Hydraena clavicula, 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 : 38-40

Hydraena clavicula , new species

Figs. 26 (habitus), 28 (aedeagus), 83 (map)

Type material. Holotype (male): South Africa: Mpumalanga Province, Uitsuk , window trap, 25° 15' S, 30° 33' E, 15 xii 1986, Endrödy-Younga (#2390) ( TMSA) . Paratypes (42): 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) (6 TMSA) ; KwaZulu-Natal Province, nr. Drummond , small stream, stony and weedy pools, elev. 457.2 m, 30° 50' S, 30° 25' E, 1 iv 1954, J. Balfour-Browne (128) (5 BMNH) ; Limpopo Province, Doornfontein , grassy pool, much blanket algae, elev. 957 m, 24° 48' S, 27° 30' E, 17 iv 1954, J. Balfour-Browne (168a) (2 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, Albany Museum catalog GEN 418J: 252400S- 305430E, 25° 24' S, 30° 54' E, (2 AMG); E. Transvaal, Berlin, river stones, elev. 1200 m , 25° 33' S, 30° 43' E, 11 xii 1986, Endrödy-Younga (#2376) (1 TMSA); E. Transvaal, Blyderiver Canyon, shore washing , 24° 35' S, 30° 49' E, 2 v 1981, Endrödy-Younga (#1765) (6 TMSA); E. Transvaal, Blyderiver Canyon, water stones , 24° 35' S, 30° 49' E, 2 v 1981, Endrödy-Younga (#1764) (5 TMSA); N. Transvaal, Louis Trichardt, 22k W., river stones , 23° 2' S, 29° 40' E, 1–5 iv 1976, Endrödy-Younga & L. Schulze (#1125) (12 TMSA); Soutpansberg, Entabeni Forest St. , river stones , 22° 58' S, 30° 16' E, 21 i 1989, Endrödy-Younga (#2606) (1 TMSA) .

Differential diagnosis. Similar in dorsal habitus to H. zimbabwensis ( Figs. 26 , 27 ); differing therefrom by larger size (ca. 1.51 vs. 1.37 mm), narrower and less coarsely punctate elytra, and metaventral plaques. The plaques of H. clavicula are longer than the width separating them (ratios 2/1/4/3), whereas in H. zimbabwensis the separation is greater than the length (ratios 2/1/2/4). The aedeagi show a similarity in basic form, but differ in proportions, shapes of the parameres, and details of the distal part ( Figs. 28, 29 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.51/0.60; head 0.24/0.37; pronotum 0.36/0.48, PA 0.38, PB 0.41; elytra 0.90/0.60.

Dorsum of head dark brown to piceous; pronotum brown near margins, gradually grading to dark brown on disc; elytra dark brown; legs brown; maxillary palpi light brown.

Frons punctures ca. 1.5xef, denser near eyes than medially; interstices weakly shining, 0.5–1xpd laterally, 1– 2xpd medially. Clypeus mcr laterally, very finely sparsely punctulate medially. Mentum moderately densely finely punctulate, dull, with shallow basomedian impression; 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 slightly larger and deeper than those of frons, interstices shining, 0.5– 2xpd, punctures denser at posterior; PF1 absent; PF2 shallow; PF3 moderately deep; PF4 shallow.

Elytra weakly arcuate laterally; summit of posterior declivity at ca. midlength; lateral explanate margin moderately wide; 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 conjointly rounded, in posterior aspect margins forming shallow angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/1/4/3. 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 very small, very 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 slender, protibiae slightly arcuate, meso- and metatibiae straight. Abdominal apex symmetrical; last tergite with apicomedian notch. Female (microslide mount, n=1): last tergite moderately sharply rounded, with moderately deep apicomedian notch, ca. 16 hooked setae, very thin, widely spaced, set back from margin such that ca. 1/3 to ½ extend beyond margin; gonocoxite not midlongitudinally divided, apical margin moderately sharply rounded, low transverse ridge evident at border of microreticulation; spermatheca simple, type C shape.

Etymology. Named in reference to the key-like shape of the aedeagus.

Distribution. A rather wide distribution in eastern and northern South Africa, with southernmost localities coastal, northern localities inland ( Fig. 83 ).

Figures

FIGURE 26. Hydraena clavicula, holotype, dorsal and lateral habitus.

FIGURE 27. Hydraena zimbabwensis, holotype, dorsal and lateral habitus.

FIGURES 28–29. Aedeagi of holotypes.

FIGURES 81–84. Geographical distributions of Hydraena species.