Key: Collin, J. E. (1944). The British species of Psilidae (Diptera). Entomologist’s Monthly Magazine, 81, 214–224.
Collin, 1944: Psila clunalis sp. n. Very much like atra Mg., having the same number (4 pairs) of dorsocentral bristles, but rather like a larger species with distinctly larger male hypopygium of different structure and different 7th abdominal tergite in female.
Male. The hypopygial shell, which is as usual cleft subapically to accommodate the anal lamellae (or cerci), is larger than in atra, and each of its two ends below these lamellae terminate in a curved finger-like process, whereas in atra the ends are bluntly and evenly rounded.
Female. Differing from atra in structure of 7th tergite; in atra this is narrow and forms part of the telescoped segments of ovipositor; in clunalis it is almost as wide as 6th, while it is somewhat tumid and quite devoid of hairs on each side, the narrow ovipositor emerging from its broadly truncate end. Length 3.5 mm. Described from a male taken at Aviemore (Inverness-shire) on June 10th 1913, and three pairs taken at Grantown-on-Spey on June 1943, these latter(included among other small Diptera) collected and posted to me by my friend Mr. Colbran J. Wainwright. This species, having the face blacker than in gracilis, might pass for fuscinervis Zett., except that the wings are in no way infuscated along the veins, and Zetterstedt’s description of ‘femoribus apice oblique ...flavis’ applies far better to gracilis than to this species, in which the femora are only narrowly and evenly yellow at tip.