THYRIDIDAE OF AFRICA AND ITS ISLANDS 23 



One is known only from the damaged holotype specimen and may be allied to a 

 widespread African species. Two species are striking endemic developments of the 

 very widespread species, Banisia myrsusalis. These are obviously very closely 

 allied to myrsusalis but show differentiation quite unlike any developments of 

 myrsusalis anywhere else over its wide distribution. One species occurs on 

 Madagascar and the other, undescribed, species is part of a complex from the South 

 African and Mascarene areas (p. 98). 



SPECIES IN THE ETHIOPIAN REGION IN RELATION 

 TO OTHER FAUNAL REGIONS 



While the comparison of species in Africa with those of other faunal regions is 

 limited, as with the genera, by our lack of knowledge of these regions, certain species 

 or species groups are of interest in showing apparent common origin between Indian 

 and African faunal elements. One pantropical species (B. myrsusalis) , which has 

 probably been widely introduced by man, is discussed on p. 58. 



Palaearctic Region 



There are few species of Thyrididae in this region ; none show any close affinities 

 with the African species. 



Neotropical and Nearctic Regions 



One species, M. magica (p. 51) has some morphological similarities to a South 

 American species, this is discussed on p. 52. 



Indo-Pacific and Australasian Regions 



At the species level, 5. suffusa (p. 99) is similar to a species from the Oriental 

 region. D. intermedia from Africa and D. taprobana from Ceylon are very similar 

 and with many common features suggesting a close common ancestry. A similar 

 case occurs with H. verticalis (Africa) and H. obscuralis (India). The males of these 

 two species are indistinguishable in external appearance and the genitalia are very 

 similar. Small differences occur in the female genitalia but the general appearance 

 is similar. H. verticalis is widespread in Africa and H. obscuralis seems to be equally 

 widespread in India. 



The possible relationship of African and Indian species of one species-group are 

 shown in Table 2. In this group the differences in morphology between the Mada- 

 gascan and Indian species are more than between the African and Madagascan one. 

 The African and Madagascan species have a single spine on each tarsal segment and, 

 while one of the Indian species is the same, the other has a pair of spines on each 

 segment. The presence of a pair of spines on the tarsi is here regarded as "ancestral" 

 to the single median tarsal spine and, unless the reduction from the two spine to the 

 one spine condition has taken place on both continents independently (always a 

 possibility), then it seems likely that the Madagascan species was derived from the 

 African one and this in turn was derived from the two-spined Indian species, either 

 directly or indirectly through the one-spined Indian species. Other morphological 



