Attested as such only here and, according to Adler (who reports the correction 'Tosibos' in one manuscript), in a comparable entry in the Ambrosian Lexicon. The name sounds Egyptian.
Eusebius and Theodoret mention a Tosobis (sic) who was leader of the Solymeis, between Lycia and Pamphylia; however, they are both quoting Plutarch, Moralia 421D, where the name is Trosobios, and thus irrelevant here.