Batrachomatus wilsoni (Mouchamps, 1964) Mouchamps, 1964

Hendrich, Lars & Balke, Michael, 2013, Revision of Australian Matini diving beetles based on morphological and molecular data (Coleoptera, Dytiscidae, Matinae), with description of a new species, ZooKeys 293, pp. 41-64 : 50-53

Batrachomatus wilsoni (Mouchamps, 1964) comb. n.

Allomatus wilsoni Mouchamps, 1964: 140 (orig. descr.); Watts 1978: 116 (descr.); Watts 1985: 23 (cat.); Lawrence et al. 1987: 351 (cat.); Nilsson 2001: 261 (cat.); Watts 2002: 30, 46 (cat.).

Type locality.

Kerrisdale [King Parrot Creek, 165 m, 37°8'8"S, 145°15'36"E], Victoria, Australia.

Type material.

Holotype ♂: Not seen. Paratype ♂: "Macalister Riv 11/46 Vic F.E.Wilson", "Wilson Coll" [handwritten label by Mouchamps], “Paratype” [red, printed label], "Paratype 3804" [blue printed label], "R.Mouchamps det., Allomatus wilsoni nsp." [handwritten, white label by Mouchamps] (MVMA).

Additional material

(2 specimens): New South Wales: 1 ex., "S NSW, Wallagaraugh River Picnic Area, 43 km SW Eden, 54m, 17.XI.2006, 37.22.079S 149.43.073E, L. & E. Hendrich leg. (NSW 112)", "DNA M.Balke 2372" [green printed label] (ZSM). Victoria: 1 ex., "E VIC, Thurra River at Hwy 1, Water Point Rest Area, 138m, 17.XI.2006, 37.34.061S, 149.16.338E, L. & E. Hendrich leg. (VIC 114)" (CLH).

Description.

Measurements. TL = 8.4-8.5 mm, TL-H = 7.5-7.7 mm; MW = 4.0-4.15 mm.

Colour. Head black with epistome and labrum lighter. Palpi and antennae brownish. Pronotum entirely black, slightly lighter at margins. Elytra completely black or with more or less developed brownish humeral patch. Ventral side black, appendages lighter with tarsi reddish brown (Fig. 6).

Structure and sculpture. Body outline oval, large, slightly convex. Head with anterior border of epistome a little excavated, not bordered. Head and pronotum surface covered by polygonal double reticulation, smaller superficial meshes inside bigger meshes, with punctures at intersections of all bigger meshes. Sides of pronotum moderately curved and convergent anteriorly. Sculpture on elytra consisting of a weak double reticulation, meshes polygonal, large, smaller and very fine punctures at intersections of very few meshes. Serial punctures on elytra distinct, large and shallow. Ventral surface covered with weakly defined reticulation, meshes, very elongate and more or less oblique or transverse. Prosternal process flat and excavated in anterior midline by median groove. Lateral borders of prosternal process clearly raised. Lateral wings of metaventrite narrow. Metacoxal lines separating metacoxal plate into three unequal parts; the median sparsely punctured, the lateral and the intralinear space almost smooth with an extremely sparse and scarcely visible microreticulation.

Male. Pro- and mesotarsi dilated and stouter than in female, furnished beneath with dense, short, stout setae arranged in groups, many of the setae ending in minute suction cups. Aedeagus: median lobe (Fig. 11 a, b); paramere (Fig. 11 c).

Affinities.

Batrachomatus wilsoni isin body outline and coloration very near to Batrachomatus daemeli but can be easily separated by the presence of a superficial polygonal double reticulation on pronotum and elytra. Batrachomatus wilsoni differs from Batrachomatus larsoni sp. n. by its larger size ( Batrachomatus wilsoni TL = 8.4-8.5 mm and Batrachomatus larsoni TL = 7.9 mm), the different elytral coloration, and the more oblong and less narrowly formed body. Furthermore, all three species can be separated by the shape of their median lobes.

Distribution.

South-eastern Australia (Fig. 13). A rarely collected species with a very limited distribution. Only known from four sites from southern New South Wales (Wallagaraugh River) to southern and south-eastern Victoria (Macalister River, King Parrot Creek, Thurra River).

Habitat.

Batrachomatus wilsoni inhabits permanent slow flowing larger rivers, at an altitude from about sea level to almost 170 m, in closed-canopy old growth forest sites. The type locality King Parrot Creek, near Kerrisdale, is in many parts a low gradient river, similar to the south-western Australian Blackwood River. The two recently collected specimens from Victoria and New South Wales were found in low-gradient river sections where the substrate was enriched with rotten leaves, wood and larger stones (Figs 18, 19). In this habitat the beetles were found in areas of medium, laminar flow, generally in deeper water (50 cm and more) under larger logs and stones, always together with numerous Batrachomatus daemeli .