I believe Juturna is regarded as a fusion of the names Juno and Turnus. To expound, the nymph Juturna is the sister of Turnus, the Italian prince whom Trojan Aeneas vanquishes in The Aeneid -- both she and Juno, an implacable adversary of the Trojan people, aid Turnus in his contention with Aeneas and therefore strive to stymie the fulfillment of Aeneas's grand destiny (that is, Aeneas is destined to found the Roman civilization).