204 PROCEEDINGS OF THE NATIONAL MUSEUM vol. loi 



60 cases of dermatitis that occurred among American troops serving 

 in North Wales during the war. The mites, in this instance, were 

 present in straw-filled mattresses upon which the men were sleeping. 



TAXONOMIC POSITION 



Mites of the subfamily Haemogamasinae ^ are parasites on small 

 mammals, occasionally free living or on birds. Dorsal shield undi- 

 vided in both sexes and in larval and nymphal stages. Anterior mar- 

 gin of epistome with simple or branching fimbriae. Body setae more 

 numerous than in other laelaptid mites. Legs with spurs only in genus 

 Ischyropoda. Sternal shield with accessory setae in genera Eaemo- 

 gamasus and Ischyropoda. Genitoventral shield of nymphal stages 

 with accessory setae only in genus Ischyropoda. Accessory anal setae 

 present in almost all specimens of most species. Anal shield separate 

 in males of genus Ischyropoda. Metapodal shields small. Three 

 genera. Distribution cosmopolitan. 



The Haemogamasinae were given status as a subfamily not upon 

 basis of adult characteristics alone, but primarily because larval and 

 nymphal stages, as well as adults, possess only a single dorsal shield. 

 In most other genera of Laelaptidae the dorsal shields develop in such 

 a way that, whether single or divided in the adult, the protonymph 

 possesses an anterior pronotal shield and a posterior pygydial shield, 

 between which are smaller, intermediate shields, which differ in num- 

 ber in various genera. The phylogenetic importance of the nature of 

 the dorsal shield was advanced by Triigardh (1911), who regarded 

 possession of two shields as a primitive feature, retained in more recent 

 genera only in the nymphal stages. Oudemans erected the family 

 Haemogamasidae in 1926, and although Vitzthum first (1931) agreed 

 with this interpretation he later (1942) reduced the group to status 

 of one of the 13 subfamilies included by him in the Laelaptidae sensu 

 lato. 



Prior to this study the following genera and species of Haemoga- 

 masinae were recognized : 



Genus HAEMOGAMASUS Berlese, 1889 



1889. H. hirsutus Berlese 1925. H. alaskensis Ewing 



1892. H. horridus Michael 1925. H. harberi Ewing 



1892. H. nidi Michael 1925. H. microti Ewing 



1905. H. americanus Banks 1925. H. twitcJielU Ewing 



1914. H. oudemansi Hirst 1926. H. quadrisetatus Vitzthum 



1915. H. sanguineus Ewing and Stover 1931. H. avisiigus Vitzthum 



1916. H. liberiensis Hirst 1931. H. mandschuricus Vitzthum 

 1920. H. arvicolarum (Berlese) 1933. H. sternaUs Ewing 



2 Order Acarl Leach, 1817 ; suborder Parasltifornies Reuter, 1909 ; supercohort Meso- 

 stigmata Canestrini, 1891; cohort Gamasidea Leach, 1815; subcohort Gamasina Kramer, 

 1885 ; family Laelaptidae Berlese, 1892. 



