A New Species of Scoloplax with a Remarkable New Tooth Morphology within Loricarioidea (Siluriformes: Scoloplacidae)
A new species of Scoloplax is described with a remarkable new tooth morphology, possessing dentary teeth with four cusps and premaxillary teeth with two to four cusps, features unique among all Loricarioidea and rare among Siluriformes. Scoloplax baileyi, new species, is further distinguished by eight diagnostic features. The new species is found in the small tributaries of Rio Unini, an important tributary to the Rio Negro, and in the Anavilhanas Archipelago, lower Rio Negro, Amazonas State, Brazil. Based on a review of scoloplacids, a new record of S. baskini is given to include the Rio Negro, increasing the number of species of Scoloplax from that basin to four.
Scoloplax baileyi, new species, INPA 35637, holotype, 14.0 mm SL, Igarapé do Ingá, right bank tributary of Rio Arara, Rio Unini basin.
Scoloplax baileyi, new species, holotype before preservation, INPA 35637, 14.0 mm SL, photograph taken a few hours after collection.
Left premaxilla of Scoloplax baileyi, paratype, INPA 35632, 16.1 mm SL. Scale = 0.5 mm.
Basipterygia of scoloplacid species. Ventral view, anterior toward top. (A) Scoloplax baileyi, paratype, INPA 35632, 16.1 mm SL; (B) S. baskini, paratype, INPA 28650, 15.6 mm SL; (C) S. dicra, INPA 27210, 11.1 mm SL; (D) S. dolicholophia, INPA 28965, 12.2 mm SL; (E) S. empousa, NUP 4806, 19.7 mm SL; (F) S. distolothrix, INPA 4006, 11.7 mm SL.
Ventral view of Scoloplax. (A) S. baileyi, INPA 35637, holotype, 14.0 mm SL; (B) S. baskini, INPA 28649, 16.3 mm SL.
Partial view of dorsal plates and associated osteology of vertebral elements. Dorsal view, anterior toward top. (A) Scoloplax baileyi, paratype, INPA 35632, 16.1 mm SL; (B) S. distolothrix, INPA 4006, 11.7 mm SL.
Dorsal view of neurocranium of species of Scoloplax. (A) S. dicra; (B) S. baileyi, paratype, INPA 35632, 16.1 mm SL. Rostral plate removed. Anterior toward left. Figure of S. dicra modified from Schaefer (1990). Scale = 1 mm.
Ventral midline plates in scoloplacid species. Ventral view, anterior toward top. (A) Scoloplax baileyi, paratype, INPA 35632, 16.1 mm SL; (B) S. baskini, paratype, INPA 28650, 15.6 mm SL; (C) S. dicra, INPA 27210, 11.1 mm SL; (D) S. dolicholophia, INPA 26257, 10.7 mm SL; (E) S. empousa, NUP 4806, 19.7 mm SL; (F) S. distolothrix, INPA 4006, 11.7 mm SL.
Geographic distribution of Scoloplax baileyi. The white line is the political border between the Brazilian states of Amazonas and Roraima.
Contributor Notes
Associate Editor: R. E. Reis.