1922] Ewing: Phylogeny of Gall Mites 215 



with a somewhat elongate body, and had even in the adult 

 stage only six legs. The mouth-parts were all but identical 

 with those of the Eriophyidae, while the tarsal armature was 

 quite similar in some respects to that of certain genera of the 

 Tetranychidae. The species was oviparous and differed veiy 

 markedly in its development from that of the spider mites. 



Recently the present writer has described* another species 

 of Phytoptipalpus taken from the jujube tree {Zizyphus jiijuha) 

 in India. This species is quite similar to the one described by 

 Tragardh. It makes galls on the bark of the jujube and lives 

 inside of these galls. So similar is this species to Tragardh's 

 paradoxus that any phylogenetic significance that attaches 

 to the one should usually apply to the other. The two species 

 are not only congeners, but are very closely related. 



The interpretation which the present writer places on the 

 meaning of the peculiar structure of Phytoptipalpus is exactly 

 the reverse of that given by Tragardh. Tragardh held that 

 the similarity between the mouth-parts of Phytoptipalpus and 

 the Eriophyidae was due to convergence, hence attached no 

 phylogenetic significance to them and was content to place his 

 new genus in the subfamily Tetranychinee next to the genus 

 Tenuipalpus. He states: "Die so geartete umbildung der 

 Mundteile von Phytoptipalpus, welche bei der Gattung Tenui- 

 palpus gewissermassen vorbereitet ist, ist ein sehr schones 

 Beisipel von • Konvergenz unter dem Einfluss von gleichen 

 ausseren Lebensbedingungen. Die Gattung Phytoptipalpus 

 lebt namlich wie die Phytoptiden in Pflanzengallen und ernahrt 

 sich von den Pflanzensaften. " 



This resemblance which Tragardh explains as being due to 

 convergence, the present writer would ascribe as due chiefly 

 to inheritance. In other words, the Eriophyid type of mouth- 

 parts is similar to the Phytoptipalpus type, not because both 

 Eriophyids and the Phytoptipalpi inhabit galls, but chiefly 

 because they have the same ancestry. This thesis I now will 

 attempt to both explain and establish. It involves a considera- 

 tion of other characters than the mouth-parts and other mites 

 than the two groups mentioned. We will start, however, 

 with the mouth-parts. I will compare first the mouth-parts 

 of the Eriophyidae with the species of Phytoptipalpus with which 

 I have worked. The name of this species is Phytoptipalpus 

 transitans. 



*Proc. Ent. Soc. Wash., Vol. XXIV, p. lOS. 



