A. Right side pseudotympanum of Tucanoichthys tucano (image reversed), specimen TCWC 20316.02, 15.5 mm SL. B. Left side pseudotympanum of Atopomesus pachyodus, specimen MZUSP 23871, 23.2 mm SL. C. Left side pseudotympanum of Priocharax varii, specimen MZUSP 125787, paratype, 13.5 mm SL. Skin removed from side of body to reveal pseudotympanum. Specimen in A was photographed after 1 day in solution of 70% ETOH to which a small amount of alizarin red S was added. Abbreviations: AC, anterior chamber of swimbladder; EpM, epaxial musculature; LLN, lateral line nerve; LS, lateralis superficialis; Op, opercle; OS, obliquus inferioris; R5–6, rib 5–6; Scl, supracleithrum.

  Part of: Mattox GMT, Conway KW (2021) Osteology of Tucanoichthys tucano Géry and Römer, an enigmatic miniature fish from the Amazon basin, Brazil (Teleostei: Characiformes: Characidae). Vertebrate Zoology 71: 645-667. https://doi.org/10.3897/vz.71.e71886