Hydraena contracolorata, Perkins, 2017

Perkins, Philip D., 2017, Hydraenidae of Madagascar (Insecta: Coleoptera), Zootaxa 4342 (1), pp. 1-264 : 72-73

Hydraena contracolorata , new species

Figs. 61 (habitus), 63 (aedeagus), 256 (map)

Type Material. Holotype (male): Antsiranana, Montagne des Francais , stream pool, elev. 171 m, 12° 20' S, 49° 20' E, 1 xi–30 xii 2004, M. Balke & D. Ottke (MD 001) ( ZSMC) . Paratypes (28): Same data as holotype (23). Antsiranana, Antsaba, Galoko Mountains , hygropetric cascade, elev. 303 m, 13° 39' S, 48° 45' E, 1 xi–29 xii 2004, M. Balke (MD 016) (4 ZSMC); Forêt d'Anabohazo, 21.6 km 247° WSW Maromandia, malaise trap- in tropical dry forest, elev. 120 m, 14° 18' S, 47° 54' E, 11–16 iii 2001, Fisher, Griswold et al. (BLF 3336) (1 CAS);

Differential Diagnosis. The smallest member of the species group (ca. 1.48 mm); differentiated by the comparatively short elytra and the light colored legs that contrast with the dark brown venter. The aedeagus is readily distinguished from that of other members of the group.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.48/0.68; head width 0.40; pronotum 0.39/0.51, PA 0.43, PB 0.43; elytra 0.87/0.68.

Dorsum with head dark brown, pronotum with large dark brown fascia, narrowly bordered anteriorly and posteriorly by light brown to testaceous; legs light brown to testaceous; maxillary palpi testaceous, distal 0.5 of last palpomere not darker.

Head with clypeus moderately coarsely and moderately densely punctate; frons moderately coarsely and moderately densely punctate, punctures ca. 2x those of clypeus, interstices 1–2xpd, weakly shining. Pronotum moderately coarsely and densely punctate, interstices narrow walls to ca. 1xpd, shining. Mentum sparsely, moderately coarsely punctate, interstices effacedly microreticulate, dull; postmentum microreticulate and dull in median depression, surrounding area dull. Genae raised, weakly if at all shining, with posterior ridge, interrupted in midline.

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

Elytra weakly arcuate laterally; summit of posterior declivity slightly past midlength; lateral explanate margins moderately wide; serial punctures round, separated by ca. 0.5xpd or less, slightly smaller than largest pronotal punctures. Intervals not raised, very weakly shining, narrow walls to ca. 0.5xpd. Apices in dorsal aspect conjointly rounded, in posterior aspect margins do not form angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.25/2/1. P1 as wide as P2; median carina very weakly sinuate in profile. P2 l/w ca. 2/1, sides converging slightly posteriorly, apex blunt and on same level as anteromedian carina of metaventrite. Plaques carinate, converging anteriorly and joining anteromedian carina, forming inverted Y-shape; plaques separated basally by ca. 4x plaque width, located at sides of deep median depression; metaventrite concave lateral to basal area of plaques. Metaventrite anteromedian carina slightly shorter than plaques; long longitudinal and slightly arcuate ridge on each side, extended posteriorly from margin of each mesocoxal cavity, almost attaining metacoxal cavity. Metaventrite concave at anterolateral angles. AIS width at arcuate posterior margin ca. 1x P2. Protibia straight, slender. Mesotibia very weakly if at all arcuate, medial margin at ca. distal 0.25 with 2–3 short stout spines, and shallowly notched. Metatibia very weakly arcuate, slender. Metafemur slender, arcuate on lateral margin, weakly sinuate on medial margin. Abdominal apex with very small apicomedian notch.

Etymology. Named in reference to the contrasting colors of the dark body and light colored legs and maxillary palpi.