Taxonomic Revision of the Genus Scorpiodoras (Siluriformes: Doradidae) with Resurrection of Scorpiodoras calderonensis and Description of a New Species
Three species of Scorpiodoras are recognized: S. calderonensis, S. heckelii, and S. liophysus; the latter species is described herein. Scorpiodoras calderonensis occurs in the upper Amazon basin, including the Solimões, Juruá, Japurá, and Tefé rivers. Its type locality, originally stated as “Calderón”, is elucidated as Tabatinga, Brazil. Scorpiodoras heckelii is the most widespread species, occurring in the Orinoco, Branco, Negro, and Amazonas rivers downstream of its confluence with Rio Negro. Scorpiodoras liophysus is only known from the middle Rio Madeira basin and presents a morphological feature unique within the genus: gas bladder without secondary bladder. An osteological description of the genus is provided, as well as redescriptions of S. calderonensis and S. heckelii. Additionally, a key allowing identification of the species is presented, as well as a biogeographic discussion.
Scorpiodoras heckelii, NMW 46613, holotype, 144.9 mm SL. Photo by Mark Sabaj Pérez.
Scorpiodoras heckelii, ANSP 182790, 82.5 mm SL, photographed live by Mark Sabaj Pérez.
Variation in gas bladder morphology in Scorpiodoras. Scale bars 5 mm.
Head and anterior body of Scorpiodoras heckelii, MZUSP 8493, 113.3 mm SL. Scale bar 5 mm.
Cranial floor of Scorpiodoras heckelii, MZUSP 8493, 113.3 mm SL. Scale bar 5 mm.
Suspensorial and opercle series of Scorpiodoras heckelii, MZUSP 8493, 113.3 mm SL, in lateral view. Scale bar 5 mm.
Schematic illustration of hyoid arch of Scorpiodoras heckelii, based on MZUSP 7941, 73.7 mm SL, in dorsal view. Scale bar 1 mm.
Schematic illustration of branchial skeleton of Scorpiodoras heckelii, based on MZUSP 7941, 73.7 mm SL, in dorsal view. Scale bar 1 mm.
Caudal skeleton (left side) of Scorpiodoras heckelii, MZUSP 7941, 73.7 mm SL. Scale bar 1 mm.
Pectoral girdle of Scorpiodoras heckelii, MZUSP 8493, 113.3 mm SL, in ventral (left) and dorsal (right) views. Scale bar 5 mm.
Schematic illustration of pelvic girdle of Scorpiodoras heckelii, based on MZUSP 7941, 73.7 mm SL, in dorsal view. Scale bar 1 mm.
Distribution of the genus Scorpiodoras. Circles represent S. heckelii, squares S. calderonensis, and triangles S. liophysus. Black symbols represent type localities.
Scorpiodoras calderonensis, MNHN A. 1980, holotype, 116.9 mm SL. Photo by Mélyne Hautecoeur.
Scorpiodoras liophysus, INPA 33829, holotype, 125.5 mm SL.
Contributor Notes
Associate Editor: R. E. Reis.