Hydraena camerosicula, Perkins, 2022

Perkins, Philip D., 2022, Thirty-three new species of water beetles in the genus Hydraena Kugelann from Cameroon (Coleoptera: Hydraenidae), Zootaxa 5203 (1), pp. 1-66 : 12-13

Hydraena camerosicula , new species

Figs. 1 , 11 (habitus), 11 (aedeagus), 42 (map)

Type Material. Holotype (male): “ Cameroon: N. Prov., 35 km N. Ngaoundere, stream, 1.v.1982, leg. P. D. Perkins ” ( MCZ) . Paratypes: Same data as holotype (3 MCZ) .

Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the comparatively large body size (ca. 1.49 mm), the deep pronotal impressions, the comparatively wide P2, the narrow median depression between the metaventral plaques, and the aedeagus ( Fig. 11 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.49/0.69; head width 0.39; pronotum 0.37/0.51, PA 0.41, PB 0.46; elytra 0.93/0.69. Habitus as illustrated ( Fig. 11 ). Dorsum brown to dark brown, frons and pronotal macula darker, maxillary palpi testaceous, tip of last palpomere not darker. Dorsum of head and pronotum moderately finely moderately sparsely punctulate, interstices shining; punctures of frons disc and pronotal disc ca. 1xef, interstices ca. 1–3xpd; clypeus dull, punctures very fine and dense. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral foveae deep, confluent with shallow posterolateral; posterosubmedial pronotal foveae moderately deep, markedly punctate.

Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins wide; on basal 1/3 punctures ca. 1xpd of largest pronotal punctures, punctures becoming gradually smaller toward posterior, each puncture with very short and very fine seta. Intervals not raised, width ca. 1–2xpd or less, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins not forming angle with one another.

Venter: Mentum very sparsely very finely punctulate, shining; postmentum very finely densely micropunctulate, dull. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.5/2/1. P1 laminate; median carina sinuate in profile. P2 comparatively wide, l/w ca. 2/1, sides parallel, apex blunt, apex raised slightly above mesoventral intercoxal process. Plaques moderately narrow, slightly arcuate, parallel, tapering anteriorly, weakly raised, located at sides of moderately deep, narrow median depression. AIS width at straight posterior margin ca. 1.5x P2. Protibia very slender, straight. All tibiae slender, straight. Abdominal apex asymmetrical, with deep off-center notch.

Distribution. Currently known only from the type locality ( Fig. 42 ).

Etymology. Named in reference to the known distribution, and to the dagger-shaped process of the aedeagus.

Figures

FIGURE 11. Hydraena camerosicula, new species, habitus and aedeagus of holotype.

FIGURES 1–2. 1. Dorsal habitus of Cameroonian species of Hydraena in Aedeagal Species Group 1; 2. Representative aedeagi of Aedeagal Species Groups 1–4.

FIGURES 42–43. Geographical distributions of Cameroonian Hydraena.