Hydraena millenaria, 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 : 21-22

Hydraena millenaria , new species

Figs. 4 , 25 (habitus), 25 (aedeagus), 40 (map)

Type Material. Holotype (male): “ Cameroon: N. W. Prov., Bamenda , stream nr. Skyline Hotel, 1.ii.1982, 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 absence of metaventral plaques, the frons and pronotum finely sparsely punctulate, the punctures of the pronotum very consistent in size throughout, and the aedeagus ( Fig. 25 ). The dorsal punctation is much finer and sparser than that of H. cameropetila and H. camerosetosa , two species which also lack metaventral plaques. All three species are in different Aedeagal Species Groups.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.20/0.53; head width 0.33; pronotum 0.31/0.44, PA 0.34, PB 0.39; elytra 0.75/0.53. Habitus as illustrated ( Fig. 25 ). Dorsum brown to dark brown, head, pronotal fascia and elytra dark brown, pronotum rather widely bordered anteriorly and posteriorly slightly lighter brown, maxillary palpi testaceous, tip of last palpomere not darker. Frons and pronotum finely sparsely punctulate, punctures of pronotum slightly larger than those of frons, very consistent in size throughout, interstices shining, ca. 1–3xpd. Clypeus medially very finely sparsely punctulate, shining; laterally densely micropunctulate, dull. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral foveae deep, posterolateral and posterosubmedian foveae shallow.

Elytra with summit of posterior declivity slightly beyond midlength; lateral explanate margins wide; on basal 1/3 punctures ca. 1xpd of largest pronotal punctures, punctures becoming gradually smaller toward posterior. Intervals shining, not raised, width ca. 1–2xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins not forming angle with one another.

Venter: Mentum very sparsely very finely punctulate, shining; postmentum very finely densely micropunctulate, surrounding areas smooth, shining. Genae raised, shining, without posterior ridge. 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 absent. AIS width at straight posterior margin ca. 2x P2. All tibiae slender, straight. Abdominal apex slightly asymmetrical, with deep and wide apicomedian notch.

Distribution. Currently known only from the type locality ( Fig. 40 ).

Etymology. Named in reference to the fact that the author’s goal of describing more than 1000 new species of water beetles is now happily attained.

Figures

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

FIGURE 25. Hydraena millenaria, new species, habitus and aedeagus of holotype.

FIGURES 39–41. Geographical distributions of Cameroonian Hydraena.