Austrelatus brazza, 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

4. Austrelatus brazza sp. nov.

Figs 29 , 30 , 33 , 82 , 91 , 92

Type locality.

Indonesia: Papua Province: Yahukimo Regency, Dekai, upper Brazza River, 04°44'27.9"S, 139°39'15.2"E, 273 m a.s.l.

Type material.

Holotype: male "Indonesia: Papua, Dekai, upper Brazza, 273 m, 2./3.vi.2015, -4,7410 139,6542, Sumoked (Pap044)" (MZB).

Paratypes: 12 males, 15 females with the same label as the holotype (MZB, KSP, NHMW, ZSM). 9 males, 3 females "Indonesia: Papua, Dekai, upper Brazza, 273 m, 2./3.vi.2015, -4,7410, -139,6542, Sumoked (Pap044)", three males with additional green text labels “7218”, “7219” and “7220” (NHMW, ZSM).

Description.

Body size and form: Beetle small, with oblong-oval habitus (Figs 29 , 30 ).

Measurements: TL 4.95-5.6 mm, TL-H 4.5-5.1 mm, MW 2.4-2.8 mm, TL/MW 2.06-2, PL 0.75-0.9 mm, PW 2.1-2.5 mm, PL/PW 0.36-0.38; DBE 0.85-0.9 mm, DBE/PW 0.4-0.41.

Holotype: TL 5.1 mm, TL-H 4.7 mm, MW 2.5 mm, TL/MW 2.04; PL 0.8 mm, PW 2.25 mm, PL/PW 0.36; DBE 0.9 mm, DBE/PW 0.41.

Colouration: Dorsally brown, with reddish head, pronotal sides, and elytral basal and apical spots (Figs 29 , 30 ).

Head yellowish red to reddish brown, usually dark brown behind eyes. Pronotum gradually dark brown medially and reddish laterally, with reddish yellow sides, sometimes also with two symmetrical reddish yellow spots at anterior margin. Elytron reddish brown to dark brown, with two reddish yellow spots at middle of base, not reaching lateral margin, spots vague and confluent, bigger or smaller; seldom with a small indistinct spot at suture; at apex with very narrow yellow spot, sometimes indistinct or developed into distinct lateral line reaching middle of elytron. Scutellum reddish brown. Antennae and other head appendages yellow. Pro- and mesolegs yellow proximally and darker distally, metalegs reddish yellow, darker distally. Venter reddish brown, with paler prosternum.

Surface sculpture: Elytron without or with 6-10 dorsal striae, submarginal stria absent, (0-10)+0 (Figs 29 , 30 ).

Head without strioles, with relatively sparse punctation (spaces between punctures 2-3 × size of punctures); punctures relatively fine, coarser medially (diameter of punctures smaller or equal to diameter of cells of microreticulation); head with a row of coarse setigerous punctures along inner margin of each eye and a very short row of punctures at frontal angle of each eye; a slightly longer puncture row forms fronto-clypeal depression at each head side; head with strong microreticulation. Pronotum with or without strioles and with thin, rather inconspicuous longitudinal wrinkles at posterior margin; pronotal punctation slightly finer than on head; coarse setigerous punctures form a broad row along pronotal margins, absent in posterior middle; disc of pronotum with a short, thin, longitudinal median scratch. Pronotal microreticulation rather weakly impressed on disc. Elytron with 0-10 dorsal striae, submarginal stria absent. Specimens without elytral stria have three well-developed puncture lines and sometimes some punctures in between. In specimens with elytral striae, 6-stria pattern observed: sometimes stria 1 reduced to very small strioles in apical elytral half and elytron appears to have only five striae; sometimes additional, usually incomplete striae present between six complete striae and elytron appears to have up to ten striae. Elytron with fine punctation; microreticulation weak. Ventral part with extremely fine, scarce, inconspicuous punctation, invisible on metaventrite and metacoxae and more distinct 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 almost 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, slightly convex medially; blade of prosternal process small, convex in middle.

Male: Protibia straight, not modified. Proclaws long, subequal in length, anterior claw more strongly curved downwards than posterior due to median incision of its inner margin. Median lobe of aedeagus with two lobes of dorsal sclerite rather narrow; lobes of dorsal sclerite subequal: 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 shorter than ones distal, especially in left paramere (Fig. 33 ).

Female: As male. There are no striolated matt forms.

Variability.

The species is so far known from one population of Brazza area only. Within it, there is insignificant variation in colouration and strong variation in elytral striation described above.

Affinities.

Based on shape of the median lobe, the species is close to A. neoguineensis . In shape of its median lobe sclerites, it is very similar and most likely closely related to A. pseudooksibilensis sp. nov. and especially to A. oksibilensis sp. nov. From A. pseudooksibilensis sp. nov., it differs by less extended yellow colouration of the elytra (absence of dorsal band), and weaker incision on the apex of the left lobe of the dorsal sclerite of the median lobe, as well as females without elytral strioles. The differences from A. oksibilensis sp. nov. see below.

Etymology.

The name refers to the Brazza River, in upper reaches of which this species was collected. The species name is a noun in the nominative singular standing apposition.

Distribution.

New Guinean endemic. Indonesia: Papua Province: Yahukimo Regency. The species is known only from the type locality (Fig. 82 ).

Habitat.

At the type locality, it was collected in puddles or pools among rotten leaves and twigs (Figs 91 , 92 ).

Figures

Figure 33. Austrelatus brazza 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 29 - 32. Habitus and colouration of 29 Austrelatus brazza sp. nov., without elytral striae 30 A. brazza sp. nov., with elytral striae 31 A. lisae sp. nov. 32 A. bormensis sp. nov.

Figures 91, 92. Habitat of Austrelatus species, Indonesia: Papua, Dekai, upper Brazza, puddles or pools among rotten leaves and twigs (PAP 044): type localities of A. brazza sp. nov. and A. debulensis sp. nov., and habitat of A. nadjae sp. nov. Photographs by MB.