1937 ] 
Exotic Syrphid Flies 
21 
Islands, Sept. 12 (C. S. Clagg). Type in the Museum of 
Comparative Zoology. 
Hypselosyrphus n. gen. 
Plate II, fig. 9. 
Small flies, related to Microdon with the weak and flat- 
tened abdomen somewhat longer than broad. Face round 
convex, with the vertex produced into a curved jutting knob. 
Scutellum sulcate, tumid, angularly directed upward. Hind 
basitarsi and forebasitarsi swollen. Hind tibiae convex, with 
a swollen ornament suggesting a load of pollen, heavily 
pilose. Hind femora not greatly thickened. No trace of 
spur from third vein is directed into the first posterior cell. 
Terminal (bent up) portions of fourth and fifth longitudinal 
veins, that is, subapical and posterior cross veins, nearly 
straight, bulging at their basal corners and making angles 
of approximately seventy-five to eighty degrees with the 
veins they join. 
Genotype: Hypselosyrphus trigonus n. sp. 
This fly suggests very strongly a trigonid bee, as do the 
species of Ubristes of the Microdontini. Microdon scutellaris 
Shannon, described from the Amazon, seems to fall into 
Hypselosyrphus , but differing in the differently colored 
abdomen. 
Hypselosyrphus trigonus n. sp. 
Plate II, fig. 9. 
Male. Front enormously swollen as a shining knob, the 
ocelli on top. Front excavated, flat, leaving a considerable 
concavity in profile. Face in profile convex, evenly rounded. 
Antennae situated at upper third. First and third joints 
subequal, the latter pointed, second quite short. Arista 
slender, as long as third joint. Color of antennae dark 
brown. Face, front and vertex shining dark mahogany red 
or brown, almost black. 
Thorax very dark brown, almost black, a row of white 
pile across at suture, and on base of scutellum, remainder 
densely erect short black pilose. Pleurae shining dark 
brown, sparsely pilose. Halteres and squamae dark blackish. 
Scutellum dark blackish, prominent, directed upward at an 
