Hydraena tibiodentipes, Perkins, 2017

Perkins, Philip D., 2017, Hydraenidae of Madagascar (Insecta: Coleoptera), Zootaxa 4342 (1), pp. 1-264 : 68-69

Hydraena tibiodentipes , new species

Figs. 57 (habitus), 59 (aedeagus), 254 (map)

Type Material. Holotype (male): Fianarantsoa, Andringitra NP, ca. 300 m W Cascade du Roi , swamp near irrigation channel, elev. 1725 m, 22° 8' S, 46° 53' E, 14 iv 2011, R. Gerecke (MD 209) ( NMW) . Paratypes (31): Same data as holotype (13); Fianarantsoa, Andringitra NP, ( Fianarantsoa ) , Cascade du Roi, elev. 1700 m , 22° 8' S, 46° 53' E, 14 iv 2011, R. Gerecke (MD 207) (1 NMW); Andringitra NP, (Fianarantsoa), helocrenes crossing road right hand of Cascade du Roi, elev. 1710 m , 22° 8' S, 46° 53' E, 14 iv 2011, R. Gerecke (MD 208) (8 NMW); Andringitra NP (Fianarantsoa) hygropetric cascade stream crossing way to cascades, 16.2°C, elev. 1722 m , 22° 8' S, 46° 53' E, 11 iv 2011, R. Gerecke (MD 198) (1 NMW); 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) (1 NMW); Andringitra NP (Fianarantsoa), small stream ca. 400 m W Cascade du Roi , elev. 1725 m , 22° 8' S, 46° 53' E, 14 iv 2011, R. Gerecke (MD 210) (2 NMW); Andringitra NP: Riambavy R. (female) cascade hygropetric habitat, N -22° 8.761, E:46° 53.4, wet rock surfaces next to high waterfall, elev. 1739 m, 22° 9' S, 46° 53' E, 8 v 2006, Bergsten et al. (P39) (1 NHRS); Andringitra NP, Riambavy R. (female) cascade, N:-22.14583, E:46.89154, elev. 1656 m, 22° 8' S, 46° 53' E, 8 v 2006, Monaghan et al. (P39MD3) (1 NHRS); Andringitra NP: Zomandao R., nr caves close to Camp Belamba, hygropetric and waterpools by the river, N -22° 8.192, E:46° 53.359, elev. 1601 m, 22° 8' S, 46° 53' E, 9 v 2006, Bergsten et al. (P39D) (3 NHRS).

Differential Diagnosis. In dorsal habitus somewhat similar to H. upsilonica , which see. Among other differences in the two species the plaques are oval in H. tibiodentipes (not carinate) and do not join with the anteromedian carina of the metaventrite to form an inverted Y-shape. The aedeagus of H. tibiodentipes might superficially be compared with that of H. bisinuata , but the shapes of the main piece and paramere, especially in lateral view, differ distinctively in the two species.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 2.21/1.00; head width 0.50; pronotum 0.52/0.67, PA 0.56, PB 0.58; elytra 1.35/1.00.

Dorsum reddish brown, head darker than pronotum and elytra; elytral epipleurs lighter than remainder of elytra, and much lighter than venter; legs brown to reddish brown; maxillary palpi testaceous, distal ½ of last palpomere not darker.

Head with clypeus finely sparsely punctate; frons more coarsely punctate laterally than medially where interstices ca. 1–2xpd. Pronotum in anterior and posterior 1/3 coarsely densely punctate, interstices narrow walls or less than 1xpd; punctures on disc distinctly smaller, interstices ca. 1xpd, shining. Mentum finely punctulate, interstices shining; postmentum slightly more densely punctate. Genae raised, shining, with posterior ridge, interrupted in midline.

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

Elytra weakly arcuate laterally; summit of posterior declivity slightly before midlength; lateral explanate margins wide; serial punctures round, separated by ca. 1xpd or slightly less, as large as largest pronotal punctures. Intervals not raised, shining, ca. 0.5xpd. Apices in dorsal aspect rather sharply conjointly rounded, in posterior aspect margins not forming angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/1/2.3/1.3. P1 almost as wide as P2; median carina weakly sinuate in profile. P2 l/w ca. 2/1, sides parallel, apex blunt and on same level as anteromedian carina of metaventrite. Plaques elongate oval, moderately widely separated, very slightly raised, located at sides of deep oval median depression. Metaventrite anteromedian carina ca. as long as plaques, attaining anterior margin of deep depression separating plaques; long and strong longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity, as long as anteromedian carina. AIS width at arcuate posterior margin ca. 1.5x P2. Protibia straight, slender. Mesotibia arcuate, widest near midlength, medial margin with 4 or 5 short sharp spines, surface of tibia notched between spines, spines longer and stronger from most proximal to most distal. Metatibia very slender, weakly arcuate, medial margin weakly emarginate and bearing row of short rather widely spaces slender setae. Metafemur rather slender, slightly more arcuate on lateral than medial margin. Abdominal apex with narrow apicomedian notch.

Etymology. Named in reference to the prominent spines of the male mesotibiae.