Leiodytes wattsi, Hendrich & Wang & Balke, 2021

Hendrich, Lars, Wang, Liang-Jong & Balke, Michael, 2021, Taxonomic revision of Australasian diving beetles in the genus Leiodytes Guignot 1936 (Coleoptera: Dytiscidae, Bidessini), Zootaxa 4990 (1), pp. 23-44 : 33-36

Leiodytes wattsi sp. nov.

( Figs 1D , 2C , 3C , 4D , 7 , 9B , 10 , 12 , 13B )

Type locality. Northern Territory, Manton Dam Recreation Area, 46 km south of Darwin .

Type material. Holotype, male. “ Australia: NT, Manton Dam Recr. Area , 46 km S Darwin, 35m, 19.VIII.2006, 12.50.270S 131.08.050 E, L. & E. Hendrich leg. (NT 1)”, “ Holotype, Leiodytes wattsi sp. nov. Hendrich, Wang & Balke des. 2021” [red printed label] ( SAMA).

Paratypes (180 specimens). 3 specimens with same data as holotype , one specimen with “MB2690” [green printed label] ( CLH, ZSM) ; 1 ex., “NT/Kakadu N.P., 10 km SW Jabiru , 22.3.1998, C.H.S. Watts leg.” ( CLH) ; 1 ex., “NT/ Manton Dam , 23.3.1998, C.H.S. Watts leg.” ( SAMA) ; 7 exs., “N.T. Manton Reservoir on Stuart Hwy in flood debris near water edge M.B. Malipatil 9.XII.1979 ” ( CLH, NTM) ; 1 ex., “ Australia : N QLD, Cape Tribulation Road S of ferry station, forest swamp, 12m, 15.IX.2006, 16.17.469S 145.19.122 E, L. & E. Hendrich leg. (QLD 35)”, “MB2690” [green printed label] ( ZSM) ; 63 exs., “N-AUS, NT, Kakadu NP, Muriella 12°51’15”S 132°45’16”E, 40 m, at light, 10.5.2006, leg. Berger & Dostal (3/06)” ( CLH, CGW, ZSM) ; 2 exs., “ Australia : NT, Magela Creek downstream, Jabiru East, 31m, 30.VIII.2006, 12.38.312S 132.53.441 E, L. & E. Hendrich leg. (NT 23)” ( CLH, ZSM) ; 1 ex., “ 12.40S 142.40E Batavia Downs QLD 03–10 Mar 1993 at light I. Cunningham ”, “ANIC Database No. 25 020938” ( ANIC) ; 3 exs., “ 17.39S 145.27E GPS QLD Millstream Falls NP 21–27 Nov. 1998 A. Calder” ( ANIC) ; 81 exs., “ AUSTRALIA Qld. Nardello´s Lagoon 15 km S Mareeba Dec 20/90 Larson” ( ANIC, CLH, ZSM) ; 17 exs., “ Papua Merauke , Wasur, pools, 20m, 15.–16.x.2011 14.42.748S 141.36.096E (Pap02)” , two specimens with “MB5016”, “MB5026” [green printed label] ( MZB; ZSM). All paratypes are provided with our red printed paratype labels .

Description of male. Externally characterized by elongate and parallel sided body, widest in middle, dense elytral punctation and almost testaceous body with vague darker markings on the elytra. Dorsoventrally more flattened. Cervical line present.

Measurements. Holotype: TL = 2.15 mm, TL-H = 1.95 mm; breadth = 1.1 mm. Paratypes: TL = 1.85–2.15 mm, TL-H = 1.7–1.9 mm; breadth 0.9–1.1 mm.

Head. Ferruginous, rather shiny, with scattered small punctures. Microreticulation clearly visible. Punctures weak anteriorly and strongly posteriorly between eyes. Cervical line present ( Fig. 3C ). Antennae ferruginous, antennomeres 2–10 almost as wide as long.

Pronotum. Ferruginous with two blackish markings posteriorly, broadest at posterior corners. Punctation of varying size, widely and evenly distributed, shiny and microsculpture absent. Sides of pronotum margined and almost evenly rounded, Basal pronotal plicae present. Striae well defined, almost 1/2 length of pronotum, strongly incurved.

Elytra. Ferruginous, with vague blackish markings and black suture ( Fig. 1D ). Coarsely and densely punctate, shiny, microsculpture absent. Striae strongly impressed, same length as basal pronotal striae but slightly straighter. Elytron simple, without a well-marked ridge.

