Euconnus (s. str.) multiinsularis, 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 : 346-349

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

( Figs 6–18 , 109 )

Type material studied. Holotype ( Japan : Kagoshima Prefecture: Takarajima Is.): ♂, three labels: “Arakizaki / Takarajima Is. / Tokara, Ryukyu” [white, printed], “ 22. iii. 1992 / S. Nomura leg.” [white, printed], “ EUCONNUS s. str. / multiinsularis m. / P. Jałoszyński, ’22 / HOLOTYPUS ” [red, printed] ( NSMT) . Paratypes (9 exx): Takarajima Is.: ♂, same data as for holotype; Tokunoshima Is.: 2 ♂♂, “Yonama / Tokunoshima Is. / Kagoshima Pref. ” [white, printed], “ 4. v. 1988 / S. Nomura leg.” [white, printed]; Okinawa-jima Is.: 1 ♂, 1♀, “[Okinawa: RYUKYU] / Mt. Nishimedake / 360m, Kunigami / 19.X. 1987 / M. Sakai leg.” [white, printed], “ Leaf litter” [white with black frame, printed]; 1 ♂, “ Yona , kunigami / Okinawa Pref. ” [white, printed], “ 15. iii. 1985 / S. Nomura leg.” [white, printed]; 2 ♀♀, “(RYUKYUS) / Mt. Yonahadake / Okinawa Island / 6. X. 1978 / K. Ishikawa ” [white, printed], ”collected from / soil by using / Berlese funnel ” [white, printed]; Amami Ôshima Is.: ♂, “ JAPAN, KAGOSHIMA Pref. / Amami Ôshima, Yui-dake / 25-28-2004, white pan trap / Toshiharu Mita leg.” [white, printed] . Paratypes in NSMT, EUMJ and cPJ, all with yellow “ PARATYPUS ” labels similar to that with holotype.

Diagnosis. Antennal club clearly trimerous and slender; head round; pronotum subconical and broadest near base but only moderately narrowing anterad, with one pair of antebasal pits connected by distinct transverse groove and with distinct sublateral carinae; protibiae in males strongly bent mesad in apical regions; aedeagus conspicuously strongly, darkly sclerotized and strongly elongate, endophallic sclerites not fused into ring-like structure, with bulbous portion nearly parallel-sided or broadest in distal third and with relatively small dorsal apical plate, which in ventral view is only slightly elongate, in proximal half weakly narrowing distad, and in distal half abruptly narrowing to form subtrapezoidal and truncate apex.

Description. Body of male ( Fig. 6 ) elongate, moderately convex; pigmentation moderately dark umbra brown, legs and palps distinctly lighter, antennal clubs not infuscate; body covered with setae distinctly lighter than cuticle; BL 1.28–1.40 mm.

Head broadest at eyes, indistinctly transverse, HL 0.28 mm, HW 0.28–0.30 mm; tempora in dorsal view about 1.5 × as long as eyes, behind eyes strongly and evenly convergent posterad, posterior margin of vertex weakly arcuate, not bulging posterodorsad. Frons and vertex with unremarkable, fine punctures, glossy; setae sparse and suberect, tempora with sparse thick bristles. Antennae slender, with loosely assembled and slender trimerous club, AnL 0.58–0.63 mm, scape and pedicel each elongate, antennomeres 3–8 each indistinctly longer than wide, 9–11 enlarged, 9 and 10 each indistinctly transverse, 11 distinctly shorter than 9 and 10 combined, about 1.5 × as long as broad.

Pronotum subconical and broadest shortly in front of base, moderately narrowing anterad; PL 0.30–0.34 mm, PW 0.33–0.35 mm. Sides weakly rounded, base with one pair of small but distinct pits connected by transverse groove, and with distinct, sharply marked sublateral carinae. Punctures and setae on disc similar to those on frons and vertex; sides of pronotum with moderately dense thick bristles.

Elytra together oval, broadest distinctly in front of middle; EL 0.70–0.80 mm, EW 0.53–0.55 mm, EI 1.33–1.45; humeral calli distinct and slightly elongate, mesally demarcated by elongate impressions; elytral apices separately rounded. Punctures distinct but shallow, those near median area of both elytra separated by spaces slightly wider than diameters of punctures; setae sparse but much longer than those on pronotal disc, suberect.

Legs slender, protibiae modified, with apical regions strongly bent mesad.

Aedeagus ( Figs 7–18 ) strongly elongate and strongly sclerotized, AeL 0.33 mm; median lobe in ventral view broadest in distal third or nearly parallel-sided, in lateral view strongly curved, dorsal apical plate in ventral view elongate, with sides weakly converging distad in proximal half, rapidly narrowed in distal region to form subtrapezoidal and truncate apex; endophallus lacking ring-like sclerotized structure, poorly demarcated and situated in apical region. Parameres slender but short, not reaching apex of median lobe, each with two long apical setae. Some variability in the shape of median lobe was found among specimens collected on various islands ( Figs 7–18 ), but differences are minor and seem to represent only interspecific variation.

Female. Similar to male but with straight, unmodified distal region of protibiae. BL 1.28–1.34 mm; HL 0.28 mm, HW 0.30 mm, AnL 0.58–0.60 mm; PL 0.30–0.31 mm, PW 0.33–0.35 mm; EL 0.70–0.75 mm, EW 0.55–0.60 mm, EI 1.25–1.27.

Distribution. Islands of northern and central Ryūkyū:Takarajima, Tokunoshima,Amami Ôshima, and Okinawajima ( Fig. 109 ).

Etymology. The adjective multiinsularis refers to a distribution on several islands.

Remarks. Although this species externally resembles closely E. nuperus , E. debilis and E. chinensis , it can be easily identified by its unique, unusually elongate and slender aedeagus.Aedeagi of specimens collected on different islands were studied ( Figs 11–18 ) and only small differences were found, attributable to intraspecific variability. No external characters differ among populations inhabiting different islands. Females can be distinguished from the three similar congeners by slightly longer and slenderer body.

Interestingly, the northern Euconnus debilis and the southern E. multiinsularis co-occur on the small island of Takarajima, which represents the southernmost known locality for the former, and the northernmost for the latter ( Fig. 109 ).

Figures

FIGURE 109. Distribution of Euconnus debilis (Sharp) and E. multiinsularis sp. n.

FIGURES 6‒10. Euconnus multiinsularis sp. n., male (Takarajima). Dorsal habitus (6); aedeagus in ventral (7, 9) and lateral (8, 10) views.

FIGURES 11‒18. Euconnus multiinsularis sp. n., examples of aedeagus from specimens collected on Amami Ôshima (11‒12), Tokunoshima (13‒14), and Okinawa-jima (15‒18) islands.