20 BULLETIN 140, UNITED STATES NATIONAL MUSEUM 



KEY TO SPECIES OF AMIDOSTOMUM 



1. Female 16.5 mm. long ; buccal capsule apparently with only 1 large tooth ; 



vulva not described as prominent ; male unknown ; imperfectly described 



species from Oidemia nigra in Europe Amidostomum monodon, p. 2G. 



Female not over 13 mm. long, or, if longer, then with a buccal capsule having 

 3 teeth, or vulva with prominent anterior lip (A. aciitum) 3. 



2. Males 11.25 to 13.5 mm. long; females 13.5 to 15.75 mm. long; vulva % of 



body length from end of tail ; imperfectly known. 



Amidostomum acutum, p. 24. 

 Males less than 9 mm. long, or (A. anseris) 10 to 17.1 mm. long 3. 



3. Spicules 120m long ; 1 tooth in buccal capsule ; externo-dorsal ray originates 



in common with dorsal ray Amidostomum chevreuxi, p. 22. 



Spicules over 150m long; 3 teeth in buccal capsule and externo-dorsal ray 

 originates in common with other rays, not with dorsal, where known 

 (unknown for A. fulicae) 4. 



4. Males 10 to 17 mm. long ; females 12 to 23.7 mm. long ; spicules 200 to 300m 



long; female tail 437m long; buccal capsule with 3 teeth and 6 paired 



ridges Amidostomum anseris, p. 20. 



Males less than mm. long; females up to 14.5 mm. long; spicules not over 

 204m long; paired ridges not reported for buccal capsule 5. 



5. Spicules 175m long; telamon 70m long Amidostomum fulicae, p. 25. 



Spicules 166m or 204m long; telamon 90 to 100m long 6. 



-8. Spicules 166^ long; telamon 90/* long; buccal capsule 27.5m wide in male, with 



1 large and 2 very small teeth Amidostomum henryi, p. 22. 



Spicules 204/x long; telamon 100m long; buccal capsule 15m wide in male, 

 with 1 large and 2 small teeth Amidostomum raillieti, p. 24. 



AMIDOSTOMUM ANSERIS (Zeder, 1800) Railliet and Henry, 1909 



Synonyms. — Ascaris mucronata Froelich, 1791, not Schrank, 1780; 

 Strongylus anseris Zeder, 1800 in part; Strongylus nodulosus Ru- 

 dolphi, 1803; Strongylus nodularis Rudolphi, 1809; Trichostrongylus 

 nodularis (Rudolphi, 1809) Shipley, 1909; Amidostomum nodu- 

 losum (Rudolphi, 1803) Seurat, 1918. 



Hosts. — Anas querquedula, Anser acuta, Anser albifrons, Anser 

 anser, A. anser domestica, A. cinereus, A. clangula, A. crecca, A. 

 fabalis, A. fuUgula, A. fusca, A. leucops, A. marila, A. mollissima, 

 A. nigra, A. penelope, A. segetum, Chloeplxaga poliocephala, Fulica 

 atra, FuUgula cristata, F. marila, Cfatlvnula chloropus, Nyroca clan- 

 gula, N. fuUgula, N. marila, and Soniateria dresseri. 



Location. — In or under the mucosa of the gizzard, proventriculus, 

 the connection between these two, the esophagus, and, according to 

 Skrjabin, the duodenum. 



Morphology. — Amidostomum (p. 19) : Slender reddish worms. 

 Cuticle transversely striated, with a longitudinal pseudo-striation 

 due to the musculature. Head end (fig. 13) slightly enlarged and 

 bearing 2 pairs of large submedian papillae. Mouth aperture oval. 

 The short wide buccal capsule has 3 pointed teeth at its base and 

 has 6 ridges grouped in pairs. Esophagus has 3 chitinous ridges 

 along its entire length. 



