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UNITED STATES NATIONAL MUSEUM BULLETIN 224 



Genus Prolepsis Walker 



Figures 187, 459, 919, 928, 1763, 1766, 1947 



Prolepsis Walker, Inseeta saundersiana, vol. 1, pt. 2, p. 101, 

 1851. Type of genus : Dasypogon lucifer Wiedemann, 182S, 

 as Prolepsis fumiflamma Walker, 1851, by inonotypy. 



Cacodaemun Schiner, Verh. zool-bot. Ges. Wein, vol. 16, p. 

 671. 1866. Type of genus : Dasypogon lucifer Wiedemann, 

 1828, original designation. Preoccupied by Thomas in 

 Coleoptera, 1857. 



Cacodaemonides Strand, Arch. Naturgesch. Berlin, vol. 92, pt. 

 8, p. 48, 1928. Unnecessary change of name. 



Medium size, stout, robust flies with broad wings, 

 mostly blackish in the males and the wings orange 

 brown in the females. Related to Disonias Loew, they 

 are quickly recognizable through the presence of several 

 extra cross veins in the subcostal cell and the remark- 

 able multispinous armature of the middle femur. This 

 latter character allies Prolepsis to the Cuban Sphageus 

 Loew. Splwgeus resembles Dizonias because they are 

 more slender and have a more slender third antennal 

 segment. The extra cross veins, however, separate 

 them from all allied genera, and they are unique among 

 the asilids. Length 15 to 20 mm. 



Head, lateral aspect: The head is unusually long, 

 the face moderately prominent, of reduced height be- 

 cause of the large, oblique subepistoma and the short, 

 concave depression immediately below the antenna. 

 For the most part the face is nearly plane, or barely 

 convex. The occiput is poorly developed, but a little 

 more prominent ventrally and medially. The eye is 

 gently recessive below. The pile of the occiput is fine 

 though bristly in character on the lower half and with 

 only weak bristles dorsalty. There is a patch of 6 

 slender bristles on each side behind the occiput. The 

 proboscis is considerably longer than the face, atten- 

 uate beginning at the middle, so that the apex is nar- 

 row and the whole is directed forward or slightly 

 upward. Palpus of two segments, the first segment 

 hemicylindrical and excavated, the second elongate, 

 slender with apical pore and with no bristles at the 

 apex. There appears to be a trace of an antepenulti- 

 mate segment present. The antenna is attached at the 

 upper fifth of the head and unusually long and con- 

 spicuous. The first segment is twice as long as the 

 second ; each bears a few, fine bristles below and setae in 

 the middle of the segments dorsally. The third seg- 

 ment is nearly three times the combined length of the 

 first two, gently widened towards the middle so that it 

 is considerably wider at this point, and bearing apically 

 a short micro-segment, obliquely truncate, with small 

 enclosed spine. The antenna in the females is bright 

 orange, in the males black. 



Head, anterior aspect: The head is nearly twice as 

 wide as high, the face at plane of antenna one-fifth 

 the head width and slightly divergent below. The face 

 is pubescent only on a narrow band beneath the antenna 

 and on the anterior margin of the cheeks. Pile is 

 absent but, except for a transverse pubescent area be- 

 neath the antenna, the whole face is densely covered 



with long, stout bristles and some shorter, bristly hairs 

 or slender bristles. The front is a little wider than 

 the face, the vertex not narrowed. Front pollinose 

 laterally and anteriorly, with a band of long, slender 

 or bristly hair along the eye margin. Vertex almost 

 without excavation, the ocellarium broad and low with 

 7 pairs of slender bristles and bristly hairs. 



Thorax: The mesonotuni is low and gently convex; 

 it is dully shining with some triangular, pale pollinose 

 spots and rather scanty, scattered, fine, nearly erect, 

 bristly pile. Acrostical bristles are developed as a 

 single or double row. Dorsocentral bristles, however, 

 are developed only opposite the postalar region, where 

 there are 4 rows, each containing 3 or 4 elements, none 

 of them very long. Humerus with numerous, quite 

 slender bristles and a little bristly pile. The lateral 

 complement contains stout bristles of moderate length ; 

 it consists of 4 notopleural in an oblique row, 3 or 4 

 shorter and weaker supraalar, 1 long and 2 or 3 short 

 postalar, and 2 pairs of seutellar bristles. The scutel- 

 lum is moderately thick and convex, the base not flat- 

 tened, the disc bearing a few stiff hairs. Pronotal 

 collar with only a wide band of numerous, fine, long 

 hairs. Posterior mesopleuron and upper sternopleuron, 

 whole middle and upper margin of the pteropleuron 

 and the posthypopleuron with considerable stiff pile. 

 Metapleuron with a wide, vertical band containing 

 numerous, long, bristly hairs. Metanotal callosity 

 pollinose only; postmetacoxal area membranous. The 

 presternum is dissociated. 



Legs: The hind femur and tibia are considerably 

 elongate in contrast to the shortened middle pair which 

 are shorter than the anterior pair. Hind tibia rela- 

 tively slender; hind femur a little narrowed towards 

 the base. Middle femur greatly swollen, especially to- 

 wards the base and middle, and with a characteristic, 

 dense patch of spikelike bristles. On the remainder 

 of the legs the bristles are more or less reduced, though 

 stout. The pile of the legs is coarse, appressed, and 

 setate, the anterior and posterior femora with some 

 erect, fine, ventral and ventromedial pile. The hind 

 femur bears 3 or 4 lateral bristles on the basal half, 

 6 ventrolateral, 5 ventromedial bristles, a medial distal 

 bristle, at the subapex 1 bristle dorsolaterally, at the 

 apex only 1 or 2 very weak bristles. Hind tibia bears 

 the following short bristles : 5 dorsolateral, 4 dorsomed- 

 ial, and 1 ventrolateral. The middle femur anteriorly 

 on the basal two-thirds has a dense patch containing 

 30 or 40 spikelike bristles; the more ventral elements 

 near the middle of the femur are longer, and also con- 

 tinued ventrally on the base to include 20 or 30 addi- 

 tional, short, spikelike bristlas. The middle tibia 

 contains a dorsal row of 5 or 6 slender bristles. Ante- 

 rior femur with 7 or 8 short, slender bristles poster- 

 odorsally and considerable other bristly hairs and 

 anterodorsally towards the base a few short bristles. 

 Anterior tibia with only poorly differentiated dorsal 

 bristles; there are 6 posterodorsal bristles which are 

 longer than the 8 or 10 anterdorsal bristles ; posteriorly 



