ON THE ENGLISH SPECIES OF RED SPIDER. 



4:9 



4. Revision of the English Species of Red Spider (Genera 

 Tetranijclius and (Jligonycliiis). By Stanley Hirst. 



(Published bj' permission of the Trustees of the Britisli Museum.) 

 [Received December 8, 1919 : Read February 24, 1920.] 



(Text -figures 1-5.) 



The following note deals with the English species of mites 

 commonly called Red Spiders, and is almost entirely based on 

 material collected by the author, the coloration being described 

 from living specimens. A good deal of confusion still exists in 

 the classification of this group — for instance, the name Tetra- 

 nychus telarius is not always used for the same species by recent 

 authors, and several distinct species {T. t'diarmm. T. llntearms, 

 T. j^opuli, and Oligonychus quercinus) are wi'ongly considered as 

 synonyms of that species. Three new species are described in 

 the present note, but one of them {T. talisice) is undoubtedly an 

 introduced form. 



My best thanks are due to Lieut. -Col. Sir David Prain (Kew 

 Gardens), Prof. W. Bateson (John Innes Horticultural Station, 

 Merton), and to the authorities of the Royal Horticultural 

 Society's Gardens, Regent's Park, for kindly allowing me to 

 collect material in the gardens under their chai-ge. 



The drawings illustrating this note have been made by Mr. Percy 

 Highley and Mr. A. J. Engel Terzi. 



Order PROSTIGMATA. 

 Superfamily Trombidioidea. 



Family T E T R A N y c h i d 



The two principal genera Tetyxmychus and Oligonychus can 

 be readily distinguished from one another by the following 

 characteristics : — 



Claw of legs always simple and i^nmodilied (never bifurcated nor 

 furnished with teeth) ; it has a slight protuberance near the base 

 bearing minute hairs Genus Oligonyclms Berlese. 



First claw of male either ending in minute teeth or bifurcated. Claw 

 of the other legs in both sexes usually either ending in tine hairs or 

 bifurcated Genus Tetranychus Dufour. 



Genus Tetranychus Dufour, 1832. 



Key to the species of Tetranychus (males) occurring in 

 England : — 



fTerminal tinger of palp minute and inconspicuous or 

 J absent 1. 



l^Terminal tinger well developed 4. 



fTerminal tinger of palp absent. 



1 All the claws of the legs bifurcated Tetranychus schizojyns 



l.<j _ _ rZaciier. 



j Terminal finger present, but minute. 



t_Cla\v of first leg alone bifurcated 2. 



Proc. Zool. Soc— 1920, No. lY. 4 



