Redescription of acanthocyclops vernalis (Fischer, 1853) and acanthocyclops robustus (sars, 1863) from neotypes, with special reference to their distinction from acanthocyclops americanus (marsh, 1892) and its invasion of Eurasia

1. Alekseev, V.R.
2. Miracle, M.R.
3. Sahuquillo, M.
4. Vicente, E.