POLYCYKTUS. 229 



POLYCYRTUS. 



Polycyrtus, Spinola, Ann. Soc. Ent. Fr. x. p. 154. 



This generic group has the general form of the body and neuration of Mesostenus ; 

 but it differs from the typical forms of Mesostenus in having a more or less well-deve- 

 loped spine on the front, and in having the mesonotum divided into three well-developed 

 lobes. Some authors regard Polycyrtus as a mere section of Mesostenus ; but in view 

 of the great extent of that genus, I prefer, if only as a matter of convenience, to keep 

 it distinct from it. 



So far as I know, Polycyrtus is less numerously represented in South and Central 

 America than Mesostenus proper. In both groups there is considerable variation in the 

 form of the body, but as a rule the species of Polycyrtus are more slenderly built. The 

 form of the areolet varies, but is generally very small ; often it is open at the outer 

 side. There is great variation in the size of the metathoracic spines; sometimes they 

 are completely obsolete, and this may also be the case with the transverse keels. 



A. Body black and yellow. (Species 1 to 24.) 



The Central American species of this section known to me may be recognized by the 

 following table : — 



1 (2) . Metathorax coarsely punctured chontalensis. 



2 (1). Metathorax impunctate or nearly so. 



3 (8). Hind tibise entirely black behind. 



4 (7) . Central black line on the metanotum broadly dilated at the trans- 



verse keel ; metatarsus not entirely yellow. 



5 (6). Metapleurae coarsely punctured, the black transverse line on the 



metanotum joined to the spiracles; apex of the wings smoky; 



body stout collinus. 



6 (5). Metapleurae scarcely punctured, the black transverse line on the 



metanotum not joined to the spiracles; apex of the wings clear 



hyaline ; body slender confirmatus. 



7 (4) . Central black line on the metanotum not dilated at the transverse 



keel ; the black on the second abdominal segment not indented 



in the middle ; metatarsus yellow nigritibialis. 



8 (11) . Tibiae broadly black at the base ; metanotum not broadly black, 



and without a transverse yellow mark through the black. 



9 (10) . A large yellow mark produced on either side at the apex on the base 



o£ the second abdominal segment ; no furrow down the centre of 

 the black longitudinal line on the metanotum; spines on the 



metathorax shortish, thick ; wings hyaline blanditus. 



10 (9) . A small yellow mark, wider than long, at the base of the second 

 abdominal segment, a distinct furrow down the centre of the meta- 

 notum ; wings smoky, especially at the apex ; spines long, acute . guatemalensis. 



