develops from wing vein L1 fly_anatomy.ontology The distal costa is sometimes also referred to as marginal vein or wing vein L1 (Blair, 2007). wing vein R1 marginal vein FBbt:00004759 https://www.ento.csiro.au/biology/drosophila/melanogaster.html?R1 radius 1 Anterior longitudinal vein of the wing blade. It is contiguous with the distal costal vein, which follows the anterior wing margin, and posterior to the proximal costal vein. presumptive wing vein L1 longitudinal vein