Copelatus bakewelli J. Balfour-Browne, 1939

Hendrich, Lars, Shaverdo, Helena, Hajek, Jiri & Balke, Michael, 2019, Taxonomic revision of Australian Copelatus Erichson, 1832 (Coleoptera, Dytiscidae, Copelatinae), ZooKeys 889, pp. 81-152 : 81

Copelatus bakewelli J. Balfour-Browne, 1939 Figures 1 , 11 , 20 , 30

Copelatus bakewelli J. Balfour-Browne 1939: 86 (original description); Watts 1978: 127 (description); Watts 1985: 26 (general distribution); Watts 2002: 42 (checklist); Nilsson and Hájek 2019: 62 (catalogue).

Type locality.

"North Australia".

Type material.

Holotype: Female, “Holotype” [round label with red frame], “Na” [hw label], “6756” [printed label], " Copelatus bakewelli B-B. Type" [hw label] (NHMUK).

Additional material studied (285 specimens).

Western Australia: 2 exs., "AUSTRALIA WA, Synnot Range 1/9/1969, 16°25'S, 125°28'E, Giuliani D.D. leg." (WAM); 1 ex., "AUSTRALIA/WA/Shire of Wyndham - East Kimberley, Gibb River Road, Drysdale River Crossing, 380 m, 14.6.1999, Hendrich leg. Loc. 9/109" (CLH); 4 exs., "AUSTRALIA/WA/ Shire of Wyndham-East Kimberley, Gibb River Road, King Edward River Crossing, 280 m, 15.6.1999, Hendrich leg./coll. Loc. 10/110" (CLH); 77 exs., "AUSTRALIA/WA/Shire of Wyndham-East Kimberley, Mitchell Plateau, Little Mertens Falls, 300 m, 15.6.1999, Hendrich leg./coll. Loc. 11/111b" (CLH, ZSM); 8 exs., "AUSTRALIA/WA/ East Kimberley, Mitchell Plateau, Little Mertens Falls, 300 m, 15.6.1999, Hendrich leg./coll. Loc. 11a/111a" (NMW); 2 exs., "AUSTRALIA/WA/Shire of Wyndham - East Kimberley, Mitchell Plateau, Port Warrender Road/Kalumburu Road, Lowya Creek, 290 m, 18.6.1999, Hendrich leg. Loc. 13/113" (CLH); 1 ex., "AUSTRALIA/WA/Shire of Wyndham - East Kimberley, Mitchell Plateau, Kalumburu Road, 25 km NW King Edward Homestead, N.N. Creek, 370 m, 18.6.1999, Hendrich leg. Loc. 114" (CLH); 4 exs., "AUSTRALIA/WA/Shire of Wyndham - East Kimberley, Gibb River Road, 10 km E Hann River, Snake Creek, 470 m, 19.6.1999, Hendrich leg. Loc. 16/116" (CLH). Northern Territory: 1 ex., "Australia: NT, Cullen River n. Cullen, at Stuart Hwy, 102 m, 23.VIII.2006, 14.02.052S 131.56.561E, L. & E. Hendrich leg. (NT 13)", "DNA Balke 2213" [green printed label] (ZSM); 1 ex., "Australia: NT, Kakadu Hwy, Harriet Creek at Hwy Cross., 153 m, 24.VIII.2006, 13.44.512S 131.54.012E, L. & E. Hendrich leg. (NT 14)", "DNA Balke 1614" [green printed label] (ZSM); 2 exs., "Australia: NT, Litchfield NP, Creek near Wanggi Falls, 191 m, 20.VIII.2006, 13.11.221S 130.43.327E, L. & E. Hendrich leg. (NT 4)", "DNA Balke 2190", "DNA Balke 2191" [green printed label] (ZSM); 2 exs., "AUSTRALIA NT Kakadu NP Alligator R. Gungaree Rainforest Dec. 22/93 S&J Peck" (ZSM); 1 ex., "NT, Horse Creek fossil site, Camfield Station [-17.1166 131.5166] 2/8/1992", “1004435” (MAGNT); 1 ex., "NT, Top Humbert Yard, Humbert River [-16.4333, 130.4666] 7/1986", “1004443” (MAGNT); 2 exs., "Bathurst Is. + Melville Is. N.T. XII. 1975 D. Curry", "QDPC 0-172712", "QDPC 0-172713" (QDPC); 2 exs., "Australia, NT, Litchfield NP, Florence Falls, 12°51'15"S, 132°45'16"E, 63 m, at light, 12.V.2006, leg. Berger & Dostal (5/06)" (CGW); 8 exs., "Australia, NT, 80 km W Roper Bar, 14°54'19"S, 133°57'28"E, 78 m, at light, 14.V.2006, leg. Berger & Dostal (7/06)" (CGW); 1 ex., "Australia, N.T./Katherine Gorge, Butterfly Gorge Walk, 150 m, 4.7.1999, Hendrich leg. Loc. 33/133" (CLH); 3 exs., "Australia, N.T. Kakadu N.P., Mary River District, 3 km ESE Gunlom Camping Area. South Alligator River, 50 m, 2.11.1996, 13°27.276'S, 132°26.268'E L. Hendrich leg./Lok. 14" (CLH); 3 exs., "Australia, N.T./Kakadu N.P., Jim Jim District, Gungurul Lookout, 50 m, 1.11.1996, 13°59.359'S, 132°19.904'E L. Hendrich leg./Lok. 11" (CLH); 19 exs., "Australia, N.T./Kakadu N.P., Mary River District, Gunlom Camping Area, 50 m, 3.11.1996, 13°26.082'S, 132°24.929'E L. Hendrich leg./Lok. 15" (CLH); 2 exs., "Australia, N.T./Kakadu N.P., Jim Jim District, Barramundie Gorge, Maguk, 50 m, 31.10.1996, 13°18.823'S, 132°26.198'E. L. Hendrich leg./ Lok. 9" (CLH); 12 exs., "Australia, NT/Kakadu N.P., Mary River District, Gunlom Waterfall Creek, 150 m, 2.11.1996, 13°26.082'S, 132°24.929'E L. Hendrich leg./Lok. 13" (CLH); 51 exs., "Australia, N.T./Kakadu N.P., Jim Jim District, 1 km S Jim Jim Falls, 70 m, 26.10.1996, 13°16.718'S, 132°49.490'E L. Hendrich leg./Lok. 3" (CLH); 39 exs., "Australia, N.T./Kakadu N.P., Jim Jim District, Jim Jim Falls Camping Area, Jim Jim Creek, 60 m, 26. & 27.10.1996 13°16.218'S, 132°49.276'E L. Hendrich leg./ Lok. 2." (CLH); 13 exs., "Australia N.T./Kakadu N.P., Nourlangie District, Gubara, 50 m, 25.10.1996, 12°50.101'S, 132°52.501'E L. Hendrich leg./Lok. 1" (CLH); 1 ex., "Australia, NT, Pine Creek, Roper Gulf (S)Waterfall Ck., 60 mi. E of Pine Ck. [-13.81667, 132.7], 7.08.1964, Carne, P.B. leg. (ANIC); 1 ex., "Australia, NT, Daly Basin, Katherine (T) Tindal, -14.51667, 132.3667, 1.12.1967, Vestjens, W.J.M. leg. (ANIC); 10 exs., "Australia: NT, Litchfield NP, TJAYNERA FALLS, 13°15'S, 130°44'E, 63 m, S. Jákl leg., 20 –27.XI.2008” (NMPC). Queensland: 2 exs., "QLD Cook, 2 km NNW Jowalbinna [-15.75, 144.25] 17/01/1994 Zborowski P. & Edwards, E.D.", “25-023624-470” (ANIC); 1 ex., "QLD Cook, 14 km ENE Heathlands [-11.68, 142.7], rainforest, 21/10/1993 Zborowski P. & Rentz D.C.F.", “25-022999-353” (ANIC); 1 ex., "QLD, Townsville [-19.4833, 146.8167], 25.3.1996, CH Watts", “25-001942” (SAMA); 1 ex., "QLD, Townsville [-19.2, 146.68], 6-11/2/1998, AJ Watts", “25-001940” (SAMA); 1 ex., "Bamaga N. Qld. March 1984 J.W. Turner", "QDPC 0-172711" (QDPC); 3 exs., "Bamaca [=Bamaga] xii.1983", "Australian QLD J. Sedlacek" (CLH); 1 ex., "Australia, Queensland, Bald Hills Station 4 km N of Isabella Falls, 15°15' 145°00', 29. December 1984, mv lamp, G. & A. Daniels" (QM).

Description of male.

Body shape. In dorsal view, oblong oval, broadest at midlength of elytra, moderately convex. Body outline continuous, without discontinuity between pronotum and elytra. Head relatively broad; anterior margin of clypeus not bordered. Pronotum broadest between posterior angles, lateral margins moderately curved. Base of elytra as broad as pronotal base; lateral margins of elytra moderately curved ( Fig. 1 ).