Ventral surface. Ferruginous. Metacoxae and metaventrite covered with numerous quite strong punctures, surface shiny, without microreticulation ( Fig. 4D ). Abdominal ventrites 1 and 3 with few shallow punctures, shiny, microreticulation absent. Metacoxal lines raised, parallel, well separated ( Fig. 4D ). Epipleuron testaceous, with few coarse punctures, shiny, lacking microsculpture, and without transverse epipleural carina at humeral angle ( Fig. 2C ). Legs completely ferruginous.

Male. Median lobe of aedeagus as in Figs 7A, B . Paramere bi-segmented and elongated as in Fig. 7C .

Etymology. Dedicated to our colleague, the Australian water beetle specialist Chris H.S. Watts (Adelaide, South Australia). The specific epithet is a substantive in the genitive case.

Differential diagnosis. This species is near to L. surianiae sp. nov. but can be distinguished by the head having a distinct cervical line, the blackish markings on elytra, the larger size ( Fig. 1D ) and by the shape of the median lobe of aedeagus ( Figs 7A, B ) and paramere ( Fig. 7C ).

Collecting notes. A lentic species. At Manton Dam L. wattsi sp. nov. was collected in very shallow water, among mats of floating grasses and debris, along the shoreline of the artificial lake (Watts in litt.). Additional specimens were obtained among roots and rotten leaves in protected embayments of a permanent creek or outflow of the dam. The latter was fringed and partly shaded by Pandanus trees ( Fig. 12A ). In Magela Creek the single specimen was obtained from a large isolated pool at the edge of a slowly flowing, permanent and shaded stream with clear water. Near Daintree ferry station the species was collected in a forest swamp ( Fig. 12B ). In the open savanna forest of southern New Guinea, L. wattsi sp. nov. was collected in remnant pools with thick layers of leaves (up to 70 cm), and margins with area of wet leaves that form small open water once stepped on ( Fig. 13B ) (see also Surbakti et al. 2021). Here, the species was syntopic with L. migrator . According to the label data most specimens were collected within or just after the rainy season, and it seems that L. wattsi sp. nov. is less common at the rest of the year. It is also attracted to light.

Distribution. Australia, Darwin and Kakadu Area (Northern Territory) and north-eastern Queensland, southern New Guinea ( Fig. 9B ).

Figures

FIGURE 1. Body outline and colour pattern of: (A) L. migrator from North Queensland, near Cardwell; (B) L. migrator from Ubirr Rock, Kakadu NP, Northern Territory; (C) L. surianiae sp. nov.; (D) L. wattsi sp. nov. (Scale bar = 1 mm)

FIGURE 2. Ventral surface of: (A) L. migrator; (B) L. surianiae sp. nov.; (C) L. wattsi sp. nov. (Scale bar = 1 mm)

FIGURE 3. Dorsal surface of head of: (A) L. migrator; (B) L. surianiae sp. nov.; (C) L. wattsi sp. nov. (Scale bar = 0.5 mm)

FIGURE 4. Morphological details of: L. migrator (A–C): (A) Head, pronotum and basal part of elytra with striae und punctation; (B) Prosternal process; (C) Metacoxae and metacoxal lines with metacoxal processes. L. wattsi sp. nov. (D): Metacoxae with numerous quite strong punctures, and metacoxal lines with metacoxal processes. Clypeodytes larsoni (E): Epipleuron anteriorly with a basal cavity posteriorly limited by a transverse carina (yellow arrows). L. migrator (F): Epipleuron anteriorly lacking a basal cavity posteriorly limited by a transverse carina (yellow arrows).

FIGURE 7. Leiodytes wattsi sp. nov.: Median lobe of aedeagus: (A) ventral view, (B) lateral view; right paramere (inner surface): (C) lateral view. (Scale bar = 0.15 mm)

FIGURE 9. Distribution of L. surianiae sp. nov. (A) and L. wattsi sp. nov. (B).

FIGURE 10. Maximum likelihood tree for Australasian Leiodytes. Neighbour joining tree (p-distances) calculated with Geneious (11.0.4.) software. The stars mark those specimens distributed over two divergent clades of L. migrator, which, however, occur syntopically.

FIGURE 12. (A) Creek at Manton Dam, Northern Territory (NT 1), habitat of L. wattsi sp. nov. and L. migrator; (B) Queensland, Forest swamp near Cape Tribulation Road, south of Daintree ferry station (QLD 35), habitat of L. surianiae sp. nov., L. wattsi sp. nov. and L. migrator (B).

FIGURE 13. (A) Shallow and exposed pools on a forest clearing near Kali Bumi, Wanggar, Nabire, W New Guinea, habitat of L. migrator; (B) Rest pool, bottom with very thick layer of leaves (up to 70 cm), and margins with area of wet leaves that form small open water once stepped on, open savanna forest in Wasur, S New Guinea, habitat of L. migrator and L. wattsi sp. nov.