Hydraena camerosemicordata, 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 : 22-23

Hydraena camerosemicordata , new species

Figs. 4 , 27 (habitus), 27 (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 chordate and convex pronotum, the very narrow metaventral plaques, and the aedeagus ( Fig. 27 ). Differentiated from H. camerocarinata n. sp., a species which also has a semichordate pronotum, by the more convex and more chordate pronotum, the deeper pronotal foveae, the area between the antero- and posterolateral pronotal foveae more strongly convex, the more acuminate elytra, and the different proportions of the ventral characters (P2/w/l/s ca. 1/0.2/2/2 vs. 1/0.15/0.15/2).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.37/0.54; head width 0.31; pronotum 0.37/0.44, PA 0.35, PB 0.31; elytra 0.81/0.54. Habitus as illustrated ( Fig. 27 ). Pronotum 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 effacedly microreticulate, weakly shining; punctures of frons disc fine and sparse, 1xef or less; punctures of pronotal disc ca. 1–2xef, interstices ca. 1–3xpd; punctures of clypeus fine, moderately dense. Labrum apicomedial excision deep and wide, free margins weakly upturned, angulate laterally and medially. Pronotum distinctly convex, especially transversely, anterior margin weakly emarginate over middle 1/2; antero- and posterolateral pronotal foveae deep, posterosubmedial foveae deep, area between antero- and posterolateral foveae distinctly convex.

Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins moderately wide; on basal 1/3 punctures 1–2xpd and deeper than largest pronotal punctures, punctures becoming gradually slightly smaller toward posterior. Intervals not raised, width ca. 1xpd, interstices between punctures of a row ca. 2–3xpd, each puncture with very short and very fine seta. Apices in dorsal aspect conjointly rather sharply 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. 1/0.2/2/2. 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, lines, straight, convergent anteriorly, very weakly if at all 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. Pro-, meso- and metatibiae slender, straight. 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 semi-chordate pronotum.

Figures

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

FIGURE 27. Hydraena camerosemicordata, new species, habitus and aedeagus of holotype.

FIGURES 42–43. Geographical distributions of Cameroonian Hydraena.