Hydraena cameroovala, 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 : 11-12

Hydraena cameroovala , new species

Figs. 1 , 10 (habitus), 10 (aedeagus), 41 (map)

Type Material. Holotype (male): “ Cameroon: C. S. Prov., 15 km. S. Mbalmayo, Nyong River , ex. leaves at margin, 22.v.1982, leg. P. D. Perkins ” ( MCZ) . Paratypes: Same data as holotype (4 MCZ) .

Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the oval body form, the small body size (ca. 1.18 mm), the posterosubmedial foveae moderately deep, confluent medially forming U-shaped impression, and the aedeagus ( Fig. 10 ). Similar in habitus to some other members of Aedeagal Group 1; reliable determinations will require dissection of males.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.18/0.56; head width 0.34; pronotum 0.31/0.44, PA 0.36, PB 0.39; elytra 0.70/0.56. Habitus as illustrated ( Fig. 10 ). Body form quite oval. Dorsum generally brown to dark brown, maxillary palpi, labrum and clypeus testaceous, pronotum with diffusely margined weakly defined macula. Dorsum of head and pronotum moderately coarsely, often very densely punctulate, frons punctures distinctly finer and less dense than pronotal punctures, interstices shining; punctures of frons disc and pronotal disc ca. 2–3xef, interstices ca. 1xpd or less; punctures of clypeus very fine, very dense, dull. Labrum apicomedially excised, free margins rounded, weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral foveae deep, posterolateral absent, posterosubmedial foveae moderately deep, confluent medially forming U-shaped impression.

Elytra with summit of posterior declivity at about posterior 1/3; 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, as are interstices between punctures of a row. Apices in dorsal aspect very slightly separately rounded, in posterior aspect margins forming strong angle with one another.

Venter: Mentum sparsely finely punctulate, shining; postmentum very finely densely micropunctulate, surrounding areas smooth, moderately shining. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/1/2/3. P1 laminate; median carina sinuate in profile. P2 l/w ca. 3/1, sides slightly converging toward blunt apex, apex raised slightly above mesoventral intercoxal process. Plaques moderately narrow posteriorly, tapering to point anteriorly, slightly converging toward one another anteriorly, weakly raised, located at sides of shallow median depression. AIS width at straight posterior margin ca. 2x P2. All tibiae slender, straight. Abdominal apex asymmetrical, with deep off-center notch.

Distribution. Currently known only from the type locality ( Fig. 41 ).

Etymology. Named in reference to the known distribution, and to the oval body form.

Figures

FIGURE 10. Hydraena cameroovala, 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 39–41. Geographical distributions of Cameroonian Hydraena.