not a species from Argentina:
Tridentopsis pearsoni Myers, 1925

published in:
Azpelicueta, M. (1990):
Tridentopsis cahuali n.sp. (Siluriformes, Trichomycteridae), a new miniature tridentine from Paraguay system, in Argentina.
Revue Suisse de Zoologie 97 (4): 981–988

remarks (from publication):
A previous record of T. pearsoni from Paraná basin, in Chaco province, Argentina, was reported by Castello et al. (1978). Unfortunately, the specimens were not found in the collection of Museo Argentina de Ciencias Naturales Bernardo Rivadavia. However, the features described and figured show that the specimens do not belong to T. pearsoni. The number of opercular odontodes resembles that of T. cahuali n.sp., although the presence of trifid opercular odontodes does not agree in the latter.

The distribution of Tridentopsis pearsoni is given as ‘Upper Amazon basin, Bolivia’ in CLOFFSCA (de Pinna & Wosiacki, 2003), Catalog of Fishes (Eschmeyer, online) and the Checklist of Catfishes (Ferraris, 2007). T. cahuali is the only species of this genus with confirmed localities within the La Plata drainage.