Hydraena duodecimata, Perkins, 2014

PERKINS, PHILIP D., 2014, A revision of the water beetle genus Hydraena Kugelann for southern Africa (Coleoptera: Hydraenidae), Zootaxa 3758 (1), pp. 1-92 : 76

Hydraena duodecimata , new species

Figs. 59 (habitus), 62 (aedeagus), 68 (map)

Type material. Holotype (male): South Africa: Northern Cape Province, No. Cape, Richtersveld, Oemsberg , shore washing in shade, 28° 27' S, 17° 10' E, 23 ix 1991, Endrödy-Younga (#2796) ( TMSA) . Paratypes (14): South Africa: Northern Cape Province, Kamiesberg Stream above Studer Pass , ca. 5 km W of Witwater, D. T. Bilton, 30° 23' S, 18° 7' E, 19 ix 2010, D. T. Bilton (IBE RA298) (1 MNCN) ; Western Cape Province, Same data as holotype (13 TMSA) .

Differential diagnosis. Differentiated from other members of the group by the elytral sculpture, which has intervals 2, 4, 6, 8, and 10 carinate, each forming slightly undulating lines ( Fig. 59 ). The aedeagus ( Fig. 62 ) distinctively differs from other members of the group

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.96/0.79; head 0.38/0.44; pronotum 0.42/0.56, PA 0.46, PB 0.46; elytra 1.17/0.79.

Dorsum of head piceous; pronotum dark brown to piceous except brown to light brown at anterior angles and narrowly along anterior and posterior margins; elytra brown, except explanate margin light brown; legs light brown to testaceous; maxillary palpi brown to light brown, distal ½ of last palpomere darker. Dorsum coarsely densely punctate.

Frons punctures ca. 3–5xef; interstices narrow walls, weakly shining. Clypeus narrowly mcr laterally, moderately coarsely but sparsely punctate medially, punctures smaller than those of frons, ca. 0.5xpd. Mentum and postmentum densely coarsely punctate, some punctures confluent; mentum with basomedian depression, postmentum with small median depression or confluent punctures. Genae raised, densely punctate, dull, with posterior ridge.

Pronotum laterally emarginate in front of and slightly more so behind middle; anterior margin straight behind eyes, shallowly emarginate behind frons, scintilla absent; coarsely densely punctate, punctures on disc ca. 2xpd frons punctures, separated by narrow walls, some walls confluent, forming irregular median line; PF1 moderately deep; PF2, PF3, and PF4 deep.

Elytra moderately widely arcuate laterally; summit of posterior declivity at ca. midlength; lateral explanate margin moderately wide in anterior ½, wider posteriorly; on basal 1/3 punctures ca. 0.5xpd of largest pronotal punctures, punctures becoming slightly finer and slightly more widely spaced toward posterior. Intervals 2, 4, 6, 8, and 10 carinate, each forming slightly undulating line, dull; interstices on basal 1/3 0.5xpd, or slightly smaller, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins do not form angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/2/17/3. P1 slightly wider than laminate; median carina very low, very weakly sinuate in profile. P2 l/w ca. 4/1, sides converging toward narrow apex, apex raised slightly above mesoventral intercoxal process. Plaques large, converging slightly toward one another anteriorly, moderately raised, located at sides of moderately deep median longitudinal depression. Metaventrite with depression lateral to each plaque; without midlongitudinal carina between intercoxal process and median depression. AIS subtriangular, deeply concave, width at slightly arcuate posterior margin ca. 1.5x P2. All tibiae slender, straight. Abdominal apex symmetrical; last tergite with apicomedian incision. Female (microslide mount, n=1): last tergite broadly rounded, without apicomedian notch, ca. 35 hooked setae, contiguous; gonocoxite midlongitudinally divided, apical margin moderately broadly rounded, low transverse ridge evident at border of microreticulation; spermatheca simple, very similar to that of H. monikae .

Etymology. Named in reference to the twelve elytral carinae.

Distribution. Currently known only from two localities in western South Africa, one each in the Western Cape and Northern Cape Provinces ( Fig. 68 ).

Figures

FIGURE 59. Hydraena duodecimata, holotype, dorsal and lateral habitus.

FIGURES 61–63. Aedeagi of H. monikae (non-type), H. duodecimata (holotype), and H. sebastiani (holotype).

FIGURES 66–70. Geographical distributions of Hydraena species.