Euconnus (s. str.) yaimanus, Jałoszyński, 2022

Jałoszyński, Paweł, 2022, Taxonomy of ' Euconnus complex'. Part XXIV. Intermediate forms between Psomophus, Eupentarius and Euconnus s. str. in the East Palaearctic fauna unify problematic subgenera (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 5194 (3), pp. 343-391 : 354-357

Euconnus (s. str.) yaimanus sp. n.

( Figs 37–47 , 110 )

Type material studied. Holotype ( Japan: Okinawa Prefecture: Iriomote-jima Is.): ♂, two labels: “JAPAN, OKINAWA Pref. / Kanpiree,St. 1(80 m)/ Iriomote-jima/ 20.iii.2004 / leg. S. Nomura ”[white, printed], “ EUCONNUS s. str. / yaimanus m. / P. Jałoszyński, ’22 / HOLOTYPUS ” [red, printed] ( NSMT) . Paratype: Yonaguni-jima Is.: ♂, “JAPAN, Okinawa Pref. / Yonaguni-jima , Mt. Kubura- / dake, FIT, 9-12.ix.2004 / Koji& Shiho Arai leg.” [white, printed]. Paratype with yellow “ PARATYPUS ” label similar to that with holotype, deposited in cPJ .

Diagnosis. Antennal club clearly trimerous and stout; head distinctly elongate, with vertex bulging posterodorsad and in males with pair of small and diffuse lateral frontal impressions connected at middle by deep transverse groove; pronotum subconical, with one pair of tiny antebasal pits connected by extremely faint, barely noticeable transverse impression, and with indistinct sublateral carinae; protibiae in males unmodified, weakly and evenly curved; aedeagus weakly sclerotized, in ventral view bottle-shaped, with asymmetrical group of strongly elongate endophallic sclerites in subapical region, longest sclerite (in ventral view on the right side) strongly curved distomesad.

Description. Body of male ( Fig. 37 ) elongate, strongly convex; pigmentation moderately dark brown, only tarsi, palps and antennal clubs indistinctly lighter; body covered with setae distinctly lighter than cuticle; BL 1.08– 1.09 mm.

Head ( Figs 46‒47 ) smaller (especially narrower) than pronotum, broadest at eyes, distinctly elongate, HL 0.25 mm, HW 0.20–0.21 mm; tempora in dorsal view over twice as long as eyes, behind eyes strongly and evenly convergent posterad, posterior margin of vertex strongly rounded, strongly bulging posterodorsad. Frons with deep transverse groove broadened at each side, median region directly behind groove convex, and region in front of groove distinctly bulging (best visible in lateral view; Fig. 47 ); each side of anterior head region with small, transverse impression. Frons and vertex with unremarkable, fine punctures, glossy; setae sparse and suberect, frontal groove posteriorly bordered by transverse row of dense and short nearly recumbent setae, tempora with dense but short thick bristles. Antennae short and compact, with compact and broad trimerous club, AnL 0.40 mm, scape and pedicel each elongate, antennomeres 3‒10 each transverse (3‒8 weakly, 9 and 10 strongly so), 11 slightly shorter than 9 and 10 combined, about as long as broad.

Pronotum subconical, broadest slightly behind middle; PL 0.25–0.29 mm, PW 0.25–0.28 mm. Base with one pair of tiny antebasal pits connected by extremely faint, barely noticeable transverse impression, and with indistinct sublateral carinae. Punctures and setae on disc similar to those on frons and vertex; sides of pronotum with sparse thick bristles.

Elytra together oval, broadest slightly in front of middle; EL 0.55–0.58 mm, EW 0.40 mm, EI 1.38–1.44; humeral calli poorly marked and mesally not demarcated by impressions; elytral apices separately rounded. Punctures distinct but very shallow, superficial and diffuse, unremarkable; setae sparse and only slightly longer than those on pronotal disc, only slightly suberect.

Legs slender, protibiae unmodified, weakly and evenly curved.

Aedeagus ( Figs 38–45 ) stout, bottle-shaped, weakly sclerotized, AeL 0.20 mm; median lobe in ventral view almost equally broad from sub-basal third to subapical region, so that sides at middle are parallel, in lateral view median lobe weakly curved, dorsal apical plate in ventral view subtrapezoidal with ( Figs 38, 40 ) or without ( Figs 42, 44 ) additional median truncate projection; endophallus in subapical region with conspicuous asymmetrical group of elongate sclerites, of which the longest is strongly curved distomesad. Parameres broad and short, not reaching apex of median lobe, each with 4–5 apical and subapical setae of various lengths, parameral base with small collar.

Female. Unknown.

Distribution. Japan, southern Ryūkyū: Iriomote-jima and Yonaguni-jima islands of the Yaeyama Archipelago ( Fig. 110 ).

Etymology. The epithet yaimanus is an adjective derived from the word Yaima, the name of Yaeyama Islands in the Yaimamuni, i.e., the Yaeyama language.

Remarks. This species is most similar to E. kirin ; see Remarks for the latter.

Males from two islands (Iriomote and Yonaguni) do not differ in external characters, although minor differences in the apical region of the aedeagus were found, and even smaller differences in the endophallic sclerites ( Figs 38–41 vs. 42–45). I treat these specimens as conspecific, but a larger sample is required to verify this assumption.

Figures

FIGURE 110. Distribution of Euconnus rectitibia sp. n., E. kirin sp. n., E. yaimanus sp. n., and E. uchinaanchu sp. n.

FIGURES 37‒45. Euconnus yaimanus sp. n., male, specimens from Iriomote-jima (37‒41) and Yonaguni-jima (42‒45). Dorsal habitus (37); aedeagus in ventral (30, 32, 42, 44) and lateral (39, 41, 43, 45) views.

FIGURES 46‒47. Euconnus yaimanus sp. n., male. Head in anterodorsal (46) and lateral (47) views.