Kakadudessus tomweiri, Hendrich, Lars & Balke, Michael, 2009

Hendrich, Lars & Balke, Michael, 2009, Kakadudessus tomweiri, a new genus and species of diving beetle from tropical northern Australia, based on molecular phylogenetic and morphological data (Coleoptera, Dytiscidae, Bidessini), Zootaxa 2134, pp. 49-59 : 51-52

Kakadudessus tomweiri sp.n.

( Figs 1–5 )

Type locality: Australia, Northern Territory, Kakadu National Park, Jim Jim Falls.

Type material: Holotype male: “ Australia N.T./ Kakadu N.P., Jim Jim District, Jim Jim Falls Camping Area, Jim Jim Creek, 60 m, 26. & 27.10.1996, S 13°16. 218´E 132° 49. 276´, Hendrich leg./ Lok. 2b”, “ Holotype Kakadudessus gen.n. tomweiri sp. n. Hendrich & Balke des. 2009” ( SAMA). 15 Paratypes: 2 males and 4 females: “ Australia N.T./ Kakadu N.P., Jim Jim District, Gungurul Lookout, 50 m, 1.11.1996, S 13°59. 359´E 132° 19. 904´, Hendrich leg./ Lok. 11” ( CLH, CHF); 7 exs., “ Australia: NT, Kakadu Hwy, Bowerbird Creek, 5 km W Mary River Roadh., small puddle, 20m, 24.VIII.2006, 13.38.142S 132.10.345E, L. & E. Hendrich leg. (NT 15a) ”, two specimens with green printed labels “ DNA M.Balke 1612” and “ DNA M.Balke 2110” ( ZSM, CLH); 1 ex., “ 15.26S 144.11E QLD Kennedy River Xing 16. Jun. 1992 T. Weir temp. pool in dry river bed, sandy base”, “ ANIC Database No. 25 019235”, “Bidessus genus new/ Allodessus / Liodessus det. T.A.Weir 1993”, “Genus A sp. 1 det. T.A.Weir 19” ( ANIC); 1 ex., “ 11.41S 142.42E QLD 14 km ENE Heathlands 26. Feb 1993 by hand rainforest P. Zborowski”, “ ANIC Database No. 25 020932 ”, “Bidessus genus new/ Allodessus /Liodessus det. T.A.Weir 1993”, “Genus A sp. 1 det. T.A.Weir 19” ( ANIC). All paratypes are provided with a red printed paratype label.

Description: Measurements: Holotype: TL = 2.20 mm, TL-H = 1.95 mm; width = 1.45 mm. Paratypes: TL = 2.20–2.25 mm, TL-H = 1.95–2.00 mm; width = 1.45–1.55 mm.

Colour: Antennae and palpi yellowish, head testaceous somewhat darkened near eyes, pronotum testaceous. Elytra dark brown with a narrow subbasal band and two subapical yellowish patches not reaching sutural line ( Fig. 1 ). Ventral side, including legs and epipleura, reddish-brown, prosternal process somewhat darkened.

Sculpture and structure: Head with cervical line; sparsely punctate, punctures weaker anteriorly with coarse microreticulation anteriorly and basally; clypeus with anterior border. Maxillary palpi fairly slender and finely bifid at tip. Basal part of pronotum narrower than base of elytra, pronotal sides slightly sinuate and cordate with well developed lateral margin, greatest width in middle. Pronotal striae well marked, strongly waved inwards and reaching two thirds of way across pronotum, but without a transverse furrow connecting them. Elytral striae well marked and of same length as pronotal striae ( Fig. 1 ). Elytra regularly and coarsely punctured, along suture punctures smaller than rest of elytra. Punctures on elytra not forming rows. Ventral side, posterior part of basal cavity of epipleura without transverse carina. Prosternal process reaching metaventrite, laterally margined, fairly elongate and narrow, lanceolate. Metaventrite with rows of punctures at midline and metacoxal lines longer than distance between them, strongly diverging anteriorly. Meta- and mesoventrites coarsely and densely punctured, punctures on all abdominal ventrites weaker and smaller.

