Riethia cauame sp. n. (Fig. 7) Type material. Holotype: Male, slide mounted in Euparal, Brazil, Roraima, Cauamé river, 09°58’29”S, 67°48’36”W, 153 m a.s.l., 03.ii.2007, leg. L. Fusari (I1-05, LEIA-UFSCar). Derivation nominis. The name cauame refers to type locality, Cauamé river. The name is treated as a noun in apposition. Diagnostic characters. Adult male of Riethia cauame sp. n. differs from other species of the genus by the combination of the following characters. Adult male: hypopygium without anal point, superior volsella hooklike with internal margin 7–8 simple setae. Median volsella present. Inferior volsella with 9 internal marginal long and large simple setae and 9 flattened scales: 5 apically pectinate and 4 distal ones non-pectinate Transverse sternapodeme without oral projections. Description. Male (n = 1).Total length near 4.0 mm. Wing length 1.8 mm. Colouration. Thorax pale with light brown vitae; abdomen and legs pale brown. Head. Temporal setae not discernable in slide preparation. Clypeus with nine setae. Antenna 1.28 mm long; AR 1.73. Palpomere 2–5 lengths: 75, 156, 156, 262 µm. Thorax (Fig. 7a). Ac absent; Dc 8; Pa 3; Scts 8. Wings. VR 1.16. Brachiolum with two setae. Veins setae on R with 19, R1 with 15 and R4+5 with 22 setae. Squama with 8 setae. Legs. Scale on fore tibia 46 µm long, with a short spine at the apex. Tibial combs of mid and hind legs partially fused; mid tibial spur anterior, 34 µm, posterior 37 µm long; hind tibial spur anterior, 34 µm, posterior 37 µm long. Lengths and proportions of the legs as in Table III. TABLE III. Lengths (in µm) and proportions of legs of Riethia cauame sp. n. male (1). Hypopygium (Fig. 7b, c). Tergite IX truncate, without anal point. Laterosternite IX with 3 setae. Transverse sternapodeme 85 µm long, without oral projections. Phallapodeme 61 µm long. Gonocoxite 135 µm long. Superior volsella hooklike, basally pubescent, with 7–8 simple setae. Median volsella short, bearing 3 simple setae. Inferior volsella with 9 marginal long and large simple setae and 9 flattened scales: 5 apically pectinate and 4 distal ones non-pectinate. Gonostylus 166 µm long. HR 0.81.

Published as part of Trivinho-Strixino, Susana & Shimabukuro, Erika Mayumi, 2018, Brazilian Pseudochironomini (Diptera: Chironomidae) Part 2. New Pseudochironomus and Riethia species, pp. 245-260 in Zootaxa 4403 (2) on pages 253-254, DOI: 10.11646/zootaxa.4403.2.2, http://zenodo.org/record/1212143