Hydraena camerocompressa, 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 : 18-19

Hydraena camerocompressa , new species

Figs. 4 , 21 (habitus), 21 (aedeagus), 42 (map)

Type Material. Holotype (male): “ Cameroon: 35 km N. Ngaoundere, stream, 1.v.1982, P. D. Perkins collector” ( MCZ) . Paratypes: Same data as holotype (6 MCZ) .

Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the very narrow P2 (l/w ca. 4/1), the unusual ratios of P2 width and plaque shape (P2/w/l/s ca. 1/1/6/5), and the aedeagus ( Fig. 21 ). Although the P2 is very narrow, as is that of H. camerocrebrata n. sp., the habitus and aedeagi of the two species markedly differ. H. cameropetila (CAM13) also has a very narrow P2, but lacks metaventral plaques.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.40/0.61; head width 0.33; pronotum 0.33/0.48, PA 0.37, PB 0.39; elytra 0.83/0.61. Habitus as illustrated ( Fig. 21 ). Dorsum brown to light brown, head and pronotal macula darker, palpi testaceous, tip of last palpomere not darker. Dorsum of head and pronotum moderately densely punctulate, more sparsely punctulate on macula than on surrounding areas, interstices shining; punctures of frons disc and pronotal disc ca. 1xef, interstices ca. 1–3xpd or slightly larger; punctures of clypeus obsolete. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; antero- and posterolateral pronotal foveae shallow, posterosubmedial foveae very shallow.

Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins narrow; on basal 1/3 punctures slightly larger than 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 and postmentum nitid, dull. Genae very slightly raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/1/6/5. P1 laminate; median carina weakly sinuate in profile. P2 narrow, l/ w ca. 4/1, sides parallel, apex blunt. Plaques narrow, straight, parallel, weakly raised, located at sides of deep median depression. Metaventrite with very short longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity. AIS weakly concave, width at straight posterior margin ca. 1.5x P2. Pro- meso- and metatibiae slender, straight. Abdominal apex with deep asymmetrical slightly off-center notch.

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

Etymology. Named in reference to the known distribution and the very narrow mesoventral intercoxal process (P2).

Figures

FIGURE 4. Dorsal habitus of Cameroonian species of Hydraena in Aedeagal Species Groups 3 and 4.

FIGURE 21. Hydraena camerocompressa, new species, habitus and aedeagus of holotype.

FIGURES 42–43. Geographical distributions of Cameroonian Hydraena.