Hydraena simplipes Zwick, 1977

PERKINS, PHILIP D., 2007, A revision of the Australian species of the water beetle genus Hydraena Kugelann (Coleoptera: Hydraenidae), Zootaxa 1489 (1), pp. 1-207 : 63-64

Hydraena simplipes Zwick, 1977

(Figs. 87, 94, 96, 262)

Hydraena simplipes Zwick, 1977: 155 .

Type Material. Holotype (male): New South Wales [either in the vicinity of Sydney or the Blue Mountains ] [labels: Umg. Sydney (via WDWilliams) // Holotype // Aedeagus drawn by P. D. Perkins // DIGITAL IMAGE captured 2004 P. D. Perkins // Hydraena simplipes Zwick Holo-Typus des. P. Zwick 1977]. Deposited in the ANIC.

Differential Diagnosis. Recognized by the combination of the large body size (ca. 2.15 mm), the very

small plaques, and, in males, the simple metatibiae (Fig. 87). Size, dorsal sculpture, pronotal shape, and plaques most similar to H. impercepta (Fig. 88); males are distinguished therefrom by the non-modified metatibiae. The aedeagi of the two species are quite distinct (Figs. 93–96).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 2.15/0.92; head 0.29/ 0.48; pronotum 0.51/0.70, PA 0.53, PB 0.62; elytra 1.36/0.92. Dorsum dark brown, head and pronotal disc piceous, legs and palpi brown, distal 1/2 of last palpomere darker (holotype is teneral, more lightly colored).

Frons punctures ca. 1–2xef; interstices narrow walls to 2xpd. Clypeus microreticulate laterally; punctation slightly smaller than frons. Mentum weakly shining, densely, finely punctate; postmentum microreticulate. Genae raised, lacking posterior ridge. Pronotum densely coarsely punctate, punctures on disc deep, ca. 3xpd those of frons, interstices narrow walls forming reticulate pattern; PF1 absent; PF2 shallow; PF3 and PF4 shallow, broad.

Elytral punctures about equal size of largest pronotal punctures. Intervals not raised, weakly shining, width ca. 0.5–1xpd; interstices between punctures of a row narrow walls to 0.5xpd. Apices in dorsal aspect separately rounded, in posterior aspect margins forming weak angle with one another.

Plaque indistinct (see notes). P1 laminate; median carina angulate in profile. P2 moderately narrow, l/w ca. 4/1, sides parallel or slightly diverging toward blunt apex. No midlongitudinal carina between mesoventral intercoxal process and plaques. Cuticle asperite under hydrofuge pubescence. AIS flat, width at arcuate posterior margin 2x P2. Profemur (male) with pointed tubercle on medial surface at about basal 1/3. Protibia straight, widest subapically. Metatibia simple. Abdominal apex asymmetrical.

Aedeagus (Fig. 94, 96) main-piece much wider in lateral than ventral view, with large, strong process on right side of apical part, medial margin of process with rounded apex and point at about midlength; left paramere as large as distal piece, with setae in three groups; right paramere lobe-shaped apically, with two groups of setae. Females are not yet known.

Distribution. Currently known from eastern New South Wales (Fig. 262).

Material Examined (6): New South Wales, 2 km N Batemans Bay , 35° 43' S, 150° 12' E, 18 April 1997, C. Watts (1 SAMA) ; 2 km S. Nowra , 34° 52' S, 150° 36' E, 27 November 1998, C. Watts (2 SAMA) ; Failford , 8 km N, 32° 0' S, 152° 27' E, 18 August 1997, C. Watts (2 SAMA) ; Sydney , 33° 52' S, 151° 12' E, 1–30 August 1961, C. Watts (1 SAMA) .