Shatalkin & Merz, 2010: This Transpalaearctic species is characterized by the presence of 4 dorsocentral setae, this character only shared with Ch. clunalis (Collin, 1944) in the Western Palaearctic Region. Ch. clunalis was described from Great Britain and was later found in Central Europe and Spain but is still unknown from Switzerland (Pape, 2007). It differs from Ch. atra by its larger epandrium in the male which gives the impression that the abdomen is parallel-sided (in Ch. atra more cone-like). Moreover, the posteroventral margin of the epandrium is extended into a tooth-like projection (Shatalkin, 1986, plate 4, fig. 9) (evenly rounded in Ch. atra). Finally, the female of C. clunalis has therefore a wider 7th tergite which is as wide as the previous one (decreasing in width in C. atra). C. clunalis exhibits a wide variation in colouration, varying from black to brown, especially on the head.
Key: Collin, 1944
Chandler, 1975: Psila nigra Fall, and P. atra Mg. are both locally frequent in marshy grasslands, but these small black species are usually collected by sweeping and the variety of vegetation in localities where I have collected them has precluded any useful observations on plant associations.