55 Acarina from the Juan Fernandez Islands. 



By 

 IVAR TRAGArDH. 



Introduction. 



Amongst the zoological collections brought home from Juan Fernandez 

 by Professor Dr. C. Skottsberg and Dr. K. Backstrom during the Swedish 

 Pacific Expedition were also some acarina, about 20 species. 



It is hardly necessary to point out that this material does not give any 

 exhaustive picture of the acarofauna of the islands but only represents a small 

 part of it. Nevertheless the material is of great interest considering how little 

 is known about the acarina of this part of the world. 



It proves that some mites either have become cosmopolitic through the 

 agency of man or display originally a very wide distribution and that some 

 genera occur all over the world, although represented by different species in 

 different parts. 



I. Phthiracarus maculatus n. sp. — Figs. 1 — 6. 



Length of propodosoma 700 ^, of hysterosoma 875 ^; height (distance 

 from dorsal to ventral side) 650 [x. 



Colour yellowish brown with patches of bluish gray of varying size. 



Texture smooth, only at high magnification very finely punctured. 



Shape (figs, i, 2). The dorsal side of the hysterosoma is very highly 

 arched, with the highest part in front of the middle, posteriorly well rounded. 

 Anterior margin slightly s-curved, as is also the ventral margin surrounding the 

 genital and anal shields. 



Propodosoma without any trace of carina, with almost parallel sides, 

 anteriorly blunt and with slightly concave posterior sides. 



It is quite smooth with perfectly even, thin edge. The inner sur- 

 face has, however, a median longitudinal ridge, separating the mandibles, and 

 branching off into two ridges curving outwards and forwards and embracing the 

 bases of the mandibles. 



Behind the middle there are 2 pairs of slender hairs pointing upwards 

 and backwards; they are placed in a transverse row on a level with the pseudo- 

 stigmatic organs and the inner (median) hair is twice as long as the lateral 

 one. The rostral hairs slender, pointing forwards; their pore is through a long 

 canal connected with the median ridge. 



