Austrelatus oksibilensis, Shaverdo & Hájek & Hendrich & Surbakti & Panjaitan & Balke, 2023

Shaverdo, Helena, Hajek, Jiri, Hendrich, Lars, Surbakti, Suriani, Panjaitan, Rawati & Balke, Michael, 2023, Austrelatus gen. nov., a new genus of Australasian diving beetles (Coleoptera, Dytiscidae, Copelatinae), with the discovery of 31 new species from New Guinea, ZooKeys 1170, pp. 1-164 : 1

20. Austrelatus oksibilensis sp. nov.

Figs 23 , 27 , 82

Type locality.

Indonesia: Papua Province: Pegunungan Bintang Regency, south from Ok Sibil, tributary Digul River, 05°03'25.9"S, 140°43'21.1"E, 359 m a.s.l.

Type material.

Holotype: male "Indonesia: Papua, S Ok Sibil, tributary of Digul Riv, 359 m, 9.vi.2018, -5,0571 140,7225, Sumoked (Pap051)" (MZB).

Paratypes: IN: Papua: Pegunungan Bintang Regency: 9 males, 6 females with the same label as the holotype (MZB, NHMW, ZSM). 7 males, 4 females "Indonesia: Papua, S Ok Sibil, tributary of Digul Riv, 359 m, 9.vi.2015, -5,0571 140,7225, Sumoked (Pap051)" (MZB, KSP, ZSM).

PNG: Western: 2 males "Tabubil, 05°18.466'S 141°19.531'E, 810 m, beaten", "25-iii-2019 - pos. 4 Dytiscidae " (SMNK). 2 males, 1 female "Papua New Guinea: Western, Tabubil, 810 m, 25.iii.2019", "S05° 18.466' "E 141°19.531' Riedel", all with additional green text labels “8679”, “8680”, and “8681” (ZSM).

Additional material.

PNG: Sandaun: 1 female "NEW GUINEA W-Sepik Pr.: Yapsiei 4°38'S- 141°05'E 250 m, 17.I.1989 Leg. M. & R. Holyński”, "water in rotten fallen trunk" (ZSM) .

Description.

Body size and form: Beetle medium-sized, with oblong-oval habitus (Fig. 23 ).

Measurements: TL 5-6.1 mm, TL-H 4.6-5.6 mm, MW 2.5-3.1 mm, TL/MW 1.97-2.03; PL 0.75-0.95 mm, PW 2.2-2.7 mm, PL/PW 0.34-0.35; DBE 0.9-1.05 mm, DBE/PW 0.38-0.41.

Holotype: TL 6.1 mm, TL-H 5.6 mm, MW 3 mm, TL/MW 2.03; PL 0.9 mm, PW 2.6 mm, PL/PW 0.35; DBE 1 mm, DBE/PW 0.38.

Colouration: Dorsally piceous, with reddish yellow to brown head, pronotal sides, and notched basal band or spots on elytron as well as elytral apical spot and narrow lateral band (Fig. 23 ).

Head reddish yellow to brown, darker behind eyes. Pronotum yellowish brown to piceous on disc and reddish yellow to brown on sides. Elytron piceous, with reddish yellow to brown basal band of different length but not reaching suture and lateral elytral margin; its anterior margin reaching elytron basally and its posterior margin strongly notched: usually with two prolongation between puncture rows, sometimes with vague basal spot near suture, sometimes band splitted into basal spots; elytron with distinct, reddish yellow to brown, elongate apical spot usually continuing laterally as a thin band maximum till middle of elytra. Scutellum usually brown to piceous. Antennae and other head appendages yellowish brown. Pro- and mesolegs yellowish brown proximally and darker distally, especially metalegs. Venter yellowish brown to dark brown, with paler prosternum. Teneral beetles paler.

Surface sculpture: Elytron without striae: 0+0, but with distinct puncture lines (Fig. 23 ).

