214 Annals Entomological Society of America [Vol. XV, 



slender and of little use in walking." Banks' basis for a belief 

 in Tarsonemid relationship is the existence of similar feeding 

 habits of the two groups and the fact that in the Tarsonemid^ 

 there is "a tendency to the reduction in number of the legs. " 



Oudemans (1910) states in his review of the families of the 

 Acarina* that the Eriophyidae are probably most nearly related 

 to the spinning mites or "perhaps even an earlier stage of the 

 Tetrany chide. " This suggestion that the gall mites are an 

 earlier stage of the Tetranychidae requires some evidence for 

 its support and an elaboration of explanations based on such 

 evidences. Until such are brought forward the suggestion 

 falls far short of a theory which can be used constructively in 

 the advancement of our knowledge of natural relationships. 



A THEORY AS TO THE PHYLOGENY OF THE ERIOPHYID^. 



It is my purpose here to state and then substantiate a 

 definite theory as to the origin of the gall mites. The theory 

 is this: The gall mites, a highly aberrant and degeneratively 

 specialized group of phytophagous parasites, have arisen 

 through the process of profound morphological change and 

 adjustment, from a recently discovered group of gall-making 

 spider mites. This group the writer has recognized as a 

 family, the Phytoptipalpidse, and it is to be regarded as a 

 transitional group between the Eriophyidae and the Tetrany- 

 chidae. I would not derive the gall mites from any living 

 species of the family Phytoptipalpidae or even from the genus 

 Phytoptipalpus; yet it appears from the evidence at hand 

 that the two or more living species of Phytoptipalpus are 

 barely out of a line of direct descent between the spider mites 

 and the gall mites. 



THE GENUS PHYTOPTIPALPUS — ITS DISCOVERY AND THE 

 INTERPRETATION OF ITS RELATIONSHIPS. 



The genus Phytoptipalpids was established in 1905 by 

 Tragardh for a very peculiar mite species named by him 

 paradoxus, which was found in galls of an African species 

 of Acacia. The species was very peculiar in several respects. 

 It evidently was a true gall making species, yet did not belong 

 to the group known as the gall mites. The mites were red. 



*Oudemans, A. C. A Short Survey of the More Important Families of Acari. 

 Bui. Ent. Research, Vol. 1, pp. 10.5-119, figs. 1-22. 



