Hydraena appetita, Published, 2007

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 : 65-66

Hydraena appetita new species

(Figs. 98, 101, 239)

Type Material. Holotype (male): New South Wales, 14 km W Delagate , 37° 2' S, 148° 44' E, 4 November 1997, C. Watts. Deposited in the SAMA . Paratypes (4): New South Wales, Same data as holotype (3 SAMA) ; South Australia, Mannum , 34° 55' S, 139° 18' E, 1–30 December 1959, C. Watts (1 SAMA) .

Differential Diagnosis. The largest known Australian Hydraena (size ca. 2.65 mm), differentiated from other large, coarsely punctate species by the larger size, the body proportions, with proportionally large elytra, and the large plaques (Fig. 98). Slightly similar in habitus to H. luridipennis (Fig. 86), but differing therefrom by the straight, non-concave, anterior lateral margins of the pronotum, the longer elytra, and the large plaques, among other characters. The aedeagus of H. appetita is quite distinct (Fig. 101).

Description. Size (length/width, mm) holotype: body (length to elytral apices) 2.63/1.07; head 0.33/ 0.53; pronotum 0.60/0.83, PA 0.60, PB 0.73; elytra 1.75/1.07.

Dorsum brown, except head and pronotal disc dark brown or piceous, legs and palpi brown, distal 1/3 of last palpomere darker.

Frons weakly microreticulate, punctures ca. 2xef; interstices ca. 0.5 to 1xpd. Clypeus punctate similar to frons, microreticulate laterally. Mentum weakly shining, very finely sparsely punctate; postmentum microreticulate. Genae raised, lacking posterior ridge. Pronotum densely coarsely punctate, punctures deep, ca. 3– 4xpd those of frons, interstices varying from narrow walls in anterior and posterior 1/3, to ca. 1xpd on disc; PF1 absent; PF2 moderately deep, separated by about width of a fovea; PF3 and PF4 moderately deep, broad.

Elytral punctures about equal in size to largest pronotal punctures. Intervals not raised, shining, width ca. 1.5xpd. Interstices between serial punctures 1xpd or smaller. Punctures near base larger and series irregular. Apices (male) in dorsal aspect narrowly, separately rounded, in posterior aspect margins forming marked angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 2/3/8/4. P1 laminate; median carina angulate in profile. P2 narrow, l/w ca. 7/3, sides parallel or slightly diverging toward blunt apex. Plaques large, located in posterior 7/10 of metaventrite on sides of median depression, plaques wider posteriorly than anteriorly, separation about equal to plaque width. No midlongitudinal carina between mesoventral intercoxal process and plaques. Cuticle asperite under hydrofuge pubescence. AIS flat, width at arcuate posterior margin 2.5x P2. Protibia (male) widened subapically; mesotibia simple; metatibia slender, straight, without setal brushes. Abdominal apex asymmetrical.

Aedeagus (Fig. 101) main-piece tubular, angled near base, with large, finger-like process on right side of apical part; right paramere wide, with setae in three groups; right paramere long and slender, much longer than left paramere, distal part only slightly widened, with setae in two groups. Females are not yet known.

Etymology. Named in reference to the large abdomen.

Distribution. Currently known from two widely separated localities, one each in southeastern South Australia and southeastern New South Wales (Fig. 239).