Riethia, Kieffer, 1917

Andersen, Trond, Malla, Annui & Giłka, Wojciech, 2024, Two new species of Riethia Kieffer, 1917 from Chile and Ecuador (Chironomidae: Chironominae, Pseudochironomini), Zootaxa 5448 (4), pp. 499-507 : 505-506

Updated key to Neotropical males of Riethia

1. Posterior margin of tergite IX with caudal projections resembling an inverted U ( Brazil)........................................................................................ .. R. fazzari Trivinho-Strixino & Shimabukuro, 2018

- Posterior margin of tergite IX straight or rounded, without caudal projections..................................... 2

2. Superior volsella short, hook-like; inferior volsella subtriangular, tapering to narrowly rounded apex; with few, scattered, flattened, apically pectinate dorsal setae and 2–3 marginal scales apically ( Brazil)............................................................................................... R. galilei Trivinho-Strixino & Shimabukuro, 2018

- Superior volsella long, curved or with distal half straight, digitiform; inferior volsella not subtriangular and tapering to narrowly rounded apex, with or without flattened, apically pectinate dorsal setae and/or marginal scales........................ 3

3. Inferior volsella strongly bent dorsally with apical part bluntly subtriangular with more than 20 broad flattened, apically pectinate setae covering dorsal surface, without marginal scales................................................ 4

- Inferior volsella not strongly bent dorsally, with marginal scales; without or with less than 20 broad flattened, apically pectinate setae............................................................................................... 6

4. Legs with dark bands; superior volsella curved, digitiform, apically pointed with microtrichia and apparently 2 weak, dorsal setae subapically ( Argentina, Brazil, Chile)................................... R. truncatocaudata ( Edwards, 1931)

- Legs without dark bands; superior volsella curved, stout, with long, narrowly triangular apex, with or without microtrichia, with 5–7 weak, dorsal setae................................................................................. 5

5. Abdomen brown, without dark bands; superior volsella with scattered microtrichia ( Ecuador)..... R. ecuadoriensis sp. nov.

- Abdomen light brown, tergites with darker brown oral bands; superior volsella without microtrichia ( Chile)................................................................................................. R. chilensis sp. nov.

6. Superior volsella with distal half straight; inferior volsella with about 10 broad scales in double row along inner margin, without broad, flattened, apically pectinate setae ( Costa Rica) ......................... R. epleri Andersen & Sanz-laParra, 2023

- Superior volsella curved; inferior volsella with both marginal scales and broad, flattened, apically pectinate setae......... 7

7. Acrostichals absent; clypeus with less than 10 setae ( Brazil)........... R. cauame Trivinho-Strixino & Shimabukuro, 2018

- Acrostichals present; clypeus with more than 25 setae........................................................ 8

8. Inferior volsella with 15 broad, flattened, apically pectinate setae dorsally and 3 broad marginal scales apically ( Brazil)............................................................. R. manauara Neubern, Trivinho-Strixino & Silva, 2011

- Inferior volsella with 6 broad flattened, apically pectinate setae dorsally and 7 broad marginal scales apically ( Brazil).................................................................. R. pantera Trivinho-Strixino & Shimabukuro, 2018