Swammerdamella tricuspis, 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 : 64

12. Swammerdamella tricuspis sp. nov. 三尖Dzĸxü

( Figs. 8A–8F )

Diagnosis. Sternite 6 of male triangularly concave. Male tergite 6 unmodified and posteriorly with a row of setae. Arms of male tergite 7 long and thin, apically acute. Three spines on the position of median process. Aedeagus long and spiral.

Description. Male ( Fig. 8A ). Body length 1.4–1.5 mm, wing length 1.2–1.3 mm.

Head. Dull brown, 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; palpus one-segmented, yellowish brown, elongate and pointed at apex.

Thorax. Dull brown, stout and matte; scutum brownish pilose. Anterior spiracular sclerite triangular. Halters concolorous with scutum, with a row of setae on stem. Legs short, and mostly concolorous with body except for yellowish-brown tarsi.

Wing ( Fig. 8B ). Membrane nearly hyaline; anterior veins sclerotized and light brown, R 1 and R 4+5 joining costa vein very close to each other; M fork complete and visible, obviously shorter than stem of M; CuA sigmoid, bent abruptly; a row of macrotrichiae on the posterior margin.

Abdomen. Strong, stout, and dull brown; segments 1–6 visible; sternite 6 ( Fig. 8C ) wide, sparsely setose, with posterior margin triangularly concave; tergite 6 ( Fig. 8D ) wide, sparsely setose, with posterior margin smoothly curved and with a row of setae. Segment 7 ( Fig. 8F ) retracted into segment 6; tergite 7 devoid of setae, both arms thin and narrow, apically acute, 3 spines in the middle of tergite 7 as ventral process; sternite 7 rounded and both arms setose apically, with 2 symmetrical sclerotised, dark-colored areas on inner margin.

Male terminalia ( Fig. 8E ). Slightly longer than wide; aedeagus long, spiral, and darker than other parts; a large lobe folded posteriorly on both sides, forming a semi-enclosed structure around the base of aedeagus; another large, densely pilose projection posteriorly stretched with a deep concavity on it.

Female. Unknown.

Type Material. HOLOTYPE: ♂, China, Jilin Province, Helong [ 和ẑ], Wolong Station [ 卧ẑäaeü] [ 42°46’ N, 128°45’ E, 737m], collected by sweep net, 2023. VII. 6, Yishen Xiao ( CAU) . PARATYPE: ♂, same data as holotype .

Distribution. China ( Jilin Province).

Etymology. This specific name is derived from the Latin adjective “tricuspis ”, meaning “which has three points”, referring to the shape of the ventral process on male tergite 7.

Remarks. This species shows some common Swammerdamella characteristics on wing and body, but the shape of male tergite 7 and terminalia are relatively unique and highly recognizable. The terminalia is also morphologically different from all other Swammerdamella species. The structure of male terminalia is simple, only with a long, spiral aedeagus while the aedeagus plate seems missing.

Figures

FIGURE 8A–8B. 8A. Swammerdamella tricuspis sp. nov., male adult. 8B. Wing. 8C. Male sternite 6. 8D. Male tergite 6. 8E. Male terminalia. 8F. Male segment 7. Scale bar 1.0 mm (8A–8B), 0.1 mm (8C–8F).