Paraneseuthia ishigakiana, 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 : 267-268

Paraneseuthia ishigakiana sp. n.

( Figs 1 , 4 , 10–11 )

Type material. Holotype: JAPAN (OKINAWA Pref.): ♂, two labels: " JAPAN, OKINAWA Pref. / ISHIGAKI- JIMA, Kabira env. / (NW), jungle and roadside, / 18 I 2017, / leg. P. JAŁOSZYŃSKI " [white, printed]; " PARANESEUTHIA / ishigakiana m. / det. P. Jałoszyński, 2018 / HOLOTYPUS " [red, printed] (NSMT).

Diagnosis. Body small (BL <1 mm); protibia in male with angulate mesal expansion and tiny denticle between proximal third and middle; aedeagus with bifurcate apex of median lobe and a pair of conspicuously large, falciform sclerites protruding from ostium; parameres strikingly broadened and in lateral view of irregular shape (not rod-like).

Description. BL 0.84 mm. Body of male ( Fig. 1 ) elongate and moderately convex, light brown, setae yellowish.

Head broadest at large, strongly convex and coarsely faceted eyes, HL 0.11 mm, HW 0.19 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 0.40 mm, antennomeres I–II elongate, III–IX each about as long as broad, X slightly 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. 1 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 0.23 mm, PW 0.28 mm; pronotal base with one pair of small lateral pits each in a subtriangular diffuse impression, impressions not connected by groove. Punctures on pronotal disc fine and inconspicuous; setae moderately long, sparse and suberect.

Elytra oval, broadest between middle and anterior third and relatively strongly narrowing posterad, evenly convex; EL 0.50 mm, EW 0.38 mm, EI 1.33; 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 equal to or smaller than 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 near proximal third, with mesal angulate expansion and a tiny denticle.

Aedeagus ( Figs 4 , 10–11 ) stout, AeL 0.23 mm; median lobe in ventral view broadest in subapical region of basal capsule, apex of median lobe with a deep median U-shaped emargination separating subtriangular apical projections, each with an additional triangular tooth at base; endophallus with a pair of very large lateral falciform projections protruding from ostium and overlapping at middle; parameres conspicuously thickened, in lateral view very broad and irregular in shape, in ventral view broad with rounded apices, each with two apical setae of unequal length.

Female. Unknown.

Distribution. Ishigaki Island (Yaeyama islands of Ryūkyū Archipelago, southwestern Japan).

Etymology. Locotypical, after Ishigaki Island.

Remarks. Males of Paraneseuthia ishigakiana and P. inexpectata differ from those of all other Japanese species in the angulate expansion of protibiae not at middle, but distinctly near the proximal third. These two species (occurring in the SW Ryūkyū and central Honshū, respectively), clearly differ in the male genital characters. The aedeagus of P. ishigakiana has remarkably massive, strongly curved projections of the endophallus and subtriangular lateral apical projections of the median lobe, whereas in P. inexpectata the endophallic sclerites are much shorter, rod-like and weakly curved, and the lateral apical lobes of the median lobe are suboval. This is the first nominal species of Paraneseuthia known to occur in the Ryūkyū Archipelago. Females of two more undescribed species have been collected in Japan, each externally clearly different from P. ishigakiana ; one comes from Okinawa Island (EUMJ), the other from Iriomote Island (cPJ).

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).