Poecilosomella formosana sp. n. (Figs 20–23) Holotype male (HNHM): TAIWAN, Ilan Hsien, Fu-Shan LTER Site, Sep 26, 2000 – over a rocky brook, leg. L. PAPP, No. 6. Paratypes (HNHM): TAIWAN, leg. L. PAPP, 2000: 1 male: data same as for the holotype; 1 female: ibid., lake shore vegetation and along a brook bed, No. 7; 1 male: ibid., Sep 27, along/over a small brook, No. 11; 1 female: ibid., 2 km downstream Bot. Garden, along a small river, Sep 27, No. 10; 1 male, 1 female: Taipei, Nanshih Chiao, Han-Lo-Da, 450 m, rocky forest undergrowth, Sep 23, No. 1; 2 males: Nantou Hsien, Shuili, forest undergrowth, Sep 30, No. 12. Measurements in mm: body length 2.05 (holotype), 2.10–2.56 (paratype males), 1.80–1.86 (paratype females), wing length 2.13 (holotype), 2.15–2.45, 1.95–2.05 (paratypes), wing width 1.02 (holotype), 1.07–1.17, 0.90–0.93 (paratypes). Body features, incl. wing and armature of mid tibia, are the same as in P. borboroides (WALKER, 1860). I consider the following two differences as well based: antennae blackish and wing with a diffuse dark spot distal to apex of R 2+3. Male abdominal sternite 5 (Fig. 22) asymmetrical, widely emarginated medially, median hairs similar to P. ornata, no thick black spinules present. Subepandrial sclerite (Fig. 20) differently shaped than in P. borboroides or P. ornata, with 3 pairs of long thick setae. Surstylus (Fig. 21) with only 1 large thick black tooth, but no process behind it as in P. ornata. Postgonite (Fig. 23) with hairs longer than in P. ornata, apex rounded, no apical process but 2 minute subapical projections. Females smaller than males, differring from females of other species in the species group as in the key below. This species is only distinguishable from P. borboroides by characteristics of the male postabdomen and genitalia. I think we can differentiate between females of the two species by the two features described above. However, males are different in all the four morphological parts depicted on Figs 20–23 vs. 1–5, i.e. there is no doubt about their identity as different species.

Published as part of Papp, L., 2002, Eighteen New Oriental Species Of Poecilosomella Duda (Diptera: Sphaeroceridae), pp. 107-156 in Acta Zoologica Academiae Scientiarum Hungaricae 48 (2) on page 124, DOI: 10.5281/zenodo.12587600