Same entries (but with mu- rather than mui- spellings, as indeed some of the Suda mss have) in Hesychius mu1772 and Photius mu564 Theodoridis; see also the scholia to Nicander, Theriaca 409, where mua/grous occurs (of a type of snake).
The LSJ entry on this headword documents something entirely different: a hero or deity of this name, or epithet, in Elis (e.g. Pausanias 8.26.7, cf. 5.14.1; Pliny the Elder, Natural History 10.75).