Hydraena torquata, Perkins, 2017

Perkins, Philip D., 2017, Hydraenidae of Madagascar (Insecta: Coleoptera), Zootaxa 4342 (1), pp. 1-264 : 133-134

Hydraena torquata , new species

Figs. 119 (habitus), 121 (aedeagus), 285 (map)

Type Material. Holotype (male): Fianarantsoa, Andringitra NP, M. Ambatoberger, spring area Exp. W, elev. 2105 m, 22° 8' S, 46° 52' E, 12 iv 2011, R. Gerecke (MD 203) ( NMW) . Paratypes (13): Antananarivo, 18.8704S 47.6708E Analamanga, Anjomara mountain next to Ambato- lampikely village, RN2, hygropetric rock, elev. 1470 m, 18° 52' S, 47° 40' E, 24 xi 2014, J. Bergsten, R. Bukontaite, J.H. Randriamihaja, T. Ranarilalatiana & S. Holmgren ( MAD14-79 ) (7 NHRS) ; Fianarantsoa, Andringitra NP, (Fianarantsoa), R. Amboahisy , right riparian springs above bridge at lower campsite, elev. 1571 m, 22° 8' S, 46° 53' E, 13 iv 2011, R. Gerecke (MD 205) (2 NMW) ; Ihorombe: Isalo NP: 300m into the canyon de Makis : S 22.48655 E 45.37966, canyon river with side pools, elev. 700 m, 22° 29' S, 45° 23' E, 13 xi 2012, R. Bukontaite & J.H. Randriamihaja ( MAD12-03 ) (4 NHRS) .

Differential Diagnosis. Somewhat similar to H. contorta in shape, dorsal punctation, and deep pronotal foveae PF2; externally differing therefrom in size (ca. 1.39 vs. 1.69 mm), color (dark brown without a pronotal macula), having a slightly differently shaped pronotum, and smaller metaventral plaques. The aedeagi of the two species are similar in being twisted such that the very large left paramere wraps around the dorsal side of the aedeagus, the right paramere is small and located on the left side; also, the main piece has a prominent lobe near midlength. Otherwise, the shapes of the two aedeagi differ markedly ( Figs. 121, 122).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.39/0.58; head width 0.35; pronotum 0.32/0.46, PA 0.37, PB 0.39; elytra 0.83/0.58.

Dorsum dark brown, head darkest; legs brown; maxillary palpi dark brown, distal 0.5 of last palpomere darker.

Head and pronotum moderately densely moderately finely punctate. Frons slightly depressed medial to eyes. Pronotal punctures slightly larger than those of head; interstices ca. 1xpd, weakly shining. Mentum punctulate in dull shallow basomedian depression, lateral areas weakly shining; postmentum densely, finely punctate, dull. Genae roundly raised, medially smooth and shining, without posterior ridge.

Pronotum slightly sinuate laterally, evidently not emarginate between anterior angle and widest part of pronotum; anterior margin straight behind eyes, very slightly emarginate behind frons; PF1 moderately shallow, deepest in midline; PF2 deep, very shallowly, if at all, confluent medially; PF3 deep; PF4 shallow.

Elytra weakly arcuate laterally; summit of posterior declivity near distal 2/3; lateral explanate margins narrow; serial punctures round, separated by ca. 1xpd, ca. same size as pronotal punctures. Intervals not raised, ca. 1xpd,very weakly shining. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.5/1.5/1.5. P1 laminate; median carina sinuate in profile. P2 l/w (w at apex) ca. 3/1, sides slightly converging, apex blunt and raised slightly above metaventral intercoxal process. Plaques very small, narrow and indistinct, partially obscured by pubescence, converging slightly anteriorly, very slightly raised, located at sides of median depression. Metaventrite with very short longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity. AIS width at arcuate posterior margin ca. 2x P2. Protibia very slightly arcuate, almost straight, slightly widened at ca. distal ¼. Mesotibia straight, widest at ca. midlength. Metatibia straight, slender. Metafemur not markedly arcuate on lateral and medial margins. Abdominal apex with moderately deep asymmetrical notch.

Etymology. Named in reference to the twisted, intricate and complex aedeagus.