Aspades hutchinsonella middle, is a distinct black spot. A conspicuous greyish fuscous patch lies on the dorsal margin contiguous to the anal angle, its rounded inner edge narrowly margined by a line of black scales, its outer extremity touched with chestnut. This patch is connected at the anal angle with a shade of the same colour, which follows the apical margin to the apex, interrupted only by a small marginal spot of the pale stramineous ground colour, immediately below the apex, by which the darker shade appears to be deflected inwards. The hindwings are grey. Aspades hutchinsonella Aspades hutchinsonella is a species
Pale crag martin often treated as the small, pale northern subspecies of the rock martin, but it is now usually considered to be a separate species. The changes in size and colour are continuous, so the evidence for separate species is not strong, although some rock martins can weigh more than twice as much as the smallest subspecies of the pale crag martin. The average weight for "P. o. fusciventris" is 22.4 g (0.79 oz) against 10 g (0.35 oz) for "P. o. obsoleta". There do not appear to be any intermediate forms where pale crag martins and rock martin populations breed close