PTEROMALIDAE OF N.W. EUROPE 363 



Sides of propodeum never so extensively hairy, the pilosity not encroaching 

 upon the median area ; if the pilosity covers nearly the whole of the callus, 

 then the basal tergite of the gaster is conspicuously hairy laterally, Hind 

 corners of propodeum not dentate . . . . . . -57 



57 (56) Both mandibles with four teeth ; pronotal collar finely but sharply and very 



regularly margined throughout anteriorly. Sides of basal tergite of gaster 

 with a conspicuous or fairly conspicuous patch of whitish hairs 



TRICHOMALUS Thomson (p. 707) 

 Left mandible with three teeth, right mandible with four ; either the pronotal 

 collar is not distinctly margined or else the sides of the basal segment of the 

 gaster have only an inconspicuous patch of hairs ..... 58 



58 (57) Head in dorsal view less transverse (1-9 to 21 times as broad as long) ; 



temples from one quarter to three quarters as long as eyes ; fore wing 

 usually with brownish cloud or clouds. Propodeum with a large, strongly 

 reticulate nucha, often also with a costula. Sides of basal tergite of 

 gaster with a relatively inconspicuous patch of hairs 



SPANIOPUS Walker (p. 702) 

 Head in dorsal view more transverse (2-2 to 2-5 times as broad as long) ; 

 temples one eighth to one quarter as long as eyes ; fore wing immaculate. 

 Either the propodeal nucha is narrow and very weakly sculptured, or there 

 is no costula. Sides of basal tergite of gaster with a conspicuous patch of 

 whitish hairs PERIDESMIA Forster (p. 701) 



59 (51) Tip of antennal clava acute or (Text-figs. 299-301) with a pointed stylus . 60 



- Tip of antennal clava obtuse or only bluntly pointed .... 62 



60 (59) Postspiracular sclerite visible only as a small subequilateral and weakly- 



sculptured triangle just in front of the tegula (cf. Text-fig. 318) ; head and 

 thorax with rather conspicuous whitish hairs ; hind tibia with two spurs, 

 but the second spur is weak, only about half as long as the first one . 195 



- Postspiracular sclerite larger, reticulate, forming a triangle which is higher 



than broad and descends well ventrad (cf. Text-fig. 20) ; head and thorax 

 often with brownish hairs, if the hairs are whitish then they are relatively 

 inconspicuous ; hind tibia with one spur . . . . . . 61 



61 (60) Gaster subcylindrical, convex dorsally, metallic ; fourth abdominal tergite 



shorter than the fifth, the latter shorter than the sixth ; fore wings 

 immaculate, the marginal vein about 2-3 times as long as the stigmal vein 



MERISUS Walker (p. 443) 



- Gaster usually more or less flattened or sunken dorsally ; if convex then more 



ovate in outline with abdominal tergites four, five and six equal or sub- 

 equal in length, and fore wing with a fuscous cloud below the marginal 

 vein. Marginal vein 1 to 2-2 times as long as the stigmal vein ; if as much 

 as twice the stigmal vein, then the gaster is sunken dorsally and is more or 

 less yellow HOMOPORUS Thomson (p. 444) 



62 (59) Distal half or more of basal cell in fore wing pilose ; gaster (Text-fig. 349) 



more or less extensively red at the base, and one bristle of each pygostyle 

 much longer than the others ; funicular segments, except the first and 

 second, not longer than broad, most often transverse ; anterior margin of 

 clypeus incised medially ; fore wing usually with fuscous markings 



ERYTHROMALUS Graham (p. 468) 



- If the basal cell of the fore wing is so extensively pilose and the gaster is also 



more or less red, then the pygostylar bristles are subequal in length and 

 relatively short, all the funicular segments are longer than broad, the 

 anterior margin of the clypeus is shallowly emarginate, and the fore wings 

 are immaculate .......... 63 



