Hydraena amplipunctata Perkins 2017, new species

Hydraena amplipunctata, new species

Figs. 62 (habitus), 64 (aedeagus), 257 (map)

Type Material. Holotype (male): Fianarantsoa, 7 km W Ranomafana, from seepage over sunlit rock at river, montane rainforest, elev. 900 m, 21° 16' S, 47° 25' E, 6 ix 1993, W. E. Steiner & M. Stebbins (USNM). Paratypes (13): Same data as holotype (5 USNM); Antananarivo, Tampoketsan Ankazobe (Antananarivo), R. Andranofeno Sud at bridge R.N.4, km 130, elev. 1450 m, 18° 20' S, 47° 10' E, 29 xi 2001, Gerecke & Goldschmidt (MD 170) (5 NMW); Fianarantsoa, Ranomena, river NW from the 1.07 km-railway-tunnel, pool, elev. 950 m, 23° 25' S, 47° 16' E, 19 viii 2001, Gerecke & Goldschmidt (MD 34c) (3 NMW).

Differential Diagnosis. Differentiated from other members of the H. tibiodentipes group by the very coarse and very dense dorsal punctation; in addition, differentiated by the very wide elytra, which are widest at about the posterior 3/4, and have the apices conjointly broadly rounded. None of the other species in the group have a similar aedeagus

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.90/0.80; head width 0.46; pronotum 0.43/0.59, PA 0.44, PB 0.44; elytra 1.16/0.80.

Dorsum dark reddish brown, head darker than pronotum and elytra; legs brown; maxillary palpi light brown, distal ½ of last palpomere not darker.

Dorsum, except clypeus, very coarsely densely deeply punctate. Mentum moderately finely punctate, shining; postmentum more densely punctate. Genae raised, shining, with posterior ridge, interrupted in midline.

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

Elytra weakly arcuate laterally, except strongly arcuate in distal 1/3; summit of steep posterior declivity at ca. midlength; lateral explanate margins very wide, especially in distal 1/3; serial punctures round, very large and deep, separated by narrow walls, making intervals zig-zag shape. Apices in dorsal aspect broadly conjointly rounded, in posterior aspect margins not forming angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.3/2.5/1.5. P1 as wide as P2; median carina very weakly sinuate in profile. P2 l/w ca. 3/1, sides parallel, apex blunt and on same level as anteromedian carina of metaventrite. Plaques carinate, parallel or slightly converging anteriorly, separated by ca. 6x plaque width, located at sides of median depression. Metaventrite anteromedian carina ca. same length as plaques, attaining anterior level of plaques; long longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity, area between ridge and anteromedian carina deeply concave. AIS width at arcuate posterior margin ca. 1.5x P2. Legs relatively long. Protibia straight, slender. Mesotibia very slightly arcuate, medial margin with 3 or 4 short sharp spines located near midlength, spines longer and stronger from most proximal to most distal, surface of tibia notched between spines. Metatibia straight, slender. Metafemur slender. Ventral hydrofuge pubescence relatively long. Abdominal apex with narrow apicomedian notch.

Etymology. Named in reference to the very coarse and very dense dorsal punctation.