Euthiconus nopporoensis, Jałoszyński, 2019

Jałoszyński, Paweł, 2019, The first record of Euthiconus Reitter in Japan, with comparative notes on remaining Palaearctic species (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4691 (1), pp. 78-82 : 78-82

Euthiconus nopporoensis sp. n.

( Figs 1–2 , 7, 10–13 )

Type material. Holotype: Japan (Hokkaido): ♂, two labels: " JAPAN, HOKKAIDO / Osawaguchi, / Nopporo Forest / Park, Ebetsu City / X–XI 2005, leg. T. / Lackner" [white, printed]; " EUTHICONUS / nopporoensis m. / det. P. Jałoszyński, 2019 / HOLOTYPUS " [red, printed] ( MHNG) . Paratype: ♀, same data as for holotype ( MHNG) .

Diagnosis. Antennomere III distinctly transverse; male protrochanters unmodified; aedeagus in ventral view with rapidly narrowed, elongate apical region with rounded distal margin.

Description. Body of male ( Fig. 1 ) elongate and moderately slender, strongly convex, moderately light brown with indistinctly lighter appendages; setae yellowish; BL 1.10 mm.

Head ( Fig. 2 ) transverse, broadest at large, strongly convex and finely faceted eyes, HL 0.13 mm, HW 0.23 mm; vertex and frons confluent, their median region distinctly impressed between arcuate (anteriorly convex) posterior margin of vertex and area between supraantennal tubercles. Punctures on frons and vertex fine, inconspicuous, cuticle glossy; setae sparse, moderately long, suberect. Antennae slender, weakly thickened distad; AnL 0.58 mm, antennomere I about twice as long as broad, II weakly elongate, III distinctly transverse, IV about as long as broad, V–VIII each indistinctly elongate, IX and X as long as broad, XI distinctly shorter than IX–X combined, about 1.8 × as long as broad.

Pronotum ( Fig. 2 ) subconical and elongate, broadest at base and weakly narrowing anterad; PL 0.28 mm, PW 0.23 mm. Anterior and posterior margins nearly straight; sides weakly rounded near anterior third and nearly straight posteriorly; pronotal base with shallow transverse groove and a pair of distinct, strongly elongate lateral impressions near each hind angle. Punctures on pronotal disc fine and inconspicuous, cuticle glossy; setae moderately long, sparse and suberect (more so on sides, especially in anterior half).

Elytra together oval, broadest slightly in front of middle, evenly convex; EL 0.60 mm, EW 0.43 mm, EI 1.41; humeral calli distinct but small; elytral apices separately broadly rounded. Punctures on elytra slightly more distinct than those on pronotum but fine, shallow and with diffuse margins; setae indistinctly thicker than those on pronotum, moderately dense and suberect.

Pygidium about as wide as long; length 010 mm.

Legs ( Figs 1 , 7 ) long and slender; protrochanter ( Fig. 7 ) unmodified.

Aedeagus ( Figs 10–13 ) slender, AeL 0.30 mm; median lobe in ventral view bottle-shaped, subcylindrical between basal and apical 1/4, gradually narrowed toward truncate base and abruptly narrowed in subapical region, apical margin rounded; endophallic structures not observable; parameres broad and barely discernible, translucent, only their base at each side of dorsal foramen well-visible as transverse ridge.

Female. Similar to male, also with impressed median area on frons and vertex; BL 1.09 mm; HL 0.13 mm, HW 0.23 mm, AnL 0.53 mm; PL 0.28 mm, PW 0.25 mm; EL 0.59 mm, EW 0.43 mm, EI 1.38.

Distribution. Northern Japan, Hokkaido, near Sapporo.

Etymology. After the type locality, the Nopporo Forest Park.

Remarks. Among Palaearctic species, Euthiconus nopporoensis is most similar to E. lustrificus ( Figs. 3–4 , 8, 14–15 ). Adults of these Far Eastern species share a similar shape of the pronotum ( Figs 2, 4 ), unmodified male protrochanters ( Figs 7, 8 ), and a similar shape of the aedeagus ( Figs 10–15 ). Adults differ in the following characters: body length ( E. nopporoensis is slightly smaller than E. lustrificus ); the shape of the antennomere III (distinctly transverse in E. nopporoensis vs. as long as broad in E. lustrificus ); setae on the pronotum (sparser in E. nopporoensis ( Fig. 2 ) and denser in E. lustrificus ( Fig. 4 )); and the shape of the aedeagus in ventral view (rapidly narrowed in the subapical region in E. nopporoensis ( Fig. 10 ) vs. evenly narrowed in E. lustrificus ( Fig. 14 )). The distribution of the third Palaearctic species is strictly European. Euthiconus conicicollis ( Figs 5–6 , 9, 16–17 ) differs from its Far Eastern congeners in having a distinctly larger body, the pronotum more strongly narrowing anterad ( Fig. 6 ), conspicuously modified male protrochanters ( Fig. 9 ), and the aedeagus with broadened apical region ( Figs 16–17 ).

Figures

FIGURES 1–6. Palaearctic Euthiconus, dorsal habitus (1, 3, 5) and close-ups of heads and pronota in dorsal view (2, 4, 6). Euthiconus nopporoensis sp. n., holotype male (1–2); E. lustrificus Kurbatov, paratype male (3–4); E. conicicollis, non-type male (5–6).

FIGURES 7–17. Palaearctic Euthiconus, protrochanter of male (7–9), and aedeagus in ventral (10, 12, 14, 16) and lateral (11, 13, 15, 17) views. Euthiconus nopporoensis sp. n., holotype male (7, 10–13); E. lustrificus Kurbatov, paratype male (8, 14–15); E. conicicollis, non-type male (9, 16–17).