Rheocricotopus taiwanensis Wang, Yan & Maa 2004

Rheocricotopus taiwanensis Wang, Yan & Maa, 2004 (Figs 1B; 4; 5) Examined material. 1 Larva (SHOU & BOLD sample ID: HJR297): China, Shaanxi, Shangluo, Shangzhou, Yancun, Jinqian River, 33.681°N, 109.844°E, 978 m a.s.l., hand net, 15.VII.2019, leg. Zhen-Yuan Liu. Description. Fourth instar larva (n = 1). Total length 4.4 mm. Body yellow with brown thoracic striations. Head Capsule (Fig. 4A). Length 370 μm, width 308 μm, length/width 1.20; mental and mandibular teeth dark brown. Antenna (Fig. 5A). Composed of one basal segment bearing five antennal segments. Segment 5 is slightly longer than segment 4. Segment 1 significantly longer and thicker than segment 2. Lauterborn organ clearly visible, shorter than segment 3. Blade length 25 μm. Ring organ located at basal segment margin. Antennal segment length (in μm): 15; 63; 22; 6; 9; 4. AR: 1.55. AAR: 0.25. LOR: 0.16. Mandible (Figs 4B, 5B). Apical tooth with three inner teeth, apical tooth length slightly less than combined inner teeth width. Seta interna with five branches. Mandible length 125 μm; width 28 μm; seta subdentalis length 8 μm. Labrum. Pecten epipharyngis with three teeth: median tooth straight, lateral teeth distinctly curved. All teeth are comparable in length, lateral teeth broader than median teeth. SI bifurcated and other sensory bristles single. Premandible (Figs 4C, 5C) single-toothed apically, lacking seta interna or inner teeth. Premandible length 55 μm; premandible teeth 25 μm. Mentum (Figs 4D, 5D). 2 median teeth, 2 accessory teeth, 5 lateral tooth pairs. Ventromental plate well-developed with rounded base (teardrop-shaped). Mental setae robust, primarily on mental extension. Setae submenti submental. Median teeth length 38 μm; VMp width 56 μm; VMp/MMT: 1.46; mentum length 117 μm; postmentum 110 μm. Remarks. The larva of R. taiwanensis can be distinguished from other related species by AR: 1.55, AAR: 0.25, LOR: 0.16, the small accessory teeth of the mentum, short antennal lobe, and the dark colored postmentum. Distribution. China (Guizhou, Hubei, Shaanxi, Taiwan, Zhejiang).