Hydraena sebastiani, 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 : 81

Hydraena sebastiani , new species

Figs. 60 (habitus), 63 (aedeagus), 66 (map)

Type material. Holotype (male): South Africa: Western Cape Province, Groot Toren farm, river shore and stones, 31° 20' S, 19° 44' E, 15 ix 1994, Endrödy-Younga (#3004) ( TMSA) . Paratypes: Same data as holotype (7 TMSA) .

Differential diagnosis. The smallest member of the group (ca. 1.80 mm) ( Fig. 60 ), which has metaventral plaques as large as those of the larger bodied H. monikae (ca. 1.92 mm); plaque ratios of both ca. 2/2/10/3. The aedeagus ( Fig. 63 ) distinctively differs from the other members of the group.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.80/0.70; head 0.30/0.43; pronotum 0.40/0.51, PA 0.44, PB 0.43; elytra 1.11/0.70.

Dorsum of head piceous; pronotum dark brown to piceous except brown to light brown at anterior angles and narrowly along anterior margin; elytra dark brown; legs and maxillary palpi brown. Dorsum coarsely densely punctate.

Frons punctures ca. 3–4xef; interstices narrow walls, very weakly shining. Clypeus mcr laterally, coarsely punctate medially, punctures slightly smaller than those of frons. Mentum and postmentum densely coarsely punctate; mentum with basomedian depression, postmentum with small median depression or confluent punctures. Genae raised, densely punctate, dull, with posterior ridge.

Pronotum laterally slightly emarginate in front of and 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; PF1 absent; PF2 shallow; PF3 deep; PF4 moderately deep.

Elytra moderately widely arcuate laterally; summit of posterior declivity at ca. midlength; lateral explanate margin moderately wide; on basal 1/3 punctures slightly smaller than largest pronotal punctures, punctures becoming slightly finer and more widely spaced toward posterior. Intervals 2, 4 and 6 very slightly raised, dull; interstices on basal 1/3 narrow walls to 0.5xpd, 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. 2/2/10/3. 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, punctate along margins, converging slightly toward one another anteriorly, weakly 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. 1x 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. 40 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 honor of the collector, Sebastian Endrödy-Younga.

Distribution. Currently known only from the type locality ( Fig. 66 ).

Figures

FIGURE 60. Hydraena sebastiani, 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.