Menomadraena concava, Perkins, 2017

Perkins, Philip D., 2017, Hydraenidae of Madagascar (Insecta: Coleoptera), Zootaxa 4342 (1), pp. 1-264 : 172-175

Menomadraena concava , new species

Figs. 163 (habitus), 165 (aedeagus), 220 (antenna, maxillary palpus), 299 (map)

Type Material. Holotype (male): Fianarantsoa, R.S. Ivohibe, 6.5 km ESE Ivohibe, camp III, sifted litter (leaf mold, rotten wood) montane rainforest, elev. 1575 m, 22° 29.8' S, 46° 57.3' E, 24–30 x 1997, B. L. Fisher (1751) ( FMNH). Paratypes: Same data as holotype (10 FMNH).

Differential Diagnosis. Differentiated from other members of the genus by the large concavity of the metaventrite ( Fig. 163). The aedeagus indicates a relationship with M. sembella , although being much larger, having a differently shaped distal part of the aedeagus, and differently shaped parameres ( Figs. 165, 168).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.98/0.95; head width 0.56; pronotum 0.40/0.77, PA 0.67, PB 0.61; elytra 1.35/0.95. Size range ca. 1.97–2.09 mm. Dorsum reddish brown, venter dark brown to piceous, legs brown to reddish brown.

Maxillary palpi short, last palpomere distinctly shorter than first antennomere. Last antennomere longer than penultimate. Labrum bilobed, pubescent, originating under overhanging anterior margin of clypeus. Subocular groove for antenna deep and wide. Clypeus anterior margin emarginate. Clypeus and frons with small, dense, flat or slightly rounded granules, setae very small and inconspicuous. Pronotal disc with dense (many contiguous) flat circular granules; lateral explanate areas and two areas basally without granules, shining; shallow midlongitudinal sulcus in anterior ½; posteroadmedian foveae confluent in midline. Postocular emarginations deep.

Elytral suture raised. Each elytron with three costae, first (from suture) terminating at ca. posterior ¾, second arcuate and continuing to apices, third terminating at ca. midlength. Each costa with unilinear row of very small granules, each with short recumbent seta. Areas between costae each with three rows of small punctures, each puncture with minute granule and seta at anterior margin. Area between third costa and explanate margin with five rows of punctures.

Mentum punctate and pubescent; postmentum sparsely pubescent, shining. Genae microreticulate, dull, without posterior ridge. Mesoventrite with very low tubercle on intercoxal process. Metaventrite virtually nonpubescent, very finely microreticulate or micropunctulate; basomedian depression large and deep ( Fig. 163). Abdominal ventrites with very fine, very short, and very sparse setae, almost glabrous, with very fine microreticulation. Mesotibia straight, pro- and metatibiae slightly arcuate toward midline.

Etymology. Named in reference to the large and deep concavity of the metaventrite.