STUDY OF VARIATION IN THE KAOES OF ZYOAENA FILIPENDULAE, L. 81 



An Essay on the Systematic Study of Variation in the Races of 

 Zygaena filipendulae, L, and of its subspecies stoechadis, Brkh. 



By EOGEK VEBITY, M.D. 



The literature dealing with this species is chaotic to a point, which 

 is equalled by few other instances. This is evidently due to the extent 

 of individual variation in some of its southern races, to its geographical 

 variations, and also to its resemblance in some regions to Z. 

 transalpina. I have again quite lately received from well known and 

 ■clever entomologists series in which the two species were mixed up 

 together under one name, showing it needs practice to separate 

 them, although to a trained eye the position of the spots on the fore- 

 wing, which I have described dealing with Z. transalpina (Ent. Rec, 

 xxxii., p. 29), seems such an easy and sure differential character that 

 no others are required. No wonder that ancient authors should have 

 got so hopelessly mixed in this genus ! Until the beginning of this 

 century collections were made up of striking individual variations ; 

 those which had been named were eagerly sought for and one or two 

 specimens were thought quite sufficient to represent them and to con- 

 stitute a " complete collection " ; intermediate specimens were generally 

 discarded; labels were by many avoided, so as not to spoil the effect 

 of the cabinet ; when a record of localities was kept, such indications 

 as " England," " Italy," " the Alps " were considered quite sufficient, 

 and dealers carefully avoided revealing the source of their specimens. 

 With such a material to work on it is easy to understand that a genus 

 like Zi/gaena, in which individual differences are in some cases much 

 more striking than specific ones, could not be unravelled. As late as 

 1899, and in an author such as Tutt, we still find the greatest 

 uncertainty as to the limits of species and, to the present day, 

 Staudinger, Seitz, Dziurzynski and others have maintained a number 

 of them, which certainly do not exist, although the two latter writers 

 have much reduced them, as compared with the first, in connection 

 with the Eastern regions. Lack of material to work upon and of field 

 observations is evident in their writings ; races, individual forms and 

 aberrations are treated on the same footing ; localities are quoted 

 without making any distinction between those where a form constitutes 

 the majority of individuals and characterises the race and those where 

 it only occurs as an extreme variation. M. Charles Oberthiir was the 

 man who really cast new light on the subject in his Etudes de Lepi- 

 dopterologie Coinparee, vol. iv. (1910). He first of all collected an 

 adequate material (18,000 specimens of Zygaena) and he then com- 

 pared large series from all sorts of localities, effectively outlining a 

 picture of their individual and geographical variations. By a critical 

 study of original descriptions and figures he then endeavoured to dis- 

 entangle the perplexities of the literature on this genus and to establish 

 the names of the different races. The object of this paper is to 

 summarise his conclusions and to try and carry his method a little 

 further, suggesting one or two alterations in nomenclature in accordance 

 with the rule of priority, and describing other races, which I have had 

 an occasion to examine. I have been fortunate enough to be able to 

 avail myself of the thorough " field experience " and knowledge 

 acquired by Signor Orazio Querci in forty years' collecting on a large 

 scale in Central Italy and of the fine series of specimens with which he 

 May 15th, 1921. 



