PTEROMALIDAE OF N.W. EUROPE 7 



not very definite. I therefore include here a new key to the families, which em- 

 bodies an attempt to cover as far as possible the extremes of variation within each. 

 Such extremes often make it difficult to define the limits of a family concisely. 

 Possibly a more mature classification may result in a reduction in the number of 

 families. Thus Eucharitidae might be united with Perilampidae ; Leucospididae 

 with Chalcididae ; Eupelmidae, and even Torymidae, with Pteromalidae ; Tetra- 

 campidae, Elasmidae, Signiphoridae, Aphelinidae, and Trichogrammatidae, with 

 Eulophidae. The problems of higher categories, however, need discussion in a 

 separate paper. 



The only reasonably comprehensive modern key to the European genera of 

 Pteromalidae is that of Boucek (in Peck et al., 1964) which is excellent and includes 

 very good figures. But as the authors state (1964 : 27) it incorporates recent 

 changes only in part. My own keys, worked out independently, embody some 

 differences of detail and emphasis as compared with that of the above authors, 

 although in the main I agree with their grouping of the genera. I regret that my 

 keys to the genera (and to the subfamilies) of Pteromalidae are so lengthy, but this 

 was unavoidable when I had to take into account the considerable range of variation 

 in some groups. 



In order to keep the size of the work within reasonable bounds, full descriptions 

 of genera and species have been omitted except in special cases (new taxa ; re- 

 description of an important type-species). Consequently a worker will have to rely 

 on the keys, which have been carefully integrated and made as detailed as possible. 



The term " sp. indet." is sometimes used in my keys and text for certain species 

 which are probably valid but which I do not wish to describe at present, either 

 because my material is inadequate or for some other reason. 



Regarding biological information, clearly many of the older host-records are un- 

 trustworthy because of erroneous identifications (in some cases both of a parasite 

 and its host). In most cases the material upon which the records were based no 

 longer exists or cannot be recognized. Where such data could be verified it has been 

 included, but in general I have been fairly ruthless in rejecting old records, knowing 

 many to be valueless or even misleading. In doing so I have no wish to disparage 

 earlier workers who produced so much of value in spite of severe practical limitations. 

 References cited refer chiefly to descriptions but include the more important ones 

 dealing with biology ; amongst the latter is the extremely valuable catalogue of 

 Peck (1963). 



Nomenclature of plants in the main follows Clapham, Tutin & Warburg (1962). 

 That of insect hosts for the most part follows Kloet & Hincks (1945, 1964). Various 

 Continental works were also consulted for species not contained in the above to 

 find as far as possible the most up to date nomenclature. 



TYPE SPECIMENS 



Most species were described before the formal designation of types had become 

 customary. A lack of type-fixation has often resulted in confusion in nomen- 

 clature. Types have been examined by the writer unless the contrary is stated. 



