4 M. W. R. de V. GRAHAM 



INTRODUCTION 



Since the publication of Walker's Monographia Chalciditum (1833-1839) and 

 volumes 4 and 5 of Thomson's Hymenoptera Scandinaviae (1876-1878), no mono- 

 graph including all the described Pteromalidae of the region has appeared. The 

 former work, though it includes nearly 250 of the species now known from Europe, 

 is of little use because of its poor descriptions and lack of keys. Thomson's work is 

 still a fundamental treatise and remarkable for its excellent descriptions, but it does 

 not include more than about half the number of genera or species now known. 

 Neither of these works was provided with illustrations. Thomson recognized 

 comparatively few of Walker's species because he was unable to see their types (or 

 indeed those of most of the species previously described by other British and 

 Continental authors). In fact, none of the 19th and 20th century writers on 

 Chalcidoidea had access to more than a negligible amount of each other's original 

 material. Consequently great confusion has arisen. In some cases the same 

 species has been listed twice in the same publication under different specific names, 

 these being sometimes placed in different genera. This has happened for instance 

 in the Check List of Kloet & Hincks (1945) which first induced me to begin a revision 

 of the British Pteromalidae. The wealth of species described by Walker clearly 

 offered a unique basis for such a revision as I was able to study his types. My 

 revision began with papers published in The Entomologist's monthly Magazine 

 (1956-1957). It soon became evident that a wider treatment of the group was 

 expedient, and that a revision was likely to be of limited use unless accompanied by 

 keys for identifying the numerous genera and species. These conclusions led to 

 the preparation of the present work. 



After the time of Thomson, publications dealing with Pteromalidae were, until 

 recently, sporadic. Ashmead (1904) keyed out the subfamilies, tribes and genera of 

 Pteromalidae, Cleonymidae and Miscogasteridae (the two latter are now included in 

 Pteromalidae). The work of Schmiedeknecht (1909), which was a compilation, 

 mainly followed that of Ashmead. In some ways these two works were an improve- 

 ment on Thomson's, but some features contained in them were retrograde. 

 Ashmead attached too high a value to the mandibular dentition and some other 

 characters, which led him to define some artificial groups which are in fact hetero- 

 geneous. Ruschka (1912-1924) and Masi (1907-1953) made notable contributions 

 to the study of Pteromalidae, by revising certain genera and species, and describing 

 new taxa. Kryger also worked on certain Pteromalidae ; his little-known paper 

 of 1934 included keys to the genera. Nikol'skaya's useful work (1952) also contains 

 keys to genera. After 1945, interest in Chalcidoidea revived and in succeeding 

 years much excellent work was done in revising older taxa and describing new ones, 

 by Boucek, Delucchi, Erdos, Ferriere, Hedqvist, Kerrich, von Rosen and others. 

 Their work need not be discussed here, because I have cited in the text all of their 

 papers dealing with European Pteromalidae. I should just like to say that I have 

 learnt a great deal from their efforts. 



I have examined the types of nearly all the species described by the chief European 

 authors (the exceptions are those described by Rondani and Kurdjumov, and many 



