Hydraena reticulata 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 : 12-13

Hydraena reticulata Zwick, 1977

( Figs. 1 , 5, 6 , 259)

Hydraena reticulata Zwick, 1977: 182 .

Type Material. Holotype (male): Northern Territory, 19 km E of Mt. Cahill , [ca. 12° 50' S, 132° 52' E], 24 May 1973, A. H. Watson [labels: " 12.50S 132.52E 19 km E by N of Mt. Cahill, NT. 24.v.73, A.H. Watson // Larva in spirit collection // More specimens in spirit tube // [pink label] // Holotype // Aedeagus drawn by P. D. Perkins // DIGITAL IMAGE captured 2004 P. D. Perkins // Hydraena reticulata Zwick Holo-Typus des. P. Zwick 1977 "]. Deposited in the ANIC.

Differential Diagnosis. Externally very similar to other members of the reticulata Group ( Figs. 1–4 ); reliable determinations will be based on study of the aedeagus. Similar to H. mitchellensis in the absence of plaques; differing therefrom in the smaller size (ca. 1.21 vs. 1.38 mm), and details of the aedeagus ( Figs. 5–7 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 1.21/0.52; head 0.19/ 0.32; pronotum 0.31/0.44, PA 0.36, PB 0.38; elytra 0.71/0.52. Dorsum dark brown, dull; legs brown; palpi light brown except distal 2/3 of last palpomere darker. Head and pronotum markedly microreticulate, setae short but distinctive.

Frons punctures ca. 1xef; interstices ca. 1xpd. Mentum and postmentum microreticulate. Genae raised, lacking posterior ridge. Pronotal punctures on disc slightly larger than those of frons, interstices ca. 1xpd; PF1 absent; PF2 deep, oblique, separated by less than width of a fovea; PF3 moderately deep, broad; PF4 shallow.

Elytral punctures slightly larger than largest pronotal punctures. Intervals not raised, very weakly shining, width about 1xpd, interstices between punctures of a row narrower, each puncture with distinctive short seta. Apices in dorsal aspect conjointly rounded, in posterior aspect margins form moderately strong angle with one another.

Plaques absent, median depression shallow. P1 laminate; median carina angulate in profile. P2 narrow, l/ w ca. 3/1, sides parallel, apex blunt. AIS flat, width at arcuate posterior margin 2–3x P2. Protibia (male) lateral surface very weakly arcuate, medial surface nearly straight, with prominent, sharp tubercle at distal 2/3; mesotibia simple; metatibia parallel-sided or nearly so for most of length, without setal brush. Abdominal apex symmetrical.

Aedeagus ( Figs. 5, 6 ) main-piece with large pointed process on right side; left paramere widest subbasally, then tapering to narrow tip which ends at level of base of flagellum, setae sparse, in a row on ventral margin; right paramere straight or very weakly arcuate, simple. Female last tergite without incisions, with two transverse ridges, setae slender, tapering.

Distribution. Currently known from northern Northern Territory (Fig. 259).

Material Examined (9): Northern Territory, 19 km E of Mt. Cahill , 12° 50' S, 132° 52' E, 24 May 1973, A. H. Watson (1 ANIC) ; Cooper Creek , 19 km E by S of Mt. Borradaile , 12° 6' S, 133° 4' E, 5 June 1973, M. S. Upton (1 ANIC) ; Kakadu N. P., Deaf Adder Gorge , 12° 16' S, 132° 40' E, 27 March 1980, M. B. Malipatil (1 MAGD) ; Kakadu N. P., Waterfall Creek , 13° 27' S, 132° 25' E, 23 August 1993, Gross & Koller (1 NMW) ; Katherine Gorge N. P., Butterfly Gorge , 13° 44' S, 131° 34' E, 5 December 1980, M. B. Malipatil (5 MAGD) .

Figures

FIGURES 1–4. Hydraena, dorsal and lateral habitus of holotypes. —1. H. reticulata. —2. H. mitchellensis. —3. H. reticuloides. —4. H. reticulositis.

FIGURES 5–8. Aedeagi of holotypes. —5. H. reticulata. —6. H. reticulata (after Zwick 1977). —7. H. mitchellensis. —8. H. reticuloides.