Xanthonomus guineensis, Shavrin, 2024

Shavrin, Alexey V., 2024, Twenty-one new species of Omaliini from the Papuan Region (Coleoptera: Staphylinidae: Omaliinae), with diagnostic and faunistic notes on some species of the genus Paraphloeostiba Steel, 1960, Zootaxa 5424 (3), pp. 251-307 : 302-305

Xanthonomus guineensis sp. n.

( Figs 142 , 152–158 )

Type material. Holotype ♂ ( Fig. 142 ): ‘ IRIAN JAYA: Paniai Prov. | Bilogay, 29. 12. 1995 | 2100-2200m | leg. A. Riedel’ <printed>, ‘ HOLOTYPE | Xanthonomus | guineensis sp. n. | Shavrin A. V. des. 2024’ <red, printed> ( NMW).

Paratypes: 5 ♂♂ (one specimen dissected), 3 ♀♀ (one specimen dissected): same data as the holotype (1 ♂, 1 ♀: cSh; 4 ♂♂, 2 ♀♀: NMW); 3 ♂♂, 1 ♀ (dissected): ‘ IRIAN JAYA: Paniai Prov. | Sinak, trail to Ilaga | 2100-2500m, 15. 12. 1995 | leg. A. Riedel’ <printed> ( NMW). All paratypes with additional red printed label: ‘ PARATYPE | Xanthonomus | guineensis sp. n. | Shavrin A. V. des. 2024’.

Description. Measurements (n=13): HW: 0.40–0.46; HL: 0.20–0.25; OL: 0.12–0.14; TL: 0.02–0.03; AL (holotype): 0.52; PL: 0.29–0.38; PWmax: 0.53–0.57; PWmin: 0.49–0.52; ESL: 0.45–0.52; EW: 0.66–0.73; MTbL (holotype): 0.35; MTrL (holotype): 0.24 (MTrL 1–4: 0.07; MTrL 5: 0.17); AW: 0.75–0.80; AedL: 0.45; BL: 1.87– 2.25 (holotype: 2.04).

Habitus as in Fig. 142 . Body dark brown, with slightly paler elytra and sometimes abdominal tergites VII–VIII; antennomeres 7–11 and femora brown; tibia yellow-brown, with paler apical portion; mouthparts, antennomeres 1–6 and tarsi yellow. Head with very fine, indistinct and dense punctation, finer and more indistinct on infraorbital portions; neck without visible punctures; pronotum with very dense and fine punctation, missing in mediobasal portion; scutellum without punctures; elytra with very fine and dense punctation similar to that in pronotum, usually finer and sparser around scutellum and along suture; abdomen with very dense and fine punctation. Head with dense and coarse microreticulation, transverse on clypeus and isodiametric in middle; neck with moderately fine transverse microreticulation; pronotum with very dense and fine isodiametric meshes about as that in middle portion of head; scutellum with dense and coarse transverse microsculpture; elytra with fine and sometimes indistinct isodiametric microreticulation, sometimes indistinct along suture; abdomen with very dense and moderately coarse isodiametric sculpture.

Head distinctly transverse, 1.8 times to twice as broad as long, with slightly elevated infraorbital portions and shallow oval anteriomedian depressions, indistinct in some paratypes; anteocellar foveae very narrow, linear, reaching level of apical third or about middle length of eyes; postocular parts very short, from indistinct and obtuse postocular carina strongly narrowed posteriad. Eyes very large, convex. Ocelli moderately large, located slightly below level of postocular carina; distance between ocelli slightly longer or about as long as distance between ocellus and posterior margin of eye. Maxillary palpi long; preapical palpomere about twice as long as wide; apical palpomere narrow, slightly longer than preapical segment, from preapical portion gradually narrowed apicad toward rounded or subacute apex. Antennomeres short, reaching basal third of pronotum when reclined, with distinctly transverse antennomere 7 and strongly transverse antennomeres 8–10; antennomeres 6–10 gradually widened apicad; four apical antennomere forming distinct loose club; basal antennomere wide, slightly more than two and a half times as long as wide, antennomere 2 about twice shorter than basal antennomere, 3 slightly shorter and about twice narrower than 2, 4 about twice shorter than 3, 5 slightly longer and distinctly broader than 4, 6 distinctly shorter and broader than 5, 7 distinctly shorter and broader than 6, 8 three times broader than 6, 9–10 about twice longer and distinctly broader than 8, apical antennomere about 1.3–1.5 times as long as 10, from middle gradually rounded toward rounded apex.

Pronotum slightly convex, 1.5–1.8 times as broad as long, distinctly broader than head, widest in middle, slightly more narrowed posteriad than anteriad; apical and hind angles widely rounded; anterior margin straight, about as long as rounded posterior margin; median part without longitudinal impressions; lateral portions narrowly bordered; laterobasal portion without depression.

Elytra 1.4 times as long as broad, short, reaching basal or middle portion of abdominal tergite III, 1.3–1.5 times as long as pronotum, slightly broadened posteriad, with slightly concave lateral margins and striagth or rounded apical margins. Hind wings fully developed.

Metatarsus about 1.4 times as long as metatibia; ventral surface of protarsomeres 1–4 with several rows of modified tenent setae.

Abdomen slightly broadened toward andominal tergite IV or V, distinctly broadened than elytra, with two very small and sometimes indistinct oval wing-folding patches in middle of abdominal tergite IV and narrow palisade fringe at apical margin of abdominal tergite VII.

Male. Femora very wide; tibia significantly broadened in middle; tarsomeres 1–4 slightly broadened, with very long tenent setae. Posterior margin of abdominal tergite VIII slightly sinuate ( Fig. 154 ). Posterior margin of abdominal sternite VIII slighly sinuate, with row of very short setae on apical margin ( Fig. 155 ). Aedeagus long, with very wide basal portion, gradually narrowed toward small and rounded apex; parameres narrow, distinctly not reaching apex of median lobe, with two long apical and two preapical setae; internal sac long and moderately wide, with two very long, narrow and curved sclerotized structure, stretching from basal to about middle part of median lobe ( Fig. 152 ). Lateral aspect of the aedeagus as in Fig. 153 .

Female. Femora, tibia and tarsomeres 1–4 moderately narrow. Posterior margin of abdominal tergite VIII ( Fig. 156 ) and sternite VIII ( Fig. 157 ) trunctate. Accessory sclerite and spermatheca not recognized.

Comparative notes. Based on the general shape and sculpture of the body X. guineensis sp. n. is similar to X. thayerae sp. n., from which it can be distinguished by the slightly larger body, wider median lobe and shorter parameres.

Distribution. Xanthonomus guineensis sp. n. is known only from the type locality in Western New Guinea, Indonesia ( Fig. 158 ).

Etymology. The specific epithet is the latinized adjective derived from the area the specimens were collected from.

Bionomics. Specimens were collected at elevations from 2100 to 2200 m a.s.l. The detailed bionomical data are unknown.

Figures

FIGURE 158. Distribution of Xanthonomus: X. toxopeanus (circle), X. latus (triangle), X. guineensis (squares), X. thayerae (diamonds).

FIGURES 141–143. Habitus of Omaliini: 141–Paraphloeostiba telnovi (holotype), 142–Xanthonomus guineensis (holotype), 143–X. thayerae (paratype). Scale bars: 1.0 mm.

FIGURES 152–157. Xanthonomus guineensis (paratypes): 152–aedeagus, parameral view, 153–aedeagus, lateral view, 154– male abdominal tergite VIII, 155–male abdominal sternite VIII, 156–female abdominal tergite VIII, 157–female abdominal sternite VIII. Scale bar: 0.1 mm.