Hydraena cameropalmula, 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 : 21

Hydraena cameropalmula , new species

Figs. 4 , 24 (habitus), 24 (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 pronotum with a macula, the absence of posterosubmedial pronotal foveae, and the aedeagus ( Fig. 24 ). Reliable determinations to distinguish this species from other similar members in Aedeagal Species Group 3 will require dissection of males.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.33/0.58; head width 0.34; pronotum 0.34/0.47, PA 0.38, PB 0.38; elytra 0.82/0.58. Habitus as illustrated ( Fig. 24 ). Dorsum testaceous to dark brown, head, pronotal macula and elytra dark brown, pronotum rather widely margined in light brown to testaceous, palpi testaceous, tip of last palpomere not darker. Dorsum of head finely sparsely punctulate, pronotum moderately coarsely, densely punctate, punctures much larger than those of frons, interstices shining, ca. 1–2xpd. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral foveae moderately deep, posterolateral foveae very shallow, posterosubmedial foveae absent.

Elytra with summit of posterior declivity slightly beyond midlength; lateral explanate margins narrow; on basal 1/3 punctures larger than largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals not raised, width ca. 1xpd 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.

Venter: Mentum and postmentum finely punctulate, shining. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/1/4/4. 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 narrow, straight, parallel or nearly so, 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 width at straight posterior margin ca. 2.5x P2. All tibiae slender, protibia very slightly arcuate, meso- and metatibiae straight. Abdominal apex with apicomedian shallow notch in tergite, into which minute apical process of ventrite fits.

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

Etymology. Named in reference to the known distribution and the palmate shape of the aedeagus.

Figures

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

FIGURE 24. Hydraena cameropalmula, new species, habitus and aedeagus of holotype.

FIGURES 42–43. Geographical distributions of Cameroonian Hydraena.