Swammerdamella flexuosa, 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 : 51-53

3. Swammerdamella flexuosa sp. nov. 多aDzĸxü

( Figs. 1A–1F )

Diagnosis. M fork complete, slightly longer than stem. Male tergite 6 wide and posteriorly with a rounded concavity. Male tergite 7 modified, median process small. A pair of tube-like, pilose structure connected to tergite 7.

Description. Male ( Fig. 1A ). Body length 1.4–1.6 mm, wing length 1.5 mm.

Head. Dull brown, slightly higher than long; antennae 10-segmented; flagellum 8-segmented, a whorl of microtrichia on each flagellomere; last flagellomere elongate, twice as long as preceding one; eyes holoptic; palpus one-segmented, apically acute and pointed at apex.

Thorax. Dull brown, stout, and matte; scutum short and dense pilose. Anterior spiracular sclerite small and triangular. Halters slightly darker than scutum, several setae present on stem. Legs concolorous with body; tarsus yellow.

Wing ( Fig. 1B ). Membrane nearly hyaline; anterior veins sclerotized and light brown, R 1 and R 4+5 short, joining costa close to each other, but the distance between the points where R 1 and R 4+5 joining the costa larger than usual Swammerdamella species; M fork diverging at the middle of wing and is slightly longer than stem; CuA sigmoid and bent smoothly to posterior margin; a row of macrotrichiae present on posterior margin of wing.

Abdomen. Strong, stout and dark brown; segments 1–6 visible; sternite 6 ( Fig. 1C ) sparsely setose, posterior margin smoothly and widely concave, with a row of setae; tergite 6 ( Fig. 1D ) devoid of setae, posterior margin concave. Segment 7 ( Fig. 1F ) retracted into segment 6; tergite 7 small, ventral process thin and short, rounded apically, 2 nearly oval lobes connected to tergite 7, with a tube-like, pilose projection; sternite 7 smoothly curved on both margins, with sparse setae on inner margin.

Male terminalia ( Fig. 1E ). Slightly longer than wide; aedeagus plate oval, sclerotized; aedeagus short; a pair of rod-shaped lobes beside aedeagus plate; another pair of lobes with 2 curves and 3 angles beneath aedeagus plate.

Female. Body length 1.6–1.8 mm, wing length about 1.5 mm. Similar to male in general morphological characters.

Type Material. HOLOTYPE: ♂, China, Gansu Province, Kangxian [ DZ县], Qinghelinchang [ ẘñū场] [ 105°51’ N, 33°12’ E, 1456m], collected by sweep net, 2023. VIII. 26, Liang Wang. ( CAU) ; PARATYPES: 2♂ 4♀, same data as holotype .

Distribution. China ( Gansu Province).

Etymology. This specific name is derived from the Latin adjective “flexuosus” which generally means a structure that “with many curves in it”, referring to the shape of male terminalia.

Remarks. The M fork of this species is also slightly longer than stem. A pair of unique, tube-like structures are present on male tergite 7, which is different from all other Swammerdamella species. This morphological character is reminiscent of Swammerdamella sessionis Cook, 1971 , but the “trapezoidal sclerites” of S. sessionis are projected from sternite 7 instead of tergite 7 according to Cook’s description.

Figures

FIGURE 1A–1B. 1A. Swammerdamella flexuosa sp. nov., male adult. 1B. Wing. 1C. Male sternite 6. 1D. Male tergite 6. 1E. Male terminalia. 1F. Male segment 7. Scale bar 1.0 mm (1A–1B), 0.1 mm (1C–1F).