Sinacrulia, Shavrin, 2023

Shavrin, Alexey V., 2023, A new genus of Omaliini from China (Coleoptera: Staphylinidae: Omaliinae), Zootaxa 5375 (3), pp. 429-438 : 430-434

Sinacrulia gen. n.

( Figs 1–17 )

Type species: Sinacrulia fortiterpunctata sp.n.

Description. Body moderately convex and slightly elongate, brown or reddish-brown ( Figs 1–2 ). Punctation of forebody very dense, large and coarse, markedly larger and deeper on pronotum and elytra, with distinct elevations between punctures in pronotum and elytra. Dorsal surface of body glossy; head with dense microsculpture in apical and lateral portions; pronotum and elytra without microreticulation; abdomen with very dense and coarse isodiametric microreticulation. Body without pubescence except of frontal portion of head with very sparse moderately long setae on apical part of clypeus and abdomen with sparse and very short recumbent setation. Body length: 2.01–2.22 mm.

Head markedly narrower than pronotum, distinctly transverse, slightly convex in middle, with wide frontoclypeal portion and distinctly convex supra-antennal elevations, widely rounded and more convex at level of antennal insertions; each laterobasal part of supra-antennal elevation with narrow elongate wrinkle diagonally or directly stretching posteriad to level of anterior margin of eyes; nuchal constriction sharp, head strongly separated from neck. Head with a pair of ocelli located near nuchal constriction at level of hind angles of temples, with indistinct and narrow anteocellar foveae slightly curved lateroapicad in front of anterior margins of each ocellus. Postocular ridges missing. Anteriomedian depressions at level of antennal insertions fine and relatively wide. Eyes large, strongly convex, about twice longer than temple (if seen dorsally). Temples moderately long, subparallel at level slightly behind eyes and then widely rounded toward neck. Antennal insertion concealed under supra-antennal elevation; antenna slightly longer than head and pronotum combined, reaching basal margin of elytra when reclined; antennomeres 1–3 strongly elongate, 4–6 small, about as broad as long or slightly elongate, 7–10 distinctly transverse. Labrum ( Fig. 3 ) small, with widely rounded latero-apical portions, widely concaved anteriorly, with four to six pairs of long anterolateral setae and two rows of of shorter setae in middle of apical portion. Mandibles ( Figs. 4–5 ) broad, each with concave latero-basal margin and subacute apex; right mandible ( Fig. 5 ) with slightly more curved apex and small obtuse tooth at distal third of cutting edge; articulations of molar lobes with strong acute dents almost in entire half of latero-apical margin. Maxilla ( Fig. 8 ) narrow, long; galea oblong, moderately narrow, with relatively dense long apical setae; lacinia very narrow, slightly curved on outer margin of apical half, with row of small thorns on apical third of inner margin; maxillary palpi moderately long, second palpomere distinctly longer than broad, third palpomere slightly transverse and slightly broader than preapical segment, apical palpomere moderately narrow, slightly less than three times as long as preapical segment, from basal part gradually narrowing apicad toward rounded apex. Labium ( Fig. 6 ) distinctly bilobed, two preapical segments distinctly transverse, apical segment about twice longer than preapical segment, with rounded apex. Mentum ( Fig. 7 ) moderately large, transverse, trapezoidal, with three short setae on lateral margins. Gular sutures relatively narrowly separated from each other at level of posterior margins of eyes, strongly divergent posteriad.

Pronotum transverse, convex, without ( S. fortiterpunctata sp.n.) or with (S. sp.) indistinct longitudinal and semioval mediobasal impressions, with slightly and widely impressed laterobasal portions, with elongate curved relatively short narrow elevation in latero-apical part; lateral margins distinctly crenulate, with indistinct and irregular (S. sp.) or with relatively regular small acute thorn-shaped crenulation. Prothorax short, strongly transverse, convex in middle, with short acute intercoxal process reaching about middle of front coxae. Mesoventrite very short, without carina, with acute elongate process, reaching apex of long and narrow intercoxal process extending to about middle of mesocoxae. Scutellum wide, triangular. Metaventrite markedly transverse, convex, with deep mesocoxal cavities and wide moderately short intercoxal process, obtuse apically and extending to mesosternal process.

Elytra convex, indistinctly depressed in mediobasal portion, moderately short and wide, extending to apical margin of abdominal tergite III or basal margin of abdominal tergite IV, slightly less than twice as long as pronotum, slightly broadened posteriad, with broad epipleura and well-developed rounded humeri, with slightly serrate lateral margins. Wings fully developed.

Legs moderately short; mesocoxae oval; metacoxae large and subtriangular; tibiae slightly widened apicad; apical half of pro- and mesotibia with elongate spines on inner and outer margins, slightly denser on protibiae; metatibiae without modification and spines, covered with long setae, denser and longer on inner margin; tarsi short, apical tarsomere long, twice longer than previous four tarsomeres combined; protarsi with very long lateral setae ( S. fortiterpunctata sp.n.).

Abdomen distinctly convex, slightly narrower or broader than elytra, with a pair of small oval and sometimes indistinct tomentose spots (wing-folding patches) in middle of abdominal tergite IV; apical margin of abdominal tergite VII with very narrow palisade fringe.

