in the text of E. virescens within MoB, note "The branching system of the forewing radial sector is further from the margin than in ariel" and goes on to say that virescens' black scales are "tinged greenish in places everywhere". I would suggest that, also given the distribution of virescens as Java, Sumatra and Borneo, the use of Ephemeroidea sp. cf. ariel is the most reasonable option for now.... but also note the colours from the original description of ariel in Hampson (Moths of British India vol 2):
"508. Ephemeroidea ariel, n. sp.
Head, thorax, and abdomen black, with copper and green reflections. Wings hyaline, the veins and margins narrowly black; the inner margin of fore wing and costa of hind wing broadly so.
Hab. Bernardmyo, Burma, 6000 feet, May (Doherty). Exp. 20 millim. Type in coll. Elwes."
seems this one is another mystery that will only be solved with voucher specimens :(