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UNITED STATES NATIONAL MUSEUM BULLETIN 224 



coarse. Ocellar protuberance low, with all the ocelli en- 

 larged. The anterior eye facets enlarged. 



Thorax : The mesonotuni of moderate height, densely 

 pollinose with abundant, short, fine pile, which is un- 

 differentiated. The following complement of bristles 

 present : 1 notopleuron, no supraalar, 1 postalar, and on 

 the scutellar margin 2 or 3 rows of numerous long, 

 bristly hairs of very weak bristles. Pleuron everywhere 

 pollinose with abundant long pile on the propleuron, 

 upper and posterior half of the mesopleuron, postero- 

 dorsal corner of the sternopleuron, and on the meta- 

 pleuron a vertical band of pile and long slender bristles. 

 Squama with a short, fine fringe, lateral slopes of the 

 metasternum without pile, the ventral metasternum 

 widely chitinized and long pilose; postmetacoxal area 

 membranous. Presternum only narrowly dissociated 

 posterolaterally. 



Legs : Femora stout but not swollen, the hind femur 

 bears abundant, short pile, a dorsolateral row of 17 

 bristles and a dorsomedial, apical row of 5 bristles; in- 

 cluded among these is the apical pair of bristles. On 

 the ventral surface are 10 or more long bristly hairs or 

 weak bristles. Middle femur with an anterodorsal, 

 apical row of 5 or 6 bristles. The anterior femur with 

 only long, stiff hairs and fine pile. All the tibiae and 

 tarsi have long, well developed bristles. Posterior tibia 

 with 4 dorsal, 7 anterior, and 4 ventral bristles. Middle 

 tibia with 3 dorsal, bristle-hairs, 4 posterior bristles, 5 

 or 6 anterodorsal, 2 antero ventral and 2 postero ventral 

 bristles. On the anterior tibia are 4 stout bristles, 2 

 posterior and 2 posteroventral, besides other slender 

 bristly hairs. Claws sharp, pulvilli well developed, and 

 the empodium long and flattened. 



Wings: The marginal and all of the posterior cells 

 open ; anal cell closed with a short stalk. Alula nearly 

 absent; ambient vein complete. The second basal cell 

 ends in two veins which are fused for a short distance 

 beyond. 



Abdomen : The abdomen is robust, nearly or quite as 

 wide as the mesonotum and with nearly parallel sides 

 to the end of the sixth segment. Males with eight ter- 

 gites. Females with eight well developed tergites, the 

 eighth as long or longer than the seventh. Female 

 terminalia with 5 pairs of long spatulate obtuse spines. 

 The eighth sternite deeply cleft. Male terminalia simi- 

 lar in most respects to Stichopogon Loew. Gonopod 

 quite short, convex, but not concealed. Eighth sternite 

 divided medially. 



Distribution : Neotropical : Lissoteles hermanni Bezzi 

 (1910) ; vanduzeei Cole (1923). 



Genus Willistonina Back 



Figures 51, 483, 935, 944, 1684, 1985, 2016 



Willistonina Back, Trans, Amer. Ent. Soc., vol. 35, p. 337, 1909. 

 Type of genus: Habromyia MUneata Williston, 1S84, by 

 original designation. 



Flies of medium size, black or greyish in color, with 

 slender tapering abdomen which is distinctly longer 

 than the wing. They are readily recognized by the rela- 



tively narrow face, strongly divergent front, the minute, 

 slender, cylindrical palpus and the large, oval, rather 

 swollen third antennal segment. These are relatively 

 minutely pilose flies and are longer than all other mem- 

 bers of the tribe. The lateral metasternal slopes lack 

 pile. Length 15 mm. 



Head, lateral aspect: The length of the head is a 

 little more than half the height. The face is extremely 

 short, plane with the eyes on the upper third, the whole 

 posterior profile is vertically plane, the lower part 

 prominent only because of the recession of the eye. 

 Eyes narrowed below, moderately recessive anteroven- 

 trally ; one-eighth of the head height is below the eye. 

 The occiput is prominent but slopes strongly towards 

 the middle of the head and away from the eye margin. 

 The occipital pile is scanty, confined to the lower half; 

 bristles begin at the middle of the head and become 

 much stronger and stouter dorsally; 12 pairs are pres- 

 ent. The proboscis is of moderate size, cylindroid, 

 slightly tapered, the apex blunt and bearing a few 

 apical and ventral hairs; there is no basal ventral pile 

 except 2 or 3 hairs in the middle of the ventral lateral 

 margin ; the proboscis is directed obliquely downward. 

 The palpus is small, rather slender, cylindrical, the first 

 segment hemicylindroid, the second porate, a little ta- 

 pered with a single stiff hair at the apex and a few hairs 

 ventrally towards the base. Antenna attached at the 

 upper third of the head, relatively short, the first two 

 segments of nearly equal length ; the third is large, oval, 

 compressed laterally and a little longer than the first 

 two segments combined and bears at its apex at a slight 

 angle a short, conical, microsegment with a minute 

 spine. Pile of first and second segments consists of a 

 few dorsal and ventral apical appressed setae. 



Head, anterior aspect: The width of the head is iy 3 

 times the height. The face below the antenna is one- 

 sixth the head width and divergent below to one-fourth 

 of the width. Subepistomal area prominent, oblique, 

 plane, pubescent and rather long. The face is densely 

 micropubescent, without pile, and with a close-set 

 double row of 10 to 12 paire of stout, downward- 

 directed bristles above the epistomal margin. The front 

 is strongly divergent, rather sunken, pollinose, with 1 

 lateral bristle and 3 or 4 lateral setae; the vertex is 

 moderately excavated with a large, low, ocellar protu- 

 berance. The ocelli are large and there are 2 pairs of 

 anteriorly directed bristles near the posterior ocelli. 

 Central eye facets are very strongly enlarged. 



Thorax: The thorax is pollinose, the mesonotal 

 height is three-fourths of its length. Pile of mesonotum 

 is short, scanty, subappressed and setate with an irregu- 

 lar acrostical row of bristles, very poorly differentiated ; 

 dorsocentral bristles become stout posteriorly where 

 there are 4 pairs, 1 pair especially long. The following 

 long, lateral, stout bristles are present: 3 notopleuron, 

 2 supraalar, 2 postalar, and 2 pairs on the scutellum. 

 Basal half of the scutellum is flat, the whole pollinose, 

 apilose, the humerus with a few short hairs only. Pro- 

 pleuron with a tuft of long, stiff pile, the collar with 

 4 pairs of quite stout bristles. The posterior pronotum 



