Hydraena camerosetosa, 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 : 29-30

Hydraena camerosetosa , new species

Figs. 5 , 38 (habitus), 38 (aedeagus), 43 (map)

Type Material. Holotype (male): Cameroon : Northwest Province. “ BRITISH CAMEROONS / Matute, / Tiko Plantation / 5.v.1949, B. Malkin ” ( UKNHM) . Paratypes: Same data as holotype (10 UKNHM) .

Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the densely punctate dorsum, the absence of metaventral plaques, and the aedeagus ( Fig. 38 ). H. camerosetosa differs from H. cameropetila , another species that lacks metaventral plaques, by a larger body size (ca. 1.33 vs. 1.20 mm), a markedly different aedeagus, and a wider mesoventral intercoxal process (P2), which is twice as wide as the P2 of H. cameropetila . Although H. cameropetila is smaller than H. camerosetosa in body length, the width of the mesocoxae are the same in the two species, making the ratio of P2 width/mesocoxa width approximately 0.12 for H. cameropetila and 0.40 H. camerosetosa .

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.33/0.55; head width 0.34; pronotum 0.34/0.46, PA 0.39, PB 0.42; elytra 0.78/0.55. Habitus as illustrated ( Fig. 38 ). Dorsum testaceous to black, head and pronotal macula dark brown to black, pronotum rather widely margined in light brown to testaceous, elytra brown, 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. 1xpd or less. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral, posterolateral, and posterosubmedial foveae very shallow.

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 separately rounded, in posterior aspect margins forming distinct angle with one another.

Venter: Mentum finely punctulate, shining. Postmentum densely micropunctulate, dull. Genae raised, dull, without posterior ridge. Metaventral plaques absent. 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. Metaventrite with very short longitudinal ridge on each side, extended posteriorly from margin of each mesocoxal cavity. AIS width at straight posterior margin ca. 2x P2. All tibiae slender, protibia very slightly arcuate, meso- and metatibiae straight. Abdominal apex with apicomedian indentation.

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

Etymology. Named in reference to the entirely setose metaventrite, which lacks plaques.

Figures

FIGURE 5. Dorsal habitus of Cameroonian species of Hydraena in Aedeagal Species Group 5.

FIGURE 38. Hydraena camerosetosa, new species, habitus and aedeagus of holotype.

FIGURES 42–43. Geographical distributions of Cameroonian Hydraena.