Hydraena camerocarinata, 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 : 22

Hydraena camerocarinata , new species

Figs. 4 , 26 (habitus), 26 (aedeagus), 42 (map)

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

Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the nearly semicordate pronotum, the widely separated and carinate mesoventral plaques, and the aedeagus ( Fig. 26 ). Refer also to the diagnosis of H. camerosemicordata n. sp.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.35/0.57; head width 0.33; pronotum 0.35/0.44, PA 0.37, PB 0.33; elytra 0.81/0.57. Habitus as illustrated ( Fig. 26 ). Pronotum almost semicordiform, anterior margin much wider than posterior margin. Dorsum brown except head and pronotal fascia black, palpi light brown to testaceous, tip of last palpomere not darker. Dorsum of head and pronotum moderately punctulate, more sparsely punctulate on fascia than on surrounding areas, interstices shining; punctures of frons disc fine and sparse, less than 1xef; punctures of pronotal disc ca. 2xef, interstices ca. 1–3xpd or slightly larger; punctures of clypeus fine, moderately dense. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; antero- and posterolateral pronotal foveae moderately deep, posterosubmedial foveae very shallow.

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

Venter: Mentum and postmentum densely micropunctulate, dull. Genae very slightly raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.15/0.15/2. P1 laminate; median carina weakly sinuate in profile. P2 l/w ca. 2.5/1, sides almost parallel, apex blunt. Plaques very small, very narrow, carinate lines, straight, convergent anteriorly, very 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. 2x P2. Protibiae slender, very weakly arcuate. Mesotibiae slender, straight. Metatibiae slender, straight, very slightly wider at midlength than apically. Abdominal apex symmetrical, with apicomedian notch.

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

Etymology. Named in reference to the known distribution and the carinate metaventral plaques.

Figures

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

FIGURE 26. Hydraena camerocarinata, new species, habitus and aedeagus of holotype.

FIGURES 42–43. Geographical distributions of Cameroonian Hydraena.