Hydraena cameroconcava, 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 : 9

Hydraena cameroconcava , new species

Figs. 1 , 6 (habitus), 6 (aedeagus), 43 (map)

Type Material. Holotype (male): Cameroon : Northwest Province. “ BRITISH CAMEROONS / Matute, / Tiko Plantation / 5.v.1949, B. Malkin ” ( UKNHM).

Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the absence of a distinct pronotal macula, the frons distinctly concave between median area and eye, the widely separated metaventral plaques that are markedly converging anteriorly (ratios P2/w/l/s ca. 1/1/4/5), and the aedeagus ( Fig. 6 ). Also refer to the diagnosis of H. camerocorona for comments on the male genitalia.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.20/0.50; head width 0.32; pronotum 0.30/0.42, PA 0.36, PB 0.37; elytra 0.67/0.50. Habitus as illustrated ( Fig. 6 ). Dorsum dark brown to black, frons and pronotal disc darker, light brown clypeus contrasting with black frons, palpi testaceous, tip of last palpomere not darker. Frons distinctly concave between median area and eye. Dorsum of head and pronotum finely sparsely punctulate, interstices shining; punctures of frons disc and pronotal disc ca. 1xef, interstices ca. 1–3xpd; clypeus dull, punctures very fine and dense. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral, posterolateral, and posterosubmedial pronotal foveae rather deep

Elytra with summit of posterior declivity at or very near posterior 1/3, where elytra transversely quite convex; 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 forming very weak angle with one another. Abdominal apex with slightly off-center apical notch.

Venter: Mentum and postmentum densely finely punctulate, dull. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/1/4/5. P1 laminate; median carina sinuate in profile. P2 l/w ca. 4/1, sides slightly converging toward rather narrow blunt apex, apex raised slightly above mesoventral intercoxal process. Plaques narrow, straight, markedly converging anteriorly, posteriorly separated by ca. 4x anterior separation, not 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 concave. All tibiae slender, protibia very slightly arcuate, meso- and metatibiae straight.

Distribution. Currently known only from the type locality ( Fig. 43 ).

Etymology. Named in reference to the concavities of the frons.

Figures

FIGURE 6. Hydraena cameroconcava, 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 42–43. Geographical distributions of Cameroonian Hydraena.