Complex sentence: Until recently only two species were recognised, "G. religiosa" and "G. ptilogenys"; earlier still all "Gracula" were considered to belong to a very variable species commonly called hill myna.
Split into simpler sentences: Until recently only two species were recognised, "G. religiosa" and "G. ptilogenys". Previously, all "Gracula" were considered to belong to a very variable species commonly called hill myna.