44 R- W. CROSSKEY 



- Abdomen without ventral papillae or with small rounded ventrolateral swellings. 



Postgenal cleft usually large and longer than postgenal bridge. The three comb- 

 teeth of mandible regularly decreasing in size or second and third subequal to each 

 other. Pupal gill histoblast not with four filaments . . . . . . 15 



15 Postgenal cleft large pentagonal (Text-fig. 263), broadly sagittate or subcordate, 



much longer than postgenal bridge. Ventral papillae absent .... 16 



- Postgenal cleft small or medium-sized, rounded and shorter than postgenal bridge 



(Text-fig. 264). Last abdominal segment with distinct fold-like swellings in 

 lateroventral position ..... ODAGMIA Enderlein (p. 107) 



16 Cuticle entirely bare. Rectal gills with or without secondary lobules ... 17 



- Cuticle of abdomen posterodorsally with scattered minute deeply divided trifid 



setae. Rectal gills without secondary lobules WILHELMIA Enderlein (p. 94) 



17 Rectal gills with secondary lobules . . . SIMULIUM Latreille s. str. (p. no) 



- Rectal gill lobes simple, without secondary lobules TETIS IMULIUM Rubzov (p. 104) 



SYSTEMATIC TREATMENT OF THE SUBGENERA 



Subgenus BYSSODON Enderlein 



Byssodon Enderlein, 1925 : 209. Type-species : Simulium forbesi Malloch, 1914 [=SimuHum 



meridionale Riley, 1887], by original designation. 

 Psilocnetha Enderlein, 1935 : 359. Type-species : Psilocnetha scapulata Enderlein, 1935 



[=Simulium griseicolle Becker, 1903], by original designation. Syn. n. 

 Titanopteryx Enderlein, 1935 : 360. Type-species : Atractocera maculata Meigen, 1804, by 



original designation. 

 Echino simulium Baranov , 1938 : 317,322. Type-species : Echino simulium echinatum Baranov, 



1938 [= Atractocera maculata Meigen, 1804], by original designation. 

 Gibbinsiellum Rubzov, 1962 : 1494. Type-species : Simulium griseicolle Becker, 1903, by 



original designation. Syn. n. 



Diagnosis, o"? : Basal section of radius bare. Pleural membrane bare. Katepisternum 

 bare. Fore tarsus slender, fore basitarsus about 6-7 times as long as its greatest breadth. $ : 

 cibarium unarmed. Tarsal claws with very large basal tooth (Text-fig. 87). Scutum with in- 

 conspicuous lyrate pattern (of same form as Wilhelmia, Text-fig. 72), in one species with pair of 

 rounded anterior black-brown spots. Abdomen thickly covered with silvery hair or scales, 

 sometimes mainly laterally. Seventh sternite undeveloped or very weak. Gonapophyses 

 simple bluntly truncate lobes. Genital fork with well formed thumb-like anterior process pre- 

 apically on each arm. Paraprocts normal although acuminate ventrally. Spermatheca without 

 polygonal pattern or internal hairs. <$ : scutum largely black but with greyish pollinose margins, 

 seen from in front showing trace of three fine dark lines similar to those of $. Genitalia with 

 large truncate styles subequal in length to or a little shorter than coxites (Text-fig. 154), style 

 with one apical spinule ; coxite not produced beyond base of style ; ventral plate broad lamel- 

 late with short parallel basal arms, haired and without teeth ; median sclerite strap-like or 

 large dilated and bifurcate ; parameres small and narrow or irregular, parameral hooks large and 

 numerous (varied in size). Pupa : Gill of varied form, arborescent (with 22-26 filaments) or 

 bifid or trifid with the branches flattened and lanceolate or subcylindrical or subspherical ; gill 

 much shorter than pupal body. Abdominal onchotaxy normal, sometimes pair of super- 

 numerary hooklets ventrally on segment 4 and with or without minute spinous hooklets dorsally 

 on segment 2 ; dorsum without spine-combs or with a few backwardly-directed spines (not 

 forming a close-set comb) on segment 8 and sometimes also segment 7 ; terminal tubercles rather 

 pointed thorn-like, directed backwards. Cocoon simple or with narrow neck, not fenestrate 

 and without median dorsal projection. Larva : Head and cephalic fans normal (but unusually 



