Ṛtvā (Ritva) is a distinguished devagandharva( a celestial sect of demigods). He was present along with the other devagandharva(s) during the birth ceremony of Arjuna.

Mahābhārata (Kinjawadekar)(1.123.57)
Mahābhārata Vols. 1-43 (Siddhāntabāgīśa)(1.117.61)