Even though it was first scientifically studied in 1929, for many decades the specimens of this moth were mistaken for the related Australian species E. colymbetella, and their distinctness was only realized in 1986.

[1] E. spinula is a small moth, slightly larger than E. colymbetella (9–12 mm – almost 0.5 in – in wingspan) and resembling it in coloration and pattern.

[1] In the male genitals of E. spinula, the clasper's harpe is divided, with a slender costal part that is covered in bristles.

Particularly notable are a group of stout setae in the center of the outer side, and a large protuberance at the base on which there is a single long bristle.

In the female genitals, the ostium forms a broad funnel, with a large sclerotized and rough plate towards the hind end on each side.

Phyllanthus marchionicus), since it has been reared from G. marchionicum fruit on Nuku Hiva, Ua Pou, and Fatu Hiva, and specimens collected by Clarke and held in the Smithsonian Institution bear pollen on the proboscis, in the same manner as other Pacific Island and Asian Epicephala which pollinate other species of Glochidion (Phyllanthus sensu lato).