Unsolved:Borysthenis

In Greek mythology, Borysthenis (Ancient Greek:) may refer to two distinct individuals:

• Borysthenes, one of the three Muses that were daughters of Apollo. Her sisters were Apollonis and Cephisso.
• the Scythian Earth-and-Water goddess Api, who was called because she was the daughter of the god of the Borysthenēs river (now the Dnipro river).

Sources

• Braund, David (2007). "Greater Olbia: Ethnic, Religious, Economic, and Political Interactions in the Region of Olbia, c.600–100 BC". Classical Olbia and the Scythian World: From the Sixth Century BC to the Second Century AD. Oxford, United Kingdom: Oxford University Press. p. 33-77. ISBN 978-0-197-26404-1. 
• Bukharin, Mikhail Dmitrievich (2013). "Колаксай и его братья (античная традиция о происхождении царской власти у скифов" (in ru). Аристей: вестник классической филологии и античной истории 3: 20–80. https://www.academia.edu/6542379.