60 ON THE ENGLISH SPECIES OF RED SPIDER. 



? Tetranychus yothersi McGregor, Ann. Soc. Ent. Amer. 1914, 

 vii. pp. 355-357, pi. xliii. figs. 1-8. 



(5 . Penis very like that of 0. simplex Banks (from date-palms), 

 being small and curved at the end. 



Palp. Terminal finger absent or very minute and inconspicuous, 

 DoiPsal sensory finger short and A'^er}^ slender. 



$ . Palp. Terminal finger not nearly so wide as in 0. idmi, 

 being short but only of moderate width ; sometimes it is slightly 

 clavate. Dorsal sensory finger quite short and slender. 



Colour whitish or pale brownish with black markings. 



JEggs variable in colour, being either whitish, pale yellow, or 

 reddish. 



Measureme7its. J , length 220 /x ; $ , 270-310 /a. 



Host plaints. Oak-trees. 



ISToTE. — Targioni Tozzetti seems to have been the first to observe 

 Tetranychus occurring on oak-trees, but he does not give the 

 species a name. 



In his ' Acari dannosi alle piante coltivate ' Berlese copies 

 Tozzetti's brief descriptions, and gives the name quercinus to this 

 mite, and mentions also the " Tetranico verde del leccio " {T. vires- 

 cens), which is probably the same species. Oligonychus brevipodus, 

 also from the evergreen-oak, seems to be another synonym of this 

 species. Both Canestrini and Berlese in later publications 

 regards this species as a synonym of Tetranychus telarius. The 

 specimens found on oaks in this country (at Wimbledon Common 

 and Kew) belong, however, to the very distinct species of Parete- 

 tranychus ( = Oligonychus) described above, which is easily recog- 

 nised by the structure of the palp. 



I take the opportunitj- to include the diagnosis of a species of 

 Oligonychus from date-palms in Mesopotamia : — 



4. Oligonychus simplex Banks?, 1914. 



? Tetranychus simplex Banks, J. Ent. Zool. Claremont, Cal. 

 1914, vi. p. 57. 



(S . Penis. Chitinsed part of penis very short, and it terminates 

 as a very minute curved hook. 



Palp. Terminal finger very like that present in 0. ulmi, being 

 rather short, but it is slightly blunter. Dorsal sensory finger 

 spindle-shaped, being rather short and slender. Spine on upper 

 surface of palp borne on a distinct angular projection. 



$ . Palp. Terminal finger more slender than in 0. idmi, but 

 still it is fairly stout. Dorsal sensory finger fairly long. 



Measurements. 6 , length 275-290 ^c ; $ , 280-385 /x. 



Host plant. Date-palm, Basra, Mesopotamia ; numerous speci- 

 mens collected by Capt. P. A. Buxton. 



