Paraneseuthia ehimensis, Jałoszyński, 2018

Jałoszyński, Paweł, 2018, Paraneseuthia Franz of Japan: two new species and rediscovery of the enigmatic P. holzneri Franz (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4532 (2), pp. 266-272 : 268-270

Paraneseuthia ehimensis sp. n.

( Figs 2 , 5–7 , 12–15 )

Type material. Holotype: JAPAN (EHIME Pref.): ♂, two labels: "[Ehime: Japan] / Narukawa, Hiromi / 5.V.1992 M.Sakai / in leaf litter " [white, printed]; " PARANESEUTHIA / ehimensis m. / det. P. Jałoszyński, 2018 / HOLOTYPUS " [red, printed] (EUMJ). Paratypes: 2 ♂♂, "(Ehime: Japan) / Namakusadani / ODAMIYAMA / 15.

X. 1994 / M. Sakai leg."; 1 ♂, [SHIKOKU] / Ooshima I. / Ehime Pref. / 22~ 23. IX. 1972 / S. Kinoshita " (paratypes in EUMJ and cPJ) .

Diagnosis. Body small (BL ± 1 mm); protibia in male with a distinct mesal denticle at middle; aedeagus with broadly and shallowly emarginate apex of median lobe with a distinct small median subtriangular projection and a pair of short, curved sclerites protruding from ostium; parameres slender.

Description. BL 0.93–1.03 mm (mean 0.98 mm). Body of male ( Fig. 2 ) elongate and moderately convex, light brown, setae yellowish.

Head broadest at large, strongly convex and coarsely faceted eyes, HL 0.13–0.14 mm (mean 0.13 mm), HW 0.23–0.24 mm (mean 0.23 mm); vertex and frons confluent and evenly, weakly convex; supraantennal tubercles small but distinct. Punctures on head dorsum inconspicuous; setae short, sparse and suberect. Antennae slender, with indistinctly delimited trimerous club, AnL 0.43–0.48 mm (mean 0.46 mm), antennomeres I–II elongate, III– VIII each indistinctly transverse, IX–X each distinctly transverse, XI broader than X, about as long as IX–X together, about 1.7× as long as broad.

Pronotum subquadrate in dorsal view, with anterior and lateral margins rounded and posterior margin nearly straight, broadest near anterior third (in Fig. 2 pronotum is slightly tilted anteroventrad and its shape differs from that seen in strictly dorsal view), sides weakly narrowing toward obtuse-angled and blunt posterior corners; PL 0.28–0.30 mm (mean 0.28 mm), PW 0.33–0.35 mm (mean 0.33 mm); pronotal base with two lateral pairs of small pits and a short median variously distinct (from moderately distinct to barely discernible) transverse impression. Punctures on pronotal disc fine and inconspicuous; setae moderately long, sparse and suberect.

Elytra oval, broadest between middle and anterior third and moderately strongly narrowing posterad, evenly convex; EL 0.53–0.60 mm (mean 0.57 mm), EW 0.40–0.45 mm (mean 0.43 mm), EI 1.29–1.41; humeral calli distinct but small, basal impressions indistinct; apices separately rounded. Punctures on elytra distinct but small and diffuse, dense, in anteromedian portion of elytra separated by spaces subequal to diameters of punctures; setae long, moderately dense and suberect. Hind wings well developed.

Metaventrite with large, elongate but shallow and diffuse impression occupying most of its length.

Legs moderately long and slender; protibiae distinctly bent at middle, with a distinct mesal denticle.

Aedeagus ( Figs 5–7 , 12–15 ) moderately stout, AeL 0.23 mm; median lobe in ventral view broadest in subapical region of basal capsule, apical portion of median lobe with rounded sides, and a shallow and broad apical emargination bearing a small median subtriangular projection; endophallus with a pair of moderately long and weakly curved lateral projections protruding from ostium and not overlapping at middle; parameres slender, unmodified, each with one apical and one subapical seta of unequal length.

Female. Unknown.

Distribution. Shikoku.

Etymology. Locotypical, after Ehime Prefecture.

Remarks. Males of Paraneseuthia ehimensis are externally indistinguishable from those of P. paradoxa ; these are the only Japanese species with the aedeagal apical margin not bifurcate, but weakly and broadly emarginate and bearing a distinct median subtriangular projection. As all Japanese congeners, P. ehimensis and P. paradoxa also have a pair of elongate endophallic sclerites, which are clearly different in each species. In the aedeagus of P. paradoxa , the endophallic sclerites are conspicuously long and strongly curved mesad, so that their distal halves overlap ( Fig. 8 ). In P. ehimensis , the endophallic sclerites are much shorter and only weakly curved. The sclerites show some variability in shape ( Figs 5–7 ). Endophallic sclerites are extricable structures; in a fully erect state they are entirely exposed and projecting from the aedeagal apex, the erection also requires the sclerites to rotate (e.g., Fig. 3G in Jałoszyński & Hoshina (2004)). Consequently, some of the variability observed in the studied specimens is caused not by true differences in shape, but by the rotation of the sclerites. However, in all studied specimens of P. ehimensis the sclerites are too short to overlap at middle, whereas those in P. paradoxa are so long and so strongly curved that they cannot occupy the subapical region of the median lobe without overlapping.

Figures

FIGURES 1–3. Dorsal habitus of males. Paraneseuthia ishigakiana sp. n. (1); P. ehimensis sp. n. (2), P. holzneri (Franz) (3).

FIGURES 4–9. Aedeagus in ventral view (4–7, 9) and endophallic sclerites in ventral view (8). Paraneseuthia ishigakiana sp. n. (4); P. ehimensis sp. n. (variability among studied specimens, 5–7), P. paradoxa (K. Sawada) (8), P. holzneri (Franz) (9).

FIGURES 10–17. Aedeagus in ventral (10, 12, 14, 16) and lateral (11, 13, 15, 17) views. Paraneseuthia ishigakiana sp. n. (10–11); P. ehimensis sp. n. (extreme forms of variability among studied specimens, 12–15), P. holzneri (Franz) (16–17).