Hydraena bucollis, Perkins, 2017

Perkins, Philip D., 2017, Hydraenidae of Madagascar (Insecta: Coleoptera), Zootaxa 4342 (1), pp. 1-264 : 142-144

Hydraena bucollis , new species

Figs. 128 (habitus), 130 (aedeagus), 290 (map)

Type Material. Holotype (male): Toamasina, Tamatave 6.3 km S Ambanizona, Andranobe Field Station, rainforest, sifted litter from flat sandy areas, some from slope, elev. 25 m, 15° 41' S, 49° 57' E, 14 xi 1993, B. L. Fisher (#886) ( FMNH). Paratypes: Same data as holotype (8 FMNH).

Differential Diagnosis. An unusual species, differentiated from other species by the combination of small size (ca. 1.17 mm), the proportionally large pronotum that is widest anterior to midlength, and the very finely sparsely punctate dorsum. Other distinctive characters are the uniform light brownish color, and the very short metaventrite that lacks plaques. The maxillary palpi are stout, and unusual in that the second palpomere is arcuate, not sinuate as in most species. The only pronotal fovea present is PF3. The very simple aedeagus is unique. This species is tentatively placed in Hydraenopsis .

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.17/0.49; head width 0.30; pronotum 0.27/0.42, PA 0.36, PB 0.36; elytra 0.73/0.49.

Dorsum light brown to very weakly ochraceous; legs light brown; maxillary palpi testaceous.

Head with clypeus and frons finely sparsely punctate, interstices shining. Clypeus lateral margin rounded. Pronotum finely punctate; interstices ca. 2–3xpd on disc, shining. Mentum and postmentum very sparsely very finely punctulate, shining. Genae raised, shining, without posterior ridge.

Pronotum laterally weakly arcuate, widest slightly anterior to midlength; anterior margin arcuate from side to side; PF1, PF2 and PF4 absent; PF3 very shallow.

Elytra weakly arcuate laterally; summit of posterior declivity slightly past midlength; lateral explanate margins narrow; serial punctures small, round, separated by ca. 1–2xpd, slightly larger than pronotal punctures. Intervals not raised, shining, ca. 1–2xpd. Apices in dorsal aspect conjointly rather sharply rounded, in posterior aspect margins not forming angle with one another.

Metaventral plaques absent. P1 almost laminate; median carina not sinuate in profile. P2 l/w ca. 3/1, sides parallel, apex blunt, apex raised slightly above metaventral intercoxal process. Metaventrite with very shallow median depression. Metaventrite without longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity. AIS width at slightly arcuate posterior margin ca. 3x P2. Protibia stout, arcuate, other tibiae straight, stout. Abdominal apex with apicomedian notch.

Etymology. Named in reference to the proportionally large pronotum, which is widely rounded anterior to midlength.