Arkhedikus is the son of Herakles and Eurypyle who is one of the daughters of King Thespius. During his stay in the court of King Thespius, Herakles impregnated 49 of 50 Thespius' daughters including Eurypyle who he lay with one night. The result of that particular encounter was Arkhedikus.
"By Eurypyle he [Herakles] had Arkhedikus"
- Apollodorus.Biblioteca, 2.7.8