Hydraena ruinosa 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 : 116-117

Hydraena ruinosa Zwick, 1977

(Figs. 192, 194, 198–200, 224, 231, 246)

Hydraena ruinosa Zwick, 1977: 180 .

Type Material. Holotype (male): New South Wales, Nepean River [ca. 33° 43' S, 150° 39' E] [labels: "Nepean R. 7.9.29 H J C // Hydraena simplicicollis lkb. // [pink label] // Holotype // Paratype // Aedeagus drawn by P. D. Perkins // DIGITAL IMAGE captured 2004 P. D. Perkins // Hydraena ruinosa Zwick Holo- Typus des. P. Zwick 1977 "]. Deposited in the ANIC.

Differential Diagnosis. Similar in some characters to H. fundata ; differing therefrom by the flatter, more elongate body form with more sharply rounded elytral apices, the thicker metatibiae, and the smaller size (ca. 1.31 vs 1.40 mm) (Figs. 192–194) The aedeagi of the two species differ markedly (Figs. 198–201).

Description [based in part on male specimen from Victoria, Kangaroo Creek; holotype is fragmentary]. Size: (length/width, mm): body (length to elytral apices) 1.31/0.55; head 0.20/0.32; pronotum 0.31/0.45, PA 0.36, PB 0.45; elytra 0.80/0.55. Head dark brown to piceous; pronotum with large dark brown macula surrounded by testaceous; elytra dark brown; maxillary palpi and legs testaceous. Dorsum strongly shining.

Frons punctures near eyes ca. 1xef, much finer and very sparse on disc. Clypeus very finely sparsely punctate on disc, very weakly, effacedly microreticulate laterally. Mentum shining, very finely sparsely punctate; postmentum microreticulate. Genae raised, lacking posterior ridge. Pronotum very finely, very sparsely punctate; PF1 and PF4 absent; PF2 very shallow, almost absent; PF3 shallow, broad.

Elytral punctures very fine and very sparse, becoming obsolete over posterior declivity. Intervals not raised, strongly shining. Apices in dorsal aspect conjointy rounded, in posterior aspect margins form weak angle with one another.

Ratios of P2 width and plaque shape (P2/w/l/s) ca. 3/2/8/3. P1 laminate; median carina straight in profile. P2 short and moderately wide, l/w ca. 4/3, sides parallel, apex blunt. Plaques large, convergent and nearly confluent anteriorly, located on sides of deep median triangular depression. AIS flat, width at arcuate posterior margin less than 2x P2. Protibia weakly arcuate on lateral margin, widest at about distal 2/3, medial margin at widest point with small spine. Mesotibia and metatibia slender, simple. Last sternite symmetrical; last tergite with very small apicomedian notch.

Aedeagus (Fig. 198–200) main-piece distally with medially bent process on right side; distal piece, in ventral view, with three terminal processes, the middle one with the gonopore bearing flagellum, the right most process forming a large lobe in lateral view; left paramere longer than right, sparse, long setae at apex and continuing along part of ventral margin; right paramere inserting much more distally than left paramere, with setae at acute apex and along part of ventral margin. Female last tergite with three incisions, delimiting four lobes, setae on disc slender, tapering, setae along margin slender, tips blunt and bent ventrad, not forming a discrete line of setae as in the luridipennis Group; gonocoxite and spermatheca as illustrated (Figs. 224, 231).

Distribution. Widely, but very sparsely, distributed from Tasmania to northern Queensland (Fig. 246).

Remarks. The color and plaque configuration of the single female available for study (paratype) do not differ significantly from those characters of males. The aedeagus of the holotype is missing the left paramere and the distal process tip is missing. I have illustrated the aedeagus of the holotype, and that of a specimen from Victoria, Kangaroo Creek (Figs. 198, 199).

Material Examined (87): New South Wales, 2 km N Batemans Bay , 35° 43' S, 150° 12' E, 18 April 1997, C. Watts (1 SAMA) ; Gilgandra , 31° 42' S, 148° 40' E, 19 November 1992, C. Watts (24 SAMA) ; Nepean River , 33° 43' S, 150° 39' E, 7 September 1929, H. J. Carter (1 ANIC) ; Prospect / St. Mary's Road , 33° 47' S, 150° 55' E, 24 March 1965, M. E. Bacchus (MEB 212) (12 BMNH) ; Queensland, 4 km S Yungaburra , 17° 17' S, 145° 34' E, 6 November 1990, D. Larson (33 MCZ) ; Harlin , 26° 58' S, 152° 21' E, 26 February 1938, A. May (1 QDPC) ; Tasmania, Nile River , 5 km NE of Deddington, cobble-bank of small river; remnant sclerophyll forest, pasture, elev. 275 m, 41° 34' S, 147° 28' E, 17 February 2000, N. Porch (72) (2 ANIC) ; Victoria, Cann River , flood debris, 37° 29' S, 149° 9' E, 20–25 May 1978, S. & J. Peck (1 ANIC) ; Healesville, Dandenong Ranges , 37° 39' S, 145° 32' E, 1–30 December 1968, C. Watts (8 SAMA) ; Kangaroo Creek on Springhill Rd. , 5.8 km E Glenlyon, amongst weeds in shallow water at edge of creek (perennial) pools, dry sclerophyll forest, elev. 510 m, 37° 18' S, 144° 18' E, 31 January 1999, N. Porch (NP 24a) (1 ANIC) ; Kororoit Creek, at Sydenham / Melton Road , organic mud and litter at edge of pool in dry creek in pasture and degraded riverine forest, elev. 110 m, 37° 41' S, 144° 38' E, 17 February 2002, N. Porch (91) (3 ANIC) .