656 M. W. R. de V. GRAHAM 



A good redescription of the typical form of nobilis was given by von Rosen (1958), 

 who later added some useful notes and photomicrographs of the female hypopygium 

 (1966 : 82, fig. 2). 



Von Rosen (1966 : 82) mentioned having reared several particularly large and 

 fine examples of nobilis from Avena [=Helictotrichon] pubescens and A. [=H.] 

 pratensis in Sweden. He stated that slight differences could be found between the 

 female hypopygium of this form and that of typical nobilis, which he illustrated by 

 photomicrographs (1966, fig. 2). On 18. vi. i960 I captured a number of both 

 sexes of this large form of nobilis on Helidotrichon sp. at Bald Hill, near Lewknor, 

 Oxfordshire. The males of this large form agree well with the lectotype of 

 Platyterma decorum Walker and are clearly conspecific with it. The females of this 

 form have a hypopygium which does appear to differ slightly from that of female 

 nobilis, and agrees with von Rosen's figure. It seems just possible that the large 

 form from Helidotrichon spp. may represent a species distinct from (although 

 extremely close to) nobilis ; if this form subsequently proves to be distinct, the name 

 decorus (Walker) will be available for it. 



The following notes on the typical form of nobilis are intended to supplement 

 von Rosen's redescription : 



$. Head and thorax varying from bronze-green through green to blue. Antennae varying 

 from testaceous with only the pedicellus infuscate proximally, to wholly brown. Legs, except- 

 ing coxae and tips of tarsi, sometimes yellow, sometimes with the femora more or less testaceous, 

 brown, or fuscous ; rarely the fore and mid tibiae are slightly darkened medially. In Scottish 

 and Irish specimens all the femora are sometimes mainly fuscous. Length 1-9 to 2-8 mm. 



Antenna (Text-fig. 546) with all five funicular segments usually subequal in length, with 

 the first segment subquadrate and the fifth moderately transverse, at most 1 -6 times as broad 

 as long ; in some specimens the first funicular segment is very slightly longer, in others very 

 slightly shorter, than the second ; the first segment is always much longer (two to three times) 

 than the third anellus ; in large specimens the proximal segments of the funicle tend to be 

 very slightly longer than broad, in small ones very slightly transverse ; the clava is at most 

 about as long as the three preceding funicular segments. Malar space 0-42 to 0-46 the length 

 of an eye. Median area of propodeum varying from nearly smooth to lightly obliquely strigose- 

 reticulate. Marginal vein 2 to 2-3 times as long as the stigmal vein, the latter weakly curved 

 or straight, the stigma small. Gaster long-ovate to lanceolate, 2 to 2-8 times as long as broad, 

 from as long as, to 1 -3 times as long as, head plus thorax. Hypopygium much as in text-fig. 549 

 with anterolateral angles relatively prominent ; median sclerotized area long, reaching much 

 farther back than the level of the hind edges of the sublateral sclerotized areas ; posterior 

 lobes relatively long. 



o*. Femora apparently always yellow. Malar space 0-4 to 0-46 length of eye. Funicular 

 segments much as in 9. Marginal vein i-8 to 2-il times as ong as the stigmal vein. 



The form decorus (Walker) is on the average slightly larger than typical nobilis 

 (<$ up to 2-8 mm., $ up to 3-2 mm., in length) and tends to be more richly coloured ; 

 the male often has the gaster extensively suffused with purple, whilst sometimes the 

 antennal clava and pedicellus, and even the base of the funicle, are conspicuously 

 infuscate so that the antenna appears variegated. The median area of the propo- 

 deum tends to be more distinctly, and sometimes strongly, strigose-reticulate. 



Britain, Ireland, Sweden, Germany, Austria, Czechoslovakia. 



