840 M. W. R. de V. GRAHAM 



Pachyneuron concolor (Forster) 



P achy neuron coccorum, auctt. [ex parte] [nee Ichneumon coccorum Linnaeus, 1758]. 



Pteromalus concolor Forster, 1841 : 28, $. 



Pteromalus concolor Forster ; Ratzeburg, 1848 : 184. 



? Pachyneuron Pruni (Forster MS.) Walker, 1850 : 128, [ex parte], 



? Pachyneuron psyllaephaga Mani, 1939 : 84, $ $. 



Pachyneuron siculum Delucchi, 19556 : 135, 6* ?> s Y n - n - 



Type material. Pteromalus concolor Forster. Syntypes in Naturhistorisches 

 Museum, Vienna ; lectotype female designated by Delucchi (1955& : 136, 137). I 

 have not seen the lectotype, but have examined another female from Forster's 

 collection which agrees with Delucchi's redescription. This species was regarded as 

 being identical with solitariurn (Hartig) by Ratzeburg (1848) and Boucek (1961c : 

 12). 



Pachyneuron pruni Walker. Walker's collection contains a male and a female. 

 He described only the female but his description does not apply well to the female in 

 his collection. His male, which appears to be a small concolor, is labelled in Forster's 

 handwriting " Pachyneuron Pruni Foerst. Aachen ". 



Pachyneuron psyllaephaga Mani. Holotype $ and allotype <$ in Pusa collection, 

 Imperial Agricultural Research Institute, New Delhi (not seen). From the 

 description and host it seems to me likely that it may be the same as concolor 

 (Forster). Mani's types were bred from nymphs of Psylla peregrina Forster, the 

 type-locality being Edinburgh ; I have seen Scottish specimens of concolor bred 

 from the same host. 



Pachyneuron siculum Delucchi. Holotype $, Sicily, 3.ix.i95o (Priesner), in 

 Museum d'Histoire naturelle, Geneva. In my opinion it is an extremely small, 

 dark-coloured female of concolor (Forster) ; I have examined a range of forms 

 intermediate between the type of siculum and typical concolor. Boucek (19650 : 18) 

 expressed the opinion that siculum was a small form of solitariurn (Htg.) ; but he 

 considered solitariurn to be identical with concolor (Forster), whereas in my opinion 

 these two are distinct. 



Widely distributed in Europe, from Britain to U.S.S.R. ; Israel. 



Biology. A number of hosts have been recorded for concolor and siculum, but 

 the data given are not always very precise and there is room for further research. 

 The species has been recorded as a parasite of Oscinella frit (L.) in Czechoslovakia 

 (Secretariat, etc., 1966 : 120-131) ; also (under the name siculum Delucchi) as a 

 parasite of Coccus hesperidum L. (ibid., 1963 : 343, 370), of Chilochorus bipustulatus 

 L., Ceroplastes floridensis Comst., Pseudococcus citriculum Green, and Saissetia oleae 

 Bern, (ibid., 1966 : 120, 125) in Israel. In the case of the records from Israel I 

 have been informed that the Pachyneuron were hyperparasitic on the above species ; 

 and it seems likely that the species is normally a hyperparasite. Recently 

 Professor G. C. Varley has reared a number of Pachyneuron concolor from samples of 

 Eriopeltis ? strelkovi Borchs. collected on Brachypodium pinnatum (L.) Beauv. 

 at Wytham Wood, Berkshire, and at Blenheim, Oxfordshire. From these samples 

 Eunotus cretaceus Walker, and five species of Encyrtidae (including Trichomasthus 



