Tucanoichthys tucano, specimen TCWC 20316.01, 14.4 mm SL, c&s (A–G), and MZUSP 18388, 15.6 mm SL, c&s (H). A. Gill arches in dorsal view. B. Gill rakers articulating with anterior edge of hypobranchial 2, left side in dorsal view. C. Ventral gill arches in dorsal view. D. Dorsal gill arches, right side, dorsal view (image reversed). E. Dorsal gill arches, right side, ventral view. F. Upper pharyngeal teeth associated with pharyngobranchial 3 and 4 tooth plates, right side, ventral view. G. Lower pharyngeal teeth associated with ceratobranchial 5, right side, dorsal view. H. Hyoid bar, right side, and urohyal, in lateral view (image reversed). Gill filaments removed in B-G. C-E share single scale bar. Abbreviations: ACh, anterior ceratohyal; BB1–3, basibranchial 1–3; BB4–5C, basibranchial 4–5 cartilage; BR, branchiostegal rays; CB1–5, ceratobranchial 1–5; DHh, dorsal hypohyal; EB1–4, epibranchials 1–4; EB5C, epibranchial 5 cartilage; GF, gill filament; GR, gill raker; Ih, interhyal; PB1–3, pharyngobranchial 1–3; PB4C, pharyngobranchial 4 cartilage; PB3–4TP, pharyngobranchial 3–4 tooth plate; PCh, posterior ceratohyal; Uh, urohyal; UPEB4, uncinate process of epibranchial 4; VHh, ventral hypohyal.

  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