Head without strioles, with relatively dense, even punctation (spaces between punctures 1-3 × size of punctures); punctures relatively coarse (diameter of punctures equal to diameter of cells of microreticulation); head with a row of coarse setigerous punctures along inner margin of each eye and a short row at frontal angle of each eye; a slightly longer puncture row forms fronto-clypeal depression at each head side; sometimes head with large shallow median depression; microreticulation strongly impressed. Pronotum with strioles, sometimes few and indistinct, at posterior angles and thin, longitudinal wrinkles at middle of posterior margin; pronotal punctation finer than on head; coarse setigerous punctures form a broad row along pronotal margins, absent in posterior middle; disc of pronotum with thin, longitudinal median scratch. Pronotal microreticulation rather weakly impressed on disc. Elytron without elytral striae but with two distinct puncture lines on disc and one less distinct laterally; two additional lines of very sparse, coarse setigerous punctures can be seen between elytral lines; elytron with very fine, inconspicuous punctation; microreticulation weak. Ventral part with fine, inconspicuous punctation, invisible on metaventrite and metacoxae and weak on abdominal ventrites; prosternum smooth medially; metaventrite and metacoxae with distinct microreticulation; on abdominal ventrites microreticulation almost invisible; metacoxal plates with more or less short longitudinal strioles, abdominal ventrites 1 and 2 with numerous, long, longitudinal strioles from margin to margin, on abdominal ventrites 3 and 4 strioles situated laterally and turn to middle, almost horizontal, abdominal ventrites 5 and 6 without strioles but with rather distinct punctation that sparser medially and forms a dense lateral area at each side.

Structures: Head relatively broad. Pronotum short and broad; lateral margins distinctly convergent anteriorly. Base of prosternum rounded anteriorly, convex medially; neck of prosternal process distinctly convex; blade of prosternal process elongate, narrow, distinctly convex in middle.

Male: Protibia straight, not modified. Proclaws long; anterior claw shorter, slightly thicker and more strongly curved downwards than posterior due to slight, median incision of its inner margin. Median lobe of aedeagus with two lobes of dorsal sclerite rather narrow; right dorsal lobe slightly longer than left one; in lateral view, apex of left dorsal lobe more or less straight, with longitudinal crest and weak but distinct incision on its lateral margin; right dorsal lobe with weakly developed, inconspicuous median impression (in right lateral view) and rounded apex. Left lobe of ventral sclerite with its sclerotised area large, very strongly sclerotised, distinctly shorter than right ventral lobe; its apex bilobed: left part short, broad, and rounded, right one long, thin, hooked; this sclerotised area hidden under right ventral lobe and between left and right lobes of dorsal sclerite, usually invisible (only hook’s apex can be visible) in left lateral view. Paramere with setae divided into distal and proximal; proximal setae distinctly sparser and slightly shorter than distal (Fig. 27 ).

Female: Usually with more numerous pronotal strioles, often occupying entire lateral sides.

Affinities.

In absence of the elytral striae and general shape of the median lobe, it is most similar and most likely closely related to A. pseudooksibilensis sp. nov. and especially to A. brazza sp. nov. but differs from them by its slightly larger body size. From A. pseudooksibilensis sp. nov., it differs also by less extended yellow colouration of the elytra (presence of lateral band, absence of dorsal one), and weaker incision on the apex of the left lobe of the dorsal sclerite of the median lobe, as well as males with pronotal strioles and females without elytral strioles. The species has median lobe very similar to that of A. brazza sp. nov. but they differ in shape of their left and right lobes of the dorsal sclerite: In A. oksibilensis sp. nov., apical part of left dorsal lobe (before incision) more elongate and part after incision flatter; apical part of right dorsal lobe more elongate. In A. brazza sp. nov., apical part of left dorsal lobe (before incision) smaller, shorter, and part after incision more prominent; apical part of right dorsal lobe shorter, more rounded. Additionally, A. oksibilensis sp. nov. has darker dorsal colouration of the body and elytron without striae: 0+0. Austrelatus brazza sp. nov. is paler dorsally and its elytron without or with 6-10 dorsal striae, submarginal stria absent: (0-10)+0.

Etymology.

The species is named after its type locality area, Ok Sibil. The name is an adjective in the nominative singular.

Distribution.

New Guinea endemic. Indonesia: Papua Province: Pegunungan Bintang Regency and PNG: Western. If the record from Sandaun is confirmed, the species will be considered more widely spread in the region (Fig. 82 ).

Habitat.

The species was collected in stream-side puddles and a water-filled fallen trunk.

Figures

Figure 27. Austrelatus oksibilensis sp. nov., median lobe A left lateral view B right lateral view C ventral view D left paramere in external view E right paramere in internal view. Scale bar: one unit - 0.1 mm (A-C).

Figure 82. Map of New Guinea showing distribution of 11 Austrelatus species.

Figures 22 - 25. Habitus and colouration of 22 Austrelatus febrisauri sp. nov. 23 A. oksibilensis sp. nov. 24 A. pseudooksibilensis sp. nov., without elytral striae 25 A. pseudooksibilensis sp. nov., with elytral striae.