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UNITED STATES NATIONAL MUSEUM BULLETIN 224 



onotum. The face is concave. Protibia with spine. 

 Length 8 to 12 mm. 



Head, anterior aspect : The head is nearly two times 

 as wide as high; the face is about a fourth the head 

 width, barely wider below with large, bare, polished, 

 central areas; is has fine, pale pubescence laterally and 

 generally has only a few, scattered hairs on the ventral 

 half and the mystax consists of 3 or 4 slender, or stout, 

 pale bristles which extend beyond the proboscis. 

 Epistoma small. Front short, wide, wider than the 

 upper face, polished and bare, with 2 or 3 submedial 

 hairs and a threadlike line of pubescence along the eye. 

 The vertex is wider ; the ocellarium large, though rather 

 low and bears large ocelli and 3 or 4 pairs of slender 

 bristles, some of them behind the ocelli. Vertex only 

 moderately excavated. 



Head, lateral aspect : The head is small, the face of 

 reduced height, and strongly concave across the middle, 

 being a little produced forward dorsally and ventrally 

 as in Brachyrrhopala. The occiput is of only moderate 

 extent with scattered, quite fine hairs below. Slender 

 bristles that begin in the middle become stouter dorsally 

 and are situated in 1 deeply placed row, with only 2 

 bristles behind the wide vertex. Proboscis short but 

 extended well beyond the face; it is rather attenuate 

 from the base to a blunt point and bears a dorsal ridge ; 

 it is very little compressed ; pile as in Brachyrrhopala. 

 Palpus of two segments, the first short, excavated, the 

 second not very long, somewhat clavate with apical 

 pore and a few bristly hairs. The antenna is attached 

 at the upper third of the head and is as long as the 

 head or slightly longer. The first two segments are 

 short, of equal length, and barely longer than wide. 

 Third segment scarcely wider than the second, of nearly 

 uniform width and a little compressed; the apex is 

 blunt, with a minute spine rather hidden by pubescence. 



Thorax : The thorax is large and exceptionally high, 

 the prothorax quite short and small. Mesonotum 

 greatly elevated, convexly arched, dull but bare, with 

 quite scattered, fine, erect hairs laterally, a prominent 

 acrostical row and dorsocentral rows of fine bristles, 

 the latter becomes longer but not stouter behind. 

 Lateral bristles are slender and consist of 1 notopleural, 

 2 supraalar, 1 on the postalar callosity, and 1 pair on 

 the scutellum with additional fine, shorter, stiffened 

 hairs. Scutellar disc with faint, transverse grooves. 

 Metanotum high without pile or bristles laterally. 

 Pleuron largely bare with a few fine hairs posteriorly 

 on the mesopleuron and sternopleuron. The hypopleu- 

 ron and lateral metasternum and the anterior coxae 

 curiously are covered with silver micropubescence. 

 Pronotum with stiff hairs only. Metapleuron with a 

 wide band of long, stiff hairs. Halteres exceptionally 

 large distally. Postmetacoxal area membranous ; pres- 

 ternum fully dissociated. Almost all the mesonotum 

 and most of the pleuron are light brick red or orange, 

 colors which, with the blackish wings, imitate the 



pattern of Macrocolus Engel and the bibionid Plecia 

 AViedemann. 



Legs : The legs are polished, shining black with very 

 sparse, scanty, fine hairs. The bristles are basally stout 

 but become very fine and sharp at apex. The hind legs 

 are elongate but slender, the hind femur is barely 

 wider distally. The slender, hind tibia is equally long, 

 is rather strongly dilated near the apex with the tarsi 

 all slender. Hind femur with 3 lateral bristles and at 

 the apex 1 dorsolateral and 2 dorsomedial bristles. 

 Tibia with 4 dorsolateral, 3 dorsomedial, and 3 ventro- 

 lateral bristles; apex with 4 bristles. Middle femur 

 with a bristly hair at the apex posterodorsally and with 

 4 anterodorsal bristles, 3 of which are quite long, 4 

 posterodorsal bristles, all short and 2 long, spikelike, 

 ventral bristles at the middle and beyond. Anterior 

 femur without bristles; tibia with 1 minute antero- 

 dorsal bristle at the base, 3 posterodorsal, 3 postero- 

 ventral bristles, and 1 long, distal ventral bristle. Apex 

 with a ventromedial, short process and straight spine 

 apposed against a small basitarsal swelling with denti- 

 cles. Ventral surface of these tarsi with dense, fine, 

 erect pile. Claws slender, sharp, pulvilli large, em- 

 podium short, strongly swollen at the base. 



Wings : The wings are dark bluish or purplish black 

 or brown, and broad. Marginal cell very widely open, 

 all posterior cells widely open. Anal cell open. Alula 

 moderately wide; ambient vein complete. "Wing 

 densely villose. The anterior crossvein enters the discal 

 cell at the middle. The posterior crossvein is well 

 developed. 



Abdomen : The abdomen at the base is not quite as 

 wide as the mesonotum. The abdomen is slightly 

 widened to the end of the fourth segment so that it is 

 subclavate but not at all conspicuously club-shaped 

 as in Brachyrrhopala. It is shining blackish and it is 

 covered with fine, scanty, subappressed hairs and some 

 pubescence on the posterior margin. First segment 

 with only bristly hairs; sides of the second with some 

 long, fine hairs. Males with seven segments, the seventh 

 quite short and the eighth concealed. Females with 

 eight segments, both the seventh and eighth short ; the 

 male terminalia are moderately large, rotate, largely 

 extruded with short, wide, simple epandium and large, 

 medially grooved, depressed, obtuse proctiger. It has a 

 very short hypandrium, rather large gonopod, and com- 

 pletely exposed genital cavity with large penis guides. 

 Females with the posterior part of the abdomen and 

 terminalia rather high; the eighth segment is some- 

 what bluntly tucked in, largely concealing the recessed 

 acanthophorites and their minute spines, which con- 

 sist of about 10 pairs on each side, short and blunt. 

 Eighth sternite protrusive, and rather trougldike. 



Distribution: Australian: Cabaza glabrata Walker 

 (1S61); honesta Walker (1859); pulchella Macquart 

 (1846), pulchella mifithorax Walker (1851); rubri- 

 thorax Macquart (1849) [ = venno Walker (1849)]. 