Male. Aedeagus short and wide, with very wide median lobe, strongly narrowed apically, with elongate accessory plates, short and moderately broad cylindrical parameres and very long flagellum spirally folded in middle portion ( Fig. 9 ).

Female. Accessory abdominal sclerite weakly sclerotized, transverse and wide ( Fig. 15 ). Gonocoxites wide and long, with relatively short styli and long apical setae ( Fig. 15 ). Spermatheca not recognized.

Immature stages unknown.

Species included. Sinacrulia fortiterpunctata sp.n.

Differential diagnosis. Based on the general shapes of the body and the aedeagus, the hind tarsomeres 1–4 together distinctly shorter than apical tarsomere and transverse preapical antennomeres, Sinaculia gen.n undoubtedly belongs to the tribe Omaliini . Regarding the general shape of small and convex body, with the presence of the distinctly crenulate lateral margins of the pronotum, Sinacrulia gen.n. can be compared with several genera which have recently been reviewed by Shavrin & Zanetti (2020): Palaearctic Acrulia Thomson, 1858 (three species), western palaearctic Dialycera Ganglbauer, 1895 (three species), Holarctic Acruliopsis Zerche, 2003 (five species), and Holarctic Hapalaraea Thomson, 1858 (six species). From all these genera Sinacrulia gen.n. can be distinguished by the following morphological features: 1) apical segment of the maxillary palpi very long and narrow, slightly less than three times as long as moderately broad penultimate segment, 2) the presence of indistinct pronotal impressions (S. sp.), 3) the shape of very broad median lobe, from widest middle strongly narrowed apically, 4) the shape of the very short parameres, reaching middle of the median lobe, 5) the presence of elongate accessory plates (“accessory lamella” according Zanetti (1987)) rounded apically at level of middle part of the median lobe, 6) the missing of sclerotized spines of internal sac, 7) the presence of very long and strong flagellum. Based on the general shape of the transverse head evenly convex in middle, without shield-like median elevation and with moderately long temples, the shape of the slightly elongate antennomere 5, and the strong punctation of the forebody, Sinacrulia gen. n. is somewhat similar to the genus Acruliopsis ( Zerche 2003, Shavrin 2013, Shavrin & Zanetti 2020), from which it differs by the missing of pubescence of the forebody, finer crenulation of lateral margins of the pronotum, longer elytra and different morphology of the aedeagus. From all genera of Omaliini it can be distinguished by the unusual shape of the aedeagus, and the presence of very long flagellum.

Natural history. The species of Sinacrulia were collected at high elevations from 2970 to 3050 m a.s.l. by sifting of litter and mosses.

Distribution. China: Yunnan ( Fig. 17 ).

Etymology. The name of the new genus is derived from the prefix Sino -, referring to China, and the genus name Acrulia , one of the relative taxa of the tribe Omaliini .

Remarks. The general structure of the aedeagus of Sinacrulia gen.n. is somewhat similar to that of some species of Omalium Gravenhorst, 1802 and Acrolocha Thomson 1858 . Almost all species of these genera have developed accessory plates, sometimes strongly sclerotized and protruded apicad between elongate median lobe, and also have similar shapes of the parameres (usually more complicated in many species Omalium ). The presence of large and long flagellum in Sinacrulia gen.n. is unique. Only species of some genera have short narrow flagellum not spirally folded in basal portion of the aedeagus (e.g. Carcinocephalus Berhauer, 1903 , Omaliopsis Jeannel, 1940 (some species), Phloeonomus Heer, 1839 , Tetradelus Fauvel, 1904 ). Usually, the very long flagellum with the spiral in basal portion of the aedeagus can be observed in some genera of the tribe Anthophagini Thomson, 1859 : Hygrodromicus Tronquet, 1982 ( Shavrin 2021b, 2022), Trichodromeus Luze, 1903 ( Zerche 1992, Shavrin 2012, 2021a).

Figures

FIGURE 17. Distribution of Sinacrulia in China (black circle: S. fortiterpunctata, white circle: S. sp.).

FIGURES 1–2. Habitus of Sinacrulia: 1–S. fortiterpunctata (holotype), 2–S. sp. Scale bars: 1.0 mm.

FIGURES 3–8. Mouthparts of Sinacrulia fortiterpunctata (holotype): 3–labrum (dorsal view), 4–left mandible (dorsal view), 5–right mandible (dorsal view), 6–labium (ventral view), 7–mentum (ventral view), 8–right maxilla (dorsal view). Scale bars: 0.1 mm.

FIGURES 9–10. Aedeagus of Sinacrulia fortiterpunctata (holotype): 9–parameral view, 10–lateral view. Scale bar: 0.1 mm.

FIGURES 11–15. Abdominal segments of Sinacrulia (Figs 11–12: S. fortiterpunctata (holotype), Figs. 13–15: S. sp.): 11–male tergite VIII (dorsal view), 12–male sternite VIII (ventral view), 13–female tergite VIII (dorsal view), 14–female sternite VIII (ventral view), 15–female genital segment (dorsal view). Scale bars: 0.1 mm.

FIGURE 16. Type locality of Sinacrulia fortiterpunctata in the Diancang Shan, Yunnan, China (photograph: M. Schülke).