134, 138). The aedeagus of H. randriamihajai clearly shows a relationship with H. elementaria , but differs 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.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.65/0.71; head width 0.38; pronotum 0.39/0.54, PA 0.42, PB 0.51; elytra 1.02/0.71.

Dorsum of head piceous; pronotum with dark brown macula or fascia, diffusely margined, borders light brown to testaceous; elytra brown; legs light brown; maxillary palpi palpi testaceous, distal ½ of last palpomere not darker.

Frons punctures ca. 1xef, slightly larger and denser near eyes than medially; interstices shining, 0.5–1xpd laterally, 3–5xpd medially. Clypeus very finely sparsely punctate, each puncture with moderately long decumbent seta. Mentum and postmentum sparsely finely punctulate, shining. Genae raised, smooth, 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 smaller and much sparser than those of frons, interstices shining, 3–6xpd, punctures larger and denser at anterior and posterior; PF1 absent; PF2 very shallow, almost absent; PF3 deep and large; PF4 absent.

Elytra weakly arcuate laterally; posterior declivity slightly before midlength; lateral explanate margins narrow; serial punctures on disc fine, slightly smaller than largest pronotal punctures. Intervals not raised, shining, ca. 3– 4xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming deep angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.1/2/1.3. P1 laminate; median carina sinuate in profile. P2 moderately narrow, l/w ca. 2/1, sides parallel, blunt apex raised slightly above mesoventral intercoxal process. Plaques very narrow lines, not carinate, converging very slightly anteriorly, margins indistinct, not raised, located at sides of very shallow median depression. AIS width at slightly arcuate posterior margin ca. 2x P2. Protibia slightly arcuate. Meso- and metatibia straight. Abdominal apex with apicomedian notch.

Etymology. Named in honor of Jacquelin Herisahala Randriamihaja, a talented Malagasy aquatic entomologist who has collected many new species of Hydraenidae .