Melampsora epitea

This rust causes galls in the form of yellow thickened spots bearing aecia on the underside of spindle leaves, the alternate host. 

The primary host, bearing uredinia and telia, is a Salix species.

This is a probably a complex of species, and the taxonomy is not clear.  Within in the overall species complex of 'Melampsora epitea' are other alternate hosts e.g. Larch, Ribes.  Some authors separate these into different species, depending on the host - so the species with Spindle as alternate host may be M euonymi-caprearum.  

Unless identified by a recognised expert, a photo is required and the specimen should be examined with a microscope. In the comments box, state the key or ID method used and describe the size and identifying characters.

Widespread and fairly frequent in Britain.

Status in Leicestershire and Rutland not known.