261) 



A NEW THRIPS DAMAGING COFFEE IN BRITISH EAST AFRICA. 



By C. B. Williams, B.A., F.E.S., 

 The John Innes Horticultural Institution, Merton, Surrey. 



The Thrips described below was submitted to me by Mr. Guy A. K. Marshall, 

 Director of the Imperial Bureau of Entomology, to whom it had been sent by 

 Mr. T. J. Anderson, the Government Entomologist in British East Africa. 



Fam. THRIPIDAE. 

 DiARTHROTHRips, gen. nov. 



General form rather slender. Chitin unreticulated. Antennae eight- segmented, 

 stylus shorter than the sixth segment. Head about as long as broad. Ocelli rather 

 far back on the head. Maxillary palps two-segmented ; labial palps one-segmented 

 (possibly a second short basal one indistinctly separated from the labium). 

 Mouth-cone somewhat long and bent downwards away from the prosternum. 

 Thorax and abdomen slender. Two long spines on the hind angles of the prothorax, 

 none at the fore angles. Wings slender, the greater part of the fore vein without 

 spines. The ninth segment of the male without stout dorsal spines. 



Type species, D. coffeae, nov. 



This genus, on account of its two-segmented maxillary palps, bears a somewhat 

 similar relation to Physothrips to that which Baliothrips does to Thrips. It is, 

 however, further separated from Physothrips by the more slender build and the longer 

 mouth-cone. The presence of ring joints at the bases of the fourth and fifth antennal 

 segments, as mentioned below in the specific description, somewhat recalls 

 Cricothrips, Trybom, from Zululand, but this character is found in species of other 

 genera (e.g. Physothrips antennatus, Bagnall) and varies in distinctness in individuals. 

 In the present species it seems to be more of the nature of a stage in the development 

 of the pigment of the segment, and in darker specimens the light separation is often 

 indistinct, particularly in the fifth segment ; it is, however, always visible. On 

 these grounds I do not consider it of generic value. From Cricothrips it is also 

 distinguished by the absence of the dorsally swollen front part of the head and 

 by the two-segmented maxillary palps. 



Diarthrothrips coffeae, sp. nov. (fig. 1). 



Female. 

 Measurements. — Head, length 0'130 mm., width 0'130 mm. ; prothorax, length 

 0-108 mm., width 0*160 mm. ; pterothorax, length 0*260 mm., width 0-206 mm. ; 

 abdomen, width about 0*20 mm. ; wing, length 0*75 mm., width (about middle) 

 0-034 mm. 



Antennae 12 3 4 5 6 7 8 



length {jLi) . . 26 36 50 56 41 50 9 18 



width (/j) ..29 24 18 18 16 17 8 6 



Total body length about 1*16 mm., antennae 0*30 mm. 

 (0205) E 



