168 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



distinct that the species must be maintained. I hoped that the specimens 

 from the Gulf of California islands, also part of Mexico, would prove 

 to belong to B. tnexicana, so that the latter could be fully described and 

 figured in both sexes. But such is not the case; they represent a new 

 and distinct species, not (as far as I can make out) very close to any 

 of those previously known, but best compared with a species from Costa 

 Rica. 



The bat on which the parasites were found is the first representative 

 of the genus Pizonyx from which any Nycteribiid has been recorded. 

 Pizonyx is, however, closely related to Myotis, several species of which 

 are hosts of species of Basilia (though the latter also infest bats of other 

 genera*). I am told that the only representative of Pizonyx is the species 

 mentioned below, and that this bat is very localized, being known only 

 from northwestern Mexico. If the host is really as restricted in distri- 

 bution as appears, the parasite may also prove to be localized and taxo- 

 nomically somewhat isolated. 



The description has been drawn up, and the drawings made, from 

 specimens in alcohol. Pencil sketches were made by myself with the aid 

 of a Zeiss drawing apparatus, and the finished drawings were done by 

 Miss D. Fitchew from these sketches, checked by viewing the actual 

 specimens. 



Basilia pizonychus, new species 



Length about 2.25-2.50 mm. The general form is shown sufficiently 

 in the figures. The eyes are distinctly two-faceted, conforming to the 

 characters of the genus. The rnesonotum is not raised behind into any 

 erection (neither a chitinous erection, as in B. 7nexicana [Bigot] nor a 

 finger-like process, as in B. boardmani Rozeboom). The ctenidium on 

 the hind margin of the basal abdominal sternite consists, in both sexes, 

 of about 52 teeth. 



The species is most nearly comparable to B. ferrisi Scott (B. speiseri 

 Ferris, nee Ribeiro),t from Costa Rica. The external distinguishing 

 characters lie mainly in the abdomen of the female: B. pizonychus has 

 the basal tergite much shorter, with fewer setae on its surface, shorter 



* See the table of American species of Basilia and their hosts in my 1936 

 paper cited above, p. 497. 



t B. ferrisi was described and figured, under the name B. speiseri, by 

 Ferris, Ent. News, xxxv, pp. 198-9, pi. iii, 1924. I made it a distinct species in 

 1936 (op. cit., p. 502), thereby confirming the opinion of Curran, who had recog- 

 nized the distinction betvYeen it and the true B. speiseri (Ribeiro). 



