Lewis & Short

Voltinĭa trĭbus, one of the Roman tribes, of unknown locality, Cic. Planc. 16, 38; 17, 43; Inscr. Grut. 418, 3; 48, 11.
Hence, Voltinĭenses, ĭum, m., the people of the Voltinian tribe, Cic. Planc. 17, 43.