162 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 105 



Physoconops (Pachydbnops) shannoni, new species 



Description: Male: Length lOK mm. Front and vertex brownish 

 yellow. A small spot above base of antennae and center of ocellar 

 swelling black. Face and cheeks yellow, the orbital margin slightly 

 poUinose. Antennae dark brown. Segment 2 about twice the length 

 of segment 1. Segment 3 IK times segment 1. Arista 3-segmented, 

 the second segment slightly produced ventraUy. Proboscis dark 

 brown, nearly twice the length of the head. Occiput more yellowish 

 at vertex. Posterior orbital stripe white pollinose. Thorax blackish 

 brown. Humeri slightly reddish, the dorsum covered with fine golden 

 pollen. A very distinct gold pollinose stripe origmating medial of 

 the humeri, extending posteriorly behind the humeri and connected 

 with a distinct gold pollinose pleural stripe extending to the middle 

 coxae. Pronotum and metanotum dorsally and laterally gold pol- 

 linose. Legs dark brownish, the coxae and tibiae partly yellow pol- 

 linose. Basal third of tibiae, basal tarsi, base of the claws, and pulvilli 

 yellow. Wings with brownish dark pattern extending to the third 

 vein, paler at the costa. Slight dark clouding along vena spuria and 

 fifth vein. Calypters yellow; halters yellow, brownish at the base 

 and tip. Abdomen black, brownish on segments 2 and 3 and genitalia. 

 Yellow at distal margin of segment 2. Golden pollinose at distal 

 margins of all the segments and covering most of segment 6. 



Female: Length 9 J^ mm. Similar to the male. Antennal segments 

 2 and 3 nearly equal. The wing more hyaline. Pollinose posterior 

 margins of abdominal segments less distinct and absent on the ter- 

 minal segments. Theca relatively small. 



Variation (in paratype) : Tip of abdomen missing. Similar to male, 

 but base of antennal segment 3 reddish. Black of front more extensive. 



Types: Holotype, male (USNM 62424); allotype, Maracaju, Mato 

 Grosso, Brazil, May, 1937, R. C. Shannon. Paratype: Same data. 



Remarks: One more specimen referred here provisionally, from 

 Argentina (Tucuman), differs in having the front entirely dark red- 

 dish with the black spot limited to the swelling at the origin of the 

 antennae. The humeri are more reddish in greater contrast with 

 the black of the thorax. Length 10 mm. 



This species is related to pictifrons, and with it differing from all 

 the other members of the subgenus in having the first posterior cell 

 hyaline. In addition to having less black on the front, this species 

 differs from pictifrons in the absence of any black on the oral keel. 



Physoconops {Pachyconops) pictifrons (Krober) 



Conops pictifrons Krober, Arch. Naturg., vol. 81, Abt. a, Heft 5, p. 133, 1915. 

 Range: Mexico to Panamd. 



