586 PROCEEDINGS OF THE NATIONAL MUSEUM vol. no 



has been collected from North American Sciurus species other than 

 from S. carolinensis and *S'. niger, it is necessary to exclude such 

 specimens from the following discussion. 



Slight but constant differences in the antennae, coupled with con- 

 stant host associations, afford a reliable method for distinguisliing 

 species of the complex.^ A search for genitalic characters, size differ- 

 ences, and other morphologic differences among the various species of 

 the sciurmus complex has been fruitless. The thoracic sternal plate 

 varies greatly in shape and size (figs. 36-38, 43, 44); the male genitalia 

 are similar (fig. 35, a-d); and patterns of chaetotaxy, although some- 

 what variable, are similar for all the species. 



There are two groups, based on the antennal characters: the sciuri- 

 nus-l'ike species have the basal antennal segment prolonged postero- 

 apically, with an enlarged seta on the prolongation (figs. 41, 42); and 

 the sciuri-like species lack the prolongation and may lack the enlarged 

 apical seta (figs. 39, 40). 



Neohaematopinus sciurinus and related species 



1. A^ sciurinus Mjoberg is found on Sciurus nigei- in North America. 

 It is characterized by having the basal antennal segment prolonged 

 posteroapically, with this prolongation bearing a spinelike apical seta, 

 by lacking a short spinelike seta on the posterior margin of the second 

 antennal segment, and by having the fourth segment longer than the 

 fifth (fig. 30). Specimens have been examined as foliov/s: From 

 Sciurus niger: Texas, Kansas, Florida, Georgia South Carolina, 

 Maryland, and Oiiio. 



2. N. semifasciatus Ferris is found on Tamiasciurus douglasi and 

 T. hudsonicus in North America. This species has the basal antennal 

 segment with the posteroapical prolongation and seta as in sciurinus, 

 but the second antennal segment has a short spinelike seta on the 

 posterior margin, and the fourth segment is equal in length to the 

 fifth (fig. 32). Specimens have been examined as follows: From 

 Tamiasciurus douglasi: California and Oregon. Fi'om Tamiasciurus 

 hudsonicus: Tennessee, Montana, and Alaska. 



3. N. callosciuri is found on Callosciurus species in Southeast Asia 

 and Malaysia. It is characterized by having a tubercle on the venter 

 of the basal antennal segment, by the posteroapical prolongation and 

 its seta being smaller than in sciurinus, and by lacking a stout spine- 

 like seta on the second antennal segment (fig. 42). The Asian specimens 

 from Callosciurus and probably those from Lariscus, reported by 

 Ferris (1923) as sciurinus, are referable to A^. callosciuri. 



3 One female sciurinus examined has aj abnormal seta on the basal antennal segment on one side (fig. 29), 

 and several sciurinus specimens in three collections are recorded as from "red squirrel." All the "red squir- 

 rels" may have been misdetermiued, and in one case the specimens were collected in Kansas where Tamias- 

 ciurus (red squirrel) does not occur. 



