74 T. OKADA 



were suggested by Lee (1964) to belong to this subgenus. Although this subgenus 

 was originally characterized by only one pair of dorsocentrals, anterior pair being 

 absent, some species have two pairs with anterior pair fine, and yet other species 

 have both anterior and posterior pairs well developed. These species are character- 

 ized in having very oblique eyes and ocellars inserted outside ocellar triangle, by 

 which they can be assigned to Dichaetophora. Consequently, the occurrence of only 

 one pair of dorsocentrals is an "archestinic" character (Stenzel, 1963) which means a 

 diagnostic character of a taxon occurring only in some individual units of that 

 taxon (cf. p. 119). 



Key to Species 



1 Antennae vertically erected from head, with the third segment remarkably swollen 

 distally. Arista with only one branch below fork. Abdominal tergites almost 

 entirely black ......... rotundicornis (p. 74) 



- Antennae recumbent on the head, with the third segment not remarkably swollen 

 distally. Arista with two branches below fork. Abdominal tergites with distinct 

 black cross-bands ......... raridentata (p. 76) 



Drosophila {Dichaetophora) rotundicornis sp. n. 



(Text-figs. 207-213) 



o\ $• Body about 1 -8 mm. Head slightly broader than thorax. Eyes dark red, triangular 

 in lateral aspect, finely pilose and faint green iridescence. Antennae yellowish brown, large, 

 upright ; second segment somewhat longer than broad ; third with thick long pubescence, 

 distally dark brown and much swollen. Arista with about four dorsal and one ventral branches 

 and a small terminal fork. Palpus yellow, tip rounded, with a prominent apical seta. Ocellar 

 triangle black, marginally pale. Periorbit yellowish grey, not sharply demarcated from front, 

 about two-thirds length of front. Front matt yellowish grey, flat, anterior one-third yellow, 

 anteriorly narrower than median length ; posteriorly twice as broad as head width. A few 

 frontal hairs present. Carina low, narrow, half of face, distally broadened. Face broad, grey- 

 brown, much broadened below, buccal margin with a broad white transverse band, narrowly pale 

 on carina and along eye margin. Clypeus dark brown. Cheeks yellowish white, somewhat 

 pollinose, about one-third as broad as the greatest diameter of eye. Occiput greyish brown. 

 Postverticals very long, longer than outer verticals. Ocellars long, inserted well outside ocellar 

 triangle. Anterior reclinate orbital slightly before and outside proclinate, three-fifths as long as 

 proclinate, two-thirds as long as posterior reclinate, thrice as distant from posterior reclinate as 

 from proclinate. Second oral about half as long as vibrissa ; succeeding orals shorter. 



Mesonotum deep greyish brown, matt. Scutellum deep greyish brown, marginally and 

 centrally somewhat pale. Thoracic pleura greyish orange, pollinose, with a dark brown longi- 

 tudinal stripe on upper half. Three humerals, median longest. Acrostichal hairs in six rows. 

 Anterior dorsocentrals two-thirds as long as posteriors ; distance between anterior and posterior 

 dorsocentrals two-thirds distance between anterior pair. Anterior scutellars divergent, as long 

 as posteriors, which are twice as distant from anteriors as from each other. Sterno-index about 

 0-3. Legs dusty yellow, coxae paler, all metatarsi as long as the other segments together. Pre- 

 apicals on all legs ; apicals prominent on mid leg. Wings hyaline ; veins yellowish brown ; 

 crossveins not clouded ; costa paler and reaches the end of i? 4 + 5 ; i? 2 +3 gently curved to costa 

 at tip ; i?4+ 5 and M slightly divergent distally. C-index about 3-5 ; 4V-index about 2-4 ; 

 4C-index about i-o ; 5x-index about 2-3 ; Ac-index about 2-0. Ci -bristles two ; C3-fringe 

 on basal three-sevenths. Halteres yellowish white. Abdominal tergites mostly black, some- 

 what glossy ; iT pale yellow at anterior corner. 



