Pachyphragma macrophyllum is another early flowering perennial. Native to Turkey and the Caucasian regions like the aforementioned Trachystemon orientalis. Both do well in shade and as it happens both are monotypic i.e. the only species in their genus.  

 Not much planted in British gardens P. macrophyllum doesn't seem to be common enough to have a common name. Some nurseries call it Caucasian Penny-Cress in reference to being of the Brassicaceae aka the crucifers/mustards/cabbage family.