174 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 105 



Range: Mexico (Guerrero), "Nicaragua, Costa Rica, Brazil (Santa 

 Catarina) . 



Material examined: Mexico: Chilpancingo, Guerrero, 4,600 ft., 

 June, H. H. Smith, 1 (male, wrong abdomen, BM). Nicaragua: San 

 Marcos, Baker, 1 female (USNM, cotype of pallifrons). 



Physoconops (Aconops) costatus (Fabricius) 



Conops costatus Fabricius, Systema antliatorum, p. 175, 1805. 



Information on the type kindly supplied b}^ S. L. Tuxen enables the 

 identification of this species for the first time since originally described. 



Range: Colombia, Brazil (Bahia). 



Material examined: Brazil: Bahia, June 10, 1929, R. C. Shannon, 

 1 male (USNM). Colombia: Rio Frio, Magdalena, Aug. 21, 1927, 

 G. Salt, 1 male (AMNH). 



Physoconops (Aconops) cntennatiis (Krober) 



Conops antennatus Krober, Arch. Naturg., vol. 81, Abt. a. Heft 5, p. 150, 1915. 

 Aconops syrphoides Blanchard, Anal. Soc. Cient. Argentina, vol. 126, p. 351, 1938. 



The front of this species is rather variable, the dark pattern being 

 reddish, black, or both. Unlike longistylus and costatus, the cheeks 

 are black. 



Range: Brazil (Bahia), Argentina (Mendoza). 



Material examined: Argentina: Mendoza, 1 male, 1 female 

 (USNM). Brazil: Bahia, May, R. C. Shannon, 1 male (USNM). 



Gyroconops, new subgenus 



This subgenus is immediately recognized by the large vertical 

 swelling extending halfway from the occiput to the base of the 

 antennae. It is covered with many short hairs, as is the dorsum of 

 the thorax. The length of the head is greater in propoiiion to the 

 height, and the base of the abdomen is wider than in other Physoconops. 

 The propleural ridge frequently has more than one bristle. 



Type: Physoconops sylvosus (Wiliiston). 



Remarks: This group was recognized as distinct by Shannon, and 

 the name used is taken from his manuscript labels. 



Physoconops (Gyroconops) abbreviatus, new species 



Description: Male: Length 6 mm. Front black. Face and cheeks 

 yellow. Oral keel black. Orbitals while pollinose. Antennae black, 

 yellowish proximally on segment 3 and distaUy on segment 2. 

 Segment 2 twice length of segment 1. Segment 3 slightl}^ longer than 

 segment 2. Proboscis black, yellowish distally, 1)2 times head height. 

 Thorax black, faint white pollinose with indistinct pleural stripe. 



