FIGURE 1 |
Rhinotridens chromocaudatus, new genus and species, holotype, MZUSP 128216, 17.57 mm SL. Brazil, Amazonas, rio Ipixuna, tributary of the rio Purus, rio Solimões basin. Scale bar = 2.0 mm.
FIGURE 2 |
Premaxilla and lower jaw of Rhinotridens chromocaudatus, µCT-scan images, paratype, MZUSP 128217, 16.37 mm SL; A. Dorsal view; B. Ventral view; C. medial view, left side. Symphyseal teeth highlighted in yellow. Ac, angular complex; Dt, dentary; Dth, dentary teeth; Lt, labial teeth; Pmt, premaxillary teeth; Pmx, premaxilla. Scale bar = 0.3 mm.
FIGURE 3 |
Cranium, pectoral skeleton, and anterior portion of axial skeleton of Rhinotridens chromocaudatus, µCT-scan images, paratype, MZUSP 128217, 16.37 mm SL; A. Left lateral view; B. Dorsal view. Ac, angular complex; AC, anterior ceratohyal; Ap, autopalatine; Boc, basioccipital; Br, branchiostegal rays; Cl, cleithrum; Dt, dentary; Ep, epioccipital; Fr, frontal; Hy, hyomandibula; Iop, interopercle; Le, lateral ethmoid; Me, mesethmoid; Mx, maxilla; Op, opercle; Osph, orbitosphenoid; Pop, preopercle; Psph, parasphenoid; Psoc, parieto-supraoccipital; Ptr, pectoral-fin rays; Ptscl, postemporo-supracleithrum; PC, posterior ceratohyal; Pmx, premaxilla; Pop, preopercle; Pt, pterotic; Pu, parurohyal; Qd, quadrate; Sph, sphenotic-prootic-pterosphenoid; Vh, ventral hypohyal; Vo, vomer; WeC, Weberian capsule. Scale bar = 0.3 mm.
FIGURE 4 |
Cranium of Rhinotridens chromocaudatus, µCT-scan images, paratype, MZUSP 128217, 16.37 mm SL; anterior view; arrow indicates right mesethmoid cornu. AC, anterior ceratohyal; Ap, autopalatine; Boc, basioccipital; Br, branchiostegal rays; Dth, dentary teeth; FPV, first post-Weberian vertebrae; Fr, frontal; Hy, hyomandibula; Iop, interopercle; Lt, labial teeth; Me, mesethmoid; Mx, maxilla; Op, opercle; Pop, preopercle; Psoc, parieto-supraoccipital; PC, posterior ceratohyal; Pmx, premaxilla; Pop, preopercle; Pu, parurohyal; Sph, sphenotic-prootic-pterosphenoid; SPV, second post-Weberian vertebrae; Vh, ventral hypohyal. Scale bar = 0.25 mm.
FIGURE 5 |
Suspensorium and opercular series of Rhinotridens chromocaudatus, left side, µCT-scan images, paratype, MZUSP 128217, 16.37 mm SL; A. Lateral view; B. Medial view; arrow indicates distal process of hyomandibula. Hy, hyomandibular; Iop, interopercle; Op, opercle; Pop, preopercle; Qd, quadrate. Scale bar = 0.2 mm.
FIGURE 6 |
Pelvic girdle of Rhinotridens chromocaudatus, digital illustration of c&s specimen, ventral view, paratype, MZUSP 128217, 16.72 mm SL. Bpt, basipterygium. Scale bar = 0.15 mm.
FIGURE 7 |
Neurocranium and associated structures of Rhinotridens chromocaudatus, µCT-scan images, paratype, MZUSP 128217, 16.37 mm SL; A. Left lateral view; B. Dorsal view; C. Ventral view. Boc, basioccipital; Ep, epioccipital; Fr, frontal; Le, lateral ethmoid; Me, mesethmoid; Osph, orbitosphenoid; Psph, parasphenoid; Psoc, parieto-supraoccipital; Ptscl, postemporo-supracleithrum; Pro, prootic; Pt, pterotic; Sph, sphenotic-prootic-pterosphenoid; Vo, vomer; WeC, Weberian capsule. Scale bar = 0.3 mm.
FIGURE 8 |
Hyoid arch of Rhinotridens chromocaudatus, µCT-scan images, paratype, MZUSP 128217, 16.37 mm SL; A. Ventral view; B. Dorsal view; anterior to left. AC, anterior ceratohyal; Br, branchiostegal rays; PC, posterior ceratohyal; Pu, parurohyal; Vh, ventral hypohyal. Scale bar = 0.3 mm.
FIGURE 9 |
Gill arches of Rhinotridens chromocaudatus, digital illustration of c&s specimen, dorsal view, paratype, MZUSP 128217, 16.72 mm SL; right dorsal elements not shown. Bb1-4, basibranchials 1 to 4; Cb1-5, ceratobranchials 1 to 5; Eb1-4, epibranchials 1 to 4; Hb1-3, hypobranchials 1 to 3; Pb4, pharyngobranchial 4; Utp, upper pharyngeal tooth plate. Scale bar = 0.1 mm.
FIGURE 10 |
Geographic distribution of Rhinotridens chromocaudatus. White dot indicates the type-locality, each symbol may represent than one lot or locality.
FIGURE 11 |
Type-locality of Rhinotridens chromocaudatus; 07°30’37”S 63°20’23”W, rio Ipixuna, rio Purus drainage, rio Amazonas basin, Humaitá Municipality, Amazonas State, Brazil.
FIGURE 12 |
Phylogenetic relationships of A. Trichomycteridae (Ochoa et al., 2020) and B. Tridentinae (Baskin, 1973; present study). See Discussion for character numbering and explanation.