Copelatus tenebrosus Regimbart , 1880

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 tenebrosus Regimbart, 1880 Figures 10 , 19 , 27 , 33 , 36

Copelatus tenebrosus Régimbart 1880: 210 (original description); Watts 1978: 124; Watts 1985: 26; Larson 1993: 53; Hendrich and Balke 1995: 44; Watts 2002: 33, 42; Hendrich et al. 2004: 118. 1

Type locality.

"[Indonesia, Sumatra] Solok, District of Rawas, Soeroelangoen".

Type material.

Not studied. The type specimens should be deposited in the Naturalis Biodiversity Center, Leiden, The Netherlands (former Rijksmuseum van Natuurlijke Historie), but they were not found during a visit of JH. The designation of the lectotype by Watts (1978: 124) based on specimens from "Siam, Bangkok" and deposited in NHMUK is invalid and concerns almost surely the type material of Copelatus pusillus Sharp, 1882 (a junior subjective synonym of C. tenebrosus ); Copelatus tenebrosus was described based on specimens from Sumatra.

Additional material studied (83 specimens).

Northern Territory: 2 exs., "AUSTRALIA NT Kakadu NP Alligator R. Gungaree Rainforest Dec. 22/93 S&J Peck" (ZSM); 2 exs., "Australia N.T. Howard Springs, 35 m, 17-18.5.2014 ca. 25 km SE Darwin ca. 12°29.82.7"S, 131°01.95.1"E M. Langer leg. (LF) Coll. Hendrich" (ZSM); 1 ex., "Australia NT Burdulba Billabong, 15 km SSW Jabiru, 12 m, 12.46.26S 132.44.86E, 2.-3.XI.2007, at light, M. Baehr leg." (ZSM); 1 ex., "Australia: NT, Georgetown Billabong, 750 m E Jabiru East, 30 m, 29.VIII.2006, 12.40.716S 132.55.861E, L. & E. Hendrich leg. (NT 20)", "DNA Balke 2411" [green printed label] (ZSM); 1 ex., "NT, Tindal near Katherine [-14.51667, 132.3667], 1.12.1967, Vestjens, W.J.M." (ANIC); 1 ex., "NT, Darwin, 12°51'24"S, 131°46'48"E, 52 m, at light, 9.V.2006, leg. Berger & Dostal (2/06)" (CGW); 1 ex., "NT, Kakadu NP, Muirella, 40 m, at light, 10.V.2006, leg. Berger & Dostal (3/06)" (CGW); 1 ex., "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); 1 ex., "Australia, Northern Territory, Muirella Park Kakadu, 18. May 1985, at light, Fay, Halfpapp" (QDPIB); 22 exs., "Australia: NT, Litchfield NP, TJAYNERA FALLS, 13°15'S, 130°44'E, 63 m, S. Jákl leg., 20 –27.XI.2008” (NMPC); 3 exs., "Australia: NT, Nitmiluk NP, Edit Falls, 14°10'S, 132°06'E, 37 m, S. Jákl leg., 3.XII.2008" (NMPC); 1 ex., "AUSTR. NT, Kakadu NP, Jim Jim Billabong, 12°56'S, 132°33'E, 5 m, 5.-8.12.[20]08, Sv. Bílý leg." (NMPC); 2 exs., "AUSTRALIA NT, Kakadu NP, Ubirr, 12°25'S, 132°57'E, 190 m, 9.-10.12.2008, Sv. Bílý leg." (NMPC); 2 exs., "AUSTR. NT, Douglas Hot Springs, 12.12.[20]08, 13°45'S, 131°26'E, 35 m, Sv. Bílý leg." (NMPC); 1 ex., "AUSTR. NT, Litchfield NP, 40 km E of Daly, 14.12.[20]08, Sv. Bílý leg." (NMPC); 3 exs., "AUSTRALIA: NT, 70 km SW of MATARANKA, 15°19'S, 132°50'E, 190 m, S. Jákl leg., 22. –23.XII.2008” (NMPC); 1 ex., "AUSTRALIA: NT, 25 km S of KATHERINE, nr Cutta Cutta caves, 14°31'S, 132°25'E, 168 m, S. Jákl leg., 23. –31.XII.2008” (NMPC). Queensland: 8 exs., "Australia: N QLD, Cape Tribulation Road S of ferry station, forest swamp, 12 m, 15.IX.2006, 16.17.469S, 145.19.122E, L. & E. Hendrich leg. (QLD 35)", two specimens with "DNA Balke 1875", "DNA Balke 1876" [green printed label] (CLH, ZSM); 1 ex., "Australia: C QLD, 10 km S Mizani, Lake Kinchant, seapage, 48 m, 24.IX.2006, 21.11.580S, 148.53.522E, L. & E. Hendrich leg. (QLD 46)", "DNA Balke 1756" [green printed label] (ZSM); 1 ex., "QLD Ingham [-18.65, 146.1666667], 23.2.1960, Harley, K.L." (ANIC); 1 ex., "QLD Ingham [-18.65, 146.1666667], 27.1.1968, Brooks, J.G." (ANIC); 1 ex., "QLD, 2 miles W of Mission Beach [-17.86667, 146.1], 18.4.1969, Common, I.F.B. & Upton, M.S." (ANIC); 1 ex., "Australia Queensland 65 km East of Hughenden [-20.8287, 144.7969], 3 Feb 1981, M.S. Moulds" (AMS); 11 exs., "QL, 10 km S Tully, S Innisfail, 30 m, 25.I.1993, leg. G. Wewalka" (CGW); 2 exs., "Australia, Queensland, The Boulders Babinda, 5. February 1975, at light in rainforest B.K. Cantrell" (QDPIB); 1 ex., "Australia, Queensland, Saibai Island, 09.23S 142.40E, 6. February 1986, at light, Houston, Hamacek" (QDPIB); 1 ex., "Australia, Queensland, Wallaman Falls Area W Ingham, 7. February 1975, at light in rainforest, B.K. Cantrell" (QDPIB); 6 exs., "Australia, Queensland, 15 km WNW of South Johnstone April-May 1988, light trap, Fay, Halfpapp" (QDPIB); 1 ex., "Australia, Queensland (22°29'13"S, 144°25'54"E) [Barcadine] Taylor, Frank H. (Collector)" (AMS); 2 exs., "Australia Qld 15 km N Cairns Jan 11, 1991 D.J. Larson" (ZSM).

