154 THE CANADIAN ENTOMOLOGIST 



NORTH AMERICAN SARCOPHAGID^: FLIES OF GENUS METOPO- 



SARCOPHAGA TOWNSEND.* 



BY R. R. PARKER, BOZEMAN, MONT. 



The writer described the species Sarcophaga pachyprocta in 1916 (Jour. 

 N. Y. Ent. Soc, vol. 24, pp. 171-175). In connection with the description it 

 was noted that the species was considered to represent a form separable from 

 Sarcophaga and possibly should be placed in a distinct genus, but the writer 

 refrained from so doing till it was possible to examine other closely related 

 species. In 1917, however, Townsend made this species the genotype of Metopo- 

 sarcophaga (Proc. Biol. Soc. Wash., vol. 30, pp. 46) but mentioned no other 

 species as belonging to the genus. In the same paper. (p. 43) Sarcophaga incurva 

 Aldrich was made the genotype of Thelyleptococnema. It is the writer's opinion, 

 •however, that the two species are congeneric and Metoposarcophaga is hereby 

 designated as the name of the genus. M. tothilli and M. pachyproctosa, new 

 species of the genus, are described in this paper. 



The following characters are common to the males of all four species: — 

 parafrontals and gense silvery grey; front broad, very prominent in profile; 

 vestiture of back of head black or with some light coloured hair close to foramen 

 (in pachyprocta) ; lateral verticals present, greater ocellars as strong or stronger 

 than uppermost pair of frontals; frontal bristles not numerous (six to seven, 

 sometimes eight or nine) ; epaulet dark ; anterior acrostichals well developed ; 

 scutellar apicals absent or weak and hair-like; lower sternopleura with bristles 

 only; vestiture of nota of short reclinate bristles that become longer and more 

 slender ventrally; vestiture of fourth ventral plate erect; posterior surface of 

 anterior tibia with two bristles about one-third from distal end (only one in 

 Sarcophaga and Ravinia) ; first genital segment much larger than second and 

 its vestiture longer; marginal bristles absent; forceps slender, bent so that prongs 

 are at a pronounced angle to the base; accessory plate at side of forceps (not 

 anterior to them as in Ravinia, etc.), erect and hiding at least part of base of 

 forceps (in tothilli and incurva only tip of forceps visible from side) ; claspers on 

 each side united basally (not separate as in Ravinia, etc.) ; posterior clasper 

 with variously shaped expanded base with bristle at upper anterior angle, 

 distally with a curved hook. 



The genus quite naturally divides into two groups, the pachyprocta group, 

 containing pachyprocta and pachyproctosa, and the incurva group containing 

 incurva and tothilli. 



The pachyprocta group is distinguished by the following characters: — • 

 three pairs posterior dorsocentrals; scutellar apicals absent; first vein bristly; 

 costal spine present; posterior tibiae of normal length; ventrally sides of fourth 

 notum with marginal bristles only; profile of genital segments as in Fig. 1; first 

 genital segment grey pollinose. The penes and claspers very similar but net 

 alike, forceps essentially the same. 



Characters of incurva group: — four pairs posterior dorsocentrals (some- 

 times five); scutellar apicals, if present, weak and hair-like; only third vein 

 bristly; costal spine vestigial; posterior tibia much shorter than femur or tarsus; 

 ventrallv sides of fourth notum clothed with long, slender bristles; profile of 



*Contribution from the Entomological Laboratory of the Montana State College, Bozeman, 

 Mont. 



June, 1919 



