Volga undermouth [SEP] parent taxon
Volga undermouth
The Volga undermouth or Volga nase ("Chondrostoma variabile") is a species of cyprinid freshwater fish. This one lives in the Emba, Ural and Volga drainages of the Caspian Sea basin, and the Don River drainage of the Black Sea basin.
It is a riverine fish but is also found in reservoirs. The distribution is in lowland areas and foothills, and the fish prefer river stretches with strong currents, including rapids. Larvae and juveniles have a superior mouth, but at 3–4 months they change
Taxon in disguise
In bacteriology, a taxon in disguise is a species, genus or higher unit of biological classification whose evolutionary history reveals has evolved from another unit of similar or lower rank, making the parent unit paraphyletic. This happens when rapid evolution makes a new species appear radically different from the ancestral group, so that it is not (initially) recognised as belonging to the parent phylogenetic group, leaving the latter an evolutionary grade.
While the term is from bacteriology, parallel examples are found throughout the tree of