ii2 T. OKADA 



Drosophila (Drosophila) immigrans Sturtevant 



Drosophila immigrans Sturtevant, 192 1 : 83 (N. America). 



Taplejung District, Sangu, rotting fruits of Bhor tree on ground, c. 6,200', 7-31. x. 

 1961, 19 (J, 15 $ ; ibid., from rotten bananas in traps, c. 6,200', x-xii.1961, 2 § ; 

 ibid., mixed vegetation by stream in gully, c. 6,200', xi. 1961-1.1962, 1 $ ; between 

 Sangu and Tamrang, mixed shrubs in deep gorge, c. 5,200', x-xi.1961, 1 $. Arun 

 Valley, below Tumlingtar, River Sabhaya, west shore, from rotten bananas in traps, 

 c. 1,800', x-xii.1961, 13 $, 27 $ ; ibid., evergreen shrubs on sandy shore, 9-17. xii. 

 1961, 1 $ ; ibid., fermented millet seeds on shore, c. 1,800', 24.xii.1961, 2 $ ; ibid., 

 east shore of River Arun, evergreen shrubs bordering dry stream-beds, c. 1,800', 

 14-23. xii. 1961, 1 $ (R.L.C.). 



Distribution : Nepal, India, Formosa, China, Korea, Japan, Philippines, Micro- 

 nesia, Hawaii, Australia, Africa, Europe, N. America, S. America. 



Drosophila (Drosophila) nasuta Lamb 



Drosophila nasuta Lamb, 1914 : 346 (Seychelles). 



Drosophila {Drosophila) nasuta Lamb : Okada, 1964b : 463 (Borneo) [synonymy] ; Wheeler 

 and Takada, 1964 : 180 (Mariana Is., Truk, Ponape, Kusaie, Wake Is.) [synonymy]. 



Taplejung District, Sangu, rotting fruits of Bhor tree on ground, c. 6,200', 7-31. x. 

 1 96 1, 16 $, 11 $ ; between Sangu and Tamrang, mixed shrubs in deep gorge, c. 5,200', 

 x-xi.1961, 1 $. Arun Valley, below Tumlingtar, River Sabhaya, west shore, from 

 rotten bananas in traps, c. 1,800', x-xii.1961, 1 $ (R.L.C.). 



Distribution : Nepal (new locality), Borneo, Sumatra, Seychelles, Formosa, 

 Japan, Moluccas, New Guinea, Micronesia, Samoa, Fiji, Hawaii. 



GEOGRAPHICAL DISTRIBUTION OF THE NEPALESE SPECIES 



Table 1 shows that the drosophilid fauna of Nepal seems to be most closely related 

 to that of Formosa, nearly one-third of the known Nepalese species being in common 

 (twenty-five species) . Much fewer Nepalese species have been found in common with 

 the adjacent areas, India, Viet-Nam or China, and this is certainly due mainly to the 

 poor knowledge of the fauna in these areas as compared with the relatively rich 

 records from Formosa. Similar relationships between the number of species in com- 

 mon and the degree of survey can be recognized among the islands of Java, Sumatra, 

 and Borneo. Of these, Java has been best surveyed and is richest in the number of 

 species in common (fourteen species) , while Borneo is poorest in the degree of survey 

 as well as in the number of species in common (three). 



Japan comes next to Formosa in the number of species in common (nineteen 

 species), which is about one-fourth of the total Nepalese species. This is undoubt- 

 edly due partly to the extensive surveys made in Japan and partly to the biogeo- 

 graphical similarity between the two countries. The latter has frequently been 

 proved concerning various groups of insects and plants, e.g., Epiophlebia (Aniso- 

 zygoptera, Odonata) and Deuterophlebia (Deuterophlebiidae, Diptera) in insects and 

 Balanophora, Burmannia, and Hydrobryum in Angiosperms, referring only to special 



