Hydrocanthus (Sternocanthus) waterhousei BLACKBURN 1888

Toledo, M. & Hendrich, L., 2006, Taxonomic revision of the Australasian Hydrocanthus SAY 1833, with description of two new species (Coleoptera: Noteridae), Linzer biologische Beiträge 38 (1), pp. 935-952 : 940-941

Hydrocanthus (Sternocanthus) waterhousei BLACKBURN 1888 ( Figs 4 , 10 , 15 , 17 , 19 )

Hydrocanthus waterhousei BLACKBURN 1888: 65 (orig. descr.).

Hydrocanthus (Sternocanthus) waterhousei BLACKBURN - WATTS 1985: 27; LAWRENCE et al. 1987: 327; LARSON 1993: 60; 1997: 273; WATTS 2001: 61; 2002: 51-55.

Hydrocanthus (Sternocanthus) waterhousi BLACKBURN 1888 (misspell.): BAMEUL 1994: 362; NILSSON & VONDEL 2005: 120.

Type material: Not studied.

M a t e r i a l e x a m i n e d: AUSTRALIA: Western Australia: 1 ex.: Gibb River Road/ Silent Grove, Bell George , 017°00'36,3''125°13'25,3''E, 19.VII.1998, Dr. W. Ullrich leg. ( NMW) ; 4 exs.: E Kimberley, Mt. Barnett, Manning River , S 016°39'22 E 125°55'43.5, 18.VII.1998, Dr. W.G. Ullrich leg. ( NHMB) ; 7 exs.: Shire of Derby, West Kimberley, Gibb River Road , Galvans Gorge , 420 m, 21.VI.1999, Hendrich leg., WA 19/119 ( CHB) ; Queensland: 5 exs.: N Queensland, 20 km E of Normanton , II.1996, at light, S. Lamond leg. ( CHB) ; 10 exs.: N Queensland, 20 km E of Normanton , I.1996, at light, riverside ( CHB) .

D i a g n o s i s: Unmistakable species, oblong, weakly convex, coloration uniformly reddish or reddish-brown. Dorsal surface glossy, not iridescent. Right side of aedeagus without transverse ridge ( Fig. 4 ).

D e s c r i p t i o n: total length: 5.9-6.35 mm; total length without head: 5.3-5.65 mm; maximum width: 2.7-2.9 mm.

Head: slightly paler on clypeus; dorsal reticulation quite impressed, made by clearly distinguished circular cells; no dots are visible on the surface. Underside of the same colour as dorsum, labrum, antennae and mouthparts testaceous.

Pronotum: almost straight on fore half; beads of lateral sides and hind side more flat than in the preceding species. Dorsal surface with a reticulation finer than on head, arranged in shallow longitudinal wrinkles finely sculptured.

Elytra: elongate, with maximum width at the base; lateral sides, in dorsal view, poorly rounded an quite angulated just behind the half their length; seen in lateral view, straight at the shoulders. Surface shining; reticulation as on pronotum; two kind of dots are clearly visible: larger ones, arranged in two longitudinal series, somewhat regular in the basal half and more sparse in the apical half; smaller and finer dots arranged longitudinally along the suture and between the rows of larger dots.

Underside: reddish-yellow, slightly darker on prosternal process, metasternal and metacoxal plate and sternites; surface covered by a sculpture of quite impressed polygonal meshes, finer on sternites. Prosternum flat, slightly narrowed between the coxae and, therefore, prosternal process not so broadened as in other species of Hydrocanthus . Punctuation on prosternum and prosternal process close and uniform. Punctuation on metasternal and metacoxal plates visibly more scattered, and almost glabrous in the middle. Legs: yellow; metafemora with few dots along fore and hind side.

: Median lobe of aedeagus ( Fig. 10 ) quite slender, broader in distal half. A trace of a transverse ridge on left side is very hardly visible. Left paramere ( Fig. 15 ) similar to that of H. australasiae but more slender.

: Similar to, not differing from male externally.

H a b i t a t: See H. australasiae ( Fig. 19 ). According to LARSON (1993, 1997) and WATTS (2002) a strictly lentic species. Also attracted to light.

D i s t r i b u t i o n: Tropical north of Australia ( Fig. 17 ). From the Kimberley Plateau in Western Australia, Kakadu National Park in the Northern Territory to Lawn Hill National Park, Normanton, Atherton Tableland ( LAWRENCE et al. 1987; LARSON 1993, 1997; WEIR 1998; WATTS 2001, 2002) and White Mountains National Park in northeastern Queensland (WEIR in litt.). First record for Western Australia.

Figures

Figs 1-6: Habitus of: (1) Hydrocanthus balkei; (2) H. pederzanii; (3) H. australasiae; (4) H. waterhousei; (5) indicus, f. typica; (6) indicus, black form (scale: 2 mm).

Figs 7-11: Median lobes of aedeagus (left lateral view, rotated): (7) Hydrocanthus balkei; (8) H. pederzanii; (9) H. australasiae; (10) H. waterhousei; (11) H. indicus.

Figs 12-16: Left paramere (inner face, rotated): (12) Hydrocanthus balkei; (13) H. pederzanii; (14) H. australasiae; (15) H. waterhousei; (16) H. indicus.

Fig. 17: Distribution of the Australasian species of the genus Hydrocanthus (Sternocanthus) after LARSON (1993, 1997), WEIR (1998) and specimens cited in this publication. Hydrocanthus australasiae (triangles), H. waterhousei (asteriks), H. balkei (square) and H. pederzanii (dots).

Figs 18-20: Habitats of Hydrocanthus in northern Australia: (18, 19) Galvan´s Gorge, Western Australia, East Kimberley. Habitat of numerous Dytiscidae and the Noteridae Hydrocanthus australasiae, H. waterhousei and Canthydrus ephemeralis WATTS 2001; (20) King Edward River Crossing, Kimberley Plateau, Western Australia. Habitat of H. australasiae.