Lewis & Short

Pīcumnus, i, m., and Pīlumnus, i, m., two brother deities of the Romans; the first a personification of the woodpecker (picus), and the second a personification of the pestle (pilum); both were companions of Mars, and tutelary deities of married people and little children, Varr. ap. Non. 528, 11 sq.; id. ap. Aug. Civ. Dei, 6, 9; cf. Isid. 4, 11, 5; Aem. Mac. ap. Non. 518, 26; cf. Serv. Verg. A. 9, 4; 10, 76.
Pilumnus was the son of Daunus, husband of Danaë and ancestor of Turnus, Verg. A. 9, 4.