"However,
aethiops and
cleora are sometimes difficult to separate without having specimens for direct comparison, or lacking any data on habitat.
A. cleora seems to be fairly selective of its habitat, preferring dune areas or other areas with very loose sand and sparse vegetation. This is probably the reason for its more developed tarsal rake, which can appear to have as few as three and as many as five, depending on the age of the specimen and the subsequent wear it would have received from nestings.
A. aethiops usually has three spines of moderate length, sometimes with a short fourth. Again, subject to wear. They are usually subject to more wear because that species tends to nest in heavier soils and is less selective about habitat." Nick Fensler's comments
here.