Hydraena genumorpha, 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 : 15-18

Hydraena genumorpha , new species

Figs. 7 (habitus), 9 (aedeagus), 80 (map)

Type material. Holotype (male): South Africa: KwaZulu-Natal Province, Karkloof Grassveld, floating debries, 29° 19' S, 30° 15' E, 12 ix 1989, Endrödy-Younga & Klimaszewski (#2753) ( TMSA). Paratypes (28): South Africa: Eastern Cape Province, Farm Dam nr. Mooi River, mud with Juncus and Nitella , 31° 0' S, 28° 30' E, 2 iv 1954, J. Balfour-Browne (134) (1 BMNH) ; KwaZulu-Natal Province, Karkloof Grassveld, floating debries, 29° 19' S, 30° 15' E, 12 ix 1989, Endrödy-Younga & Klimaszewski (#2753) (12 TMSA); Limpopo Province, Doornfontein , grassy pool, much blanket algae, elev. 957 m , 24° 48' S, 27° 30' E, 17 iv 1954, J. Balfour-Browne (168a) (1 BMNH); N. Transvaal, Waterberg, Haakdoringboom farm, shore washing , 24° 11' S, 27° 50' E, 11 ii 1976, A. Strydom, Endrödy-Younga (#1029) (2 TMSA); Mpumalanga Province, E. Transvaal, Potholes , shore washing, elev. 1050 m , 24° 31' S, 30° 50' E, 4 v 1981, Endrödy-Younga (#1774) (9 TMSA); Khalava, Mutale River, Camp Drift , sandy edges, elev. 1249 m , 22° 30' S, 30° 54' E, 25 iv 1954, J. Balfour-Browne (194) (2 BMNH); Western Cape Province, Heuningnes River , shore washing , 34° 42' S, 20° 2' E, 28 x 1983, Endrödy-Younga (#2028) (1 TMSA) .

Differential diagnosis. Very similar in size and habitus to most members of the Cooperi Group ( Fig. 7 ). The metaventral plaques are more elongate than in the other members (ratio ca. 1.5/1/4/4 vs. ca. 2/1/1/5). However, reliable determinations will require careful examination of the aedeagus ( Fig. 9 ). See also the diagnosis of H. reflectiva .

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.39/0.58; head 0.22/0.36; pronotum 0.33/0.45, PA 0.39, PB 0.42; elytra 0.85/0.58. Dorsum of head dark brown to piceous; pronotum brown at margins, gradually grading to dark brown on disc; elytra brown; legs light brown; maxillary palpi testaceous, except distal ½ of last palpomere slightly darker.

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

Pronotum laterally slightly emarginate behind middle; anterior margin straight behind eyes, emarginate behind frons, scintilla absent; punctures on disc ca. 1xpd of largest punctures of frons, interstices shining, 1–3xpd, punctures larger and denser at anterior and posterior; PF1 absent; PF2 very shallow; PF3 moderately deep; PF4 very shallow or obsolete.

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, shining, on basal 1/3 ca. 1–2xpd, as are interstices between punctures of a row. Apices in dorsal aspect weakly separately rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 1.5/1/4/4. P1 laminate; median carina sinuate in profile. P2 l/w ca. 4/1, sides slightly converging toward blunt apex, apex raised slightly above mesoventral intercoxal process. Plaques narrow, elongate oval, parallel or very slightly converging toward one another anteriorly, weakly raised, margins not strongly demarcated, 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 slender, protibiae very slightly arcuate, meso- and metatibiae straight. Abdominal apex symmetrical; last tergite with apicomedian notch. Female (microslide mount, n=1): last tergite moderately broadly rounded, with minute apicomedian notch, ca. 36 hooked setae; 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 'bent' shape of the aedeagus.

Distribution. A very wide but very sparse distribution pattern, from southernmost tip of the cape northward to Mpumalanga Province, South Africa ( Fig. 80 ).

Figures

FIGURE 7. Hydraena genumorpha, holotype, dorsal and lateral habitus.

FIGURES 8–9. Aedeagi of holotypes.

FIGURES 79–80. Geographical distributions of Hydraena species.