Data from: Taxonomic challenges in freshwater fishes: a mismatch between morphology and DNA barcoding in fish of the north-eastern part of the Congo basin

This study evaluates the utility of DNA barcoding to traditional
morphology-based species identifications for the fish fauna of the
north-eastern Congo basin. We compared DNA sequences (COI) of 821 samples
from 206 morphologically identified species. Best match, best close match
and all species barcoding analyses resulted in a rather low identification
success of 87.5%, 84.5% and 64.1%, respectively. The ratio
‘nearest-neighbour distance/maximum intraspecific divergence’ was lower
than 1 for 26.1% of the samples, indicating possible taxonomic problems.
In ten genera, belonging to six families, the number of species inferred
from mtDNA data exceeded the number of species identified using
morphological features; and in four cases indications of possible synonymy
were detected. Finally, the DNA barcodes confirmed previously known
identification problems within certain genera of the Clariidae, Cyprinidae
and Mormyridae. Our results underscore the large number of taxonomic
problems lingering in the taxonomy of the fish fauna of the Congo basin
and illustrate why DNA barcodes will contribute to future efforts to
compile a reliable taxonomic inventory of the Congo basin fish fauna.
Therefore, the obtained barcodes were deposited in the reference barcode
library of the Barcode of Life Initiative.