Hydraena vadosa, 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 : 47-49

Hydraena vadosa , new species

Figs. 34 (habitus), 36 (aedeagus), 81 (map)

Type material. Holotype (male): South Africa: Eastern Cape Province, Ciskei, Amatole , Pirie For., sift. wet forest ditch, 32° 43' S, 27° 17' E, 8 xii 1987, Endrödy-Younga (#2561) ( TMSA) . Paratypes (273): South Africa: Eastern Cape Province, Amatole, Pirie Forest Station , shore washing, 32° 43' S, 27° 17' E, 8 xii 1987, Endrödy- Younga (#2563) (14 TMSA) ; Ciskei, Amatole, Pirie For., sift. wet forest ditch, 32° 43' S, 27° 17' E, 8 xii 1987, Endrödy-Younga (#2561) (231 TMSA) ; Transkei, Port St. Jones , Silaka, water collection, 31° 33' S, 29° 30' E, 30 xi 1987, Endrödy-Younga (#2543) (3 TMSA) ; Transkei: S. coast, Dwesa forest reserve, shore washing, forest, 32° 17' S, 28° 50' E, 3 iii 1985, Endrödy-Younga (#2181) (22 TMSA) ; Mpumalanga Province, E. Transvaal, Blyderiver Canyon, shore washing, 24° 35' S, 30° 49' E, 2 v 1981, Endrödy-Younga (#1765) (3 TMSA) .

Differential diagnosis. The dorsal habitus of this species is somewhat similar to that of H. injectiva ( Figs. 22 , 34 ), but that species is smaller (ca. 1.31 vs. 1.69 mm), has different metaventral plaques, and the aedeagi of the two species differ markedly ( Figs. 24 , 36 ). In addition, the pronotal foveae PF2 are shallowly confluent in H. vadosa , and clearly separated in H. injectiva . It is the largest species in the group (ca. 1.69 mm) and the aedeagus is quite divergent from the others; it is quite possible that the species will eventually be placed in another, as yet unknown, group.

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.69/0.71; head 0.28/0.41; pronotum 0.41/0.56, PA 0.44, PB 0.49; elytra 1.00/0.71. Dorsum of head dark brown to piceous; pronotum brown at borders, slightly lighter at anterior border, gradually grading to dark brown on disc; elytra dark brown; legs brown; maxillary palpi light brown.

Frons punctures ca. 1xef, slightly 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 and postmentum densely finely punctulate, dull or interstices weakly shining. 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 slightly larger and deeper than those of frons, interstices shining, 1–3xpd; PF1 absent; PF2 shallow, and very shallowly confluent in midline; PF3 moderately deep; PF4 very shallow or obsolete.

Elytra weakly arcuate laterally; summit of posterior declivity at ca. posterior 1/3; lateral explanate margin moderately wide, terminating rather abruptly at ca. posterior 1/7; 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 very weakly separately rounded, in posterior aspect margins forming deep angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/1.5/6/5. P1 laminate; median carina sinuate in profile. P2 l/w ca. 5/2, sides parallel, apex blunt, apex raised slightly above mesoventral intercoxal process. Plaques moderately wide, slightly arcuate toward midline, slightly converging toward one another anteriorly, weakly raised, margins not strongly demarcated anteriorly, 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, straight; protibiae with inner surface flattened in distal 1/2. Abdominal apex symmetrical; last tergite with small apicomedian notch. Female (microslide mount, n=1): last tergite moderately broadly rounded, with minute apicomedian notch, ca. 10 non-hooked, very fine, rather widely spaced setae, set rather far back from margin; gonocoxite not midlongitudinally divided, apical margin moderately broadly rounded, low transverse ridge evident at border of microreticulation; spermatheca simple, but rather large, type C shape.

Etymology. Named in reference to the very shallow, and confluent, pronotal foveae PF2.

Distribution. Currently known from areas near the coast in eastern Eastern Cape Province, and one locality in Mpumalanga Province, South Africa ( Fig. 81 ).

Figures

FIGURE 22. Hydraena injectiva, holotype, dorsal and lateral habitus.

FIGURE 34. Hydraena vadosa, holotype, dorsal and lateral habitus.

FIGURES 24–25. Aedeagi of holotypes.

FIGURES 36–37. Aedeagi of holotypes.

FIGURES 81–84. Geographical distributions of Hydraena species.