Small, rare and little known: new records and species of Cardiomya (Bivalvia: Cuspidariidae) from Brazil Author Lima, Tarcilla Carvalho De 7FFCF3E3-A9BF-469F-964A-62C618DE5192 Universidade Federal do Rio de Janeiro, Instituto de Biologia, Laboratório de Malacologia. C. E. P. tarcillacarvalho@gmail.com Author Oliveira, Cléo Dilnei de Castro 4BE74DFD-DD38-4315-A461-1E05F9706642 Universidade Federal do Rio de Janeiro, Instituto de Biologia, Laboratório de Malacologia. C. E. P. cleo.oliveira@gmail.com Author Absalão, Ricardo Silva D89BFB87-8BAF-44C4-AABD-5A40E202EE4C Universidade Federal do Rio de Janeiro, Instituto de Biologia, Laboratório de Malacologia. C. E. P. absalao@hotmail.com text European Journal of Taxonomy 2020 2020-03-26 619 1 20 journal article 22460 10.5852/ejt.2020.619 5dc6e760-5dcb-4928-a58e-c88c8524b8f9 3777241 BBB01195-73A4-44DB-8454-CC86B9C21EDF Dichotomous key of the species from Brazilian waters 1. Complete ribs covering the entire shell flank ................................................................................... 2 – Complete ribs restricted to posterior half of the shell flank .............................................................. 3 2. Anterodorsal margin descending ...................................................................................................... 4 – Anterodorsal margin forming a shoulder .......................................................................................... 5 3. Rostrum short ........................................................................................................... Cardiomya sp. 3 – Rostrum very short ........................................................................................................................... 8 4. Numerous ribs (~ 20); equidistant ....................................... Cardiomya cleryana ( d’Orbigny, 1842 ) – Few strong ribs (~ 6–12); very spaced; distributed throughout the shell flank .................................. ......................................................................................... Cardiomya ornatissima ( d’Orbigny, 1853 ) 5. Shell flank rounded ........................................................................................................................... 6 – Shell flank elliptical to trapezoidal ................................................................................................... 7 6. Rostrum long ............................................................................ Cardiomya perrostrata (Dall, 1881) – Rostrum very short .................................................................................................. Cardiomya sp. 1 7. Ribs (~ 30–50) equidistant, evenly distributed throughout the shell to the rostrum ........................... ...................................................................................................... Cardiomya striata (Jeffreys, 1876) – Ribs (~ 18–35) more spaced in the posterior part of the shell flank.................................................... .................................................................................................... Cardiomya striolata ( Locard, 1897 ) 8. Anterodorsal margin forming a shoulder .............................................. Cardiomya minerva sp. nov. – Anterodorsal margin descending ............................................................................. Cardiomya sp. 2