Tune, 1921.1 P,ari!kr: Rkvisiox OF Gknl's Ligyrocoris Stai.. 101 



and Pamcra constricta Say. tlio last named in error. Plociowcnis 

 diffikius Ulil. and Pamcra coiitracta Say were placed as synonyms of 

 sylz'cstris L. which arrangement was accepted hy Uhlcr, until 1908, 

 when \'an Duzee^ properly separated difftisus as distinct, L. contracta 

 is also considered as distinct from the Pal.earctic sylvcstris by Van 

 Duzee. As discussed later I cannot concur in this opinion. Since 

 Stal's time the genus has increased somewhat in size hy the addition 

 of new species and the transference of others. 



The genus Ligyrocoris is rather widespread, represented in th'.' 

 Palxarctic faunal realm l)y two species — sylrcstris in northern 

 Europe and .\sia and icri)iiiialis in Japan, while in the present paper 

 twenty species are shown to occur in the Xcarctic-Xeotropical realms. 

 While only five species are known from the Northern United States 

 fifteen species are listed from the Upper and Lower Sonoran fauna! 

 areas of the United States and Mexico. 



Kev to Species. 



1. Head and thorax dull, not shining, most commonly black. Coriuni with 



or without post-nu-dian fascia. Basal segment of antenna short, much 

 shorter than basal segment of rostrum (subgenus Ligyrocoris Stal)...7 

 — . Head and thorax shining, commonly castaneous. Corium with postniedian 

 fascia and preapical pale spot. Basal segment of antenna long, quite 

 or nearly as long as basal segment of rostrum. Males frequently with 

 tibial tooth (Seoligyrocoris n. subg., type, aurivillianus Dist.) 2 



2. Fore tibia of males much curved and armed with a stout median tooth. 



Terminal segment of antenna with or without pale basal ring 3 



— . Fore tibia of males cither straight or curved but unarmed with a median 

 tooth. Terminal segment of antenna not pale ringed at base 5 



3. Terminal segment of antenna pale ringed at base, .\nterior lobe of pro- 



notum longer than wide and two or three times as long as posterior lobe. 



Larger species, over 6 mm. long 4 



— . Terminal segment of antenna not pale ringed at base, .\nterior lobe of 

 pronotum slightly wider than long, short, only a little longer than pos- 

 terior lobe. Tibial tooth nearer apex than base. Smaller species 4 mm. 

 long (Southwest U. S.) nitidicollis Stftl. 



4. .interior lobe of pronotum never more than twice as long and plainly nar- 



rower than posterior lobe. Interocular space narrow, plainly less than 

 twice the diameter of eye. Apex of membrane with a triangular pale 

 spot. Tibial tooth nearer to base than apex. Narrow elongate iTex.'*. 



aurivillianus Dist 

 3 Van Duzee, Canad. F.nt.. XI., no, 1908. 