Description of male.

Body shape: In dorsal view, elongate oval, broadest in basal third of elytra, moderately convex. Body outline with little discontinuity between pronotum and elytra. Head relatively broad; anterior margin of clypeus truncate. Pronotum broadest just before posterior angles, lateral margins moderately curved. Base of elytra slightly broader than pronotal base; lateral margins of elytra moderately curved ( Fig. 10 ).

Colouration. Body dark red-brown to black, clypeus anteriorly, anterior angles of pronotum, sides of elytron towards apex, parts of ventral side and appendages yellowish to dark ferruginous ( Fig. 10 ).

Dorsal surface sculpture: Whole surface shiny ( Fig. 10 ). Head uniformly microreticulated, reticulation composed of moderately deeply impressed meshes. Punctation composed of coarse setigerous punctures, and very small punctures spread sparsely on surface; rows of coarse punctures present around inner margin of eyes and in small depression anterolaterally of eyes. Pronotum with lateral beading very thin and indistinct. Microreticulation and punctation similar to that of head; row of coarse setigerous punctures present along anterior margin, basal margin (except basomedially), and laterally close to sides. Posterior angles of pronotum with quite dense shallow short striae. Elytra with microreticulation similar to that of head and pronotum, but less impressed. On each elytron six well impressed discal and one submarginal longitudinal striae, progressively closer towards sides; stria 1 (sutural stria) shortened at basal third, striae 2-4 almost complete, striae 5 and 6 a little shorter basally. Submarginal stria expanding from behind midlength of elytron to end of stria 5. Serial punctures on elytra, in striae 2-4 and 6, rather weak.

Antennae and legs: Antenna with antennomeres long and slender. Protibia strongly modified, distinctly broadened anteriorly (2/3rd) and strongly narrowed basally (1/3rd). Pro- and mesotarsomeres 1-3 moderately broadened, with adhesive discs on their ventral side; claws simple.

Ventral part: Strongly microreticulated, with intermixed, sparsely distributed, very small punctures. Prosternal process narrow, distinctly bordered laterally, bluntly pointed at tip. Lateral parts of metaventrite ("metasternal wings") tongue-shaped, slender. Metacoxal lines very close posteriorly, moderately diverging anteriorly. Metacoxae and abdominal ventrites 1-3 with several longitudinal striae of different lengths.

Male genitalia: Median lobe apically more or less evenly narrow in ventral view, and very strongly curved downwards in lateral view ( Fig. 19A, B, C ). Shape of paramere broad triangular, with weak, short setae along dorsal margin of subdistal part ( Fig. 19D ).

Female.

Similar to male in habitus. Protibia simple, not angled basally and only slightly broadened distally; pro- and mesotarsomeres not broadened, without adhesive setae.

Measurements.

TL = 4.2-4.5 mm; TL-H = 3.8-4.1 mm; MW = 1.9-2.0 mm.

Variability.

All Australian specimens studied are rather uniform and vary only in body length.

Differential diagnosis.

The species is similar to C. marginatus but can be easily separated by the smaller size (smallest species of the genus in Australia), fully developed inner striae of elytra, and the shape of the median lobe.

Distribution.

This is the most widespread species in the Indomalayan and Australasian realms. It occurs from Nepal, India, and Sri Lanka over Myanmar, Laos, Vietnam, Thailand, Philippines, Indonesia ( Hendrich and Balke 1995), Malaysia, and New Guinea ( Hendrich et al. 2004) to coastal northern and eastern Australia, south to Townsville ( Fig. 27 ).

Habitat.

The wide distribution of this species owes to the ability of adaptation to manmade habitats like rice or paddy fields and shallow irrigation ditches ( Hendrich et al. 2004). In Australia, C. tenebrosus inhabits open, treeless and seasonally flooded meadows, billabongs, ponds, paddy fields ( Larson 1993), puddles, swamps and roadside ditches with dense vegetation, often with mats of floating grasses ( Figs 33A, B , 36A, B ). The species is not that common in Australia as it is in many other countries of Southeast Asia ( Hendrich and Balke 1995; Hendrich et al. 2004), and its population density in one spot is always very low.

Figures

Figure 10. Habitus and colouration of Copelatus tenebrosus, male. Total length 4.4 mm.

Figure 19. Copelatus tenebrosus 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 33. Habitat of Copelatus tenebrosus and C. portior A Queensland, swamp forest at Cape Tribulation Road B shallow and ephemeral swampy puddles with rotten leaves, roots and twigs, Queensland, Cape Tribulation Road. Photographs by L. Hendrich.

Figure 36. Habitat of Copelatus tenebrosus A Northern Territory, Georgetown Billabong, 750 m east of Jabiru East, 30 m, beetles were in very shallow water among the sedges B Queensland, 10 km south of Mizani, Lake Kinchant, beetles were in shallow water among mats of floating grasses, 48 m. Photographs by L. Hendrich.

Figures 27, 28. Distribution of 27 Copelatus tenebrosus 28 C. martinbaehri sp. nov.