Orbellia fusca Zeng, Wei & Yang, 2025, sp. nov.
Creators: name: Zeng, Wei
name: Wei, Hongxia
name: Yang, Ding
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Heleomyzidae
Orbellia
Orbellia fusca

description: Orbellia fusca sp. nov.
(Figs. 12–19)
Diagnosis. Palpus primarily dark brown with a yellowish tinge near base, overall thickened, with distal end rounded and slightly tapered. Mouth edge with a narrow, heavily sclerotized brown margin. Postpronotum and mesonotum without distinct color difference, only a slightly yellowish brown tinge in middle. 2 pairs of scutellar setae.
Description. Body length 5.2 mm, wing length 5.0 mm [Holotype ♀].
Female. Head (Figs. 13–14) brownish grey with pale pruinesence; ocellar triangle and area in front of fronto-orbital setae brown, but frons light yellow. Area adjacent to ocellar triangle dark, and anterior frons light, occiput brown; gena posteriorly brown, anteriorly slightly yellowish grey. Eyes brownish orange. Hairs and setae on head dark brown. 2 pairs of fronto-orbital setae exclinate, anterior one slightly shorter than posterior one. Antenna brown; pedicel with 1 black dorso-apical seta and 1–2 rows of circle setae. First flagellomere round with brownish velvet, 0.23 times as long as head height; arista pubescent, brownish, 2.9 times longer than first flagellomere, distinctly enlarged at base. Proboscis pale yellow with one pair of vibrissae; hairs on proboscis pale golden; palpus primarily dark brown with a yellowish tinge near base, overall thickened, with distal end rounded and slightly tapered. Mouth edge with a narrow, heavily sclerotized brown margin.
Thorax (Figs. 12, 14) dark brown, mesonotum with pale pruinescence. Postpronotum and mesonotum without distinct color difference, only a slightly yellowish brown tinge in middle. Scutum without obvious stripe. Hairs and setae on thorax dark brown. Postpronotum with 1 well developed postpronotal seta and 9 short setae; 1 proepisternal seta, 1 weak proepimeral seta less than half as long as proepisternal seta; 2+4 dorsocentral setae, posterior one longest, gradually decreased in length towards front, 2–3 irregular rows of acrostichal setae between them; katepisternum with 1 long seta and 3 slightly short setae (0.85 times longer than longest seta); anepimeron and anepisternum bare. A pair of prescutellar setae present. Scutellum same as mesonotum in color, slightly tinged with yellowish brown in middle, rounded apically, with 2 pairs of scutellar setae.
Wing (Fig. 15) 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 golden hairs. Halter pale yellow with halter stem slightly tinged brown.
Legs brownish, except fore and mid trochanters and tibiae brownish yellow at distal ends. Hairs and setae on legs dark brown. Fore femur with 1–2 irregular rows of antero-dorsal setae and one row of ventral setae fewer than 10 setae, setae on middle part more developed than those on dorsum; hind femur without obvious long seta. Fore tibia with 1 longer preapical dorsal seta; mid tibia with 4 anterior setae in middle, slightly more developed than surrounding; 2 long strong preapical dorsal spines and 4 strong short preapical ventral spines; hind tibia with 1 long thin dorsal preapical seta. Tarsomere 4 of all legs shorter than tarsomere 3 or 5.
Abdomen brownish yellow in both tergites and sternites. Tergite 7 elongated, and tergite 8 about 1/3 as long as tergite 7. Hairs and setae on abdomen dark brown.
Female genitalia (Figs. 16–19): Tergite 9 with several short setae. Cercus brownish yellow, symmetrical, rounded at apex, distal and proximal part with sparse hairs and several long thin brown setae. Two spermathecae dark brown and well sclerotized (Fig. 19), one of which slightly elongated and hemispherical in shape (with a rounded apex, a flattened base, and height-to-base diameter ratio of 1.5:1.9), while another consists of two identical hemispherical bodies clustered together; spermathecal ducts colorless, transparent, or slightly tinged with pale brown.
Male. Unknown.
Type material. Holotype ♀, China, Liaoning, Fushun, Liaoning Dahuo Fang National Wetland Park, [41°55'4.02"N, 124°19'10.56"E], approximately 200 m, 2020. XI. 7, Yan Li & Yuetian Gao (CAU).
Distribution. China (Liaoning).
Remarks. The new species with 2 pairs of scutellar setae, is similar to the Caucasian species O. cuniculorum, O. tetrachaeta and O. zaitzevi, especially O. cuniculorum and O. zaitzevi.
First, it can be distinguished from the Georgian species O. zaitzevi by it darkened palpus (in O. zaitzevi palpus pale yellow). Furthermore, it can be distinguished from the European species Orbellia cuniculorum, by following characteristics: palpus almost entirely dark brown and thick (in O. cuniculorum, palpus yellow with slightly darkened tip and comparatively thin); vein C light brown, not darkened (in O. cuniculorum, vein C dark brown and slightly thickened).
Etymology. The species name fusca is a Latin adjective meaning "dark" or "dusky", referring to the overall dark or brownish coloration of the species.
description: Published as part of Zeng, Wei, Wei, Hongxia & Yang, Ding, 2025, First record of the genus Orbellia (Diptera: Heleomyzidae) in China with descriptions of two new species, pp. 171-180 in Zootaxa 5632 (1) on pages 175-179, DOI: 10.11646/zootaxa.5632.1.10, http://zenodo.org/record/15371356