Hydraena antsahabe, Perkins, 2017

Perkins, Philip D., 2017, Hydraenidae of Madagascar (Insecta: Coleoptera), Zootaxa 4342 (1), pp. 1-264 : 49-51

Hydraena antsahabe , new species

Figs. 38 (habitus), 39 (aedeagus), 245 (map)

Type Material. Holotype (male): Antsiranana, Forêt d' Antsahabe, 11.4 km 275° W Daraina , malaise trap, tropical dry forest, elev. 550 m, 13° 12' S, 49° 33' E, 12 xii 2003, B.L.Fisher ( BLF 10117 ) ( CAS). Paratypes: Same data as holotype (10 CAS).

Differential Diagnosis. Similar in habitus to H. acicula ; also similar in size, shape and separation of the metaventral plaques; slightly larger than H. acicula in body size (ca. 1.37 vs. 1.22 mm). Reliable determinations will require dissection of males; the aedeagi differ distinctively in shapes of both the main piece and the paramere ( Figs. 39, 40).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.37/0.56; head width 0.34; pronotum 0.31/0.45, PA 0.37, PB 0.36; elytra 0.81/0.56.

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

Head with clypeus finely sparsely punctate and microreticulate, dull; frons punctures much larger, interstices 0.5–2xpd, shining. Pronotum moderately densely moderately coarsely punctate, punctures in anterior and posterior 1/3 larger than those of head; interstices narrow walls to 0.5xpd; disc punctures finer and sparser, interstices ca. 1– 2xpd, shining. Mentum sparsely finely punctulate, effacedly microreticulate, weakly shining; postmentum effacedly microreticulate in shallow median depression, dull, lateral areas shining. Genae raised, shining, with weakly demarcated posterior ridge, interrupted in middle.

Pronotum arcuate laterally; anterior margin straight behind eyes, emarginate behind frons; PF1, PF2 and PF4 absent; PF3 shallow.

Elytra weakly arcuate laterally; summit of posterior declivity near midlength; lateral explanate margins moderately narrow; serial punctures slightly rectangular, each with minute granule at anterior margin, ca. 1xpd. Intervals not raised, weakly shining, ca. 1xpd. Apices in dorsal aspect conjointly rather sharply rounded, in posterior aspect margins not forming angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/2/2.5/1. P1 almost as wide as P2; median carina weakly sinuate in profile. P2 l/w ca. 2/1, sides slightly converging to blunt apex, apex at same level as anteromedian carina of metaventrite. Plaques very large, oval, parallel, narrowly separated, slightly raised, located at sides of narrow median depression. Metaventrite anteromedian carina slightly shorter than plaques, terminating just slightly anterior to anterior extreme of plaques; long longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity to ca. midlength of metaventrite. AIS width at slightly arcuate posterior margin ca. 2x P2. Protibia very weakly arcuate, almost straight, moderately wide. Mesotibia very weakly arcuate, stout, widest near midlength, medial margin distal 1/2 with 4–5 short stout spines, margin notched between spines. Metatibia straight. Metafemur lateral margin strongly arcuate, medial margin weakly bisinuate. Abdominal apex with small apicomedian notch.

Etymology. Named in reference to the type locality.