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

10. Swammerdamella planus sp. nov. BḆDzĸxü

( Figs. 6A–6F View FIGURE 6 )

Diagnosis. M fork complete, slightly longer than stem. Posterior margin of male tergite 6 unmodified. Male tergite 7 with a small ventral process and a pair of lobes. Aedeagus obvious, flattened and strongly sclerotized.

Description. Male ( Fig. 6A View FIGURE 6 ). Body length 1.8–2.2 mm, wing length 2.0– 2.1 mm.

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

Thorax. Dull brown, stout, and matte; scutum densely short pilose. Anterior spiracular sclerite relatively small, short and triangular. Halters concolourous with scutum, stem with a row of setae. Legs short, and mostly concolourous with body, except for yellowish brown hind tarsus and distal hind tibia.

Wing ( Fig. 6B View FIGURE 6 ). Membrane nearly hyaline; anterior veins sclerotized and light brown, R 1 and R 4+5 short, joining costa close to each other; M fork divergent at middle of wing and slightly longer than stem; CuA sigmoid and gently bent to posterior margin; only few macrotrichiae present on posterior margin of wing.

Abdomen. Strong, stout and dark brown; segments 1–6 visible; sternite 6 ( Fig. 6C View FIGURE 6 ) sparsely setose, posterior margin smoothly concave; tergite 6 ( Fig. 6D View FIGURE 6 ) sparsely setose, posterior margin flat and unmodified. Segment 7 ( Fig. 6F View FIGURE 6 ) retracted into segment 6; tergite 7 modified, ventral process small, rounded apically, with a pair of oval lobes on both sides; sternite 7 rounded.

Male terminalia ( Fig. 6E View FIGURE 6 ). Slightly longer than wide; aedeagus oval, dark and flattened, basally with 2 symmetric processes; a large and apically twisted projection present beneath aedeagus.

Female. Unknown.

Type Material. HOLOTYPE: ♂, China, Gansu Province, Tanchang [ âē], Zedangcuo [ āīDz] [ 104°22’ N, 33°52’ E, 2649m], collected by sweep net, 2024. VIII. 1, Yishen Xiao ( CAU) . PARATYPES: 2♂, same data as holotype .

Distribution. China ( Gansu Province).

Etymology. This specific name is derived from the Latin adjective “planus ”, which means “flat”, referring to the flattened aedeagus.

Remarks. This species can be readily distinguished from most species of this genus by the length of M fork, which is slightly longer than its stem. S. planus is confirmed to belong to Swammerdamella because of the typically concealed, modified tergite 7 and adjacent R 1 and R 4+5. The male tergite 7 of this species is also highly recognizable by the short and small ventral process and a pair of oval lobes.