10 ROBERT NEWSTEAD — A REVISION OF THE TSETSE-PLIES (gLOSSINa), 



Group II.— The Palpalis G-roup. 



To this division belong the following species : — G. palpalis, R.D., G. caliguwa, 

 Aust., G. tacldnoides, VVestw., G. fuscipes, Newst., and G. pallicera. Big. In 

 all of these the superior claspers of the males are connected by a thin and 

 finely spinose membrane which is deeply divided medially, but in all cases 

 the distal extremities of the claspers are quite free and widely separated. 

 In G. palpalis and G. tacldnoides the claspers are identical in structure, 

 though generally those of the latter are relatively smaller ; in both species, 

 also, the distal portion is produced into a single more or less falciform or 

 tooth-like process. The claspers in G. pallicera are suddenly truncated* at 

 the distal extremity, the inner half of which is furnished with minute spines ; 

 furthermore, they are much broader basally than in the other species which 

 are included in this group. 



Group III.— The Morsitans Group. 



This group comprises G. morsitans, Westw., G. suhmoi'sitans, Newst,, G. 

 pallidipes, Aust., and G, longipalpis, Wied. In these the superior claspers are 

 completely united by a spinose membrane and they are also fused medially. 

 That they are of a very remarkable form may be gathered by a glance at the 

 illustrations (figs. 14, 15, 16 and 17), their shape somewhat resembling the 

 scapula of a mammal in miniature, and they are altogether much more highly 

 complicated structures than those in either of the proceeding groups. 



Thus we see, in these three groups, forms which are so widely different as to 

 lead one to assume, without taking the other external features into consideration, 

 that they represent three distinct genera. Certain it is that these insects afford 

 an interesting illustration of the fact that a high degree of diflerentiation in one 

 set of morphological characters is not incompatible with the retention of others 

 apparently of a more ancestral type. 



General characters of the Male Armature.! 



The sexual organs of the males of all the species of the genus Glossina, as 

 has been shown, are strikingly characteristic in form. Externally the hypopygium 

 (fig. 1) is broadly oval in shape and is highly convex, " its longer axis lying in 

 the antero-posterior direction, with a vulviform median groove (the anus) 

 running from the anterior margin to beyond the middle. "J This hypopygium is 

 articulated to the eighth abdominal segment : and when closed (fig. 1) the arma- 

 ture is completely hidden ; the superior claspers (fig. Isc) then lie in a horizontal 

 position with the apices pointing towards the distal portion of the abdomen. If 



* The distal margin may eventually be found to possess a tooth-like process similar to that in 

 other members of this group, but there is no trace of these in the example before me ; further 

 details cannot be given until more material comes to hand. 



t Wesche (Trans. Linn. Soc. Lond. 2nd ser. Zool. IX., 1906, pp. 339-386, pi. 23-30) has dealt 

 with the armature of four species of Glossina, but unfortunately I find myself unable to agree 

 with many of his statements and conclusions. There is also an earlier paper by the same 

 author (Journ. Quek. Micr. Club, 1905, p. 236) dealing exclusively with the genitalia of 



inajMlpali 

 f Austen. Monograph of the Tsetse flies, p. 65. 



