Two new species of Austrelatus diving beetles from continental Southeast Asia, linking the distribution area of the genus (Coleoptera: Dytiscidae: Copelatinae) Author Hájek, Jiří Department of Entomology, National Museum of the Czech Republic, Cirkusová 1740, CZ- 193 00 Praha Author Shaverdo, Helena Naturhistorisches Museum Wien, Burgring text Acta Entomologica Musei Nationalis Pragae 2024 Acta. Ent. Mus. Natl. Pragae 2024-10-01 64 2 243 247 https://doi.org/10.37520/aemnp.2024.016 journal article 10.37520/aemnp.2024.016 1804-6487 14655591 187DAF15-7C4F-4A4C-9AA3-8753B824CCCB Austrelatus mirai sp. nov. ( Figs 1, 3–4 ) Type locality. Malaysia , Selangor State , Rawang Township, Templer Park Forest Reserve, ca. 03°17′N 103°38′E . Type material. HOLOTYPE : Ô ( NHMW ), labelled: ‘ MALAYSIA 21.I.1992 / SELANGOR : Templer / Park N K.L. / leg. Jäch (1) [p] // HOLOTYPE Ô / AUSTRELATUS / mirai sp. nov. / J. Hájek & H. Shaverdo det. 2024 [p, red label]’. PARATYPES : 1 Ô 2 ♀♀ , same label data as holotype ( NHMW , NMPC ). All paratypes are provided with the respective red printed labels. Description. Male holotype . Habitus ( Fig. 1 ) elongate oblong oval, broadest in one third of elytral length, dorsally convex; body outline continuous, without angle between base of pronotum and elytra. Dorsal surface submatt. Colouration. Head ferruginous with darker circumocular band; pronotum ferruginous, somewhat darkened along anterior and posterior margin; elytra brown-blackish with paler base; appendages orange; ventral side ferruginous. Head moderately broad, ca. 0.66× width of pronotum, semicircular. Anterior margin of clypeus indistinctly concave. Antenna with antennomeres long and slender. Reticulation consisting of very weakly impressed, hardly perceptible polygonal isodiametric meshes. Punctation double, consisting of coarse setigerous punctures and fine punctures spread sparsely on surface; row of coarse punctures present alongside inner margin of eyes, several punctures present also in fronto-clypeal depressions. Surface between eyes with several short longitudinal strioles; a few short transverse strioles present also in centre of head. Pronotum strongly transverse (width/length ratio = 2.46), broadest between posterior angles, lateral margins moderately curved. Lateral sides with thin beading except for anterior angles. Reticulation similar to that of head, but even less perceptible. Punctation similar to that of head; rows of coarse setigerous punctures present along anterior margin, close to lateral sides and in shallow basolateral depressions along basal margin. Whole surface of pronotum covered with long longitudinal strioles. Scutellum transversely triangular. Elytra. Base of elytra as broad as pronotal base; lateral margins of elytra slightly diverging in basal third, subparallel in middle third, distinctly narrowing to apex in apical third. Eleven dorsal striae and one submarginal longitudinal stria present on each elytron: all striae beginning at base; striae 1, 3, 5–6, 8 and 11 ending subapically; striae 2 and 4 longest, ending close to apex; striae 7, 9–10 progressively shorter, the latter ending at apical fourth; submarginal stria long, beginning before elytral mid-length and ending subapically. Reticulation similar to that of head. Punctation consisting of coarse setigerous punctures and very fine sparse punctures; coarse punctures present along elytral striae and lateral margins of elytra. Legs. Protibia broadened anteriorly, club shaped. Pro- and mesotarsomeres 1–3 distinctly broadened, with rows of adhesive setae on their ventral side; posterior (outer) protarsal claw slightly broader and more curved than anterior claw. Ventral surface. Prosternum sinuate anteriorly, obtusely keeled medially; rather coarsely punctate; reticulation consisting of fine transverse meshes. Prosternal process shortly lanceolate, in cross-section convex, apex obtuse; process distinctly bordered laterally; reticulation consisting of shallow, hardly perceptible polygonal meshes. Metaventrite with reticulation consisting of transverse polygonal meshes; lateral parts of metaventrite (“metasternal wings”) tongue-shaped, slender. Metacoxal lines nearly complete, absent only close to metaventrite. Metacoxal plates covered with rather long, oblique strioles; reticulation consisting of elongate, longitudinal polygonal meshes. Metacoxal processes rounded at posterior margin.Abdominal ventrites I–II with longitudinal strioles; ventrites III–IV with oblique strioles laterally; ventrite V with a few transverse striolae laterally. Tuft of setae present antero-medially on ventrites III–V; ventrite VI with setigerous punctures laterally on either side. Abdominal reticulation consisting of elongate polygonal meshes, longitudinal on ventrites I–II, oblique on ventrite III and transverse on ventrites IV–VI. Punctation consisting of fine, sparsely distributed punctures. Male genitalia. Median lobe of aedeagus in lateral view sickle-shaped, widest after mid-length, then rather subparallel and in apical eighth tapering to pointed apex ( Fig. 3a ); in ventral view, indistinctly constricted in two thirds of its length, then tapering to pointed apex ( Fig. 3b ); ventral lobe apically pointed, closely pressed from left side to dorsal lobe in ventral view ( Fig. 3b ). Paramere narrowly triangular, with basal part broad, laterally rounded; distal part narrow, subparallel, apically with long setae; apical lobe club-shaped ( Fig. 4 ). Female . Identical to male in habitus. Pro- and mesotarsomeres 1–3 not dilated, without adhesive setae; proclaws slender. Variability. All specimens of the type series are identical. Small variability can only be seen in extent of longitudinal striolae on pronotum. Measurements. TL: 5.0– 5.6 mm (mean value: 5.35 ± 0.20 mm ); holotype : 5.6 mm . TL-h: 4.5–4.9 mm (mean value: 4.75 ± 0.15 mm ); holotype : 4.9 mm . MW: 2.3–2.5 mm (mean value: 2.45 ± 0.10 mm ); holotype : 2.5 mm . Figs 1–6. 1–2 – habitus of Austrelatus holotypes: 1 – A. mirai sp. nov. ; 2 – A. riberai sp. nov. 3–6 – male genitalia of Austrelatus : 3–4 – A. mirai sp. nov. ; 5–6 – A. riberai sp. nov. 3, 5 – median lobe in lateral (a) and ventral (b) view; 4, 6 – parameres. Scale bar = 0.5 mm (Figs 3–6). Differential diagnosis. With rather small body length, more or less unicolour ferruginous colouration and presence of 11 dorsal striae + a submarginal stria on each elytron, the new species is most similar to South Indian Austrelatus boukali (Hendrich & Balke, 1998) and A. davidi (Wewalka, 2017) . However, A. mirai sp. nov. can be recognised from those species based on more subparallel habitus, presence of long striolae on pronotum, and different shape of male genitalia. We assume, that the new species is most closely related to several, so far undescribed, Austrelatus species from Borneo Island (J. Hájek et al., unpublished data). Etymology. The new species is dedicated to Miroslav Vít (Chyňava, Czech Republic ); the specific epithet is a noun in the genitive case. Collecting circumstances. The species was collected in the ca. 2–3 m wide forest stream with bottom of granite stones and much sand between them and some leaf litter ( Fig. 7 ). The altitude was ca. 200 m a.s.l.; there was a primary forest in the stream’s upper reaches (M. A. Jäch, pers. comm.). Distribution. Austrelatus mirai sp. nov. is known only from the type locality in Selangor State , Peninsular Malaysia .