Swammerdamella venusta, Xiao & Hong & Li & Yang, 2025

Xiao, Yishen, Hong, Dawei, Li, Zhu & Yang, Ding, 2025, First report of the genus Swammerdamella Enderlein, 1912 (Diptera: Scatopsidae) in China, with descriptions of nine new species, Zootaxa 5723 (1), pp. 49-70 : 66-67

13. Swammerdamella venusta sp. nov. 优sDzĸxü

( Figs. 9A–9F )

Diagnosis. M fork complete, slightly longer than stem. Posterior margin of male sternite 6 smoothly concave. Male tergite 6 setose, with its posterior margin truncated. A wide and trapezoidal median process on male tergite 7. Aedeagus oval and obvious.

Description. Male ( Fig. 9A ). Body length about 1.6 mm, wing length 1.9 mm.

Head. Yellowish brown, slightly higher than long; antennae 10-segmented; flagellum 8-segmented, each flagellomere with a whorl of microtrichia; last flagellomere distinctly elongate, 3 times longer than preceding one; eyes holoptic, meeting over antennae; palpus one-segmented, light brown, elongate and pointed at apex.

Thorax. Yellowish brown, stout and shining; scutum darker colored, with sparse and brownish setae. Anterior spiracular sclerite relatively small, triangular. Halters concolorous with scutum, with a row of setae on stem. Legs short, concolorous with body, distal part of tibia slightly lighter than its basal part.

Wing ( Fig. 9B ). Membrane nearly hyaline; anterior veins sclerotized and light brown, R 1 and R 4+5 joining costa close to each other; M fork complete, highly visible, slightly longer than stem; CuA sigmoid, smoothly angled; a row of macrotrichiae on posterior margin.

Abdomen. Strong and stout, tergites and sternites dull brown; segments 1–6 visible; sternite 6 ( Fig. 9C ) wide, setose and smoothly concave on its posterior margin; tergite 6 ( Fig. 9D ) relatively rectangular, setose, truncated posteriorly. Segment 7 ( Fig. 9F ) retracted into segment 6; tergite 7 with thin lateral arms and apically acute, ventral process wide and trapezoidal; sternite 7 rounded, inner margin smoothly rounded and sparsely setose, ending laterally with 2 apically truncated arms.

Male terminalia ( Fig. 9E ). Slightly longer than wide; aedeagus plate oval, obviously darker than other parts, with 2 oval lobes on each side; a pair of thin, slender lobes beneath the aedeagus, elongate, dorsally pointed, and gently twisted apically like a hook.

Female. Unknown.

Type Material. HOLOTYPE: ♂, China, Hubei Province, Shennongjia Forestry District [ öṝĕū区], Shennongding [ öṝȗ] [ 31°26’ N, 110°18’ E, 2394m], collected by Malaise trap, 2022. VIII. 26, Siqi Wang & Bintao Du ( CAU).

Distribution. China ( Hubei Province).

Etymology. This specific name is derived from the Latin adjective “venustus”, which means “charming”, referring to the unusual morphological character of wings and the elegant shape of male terminalia.

Remarks. S. venusta is another species from the Oriental Region. This species shares the unique elongated M fork with S. planus sp. nov. and S. flexuosa sp. nov. mentioned above. S. venusta can be easily distinguished from other species in this genus by the delicately curved male terminalia and the trapezoidal, truncated ventral process of male tergite 7.

Figures

FIGURE 9A–9B. 9A. Swammerdamella venusta sp. nov., male adult. 9B. Wing. 9C. Male sternite 6. 9D. Male tergite 6. 9E. Male terminalia. 9F. Male segment 7. Scale bar 1.0 mm (9A–9B), 0.1 mm (9C–9F).