Morphotaxonomy of the Simulium (Simulium) tuberosum species group (Diptera: Simuliidae) in Thailand Author Tangkawanit, Ubon Author Kuvangkadilok, Chaliow Author Baimai, Visut Author Adler, Peter H. text Zootaxa 2009 2048 31 46 journal article 10.5281/zenodo.186496 a6aa7826-075e-4c7e-a095-ea3a3cd23017 1175-5326 186496 Simulium unknown species 2 This taxon was recognized cytologically based on 8 larvae from Champa Thong waterfall in Phayao Province ( Tangkawanit et al. 2009 ). The larvae are morphologically similar to those of S. yuphae , but lack head spots and infuscation on the frontoclypeal apotome. The larva of S. unknown species 2 is described below, but we defer formal description and naming of this species until pupae and adults are available. Body grayish black to grayish brown. Head capsule yellowish to light brown; head spots faint ( Fig. 2 I); ventral surface of head capsule whitish yellow except area along margins of postgenal cleft dark brown; faint negative transverse spot on each side of postgenal cleft ( Fig. 3 J). Antenna longer than stem of labral fan; length ratios of articles (proximal to distal) 1.00: 1.05: 0.76. Labral fan with 36–38 primary rays. Hypostoma with median tooth and each lateral tooth longer than others; 5 or 6 hypostomal bristles per side. Postgenal cleft deep, triangular, pointed anteriorly ( Fig. 3 J). Abdominal cuticle nearly bare; both sides of anal sclerite moderately covered with simple colorless setae. Anal sclerite X shaped with broadened anterior arms 0.8–0.9 times as long as posterior arms. Abdominal segment IX lacking ventral tubercles. Posterior circlet with 70–80 rows of hooklets and up to 14 hooklets per row.