Hydraena cameroflagellata, 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 : 28-29

Hydraena cameroflagellata , new species

Figs. 5 , 36 (habitus), 36 (aedeagus), 42 (map)

Type Material. Holotype (male): “ Cameroon: C. S. Prov., 15 km. S. Mbalmayo, Nyong River , ex. leaves at margin, 22.v.1982, leg. P. D. Perkins ” ( MCZ) . Paratypes: Same data as holotype (2 MCZ); Akonolinga, moist secondary forest and plantation, at light, 7.i.1978, leg. Gardensforhall & Samuelson (1 LUM) .

Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the small size (ca. 1.05 mm, smallest species in Cameroon), the very narrow, very short, carinate or subcarinate, and widely separated plaques (P2/w/l/s ca. 1/0.2/2/2), and the male genitalia ( Fig. 36 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.05/0.45; head width 0.27; pronotum 0.27/0.37, PA 0.31, PB 0.33; elytra 0.77/0.45. Habitus as illustrated ( Fig. 36 ). Dorsum light brown to 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 moderately sparsely punctulate, pronotum moderately finely, moderately densely punctate, punctures ca. 1xpd of largest punctures of frons, interstices shining, ca. 1–3xpd. Labrum apicomedially excised, free margins weakly upturned. Pronotum with anterior margin weakly emarginate over middle 1/2; anterolateral foveae moderately deep, posterolateral shallow or absent, posterosubmedian foveae shallow, medially confluent forming U-shaped impression.

Elytra with summit of posterior declivity slightly beyond midlength; lateral explanate margins narrow; on basal 1/3 punctures slightly 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 weak angle with one another.

Venter: Mentum moderately sparsely very finely punctulate, shining; postmentum very finely densely micropunctulate, dull. Genae raised, shining, without posterior ridge. Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1/0.2/2/2. P1 laminate; median carina sinuate in profile. P2 l/w ca. 2/1, sides slightly converging toward blunt apex, apex raised slightly above mesoventral intercoxal process. Plaques very narrow, slightly arcuate, slightly converging toward one another anteriorly, raised, located at sides of deep median depression. AIS width at straight posterior margin ca. 1.5x P2. Protibia slender, very weakly arcuate. Meso- metatibiae slender, straight. Abdominal apex symmetrical, with very small apicomedian notch.

Distribution. Currently known only from the type locality ( Fig. 42 ).

Etymology. Named in reference to the known distribution, and to the very long aedeagal flagellum.

Figures

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

FIGURE 36. Hydraena cameroflagellata, new species, habitus and aedeagus of holotype.

FIGURES 42–43. Geographical distributions of Cameroonian Hydraena.