Previously included in Aylostera atrovirens. See that species for details. A. ritteri is sometimes confused with A. pseudoritteri and it can be difficult to find true plants in nurseries.
The original description of Aylostera ritteri is here.
Plants of this species which we have in the collection include:
Aylostera ritteri RH1386
Aylostera ritteri WR493
Aylostera ritteri WR520