The scotch argus (Erebia aethiops) is a locally abundant
butterfly typically on the wing during August in large
areas of Scotland and at two sites in northern England.
It is currently accepted by many that in Scotland two
subspecies – Erebia aethiops caledonia (Vérity) and
Erebia aethiops aethiops (Esper) - exist in different
areas and that these differ morphologically.
E. a. caledonia is slightly smaller and has three ocelli
(eyespots) on the upper fore and hind wing, whereas
E. a. aethiops has four or more ocelli. We have surveyed
four areas presumed to hold either one or the other
subspecies but found that both forms exist in all areas
and that E. a. caledonia was always the more common
form. While there may be other areas that are the sole
domain of one or the other form, our findings do not
support the contention that two subspecies exist. These
findings and the fact that there is continuous variation
between the two variant extremes represented by
E. a. caledonia and E. a. aethiops leads us to suggest
that the subspecies E. a. caledonia is invalid and that this
form ought to be considered only as a variant of the
nominate species Erebia aethiops aethiops (Esper)
