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 y, of hysterosoma 875 u; height (distance 
from dorsal to ventral side) 650 wu. 
Colour yellowish brown with patches of bluish gray of varying size. 
Texture smooth, only at high magnification very finely punctured. 
Shape (figs. 1, 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. 
