Two descriptions of depressus, one by Mulsant & Rey, under the generic name Heterogaster, the other by Dallas under his new generic name Orsillus, were published the same year 1852. Puton (1869a, 1878c, 1899) credited the name to Mulsant & Rey; Oshanin (1906), followed by Stichel (1958) and J.A. Slater (1964a) credited it to Dallas. The manuscript of Mulsant & Rey was received Jan. 2, 1852 by Annls Soc. linn. Lyon (the exact dates of publication of the issue and of volume one of Mulsant & Rey's Opuscula Entomologica (1852), where the description of the species was given as well, are unknown); Dallas' book was published just after June 6 (date of Gray's introduction. Both type series seem lost (at the BMNH there are no Dallas' specimens, and the species is labelled with Mulsant & Rey authorship, as well as in the MNHN). We are possibly facing a case of homonymy-synonymy in the same year, the species name itself being rather naturally suggested by the very depressed body of the insect. So the discussion about priority appears purely academic. We have followed here Puton (1878c), the first monograph covering the genus Orsillus.
The record of O. pinicanariensis from Lanzarote (Canay Islands) in Heiss et al. (1996) refers to this species.
The record from Albania (Péricart, 2001a) has to be confirmed.