PROCEEDINGS OF THE UNITED STATES NATIONAL MUSEUM 



issued aM|"ftVvA- Slji^i l>y '^c 



SMITHSONIAN INSTITUTION 

 U. S. NATIONAL MUSEUM 



I 



Vol.87 Washington : 1939 No. 307 { 



A NEW TREMATODE FROM THE LOON, GAVIA IMMER, 

 . AND ITS RELATIONSHIP TO HAEMATOTREPHUS 

 . FODIENS LINTON, 1928 



By W. Carl Gower 



Linton (1928) described a trematode, Haematotrepkus jodiens 

 (Cyclocoelidae), from the intestine and pancreas of a loon {Gavia 

 immer) taken at Woods Hole, Mass. He obtained one specimen from 

 the intestine and several from cysts in the pancreas. Although these 

 two forms are strikingly different, he included them as morphological 

 variations of the above species. Witenberg (1928) questioned that 

 Linton's species belonged to the Cyclocoelidae and further commented 

 that "the generic identification of this species remains problematical." 

 Later, Ejsmont (1931) transferred H. jodiens to the genus Diasia 

 Travassos (Pachytreminae: Opisthorcliiidae) but did not comment on 

 the two morphological types described by Linton. 



The writer, through the courtesy of Dr. E. W. Price, of the United 

 States Bureau of Animal Industry, obtained Linton's material for 

 study from the United States National Museum Helminthological 

 Collection. The material consisted of two slides, Nos. 7915 and 7916, 

 the former containing one specimen of the "free form" and the latter 

 two complete specimens and three fragments of the "encysted form." 

 Linton designated No. 7915 as the type. 



A study of this material shows that Linton was dealing with two 

 distinct species rather than two morphological forms of the same 

 species. The "free form" should be retained in the genus Diasia as 

 indicated by Ejsmont, but the "encysted form" is regarded as represent- 

 ing a new species belonging to the genus Amphimervs Barker (Opis- 

 thorchiinae). In view of Linton's very brief description, both species 



157168—39 139 



