Subfamily Megapodinae 



The group of curious flies to which Megapoda Mac- 

 quart and its allies belong is regarded as a subfamily. 

 All the members of the group are distinguished by the 

 closed marginal cell, except Senobasis Macquart, and 

 by the strongly developed and elongate protuberance 

 on the anterior tibia, to which is attached a stout spine 

 with accompanying, extensive flange on the basitarsus. 

 Moreover, they are characterized by the exceptionally 

 elongate proboscis and the long, one-segmented palpus. 

 The palpus reminds one of the type of palpus found in 

 Phellus Walker and its allies, except that in those 

 genera there are two segments. The third antennal seg- 

 ment is stout and at its apex bears a prominent pit with 

 a spine that is usually visible. These flies have a slow, 

 lumbering flight and elongate legs; they tend to have 

 a drooping head and abdomen and usually hang them- 

 selves from stems and leaves of rank grass and 

 vegetation. 



In the female the ovipositor is formed by a broad, 

 triangular, platelike, convex, eighth tergite and an in- 

 completely divided ninth tergite without any spines. 

 Apposed to this structure below are the corresponding 

 sternites. The entire structure forms a shovellike, 

 semitubular apparatus. In the males the terminalia 

 are large, bulblike, extended chiefly posteriorward with 

 the ninth tergite forming a broad, convex, elongate, un- 



divided, shovellike structure, free but tightly fitting 

 against the large, lateral processes to which it is not 

 fused. The eighth tergite is very short, nearly con- 

 cealed and the terminalia are rotate 180 degrees. Al- 

 though Senobasis Macquart differs rather strongly in 

 appearance from the other members of the group, it 

 agrees in the long, tibial process, the type of proboscis 

 and the quite similar palpus and antenna. The vena- 

 tion, except for the open marginal cell, is similar. This 

 genus is the largest within the group in number of 

 species. 



These flies are entirely confined to the Neotropical 

 region, ranging as far north as the valley of Tepotzlan 

 immediately south of Mexico City, where I have ob- 

 served the flies of Pseudoryclus Camera. They ex- 

 tend southward to northern Chile. 



Pronomopsis Hermann is found in the Andean re- 

 gions at high altitudes, and in northern Chile, Bolivia 

 and Peru. Senobasis Macquart has a wide distribution 

 in South America. Pseudoryclus Carrera ranges from 

 Peru and the Amazon basin to Mexico. Megapoda 

 Macquart comes from the forested Atlantic region south 

 of Matto Grosso and west of Amazonas state. Pseu- 

 dorus Walker is limited to the equatorial region and 

 Doryelus Jaennicke is found in almost the whole of the 

 Neotropical region. 



KEY TO GENERA OF MEGAPODINAE 



1. Marginal cell open; male ninth tergite with a pair of apical 



processes ; lateral process forceps-like. Female terminalia 

 short. Face plane ; its height reduced, lower part extended 

 forward. Fourth posterior cell closed and stalked. 



Senobasis Macquart 

 Marginal cell closed and petiolate 2 



2. Face moderately produced, concave or at least with a supra- 



epistomal lip or ridge; face apilose and niystax confined to 

 a few epistomal bristles ; occiput largely or wholly reduced 

 by posterior development of eye; fourth posterior cell 



closed or open 3 



Face strongly produced, slightly convex, and forming a sharp, 

 overhanging beak or hood above epistoma ; more than 

 ventral half of face densely covered with bristly pile ; lat- 

 eral occiput strongly developed and prominent above and 

 below ; fourth posterior cell closed with a long stalk. 



Pronomopsis Hermann 



3. Face strongly concave beneath antenna ; its height reduced ; 



third antennal segment large, thick, greatly expanded dor- 



sally and ventrally ; fourth posterior cell narrowly open 



or closed with a short petiole 4 



Face without concavity, supraepistomal margin transversely 

 ridged. Third antennal segment elongate, 2 or 3 times as 

 long as wide. Legs elongate ; femora and tibiae long, 

 especially posterior pair. Large, elongate, often blue-black 

 flies ; fourth posterior cell closed with a long petiole. 



Megapoda Macquart 



4. Mesonotum strongly humped and swollen and projecting an- 



teriorly ; sometimes overlapping head. Posterior tibia and 



tarsus not dilated Pseudorus Walker 



Mesonotum normal. Flies with drooping head and 

 abdomen 5 



5. Apical part of posterior tibia and posterior basitarsus thick- 



ended and clothed with bristly pile or setae. 



Doryclus Jaennicke 

 Posterior tibia and basitarsus not swollen ; pile normal. 



Pseudoryclus Carrera 



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