Yes, I think A thysanoma and M. ursina are often difficult to tell apart. Both moths have a concave shaped forewing termen, but it seems to be more pronounced in A. thysanoma. Comparing them on Bold Systems 4 is instuctive. Markings along the costa seem more distinnt in M. ursina, Many A. thysanoma seem to have the distinct basal forewing diffuse 'dot' whereas in M. ursina it seems, to me at least. to lack that dot. Until recently, we haven't had mnany local examples to compare them.