670 M. W. R. de V. GRAHAM 



Platymesopus aspilus (Walker) Graham, 1957c : 227. 

 Platymesopus elongatus (Thomson) Graham, 1957^ : 22 &- 

 Mesopolobus aspilus (Walker) von Rosen, 1958 : 218, $. 

 Mesopolobus elongatus (Thomson) v. Rosen, 1959a : 153-160, o* $. 

 Mesopolobus elongatus (Thomson) ; v. Rosen, 1960a : 24, o* ?• 



Type material. Pteromalus aspilus Walker. Lectotype $ designated by Graham 

 (1957c : 227). 



Eutelus elongatus Thomson. Lectotype designated by Graham (1957a 1 : 228-229). 



When writing my earlier paper (1957a 1 : 228-229) I regarded aspilus (Walker) 

 and elongatus (Thomson) as distinct species ; at that time nothing was known about 

 the biology of either. Von Rosen (1959a : 153-160) published a valuable account 

 of the biology and variation of M. elongatus (Thomson) with a redescription of 

 the species, many specimens of which he had bred in Sweden from galls of 

 Oligotrophus juniperinus (L.) on twigs of Juniperus. These specimens were 

 compared with the lectotype of elongatus and found to be the same. Early in i960 

 I gathered a number of the galls made by Taxomyia taxi (Inchb.) on shoots of 

 Taxus baccata L. growing wild on the slopes of the Chiltern Hills, near Lewknor, 

 Oxfordshire. During April, May and June several Mesopolobus emerged from the 

 above galls and I was able to ascertain that they were parasitizing the Taxomyia. 

 I found that these Mesopolobus agreed with my notes on the lectotype of elongatus 

 (Thomson) and also with von Rosen's (1959a) redescription of that species. In 

 most of these specimens the body is a rather bright green, some (especially small 

 examples) tending towards bronze-green. Von Rosen (1959a : 157) mentioned that 

 his specimens from Oligotrophus juniperinus were " mehr smaragdgriin ". I am 

 convinced that the material from both Taxomyia and Oligotrophus can be referred 

 to aspilus. At the beginning of October, 1960, in the same locality in Oxfordshire, 

 I observed many females of a Mesopolobus on terminal shoots of wild Taxus trees 

 and collected a number of them. Most of them agreed exactly with the lectotype 

 of Mesopolobus aspilus (Walker) and had the body bronze or coppery-tinged. In 

 May 1965, I reared a female which also agrees with aspilus, from a gall of Taxomyia 

 taxi. After comparing all these specimens I consider that elongatus (Thomson) 

 must be a form of aspilus (Walker). The colour of the body varies from bright 

 green to copper ; the legs may be mainly pale, or on the other hand rather extensively 

 infuscate ; and the relative length of the gaster varies considerably. In all these 

 respects, however, variation appears to be continuous. 



Britain, Sweden. 



Biology. See discussion above. Besides the Cecidomyiidae mentioned as hosts, 

 von Rosen (1959a : 153) says that he saw two females reared from Euura amerinae 

 (L.) (Hym., Tenthredinidae) which agreed well with his specimens of elongatus from 

 Oligotrophus. 



Mesopolobus juniperinus v. Rosen 



Mesopolobus juniperinus v. Rosen, 1958 : 218-220, o* $• 

 Mesopolobus juniperinus v. Rosen, 1960a : 28-29, c? ?■ 



