Notes on the Morphology of the Larva of Pneumonyssoides caninum (Chandler and Ruhe, 1940) Fain, 1955 (Acarina: Halarachnidae)

Abstract

Gamasid mites of the family Halarachnidae are parasitic in the respiratory tracts of mammals. Of the various genera in this family only Pneumonyssoides appears to be of importance in canine animals. Pneumonyssoides caninum has been reported as occurring in the nasal cavity and paranasal sinuses of dogs from various parts of the world. Although they live in the upper respiratory tract where they are not easily seen, no lesions or symptoms have been described that could be definitely attributed to their presence. Fain (1955) described a new species, Pneumonyssoides phacochoeri, from the nasal cavity of the wart-hog and in this publication transferred Pneumonyssus caninum Chandler and Ruhe, 1940, to the genus Pneumonyssoides. He justified the inclusion of P. caninum in the new genus by his modification of the diagnosis of Pneumonyssus by Furman (1954). This revision was accepted by Strandtmann and Wharton (1958) and is included in their classification of mesostigmatid mites. These authors stated that the status of the 5 genera recognized in the family Halarachnidae Oudemans, 1906, was rather tenuous and was certainly not the final word. Furthermore, they indicated that very likely a separate genus will have to be erected for the mites for each of the various unrelated groups of hosts. Chandler and Ruhe (1940) in their description of the female of this species, listed some of the morphological characteristics of the larva and included a description of the larval hypostome. Furman's account of the characteristics of the male was included in his revision of the genus. The entire larva of P. caninum is described here for the first time. The following description of the larva is based on 10 specimens. All measurements are given in millimeters, and drawings were made from lacto-phenol-cleared specimens with the aid of a camera lucida.