Hydraena camerolatula, 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 : 20

Hydraena camerolatula , new species

Figs. 4 , 23 (habitus), 23 (aedeagus), 43 (map)

Type Material. Holotype (male): Cameroon : Northwest Province. “ BRITISH CAMEROONS. / Mamfe, 7-11.i.1949 / B. Malkin coll. // Rain forest; clear stream / Gravel and sand” ( UKNHM) . Paratype: Same data as holotype (1 UKNHM) .

Differential Diagnosis. Differentiated from other members of the genus in Cameroon by the combination of the moderately densely punctate dorsum, the relatively wide mesoventral intercoxal process (P2, l/w ca. 2/1), and the aedeagus ( Fig. 23 ). Hydraena cameropetila is also densely punctate, but much smaller (1.20), and lacks plaques. H. camerocrebrata is also densely punctate, but much smaller (ca. 1.33 vs. 1.50), and the plaques are larger (P2/w/l/s ratios ca. 1/1/6/6 vs. 1/0.2/2/2). Also refer to the diagnosis of H. camerocrebrata .

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.49/0.62; head width 0.36; pronotum 0.37/0.50, PA 0.42, PB 0.44; elytra 0.88/0.62. Habitus as illustrated ( Fig. 23 ). Dorsum light brown 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 moderately finely sparsely punctulate, pronotum moderately coarsely, moderately 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 and posterolateral foveae moderately deep, posterosubmedial foveae very shallow.

Elytra with summit of posterior declivity slightly beyond midlength, where elytra transversely quite convex; lateral explanate margins moderately wide; 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 very finely punctulate, 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 relatively wide, l/w ca. 2/1, sides parallel or slightly diverging toward blunt apex, apex raised slightly above mesoventral intercoxal process. Plaques very narrow, very indistinct, straight, parallel, 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. 1x P2, or slightly narrower than P2. All tibiae slender, protibia very slightly arcuate, meso- and metatibiae straight. Abdominal apex with slightly off center 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 relatively wide mesoventral intercoxal process (P2).

Figures

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

FIGURE 23. Hydraena camerolatula, new species, habitus and aedeagus of holotype.

FIGURES 42–43. Geographical distributions of Cameroonian Hydraena.