Austrelatus mirificus, 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

16. Austrelatus mirificus sp. nov.

Figs 37 , 41 , 83

Type locality.

Papua New Guinea: Sandaun Province, Mianmin, 04°52'51.5"S, 141°31'42.4" Е, 700 m a.s.l.

Type material.

Holotype: male "Papua New Guinea: Sandaun, Mianmin (pool), 700 m, 21.x.2008, 04.52.858S 141.31.706E, Ibalim (PNG 198)" (ZSM).

Paratypes: PNG: Sandaun: 8 males, 7 females with the same label as the holotype (NHMW, ZSM). For additional paratypes see Appendix 1.

Description.

Body size and form: Beetle small, with oval habitus (Fig. 37 ).

Measurements: TL 4.85-5.5 mm, TL-H 4.3-5 mm, MW 2.6-2.9 mm, TL/MW 1.84-1.9; PL 0.7-0.8 mm, PW 2.1-2.4 mm, PL/PW 0.33; DBE 0.9-1 mm, DBE/PW 0.4-0.43.

Holotype: TL 5.15 mm, TL-H 4.7 mm, MW 2.8 mm, TL/MW 1.84; PL 0.75 mm, PW 2.4 mm, PL/PW 0.33; DBE 1 mm, DBE/PW 0.42.

Colouration: Dorsally piceous, with yellow head, pronotal sides, and very prominent elytral colouration of basal band/spots and narrow longitudinal bands (Fig. 37 ); if elytral colour pattern maximally reduced, then present as basal band and interrupted apicolateral band; if fully developed, elytra almost completely yellow, with piceous disc and narrow spaces laterally.

Head yellow to brownish yellow, dark brown behind eyes, sometimes with vague, V-like, brown spot medially that can be merged with brownish posterior margin. Pronotum dark brown to piceous, slightly paler anteriorly and laterally, with yellow to reddish yellow sides. Elytron piceous, with yellow to reddish yellow basal band of different length but not reaching suture and lateral elytral margin; its anterior margin usually reaching elytron basally and its posterior margin with three distinct prolongations; often prolongation near suture separated from band in form of elongate spot disconnected with anterior elytral margin; elytron with a distinct yellow to reddish yellow pattern of three, narrow, longitudinal bands that can be very differently developed; lateral band always present, can be interrupted, be only in apical elytral half, or reaching almost to elytral shoulder; apically it forms a loop and continues upwards as a first elytral band that can be absent, be very short, or strongly developed and reaching to second prolongation of basal band; second elytral band situated between lateral and first bands, closer to first one; can be absent, partly present, or strongly developed and reaching to basal band; first band more often reduced than second one. Scutellum yellowish to piceous. Antennae and other head appendages yellow to yellowish brown. Legs yellow to yellowish brown proximally and darker distally, especially metalegs. Venter reddish brown to brown, with paler prosternum. Teneral beetles paler.

Surface sculpture: Evident tendency for forming 6-stria dorsal pattern on elytron. Elytron with 2-10, sometimes uncomplete, dorsal striae, submarginal stria usually absent (2-10)+(0-1) (Fig. 37 ).

Head without strioles, with relatively dense, even punctation (spaces between punctures 1-3 × size of punctures); punctures relatively large (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 very short row of much weaker 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 usually with distinct strioles at posterior angles, with short, thin, rather inconspicuous longitudinal wrinkles at middle of 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 short, thin, longitudinal median scratch. Pronotal microreticulation rather weakly impressed on disc. Elytron with 2-10 dorsal striae, submarginal stria usually absent, present apically only in some specimens. Using 11-stria pattern: stria 1 completely reduced (only weak strioles can be find in very few specimens); striae 2, 4, 6, 8, 10, and 11 usually present complete or slightly reduced basally, stria 2 can be more distinctly reduced basally; remained striae usually differently developed, often present as weak strioles, especially in apical half or completely reduced. Only one specimen with stronger stria reduction: striae 1-3, 5, 7, 9 completely absent, striae 4, 6, 8 reduced to differently developed puncture lines, striae 10 and 11 present, slightly reduced basally. Elytron with distinct, 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 weak 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. Abdominal ventrite 6 broadly rounded or slightly truncate.

Male: Protibia straight, not modified. Proclaws simple, subequal in length: anterior claw very slightly shorter than posterior one. Median lobe of aedeagus with two lobes of dorsal sclerite rather narrow; in lateral view, apex of left dorsal lobe evenly curved downwards; left dorsal lobe dorsally relatively narrow, with distinct denticulation (spinulae) visible also in lateral left view; right dorsal lobe with small, elongate median impression and modified apex: swollen, very broadly rounded, its outer margin more strongly curved; left lobe of ventral sclerite with its sclerotised area distinct, much shorter than right ventral lobe. Paramere with setae not divided into distal and proximal; more distally situated setae denser and longer than more proximal ones (Fig. 41 ).

Female: As male.

Variability.

Colouration: The species distinctly varies in intensity of yellow colouration of dorsal surface, especially elytra. The strongly developed yellow elytral pattern is characteristic for the Sandaun populations. Their representatives always have yellow longitudinal elytral bands though in most specimens not completely developed. There is only one specimen from Bewani without elytral bands. The most reduced yellow elytral pattern is characteristic for the East Sepik populations; their representatives have no yellow longitudinal elytral bands. Specimens of the Madang population are rarely without yellow longitudinal elytral bands though the specimens with intensive yellow colouration are less then in the Sandaun. Indonesian specimens are with yellow longitudinal elytral bands, except for the specimen from Sarmi Regency (Foja Mts).

Elytral striation: The species evidently varies in number and degree of development of elytral striae. The maximal number of the striae is ten and is characteristic for the Sandaun populations, although specimens with the 6-stria pattern prevail in the Bewani populations. The representatives of the East Sepik and Madang populations have almost exclusively the 6- stria pattern of the elytron, as well as specimens from the Cyclops Mts. Papuan specimen from Elelim has eight elytral striae. The most interesting is the male from Sarmi (Foja Mts) with strongly reduced elytral pattern described above.

Affinities.

Based on size, oval body shape, partly dorsal colouration and shape of the median lobe, this species is extremely similar and most likely related to A. nadjae sp. nov. but differs from it by presence of the elytral striae, more intensive yellow colouration (presence of longitudinal elytral bands), absence of elytral strioles in females (see under “Female” for both species), and differences in shape of the median lobe: right dorsal lobe with distinctly smaller median impression in right lateral view; apex of right dorsal lobe less “swollen”, smaller, its outer margin more strongly curved; left dorsal lobe dorsally narrower (in dorsal view), with more distinct denticulation well visible in lateral left view due to apex curved more to left than downwards as in A. nadjae sp. nov.

Etymology.

The species name is a Latin adjective Austrelatus mirificus (wonderful) meaning beautiful dorsal colouration of the species.

Distribution.

New Guinean endemic. The species has rather broad distribution, found in the Papuan Province of IN and the Sandaun, East Sepik, and Madang provinces of PNG (Fig. 83 ).

Habitat.

According to the type locality labels, all specimens were collected in a pool.

Figures

Figure 41. Austrelatus mirificus 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 83. Map of New Guinea showing distribution of seven Austrelatus species.

Figures 36 - 39. Habitus and colouration of 36 Austrelatus neoguineensis (Zimmermann, 1919), lectotype 37 A. mirificus sp. nov. 38 A. securiformis sp. nov. 39 A. testegensis sp. nov.