Colin Hart in his British Plume Moths of 2011 refers to the present species as being part of a difficult clade including
S. bipunctidactyla.
S. inopinata was raised to species level in 2002 by Bigot and Picard, and natively occurs from southern France to Italy. On rare occasions individuals of
S. inopinata have occurred in Britain where they have been misidentified as
S. bipundidactyla or
arida.
The forewings of specimens found in Britain are plain brownish-grey with a large black spot at the base of the cleft, with few other markings. The foodplant,
Chaenorhinum rubrifolium, a relative of toadflax, does not occur in Britain (Plant, 2011).
Hart identified (2011) six specimens from collections, one from Dorset, two from Sussex, two from Devon and a rather extraordinary example from Westerness in Scotland. The latest of these was at Prawle Point, Devon in 1996.