Male: Pro- and mesotarsi not expanded. Inner edge of mesotibia straight. Penis not strongly modified and of general Bidessini type, in ventral view very elongated, strongly tapered at tip ( Figs 2–3 ). Parameres bisegmented, thin, slender and very elongate ( Figs 4–5 ), only slightly bifid anteriorly.

Variation: This species has a very disjunct distribution. Yet, we observed no morphological differences between the specimens from Queensland and those from the Northern Territory.

Etymology: The species is named after the Australian entomologist and water bug specialist Tom Weir (ANIC, Canberra), who collected the first specimen of this remarkable species and independently recognized the genus and species as new (noun in apposition in the genitive case).

Differential diagnosis: On first view the species is similar to one of the colourful species of the genera Bidessodes Régimbart, 1900 , e.g. smaller specimens of the Australian B. flavosignatus Zimmermann, 1922 , and to Limbodessus capeensis Watts & Leys, 2005 , but can easily be distinguished from these species by its less oblong and more parallel sided body, the more sinuate and broadly margined pronotum, and the form of the male genitalia.

Distribution: Northern Territory (Kakadu National Park and headwaters of Mary River) and northeastern Queensland (Cape York Peninsula) ( Fig. 6 ). Probably more widespread in tropical northern Australia.

Habitat: All specimens were collected in small to medium sized (1–5 sqm), shaded and shallow rest pools in the river beds of intermittent creeks and streams during the dry season ( Figs 8–11 ). The bottom at all sampling sites, in the Northern Territory and Queensland, consisted of coarse sand or gravel. All pools were enriched with a thin layer of rotten leaves but without any submerged or emerged vegetation. At all places in the Northern Territory some floating roots from riverine Eucalypt trees were present.

At Jim Jim Creek it was associated with three species of Bidessodes , three species of Hydrovatus Motschulsky, 1853 , Copelatus irregularis W.J. Macleay, 1871 , C. nigrolineatus Sharp, 1882 , Hyphydrus contiguus Wehncke, 1877 , Laccophilus cingulatus Sharp, 1882 , Megaporus ruficeps (Sharp, 1882) , Tiporus collaris (Hope, 1841) , T. undecimmaculatus (Clark, 1862) . At Bowerbird Creek the new species was collected with Copelatus nigrolineatus Sharp, 1882 , numerous Hydroglyphus basalis (W.J. Macleay, 1871) , Hydroglyphus godeffroyi (Sharp, 1882) , Limbodessus compactus (Clark, 1862) , and at Gungurul lookout it was associated with four species of Bidessodes , Clypeodytes feryi Hendrich & Wang, 2006 , C. larsoni Hendrich & Wang, 2006 , C. weiri Hendrich & Wang, 2006 , Copelatus bakewelli J. Balfour-Browne, 1939 , C. daemeli Sharp, 1882 , C. nigrolineatus Sharp, 1882 , Hyphydrus contiguus Wehncke, 1877 , H. lyratus lyratus Swartz, 1808 , Laccophilus clarki Sharp, 1882 , Limbodessus compactus (Clark, 1862) , Sekaliporus kriegi Watts, 1997 , Tiporus centralis ( Watts, 1978) , T. collaris (Hope, 1841) , T. josepheni ( Watts, 1978) , T. undecimmaculatus (Clark, 1862) , lots of Hydroglyphus and a few Batrachomatus wingii Clark, 1863 (all Dytiscidae ).

Figures

FIGURE 1. Kakadudessus tomweiri sp. n., habitus of paratype, total length 2.2 mm, drawing by D. Paramonov, Riga, Latvia.

FIGURES 2 – 5. Kakadudessus tomweiri sp. n., male genitalia: 2) median lobe lateral aspect, 3) median lobe ventral aspect, 4) left paramere, 5) right paramere (scale bar 0.4 mm).

FIGURE 6. Kakadudessus tomweiri sp. n., distribution.

FIGURES 8 – 11. Kakadudessus tomweiri sp. n. 8) Gungurul lookout in Kakadu National Park (locality 11, 1996), the white arrow marks the small rest pool near the bank; 9) Bowerbird Creek at Mary River Roadhouse near main road; 10 – 11) Small rest pool in the almost dry river bed of the Bowerbird Creek, 200 m upstream from main road (locality 15 a, 2006). All photos by Lars Hendrich.