Three new species of caddisflies (Trichoptera, Hydroptilidae, Polycentropodidae, Leptoceridae) from Khon Phapheng Waterfall, the Mekong River, Laos Author Thamsenanupap, Penkhae Faculty of Environment and Resource Studies, Mahasarakham University, Mahasarakham Province, Thailand Author Malicky, Hans Sonnengasse 13, A- 3293 Lunz am See, Austria Author Vongsombath, Chanda Faculty of Environmental Sciences, National University of Laos, Dong Dok Campus, Vientiane, PDR, Laos Author Laudee, Pongsak https://orcid.org/0000-0003-3819-7980 Faculty of Innovative Agriculture and Fishery Establishment Project, Prince of Songkla University, Surat Thani Campus, Muang District, Surat Thani Province, Thailand pongsak.l@psu.ac.th text ZooKeys 2021 2021-08-12 1055 149 159 http://dx.doi.org/10.3897/zookeys.1055.66536 journal article http://dx.doi.org/10.3897/zookeys.1055.66536 1313-2970-1055-149 0A16D86E946F4E2698B5FAB2AC33645F CFDE91ABE2175C05A56157CEB93A6E75 Setodes karrilai Laudee & Malicky sp. nov. Figure 3 Type material. Holotype . Male. Laos: Pakse Province : Champasak, Khonphapheng waterfalls, Mekong river, 13°57'30"N , 105°59'14"E , elev. 64 m, 8.iv.2019, Pongsak Laudee. (PSUNHM). Paratypes : same data as the holotype; Laos: Vientiane province : Nam Lik river, 18°31'29"N , 102°31'19"E , elev. 180 m, 8.iv.2019, Pongsak Laudee; Laos, Pakse province : Champasak, Don Khon, Mekong river, 13°57'45"N , 105°55'07"E , elev. 84 m, 8.iv.2019, Pongsak Laudee; Laos: Vientiane province : Nam Ngum river, 18°31'29"N , 102°31'37"E , elev. 180 m, 8.iv.2019, Pongsak Laudee. 31 males: 10 males (PSUNHM), 8 males (CHM), 5 males (NMPC), 5 males (CUAC). Diagnosis. The male genitalia of S. karrilai sp. nov. are similar to those of S. omphale Malicky & Changthong in Malicky et al. 2004 from Thailand. Both species share similar characteristics of five lobes of each inferior appendage. However, the most prominent difference is the structure of segment X, i.e., the distal part of segment X in S. karrilai sp. nov. has a brush-like process, visible in lateral and dorsal views, which is lacking in S. omphale . In addition, the phallus of S. karrilai sp. nov. has a pair of very long, thin, pointed parameres with distal 1/3 bent and twisted meso-upward; whereas the parameres of S. omphale are curved downward. Description. Length of each male forewing 6.5-7.0 mm (n = 18); color in alcohol of head, thorax, forewings, and abdomen yellow; femora and tibiae brown or dark brown; wings clear and transparent, yellowish with brown veins. Male genitalia as in Figure 3 . Segment IX somewhat triangular with long sinuous edges posteriorly, convex anteriorly in lateral view (Fig. 3B ); square in ventral view (Fig. 3C ). Segment X long, slender, divided into basal segment and apical segment (Fig. 3A, B ); basal segment mostly tubular with shallow and broad excision apically, apical segment slender, tubular with brush of straight hairs at posterior end in dorsal view (Fig. 3A ); in lateral view, basal segment tubular, apical segment thicker apically and with apical brush (Fig. 3B ). Preanal appendages very small, leaf-like with scattered setae (Fig. 3A, B ). Inferior appendages each five-lobed (Fig. 3B ); dorsal lobe long, tubular and erect basally then curved caudad, two finger-like mesal lobes tubular and with upper mesal lobe longer than lower mesal lobe, basoventral lobe small and knot-like, ventral lobe very long and sword-like with scattered setae in lateral view (Fig. 3B ). Phallus long, slender, bent downwards with pair of very long, thin, and pointed parameres with distal 1/3 bent and twisted meso-upward in lateral view (Fig. 3D ). Etymology. The species epithet honors Assoc. Prof. Dr Seppo Karrila, Faculty of Science and Industrial Technology, Prince of Songkla University, Surat Thani Campus. Figure 3. Setodes karrilai , sp. nov. Male genitalia A segment X, preanal appendages, dorsal B segments IX and X, preanal appendages, inferior appendages, left lateral C segment IX, inferior appendages, ventral D phallus, left lateral. Abbreviations: Seg IX = segment IX, Pre = preanal appendage (paired), Inf = inferior appendage (paired).