Lewis & Short

Castŭlo, ōnis, m. (Liv.), and f. (Sil.), = Καστούλων, a town in Hispania Tarraconensis, near the borders of Baetica, now the village Cazlona, Liv. 24, 41, 7; 28, 19, 2 sq.; Sil. 3, 99; 3, 391; Plin. 3, 2, 3, § 17.
Hence,

    1. 2. Castŭlōnensis, e, adj., of Castulo: saltus, Asin. ap. Cic. Fam. 10, 31, 1; Caes. B. C. 1, 38; Liv. 22, 20, 12; and as subst.: Castŭlōnenses, ium, m., the inhabitants of Castulo, Plin. 3, 3, 4, § 25.