Orbellia zhangi, Zeng & Wei & Yang, 2025

Orbellia zhangi sp. nov.

( Figs. 1–11 View FIGURE 1 View FIGURES 2−6 View FIGURES 7−11 )

Diagnosis. First flagellomere brownish orange, slightly dark at tip. Palpus yellowish orange, not darkened at tip. Postpronotum color distinct from mesonotum, slightly lighter and yellowish orange. 3 pairs of scutellar setae. Surstylus finger-like at tip with a concavity at apex in outer surface, about 2.3 times as long as basal width.

Description. Body length 3.6–5.6 mm, wing length 5.0– 6.7 mm [Holotype ♂, body length 4.7 mm, wing length 5.9 mm. Paratypes 1 ♂, body length 3.6 mm, wing length 5.0 mm; 1 ♀, body length 5.6 mm, wing length 6.7 mm].

Male. Head ( Figs. 2–4 View FIGURES 2−6 ) brownish grey with pale golden pruinesence; ocellar triangle brown, frons brownish yellow with pale yellow markings, occiput almost brown; gena posteriorly brownish yellow, anteriorly slightly paler. Eyes brownish yellow. Hairs and setae on head dark brown. 2 pairs of fronto-orbital setae directed outwards, much shorter than ocellar seta, anterior one slightly shorter than posterior one (observed in paratypes, left anterior one broken off in holotypes). Antenna brownish orange; pedicel with 1 black dorso-apical seta and 1–2 rows of circle setae. First flagellomere slightly dark at tip, round with pale golden velvet, 0.20 times as long as head height; arista pubescent, brownish, 3.35 times longer than first flagellomere. Proboscis brownish yellow with one pair of vibrissae; hairs on proboscis pale golden; palpus yellowish orange, not darkened at tip, with several short setae.

Thorax ( Fig. 5 View FIGURES 2−6 ) brownish grey, postpronotum color distinct from mesonotum, slightly yellowish, mesonotum with pale golden pruinescence. Scutum covered with stained patches, without obvious stripe observed. Hairs and setae on thorax dark brown. Postpronotum with 1 well developed postpronotal seta and 11–12 short setae; 1 proepisternal seta, 1 thin proepimeral seta half as long as proepisternal seta; 2+4 dorsocentral setae, posterior two longest, gradually decreased in length towards front, 6 irregular rows of acrostichal setae between them; katepisternum with 1 long seta and 4 irregular short setae, about half as long as long setae; anepimeron and anepisternum bare. A pair of prescutellar setae present. Scutellum rounded apically with 3 pairs of scutellar setae broken (in holotpye, in paratype only anterior two on right remained, slightly bent inward and backward).

Wing ( Fig. 6 View FIGURES 2−6 ) nearly hyaline, slightly brownish yellow; veins brownish yellow, crossveins r-m and dm-m without obvious dark markings on membrane; costal spines inconspicuous. Horizontal position where vein R 1 connects with vein C between crossveins r-m and dm-m. Calypter and alula nearly hyaline with pale grey hairs. Halter whitish yellow.

Legs brownish yellow except femora darkened dorsally, with pale golden pruinescence. Hairs and setae on legs dark brown. Fore femur slightly thickened with two irregular rows of 12 long dorsal setae and slightly dense short ventral setae; mid femur with 4 antero-dorsal setae in middle; hind femur without obvious long seta. Fore tibia with 1 longer preapical dorsal seta; mid tibia with 2 long strong preapical spines and 3 short strong preapical spines; hind tibia with 1 long preapical dorsal seta.

Abdomen brownish grey dorsally, except apex yellowish orange and tergites 2−5 with narrowly paler posterior band. Hairs and setae on abdomen dark brown. Tergites with long setae longer at posterior margin.

Male genitalia ( Figs. 7–11 View FIGURES 7−11 ): Epandrium large, yellowish orange, with sparse black setae. Hypandrium symmetrical. Surstylus finger-like at tip, with a concavity at apex in outer surface, about 2.3 times as long as basal width, directed inward. Cercus symmetrical, apically rounded, slightly enlarged from middle to apex, brownish yellow, covered with slightly long setae, with longer setae at tip. Phallus with a row of 14 short stout finger-like structures in middle portion (occupying about half of its total length) and a small, rounded protrusion at basal 1/3, with a conical, spiny structure covering dorsal surface.

Female. Body length 5.6 mm, wing length 6.7 mm. First flagellomere 0.24 times as long as head height; arista pubescent, brownish, 3.60 times longer than first flagellomere. Scutum darker than male. Postpronotum slightly lighter than mesonotum. Mesonotum without obvious stripes. Scutellum with 3 pairs of scutellar setae equal in length. Fore femur slightly thickened with one row of long ventral setae. Tergites 7–8 yellowish orange, tergite 7 extremely short.

Type material. Holotype ♂, China, Beijing, Xijiao Park [39°56'31.59"N, 116°20'12.33"E], approximately 45 m, 1952. XI. 19, Yiran Zhang (light trap) ( NACRC, IOZ) GoogleMaps . Paratypes: 1 ♂, China, Beijing, Xijiao Park [39°56'61.84"N, 116°20'36.15"E], approximately 45 m, 1952. XI. 12, Yiran Zhang (Light trap) ( NACRC, IOZ) ; 1 ♀, same as holotype.

Distribution. China (Beijing).

Remarks. The new species is similar to Orbellia amurensis from the Russian Far East (southern region). Base of surstylus width in new species approximately 3.0 times width of middle, while in O. amurensis base of surstylus width approximately 2.0 times width of middle. Phallus in new species has a row of 14 short, stout, finger-like structures in middle portion, while O. amurensis has 8 spines.

Another similar species is Russian species O. obscura Gorodkov, 1972 , which features a slender, finger-like structure extending from middle to apex of surstylus, but can be distinguished from it by the following characteristics: first flagellomere primarily brownish yellow with distal end darkened (in O. obscura , first flagellomere entirely dark); frons yellowish orange (in O. obscura , frons dark grey); surstylus with a concave apex, with setae on inner surface but absent on outer surface (in O. obscura , surstylus with a rounded apex with setae on both inner and outer surfaces).

The holotype and two paratype specimens are in relatively poor condition. Upon examining specimens, it was observed that some of dorsocentral setae and fronto-orbital setae broken. Specifically, dorsal setae of holotype missing. Fronto-orbital setae noticeably unequal in length among available specimens. However, it should be noted that, in context of species in this genus, variation in length of setae, particularly dorsal and fronto-orbital setae, is not a prominent distinguishing feature and should not be relied upon as a definitive character for species identification.

Etymology. The species name zhangi is derived from the surname of the Chinese collector Yiran Zhang.