15 



Several varieties or races of Glossina morsitans, Westw., have been 



described. " Relying chiefly on certain differences in the internal 



genital appendages of the male " (Austen), Newstead in 1910 described 



a form which he termed Glossina submorsitans, regarding it "as a 



shccics allied to the true G. morsilans, Westw." Austen, however, 



" after making a minute external examination of .... typical 



and other specimens of G. morsitans, Westw., .... from many 



different localities in Africa, and comparing with them the types of 



the supposed new species .... " considers that " it is impossible 



I to regard G. submorsitans, Newst., as specifically distinct from G. 



morsitans, Westw., and that it is in reality nothing more than a form 



or race of the latter." Austen adds that " G. morsitans is the most 



j widely distributed of all the Tsetse-flies, and it is, therefore, not 



j surprising to find that even morphological characters are not absolutely 



I identical in the case of specimens from localities situated at the opposite 



i extremities of its area, and separated from one another by some 



thousands of miles." ' The form submorsitans," continues Austen, 



| " has hitherto been found in West Africa and the Anglo-Egyptian 



i Sudan, and it is of course possible that, e.g., a male from Northern 



| Nigeria belonging to this form might be incapable of mating with 



a female of the typical race of G. morsitans from the Bechuanaland 



I Protectorate. Still, if the area of G. morsitans could be traversed 



from end to end, . . . . it is not unreasonable to suppose that 



it would be found that the form submorsitans constitutes, as it were, 



one end of a chain of groups of interbreeding Tsetse-flies, of which the 



other extremity would be represented by typical Glossina morsitans, 



Westw." 1 



Mention may also be made of two varieties of G. morsitans found by 

 Dr. J. O. Shircore among some hundreds of typical representatives 

 of the species collected in the Dowa district, Nyasaland, and described 

 by him (138) under the names G. morsitans, Westw., var. pallida, 

 and G. morsitans, Westw., var. par ado xa. 



The question of the races or varieties of G. morsitans is perhaps an 

 indication that there is still work to be done before the limits of species 

 within the genus Glossina can be regarded as finally established. 



Glossina pallidipes, Austen (Plate II, Fig, 2). The author of this 

 species summarizes its distinctive characters as follows : " Medium- 

 sized or rather large species, closely resembling the West African 

 G. longipalpis, Wied., but distinguishable owing to the coloration of 

 the last two joints of the front and middle tarsi. Front in <$ very 

 narrow ; dorsum of thorax olive-grey, smoke-grey, or drab-grey, with 

 the usual dark brown, longitudinal markings generally much reduced, 

 broken up, and but little conspicuous ; abdomen buff, dorsum with 

 dark brown or clove-brown bands . . . , ; legs buff, last two 

 joints of hind tarsi clove-brown, front and middle tarsi either entirely 

 pale or, at most, last two joints of front tarsi faintly brownish at the 

 tips, and last joint and distal half of penultimate joint of middle tarsi 

 light brown never so dark as to form a sharp contrast with the 

 remaining joints." 



" The area of distribution of G. paUidipes, which is the eastern 

 representative of the West African G longipalpis, Wied., includes the 

 south-eastern and eastern portions of the African continent, and extends 



1 All West African specimens of Glossina morsitans really belong to the form 

 submorsitans, though it is only by examining the male genital appendages that the 

 latter can be distinguished from the typical race. 



