Hydraena cameroancylis, 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 : 17-18

Hydraena cameroancylis , new species

Figs. 4 , 19 (habitus), 19 (aedeagus), 41 (map)

Type Material. Holotype (male): “ Cameroon: C. S. Prov., 15 km. NW Yaounde, Isali River nr. Nouma, 2.i.1983, leg. P. D. Perkins ” ( MCZ) . Paratype: Same data as holotype (1 MCZ) .

Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the anterolateral pronotal foveae large and deep, posterolateral pronotal foveae absent, the brown to dark brown dorsum, and the aedeagus ( Fig. 19 ). Similar in dorsal habitus to H. cameropalmula and H. millenaria ; reliable determinations will require examination of the aedeagus.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.35/0.60; head width 0.36; pronotum 0.33/0.48, PA 0.40, PB 0.43; elytra 0.85/0.60. Habitus as illustrated ( Fig. 19 ). Dorsum brown to dark brown, frons and diffusely margined pronotal disc darker, palpi testaceous, tip of last palpomere not darker. Dorsum of head and pronotum moderately sparcely moderately coarsely punctulate, more sparsely punctulate on pronotal disc than on surrounding areas, interstices shining; punctures of frons disc and pronotal disc ca. 1–2xef, interstices ca. 1–2xpd or slightly larger; punctures of clypeus very fine, very dense, dull. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral pronotal foveae large and deep, posterolateral pronotal foveae absent, posterosubmedial foveae very shallow.

Elytra with summit of posterior declivity at or very near midlength; lateral explanate margins wide; punctures moderately coarse, on basal 1/3 punctures ca. 2xpd of largest pronotal punctures, 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 conjointly rounded, in posterior aspect margins forming moderate angle with one another.

Venter: Mentum very sparsely very finely punctulate, shining; postmentum very finely densely micropunctulate, moderately shining. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.5/2/2.5. P1 laminate; median carina sinuate in profile. P2 l/w ca. 3/1, sides parallel, apex blunt, apex raised slightly above mesoventral intercoxal process. Plaques narrow, short, slightly converging toward one another anteriorly, not raised, located at sides of deep median depression. AIS width at straight posterior margin ca. 1.5x P2. All tibiae slender, straight. Abdominal apex symmetrical, with apicomedian notch.

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

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

Figures

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

FIGURE 19. Hydraena cameroancylis, new species, habitus and aedeagus of holotype.

FIGURES 39–41. Geographical distributions of Cameroonian Hydraena.