The third pattern, found in B. melanurus, has the caudal fin completely dark. The coloration pattern is useful for separating species, but apparently does not allow inferences about phylogenetic relationships to be safely made, since this character is widespread in this family.
The third pattern, found in B. melanurus, has its tail fin entirely black. The coloration pattern is useful for distinguishing species, but it does not provide a reliable basis for drawing conclusions about evolutionary relationships, as this characteristic is widespread within this family.