Hydraena rosannae Audisio, Trizzino & De Biase, 2009

Audisio, Paolo, Trizzino, Marco, Biase, Alessio De, Mancini, Emiliano & Antonini, Gloria, 2009, A new species of Hydraena (Coleoptera: Hydraenidae) of the H. evanescens complex from Sardinia *, Zootaxa 2318, pp. 281-289 : 283-285

Hydraena rosannae Audisio, Trizzino & De Biase , sp. nov.

( Figs 1, 7–8, 11)

Diagnosis. Small-sized (length 1.94–2.21 mm), elongate orange species with yellowish to orange legs and antennae; pronotum 0.62–0.81 times width of combined maximum elytral width ( Fig. 1). Similar to the widespread Sardinian H. tyrrhena Binaghi, 1961 and to the Corsican H. evanescens Rey, 1884 , recently redescribed by Audisio and De Biase (1995), but with a much less deep emargination on dorsal profile of aedeagus (in lateral view), slightly more inflated apical portion of male hind tibiae, and slightly sinuose and dilated middle portion of male front tibiae ( Fig. 1).

Type material. Holotype ♂: Italy, Sardinia (Medio Campidano province), above Villacidro, Cannisoni River , 390 m a.s.l., 39.24. 37.28 N, 8.38. 27.39 E, 19.V.2008, M. Trizzino, P. Audisio, G. Nardi & M.Bardiani leg. (CAR).

Paratypes: same data as holotype, 2 ♂, 3 ♀♀ ( CAR, CDL, CDM) .

Description. Male [measurements refer to holotype]. Length (apex of labrum – apex of pygidium) 2.21 mm; breadth (at elytral widest point) 0.70 mm, pronotal breadth 0.57 mm. Elongate, scarcely convex ( Fig. 1), orange with shiny reflections. Legs, antennae and lateral edges of pronotum yellowish to pale orange.

Labrum with deep, V-shaped notch anteriorly; margins very slightly upturned. Fronto-clypeal suture almost straight. Middle of frons moderately densely punctate, interstices shining; lateral portions of frons densely and rugosely punctate, punctures and interstices microreticulate; paraocular grooves shallow. Eyes moderately large, protruding, with more than 20 facets visible in dorsal view. Maxillary palpi very long, about twice as long as distance between eyes. Antennae small, of normal shape for members of the Haenydra lineage ( Fig. 1).

Pronotum nearly exagonal, about 1.15 times wider than long; anterior margin slightly concave; anterior angles slightly obtuse; lateral margin moderately produced at middle, strongly convergent at anterior angle, sinuately convergent at posterior angle; lateral rim minutely crenulate; disc moderately convex, sparsely to moderately densely punctate, more densely punctate near anterior and posterior margins, smooth and punctate between punctures, foveae hardly perceptible; anterior and posterior sublateral foveae well impressed, elongate; lateral portion of pronotum evenly deflexed, sparsely punctate ( Fig. 1).

Elytra elongate, nearly 1.8 times as long as their combined width, slightly and regularly arcuate at sides, apically produced and only very weakly declivitous; moderately declivitous laterally; with seven rows of punctures between suture and shoulder; strial punctures moderately large, distinctly impressed and forming regular lines moderately deeply impressed in middle of each elytron; punctures rather densely arranged within lines; intervals and interstices almost flat and glabrous or superficially microreticulate; intervals slightly wider than one puncture diameter; explanate margin and pseudepipleura relatively narrow and long, not reaching apex ( Fig. 1).

Pygidium in male as in Fig. 1.

Mentum and submentum microreticulate. Transverse genal ridges not very prominent, glabrous.

Prosternum with median keel. Mesoventrite with a pair of sublateral distinct glabrous streaks; very deeply impressed between disc and posterior process. Metaventral disc shallowly impressed between well developed, posteriorly divergent plaques.

First ventrite without glabrous areas behind metacoxal sockets; abdominal sternites III–VI more or less entirely covered with hydrofuge pubescence; abdominal sternites VII and VIII largely glabrous.

Aedeagus ( Figs 7–8): main piece (length ca. 472 µm) oriented as in Figs 7–8, with only two small, short, and hardly distinct setae on left side, apparently without setae on right side; distinctly bisinuous in apical half (dorsal view); with subtruncate projection before the middle (dorsal view), and with proximal obtuse projection on dorsal side of apical fifth; apical third short and thick (lateral view), apex acute; dorsal outline (lateral view) with a very wide and shallow arcuate emargination at distal third; prebasal tooth (lateral view) not very prominent.

Phallobase more or less symmetrical (in dorsal view). Distal mobile lobe small, elongate, composed of two parts: an elongate piece and a very thin and short flagellum.

Secondary sexual characters. Male elytral apices convergent posteriorly, slightly conjointly rounded ( Fig. 1); in female only slightly more acuminately convergent (with small sutural notch). Male femora slightly more strongly built. Male protibiae slightly but distinctly dilated and hardly curved along their inner edge. Male mesotibia not dilated subapically, with a row of short spines and 11–12 minute denticles along their inner edge. Male metatibia slightly but distinctly dilated in distal half, with fringe of very long hairs along their inner edge.

Female. Last abdominal tergite and sternite as in Figs 9–10.

Variability. Length variable between 1.94 and 2.21 mm.

Distribution. Known with certainty only from the Sulcis-Iglesiente area around Villacidro (Medio Campidano province), SW Sardinia.

Biological notes. The type specimens were collected under stones in a stream with relatively fast-running water, on a granodioritic substrate, at nearly 400 m a.s.l.

Etymology. This species is named after Mrs Rosanna Calabrò (M.T.’s wife).