Nipponophloeostiba explanata, Shavrin, 2023

Shavrin, Alexey V., 2023, Two new species and a new record of Omaliini McLeay, 1825 (Coleoptera: Staphylinidae: Omaliinae) from Indonesia, Zootaxa 5258 (2), pp. 245-250 : 246-248

Nipponophloeostiba explanata sp. n.

( Figs 1 , 3–6 )

Type material. HOLOTYPE: ♂ (dissected; right hind leg glued on the same card under the specimen): ‘ BALI 12 km NW of | Bedugul ( Buyan lake) | 29.Apr.-2.May2001 | Bolm lgt., 950 m’ <printed>, ‘HOLOTYPE | Nipponophloeostiba | explanata sp. n. | Shavrin A.V. des. 2023’ <red, printed> ( SMNS) .

Description. Measurements: HW: 0.42; HL: 0.32; OL: 0.11; TL: 0.10; AL: 0.52; PL: 0.35; PWmax: 0.40; PWmin: 0.33; ESL: 0.45; EW: 0.45; MTbL: 0.22; MTrL: 0.15 (MTrL 1–4: 0.05; MTrL 5: 0.10); AW: 0.50; AedL: 0.30; BL: 2.33.

Habitus as in Fig. 1 . Body reddish-brown, with slightly darker head and slightly paler laterobasal portions of pronotum and abdomen; antennomeres 6–11 brown; mouthparts, antennomeres 1–5, legs and intersegmental membranes between abdominal tergites yellow. Head with sparse punctation, finer in apical and denser in middle portions; neck without punctures; pronotum with very fine and sparse punctation, slightly finer than that of middle portion of head, sparser in middle; scutellum without punctures; elytra with moderately fine punctation, denser than that on pronotum, deeper in mediobasal third, finer and sparser along suture and apical portions; abdomen without distinct punctation. Head with dense and relatively coarse microsculpture, transverse in apical and longitudinal in middle and lateral portions; neck with coarse transverse microreticulation; pronotum with dense and longitudinal microsculpture, slightly finer and denser than that of head; elytra with dense and regular sculpture, slightly coarser than that of pronotum, longitudinal in middle and subdiagonal in laterobasal and apical portions; abdomen with dense and transverse microsculpture.

Head 1.3 times as broad as long, with deep and long anteocellar foveae (grooves in front of ocelli), subdiagonally extending anteriad to level of apical third of eyes; middle portion without impressions; basal margin of head somewhat widely concave; posterior portions between ocelli and temples with narrow, distinctly elevated and relatively straight carina, almost reaching posterior margin of eyes; postantennal impressions indistinct; temples (postocular parts) long, not expanded laterad, about as long as longitudinal length of eyes. Eyes large, moderately convex. Ocelli moderately small, located very close to posterior very narrow constriction, distance between ocelli short, about two and a half times shorter than distance between ocellus and posterior margin of eye. Maxillary palpi long; preapical palpomere indistinctly longer than broad; apical palpomere narrow, about 1.5 times as long as preceding segment, from about middle gradually narrowing toward acute apex. Antennae reaching apical third of pronotum when reclined; antennomeres 6–10 distinctly transverse; basal antennomere wide, about 1.7 times as long as broad, antennomere 2 small, about as long as broad, 3 narrow, about as long as 2, 4–5 very small, about as broad as 3, 6 about 1.8 times broader than 5, 7–10 distinctly broader than 6, apical antennomere slightly narrower and more than twice as long as 10, from middle gradually narrowed toward rounded apex.

Pronotum subtrapezoidal, 1.1 times as broad as long, slightly narrower than head, widest in about middle, with moderately straight margins in apical third, from middle gradually narrowed posteriad; anterior and posterior angles rounded; anterior margin widely rounded in middle, with two distinct, small and convex tubercles at level of lateral margins of neck; posterior margin rounded; median part with distinct longitudinal and very narrow band; lateral portions narrowly bordered, with distinctly impressed laterobasal portions.

Elytra as broad as long, reaching basal margin of abdominal tergite III, 1.2 times as long as pronotum, parallelsided, with slightly rounded apical margins. Hind wings fully developed.

Metatarsus 1.4 times as long as metatibia.

Abdomen long, relatively parallel-sided, slightly broader than combined length of elytra, with two small, suboval wing-folding patches in middle of abdominal tergite IV and indistinct palisade fringe at apical margin of tergite VII.

Male. Posterior margin of abdominal tergite VIII widely truncate ( Fig. 5 ). Posterior margin of abdominal sternite VIII widely rounded ( Fig. 6 ). Aedeagus with wide basal portion, gradually narrowed apically, with relatively wide median lobe; parameres gradually broadened apically, distinctly reaching apex of median lobe, with two long apical, three preapical setae and one additional seta on middle surface of each paramere; internal sac without visible structures ( Fig. 3 ). Lateral aspect of the aedeagus as in Fig. 4 .

Female unknown.

Comparative notes. Based on the proportions and the long posterior carina of the head, N. explanata sp. n. is similar to Bornean N. thayeri Shavrin, 2020 and N. longilobata Shavrin, 2020 , known from Laos and Indonesia. From N. thayeri it differs by the slightly narrower pronotum, shorter elytra and broader median lobe. Regarding the coloration of the body, length of the elytra and broadened median lobe, the new species is more similar to N. longilobata , from which it differs by the different shape of the apical portions of distinctly shorter parameres. From both species it can be distinguished by the slightly larger body, and features of the setation of the parameres.

Distribution. Nipponophloeostiba explanata sp. n. is known only from the type locality near Bedugul (Buyan) Lake in Bali, Indonesia.

Bionomics. The specimen were collected at an elevation of 950 m a.s.l.

Etymology. The specific epithet is the Latin explanatus, - a, - um (widened). It alludes to the broadened apical portions of the median lobe and parameres of the aedeagus.

Figures

FIGURES 1–2. Habitus of Omaliini: 1–Nipponophloeostiba explanata (holotype), 2–Phloeostiba mamasa (holotype). Scale bar: 1.00 mm.

FIGURES 3–6. Nipponophloeostiba explanata: 3–aedeagus (lateral view), 4–aedeagus (parameral view), 5–male tergite VIII (dorsal view), 6–male sternite VIII (ventral view). Scale bar: 0.10 mm.