Hydraena nomenipes, 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 : 65-68

Hydraena nomenipes , new species

Figs. 47 (habitus), 49 (aedeagus), 78 (map)

Type material. Holotype (male): South Africa: Eastern Cape Province, Transkei: S. coast, Dwesa forest reserve, shore washing, forest, 32° 17' S, 28° 50' E, 3 iii 1985, Endrödy-Younga (#2181) ( TMSA) . Paratypes (80): South Africa: Eastern Cape Province, Ciskei, Amatole , Pirie For., UV light collection, 32° 43' S, 27° 17' E, 8 xii 1987 , Endrödy-Younga (#2565) (1 TMSA) ; Transkei , Port St. Jones, Silaka, water collection, 31° 33' S, 29° 30' E, 30 xi 1987, Endrödy-Younga (#2543) (13 TMSA) ; Transkei : S. coast, Dwesa forest reserve, shore washing, forest, 32° 17' S, 28° 50' E, 3 iii 1985, Endrödy-Younga (#2181) (66 TMSA) .

Differential diagnosis. Both sexes have highly modified tibiae, which are markedly flattened and slightly widened at the basal bend, and the femora are apically widened to accommodate the widened tibial base. These characters differentiate this species from all other known southern African Hydraena . The only other hydraenid which has similarly modified tibiae is Mesoceration compressum Perkins which, very curiously, was collected at the very same site and time as H. nomenipes (Sebastian Endrödy-Younga site #2181)!! The aedeagus of this species does not suggest placement in the other species groups ( Fig. 49 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.32/0.56; head 0.21/0.34; pronotum 0.32/0.46, PA 0.36, PB 0.39; elytra 0.79/0.56.

Dorsum brown except head dark brown near eyes; legs brown; maxillary palpi light brown.

Frons punctures ca. 1xef, slightly denser near eyes than medially; interstices shining, 0.5–1xpd laterally, 1– 3xpd medially. Clypeus mcr laterally, very finely sparsely punctulate medially. Mentum and postmentum densely finely punctulate, dull. Genae raised, shining, without posterior ridge.

Pronotum laterally rather broadly rounded, slightly emarginate behind middle; anterior margin straight behind eyes, emarginate behind frons, scintilla absent; punctures on disc finer and sparser than those of frons, interstices shining, 2–5xpd; PF1 absent; PF2 very shallow, almost imperceptible; PF3 shallow; PF4 absent.

Elytra weakly arcuate laterally; summit of posterior declivity at ca. posterior 1/3; lateral explanate margin narrow; on basal 1/3 punctures ca. 1xpd largest pronotal punctures, punctures becoming finer and more widely spaced toward posterior. Intervals not raised, weakly shining, on basal 1/3 ca. 2–3xpd, as are interstices between punctures of a row. Apices in dorsal aspect conjointly rounded, in posterior aspect margins forming very shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1.5/1.5/4/4. 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. Plaques narrow, slightly converging toward one another anteriorly, weakly raised, located at sides of moderately deep median depression. Metaventrite without midlongitudinal carina between intercoxal process and median depression. AIS width at slightly arcuate posterior margin ca. 2x P2. All tibiae (both sexes) markedly flattened and slightly widened at basal bend, femora apically widened to accommodate widened tibial base; tibiae straight distal to basal bend. Abdominal apex symmetrical; last tergite with apicomedian notch. Female (microslide mount, n=1): last tergite moderately broadly rounded, with minute apicomedian notch, ca. 10 non-hooked, very slender setae, widely spaced; gonocoxite not midlongitudinally divided, apical margin moderately broadly rounded, low transverse ridge evident at border of microreticulation; spermatheca simple, type C shape.

Etymology. Named in reference to the distinctively modified legs.

Distribution. Currently known only from a few localities in southeastern Eastern Cape Province, South Africa ( Fig. 78 ).

Figures

FIGURE 47. Hydraena nomenipes, holotype, dorsal and lateral habitus.

FIGURES 48–49. Aedeagi of holotypes.

FIGURES 77–78. Geographical distributions of Hydraena species.