MEOAPODINAE 



ROBBER FLIES OF THE WORLD 



421 



Genus Senobasis Macquart 



Figures 245, 675, 1276, 1286, 2107, 2131, 2165 



Senobasis Macquart, Dipteres exotiques, vol. 1, pt. 2, p. 52, 1838. 

 Type of genus: Senobasis analis Macquart, 1838. Desig- 

 nated by Bromley, 1934, the first of two species. 



Stenobasis Agassiz, Nomenclator zoologicus . . ., Index, p. 338, 

 1846. Emendation. 



Astylium Rondani, Nuovi Annali Sci. Nat. Inst. Bologna, ser. 

 3, vol. 2, p. 185, 1850. Type of genus: Astylium claviger 

 Rondani, 1850, by montypy. 



Lochites Schiner, Verh. zool.-bot. Ges. Wien, vol. 16, p. 671, 1866. 

 Type of genus: Dasypogon ornatus Wiedemann, 1819, by 

 original designation. Preoccupied Hymenoptera, 1S57, and 

 Aves, 1859. 



Astylum Kertfsz, Catalogus dipteroruni . . ., vol. 4, p 83 

 1909. Emendation. 



Stenobasis Kertesz, Catalogus dipterorum . . ., vol. 4, p. 123, 

 1909. Emendation. 



Loohitomyia Brethes, Rev. Chilena Hist. Nat, Santiago, vol. 28, 

 p. 105, 1925. Unnecessary change of name. 



Large flies which can be readily identified from the 

 clavate antenna, the very prominent protibial spur and 

 spine, and the basitarsal flange, associated at the same 

 time with a 1-segmented palpus and the open marginal 

 cell. It is a distinctive Neotropical genus, with elon- 

 gate, sometimes slightly clavate abdomen. Length 15 

 to 25 mm. 



Head, lateral aspect: The head is comparatively 

 short, the face short above, becoming gradually longer 

 below; the occiput is scarcely visible in profile and 

 only over the middle and lower portion. The lateral 

 occipital margin is slightly concave, and the pile begins 

 well away from the eye margin and covers the entire 

 remainder and consists of numerous, long, slender, 

 bristly hairs. At the upper eye corners and behind 

 the occiput on each side are 1 or 2 slender bristles. 

 The proboscis is elongate, laterally compressed, bluntly 

 pointed, with a prominent, dorsal carina arising 

 abruptly at the basal f ourth and continuing beyond the 

 middle. Basal half below with a few fine, long, coarse 

 hairs. Palpus prominent, elongate, subsigmoid, cylin- 

 drical, composed of 1 segment and perhaps with a trace 

 of a basal segment ; it bears on all sides, except medially 

 on the basal half, numerous, long, bristly hairs which 

 become stouter at the apex. The antenna attached at 

 the upper third of the head and approximately as long 

 as the head; the first and second segments are stout 

 and subequal, and together not quite as long as the third. 

 They bear a few, long, stout bristles ventrally and 1 or 

 2 dorsally on the second segment and both with some 

 shorter bristly hairs. The third segment is strongly 

 attenuate on the basal half, clubbed apically, with an 

 apical pit and more or less concealed spine. 



Head, anterior aspect: The head is wide and flat- 

 tened anteriorly with greatly enlarged facets ; the face 

 at antenna is about a fifth the head width, its sides 

 nearly parallel; the face cover consists of pubescence 

 with fine, scanty, scattered, long, bristly hairs more or 

 less confined to the lower half, and with 2 or 3 pairs of 

 long, quite stout bristles above the epistoma and concen- 



Text-Figure 28. — Pattern of distribution of the genus Senobasis 

 Macquart. 



trated near the middle. The lower face tends to be a 

 little compressed and slightly beaklike. Subepistomal 

 area large, conspicuous, polished, and oblique. The 

 front is flattened and pollinose, with on the middle of 

 each half a tuft of long, bristly hairs. Upper front 

 slightly divergent ; the vertex is slightly convergent, the 

 vertex moderately excavated; the ocellarium is low ami 

 broad with 3 or 4 pairs of short, weak bristles behind 

 the ocelli. 



Thorax : The thorax is long and rather low but with 

 the anterior edge high and abrupt. Mesonotum dull, 

 with lateral and vittate pollinose areas and broadly bare 

 over the middle, except for a patch of scattered, bristly 

 pile medial to the humerus and continued as a row of 

 slender, dorsocentral bristles the entire length of the 

 thorax, each row sometimes doubled posteriorly. 

 Acrostical elements appear to be absent. Humerus with 

 bristly pile. The lateral complement of stout bristles 

 consists of 1 notopleural, 2 or 3 supraalar, 2 postalar, 

 and no scutellar bristles. Scutellum thick, flattened, 

 pollinose, generally apilose. The whole pleuron is 

 pollinose, with fine, abundant pile on the propleuron, 

 a few scattered hairs on the posterior mesopleuron, 

 upper sternopleuron, more numerous on the hypopleu- 

 ron and the metapleuron with a scattered vertical band 