Colouration: Body black, clypeus anteriorly, sides of pronotum, base of elytra, and humeral angle of elytra paler, ferruginous; ventral side reddish, appendages testaceous ( Fig. 1 ).

Dorsal surface sculpture: Whole surface shiny ( Fig. 1 ). Head uniformly microreticulated, reticulation composed of moderately deeply impressed isodiametric meshes. Punctation composed of very small punctures, sparsely spread on surface; rows of deep and coarse punctures present around inner margin of eyes and in small depression anterolaterally of eyes. Pronotum with some moderately strong, short striae, more dense and weak laterally; lateral beading of pronotum very thin and indistinct. Microreticulation and punctation similar to that of head; row of coarse setigerous punctures present along anterior margin, basal margin (except for basomedially), and laterally close to sides. Elytra with microreticulation similar to that of head and pronotum, but less impressed. Punctation consisting of very fine sparse punctures. Each elytron with 11 strongly impressed discal and one submarginal longitudinal striae, intervals subequal, alternate striae tending to be shorter apically; subbasal stria reaching from middle of elytron almost to end of stria 10.

Antennae and legs: Antenna with antennomeres long and slender. Protibia straight, not modified. Pro- and mesotarsomeres 1-3 distinctly broadened, with adhesive discs on their ventral side; claws simple.

Ventral part: Finely microreticulated, with intermixed, sparsely distributed, very small punctures. Prosternum obtusely keeled medially. Prosternal process shortly lanceolate, apex obtuse; distinctly bordered laterally. Lateral parts of metaventrite tongue-shaped, very slender. Metacoxal lines almost complete and absent only close to metaventrite. Metacoxae with some short and deep striae, and abdominal ventrites 1-3 with numerous longitudinal striae.

Male genitalia: Median lobe consisting of a few sclerites, closely attached together; apex in lateral view thin and elongate ( Fig. 11A, B ). Shape of paramere narrowly triangular, with thin, elongate subdistal part and weak but evident long setae along dorsal margin ( Fig. 11D ).

Female.

Similar to male in habitus. Pro- and mesotarsomeres not broadened, without adhesive setae. Pronotal striae finer and denser.

Measurements.

TL = 5.1-5.25 mm; TL-H = 4.5-4.65 mm; MW = 2.45-2.50 mm.

Variability.

All specimens studied are rather uniform in shape and colour, and vary only little in body length.

Differential diagnosis.

Copelatus bakewelli is close to the form of C. daemeli with 11 elytral striae and C. irregularis but smaller and without testaceous basal and apical markings on the elytra. Pronotal striae are weak (absent in C. daemeli ) and the male protibia is not bent as in C. irregularis . Furthermore, all three species can easily be separated by the form of their median lobes.

Distribution.

Endemic. The species occurs from the Kimberley region in north-western Australia and in the Arnhemland in the Northern Territory to northern Queensland. In that area, the species is mainly distributed in rainforest pockets of the stone country ( Fig. 20 ).

Habitat.

A lentic species, which occurs in isolated pools of different size in otherwise dry riverbeds of seasonal streams, creeks and rivers. The bottom is consisted of gravel, sand and a layer of rotten plant debris. Occasionally, it occurs in protected bays, at the edge of large (25-50 m width), slow flowing and shallow (up to 20 cm depth) rivers, shaded by old riverine Melaleuca trees. There, the adults can be found among floating roots and organic debris of the paperbark trees. In northern Australia, at Gunlom waterfall, a large series was collected in a small (ca. 50 cm², 10 cm depth), water filled and shaded pothole ( Fig. 30 ), filled up with rotten leaves. In Kakadu and the Kimberley region, C. bakewelli is more or less restricted to the stone country and the monsoon rainforest pockets. The species is also attracted to light.

Figures

Figure 1. Habitus and colouration of Copelatus bakewelli, female. Total length 5.2 mm.

Figure 11. Copelatus bakewelli A median lobe in lateral view, right side B median lobe in lateral view, left side C median lobe in ventral view D left paramere in external view. Scale bar: 0.5 mm.

Figure 30. Habitat of Copelatus bakewelli, rocky pool, with rotten leaves near Gunlom Waterfall, Northern Territory. Photographs by L. Hendrich.

Figures 20, 21. Distribution of 20 Copelatus bakewelli 21 C. daemeli.