Allocreadium priacanthi MacCallum, 1921 accepted as Pseudopecoelus priacanthi (MacCallum, 1921) Manter, 1947 (original description)
Anisocoelium hippoglossi MacCallum, 1921 accepted as Derogenes varicus (Müller, 1784) Looss, 1901 (original description)
Cephalogonimus trachysauri MacCallum, 1921 accepted as Paradistomum trachysauri (MacCallum, 1921) Dollfus, 1922 (original description)
Cotylogaster chaetodipteri MacCallum, 1921 accepted as Lobatostoma ringens (Linton, 1905) Eckmann, 1932 (original description)
Cyclocoelum halcyonis MacCallum, 1921 accepted as Selfcoelum halcyonis (MacCallum, 1921) Dronen & Blend, 2015 (original description)
Diplostomum cinosterni MacCallum, 1921 accepted as Herpetodiplostomum cinosterni (MacCallum, 1921) Zerecero, 1947 (original description)
Diplostomum minimum MacCallum, 1921 accepted as Posthodiplostomum minimum (MacCallum, 1921) Dubois, 1936 (original description)
Eurostomum MacCallum, 1921 accepted as Azygia Looss, 1899 (original description)
Eurostomum micropteri MacCallum, 1921 accepted as Azygia micropteri (MacCallum, 1921) Skrjabin & Guschanskaja, 1958 (original description)
Eustomos MacCallum, 1921 (original description)
Eustomos chelydrae MacCallum, 1921 (original description)
Globoporum MacCallum, 1921 (original description)
Globoporum moronis MacCallum, 1921 (original description)
Lecithaster anisotremi MacCallum, 1921 accepted as Lecithophyllum anisotremi (MacCallum, 1921) Yamaguti, 1971 (original description)
Monostoma sphargidis MacCallum, 1921 accepted as Pyelosomum renicapite (Leidy, 1856) Ruiz, 1946 (original description)
Paragonimus trachysauri MacCallum, 1921 accepted as Paradistomum trachysauri (MacCallum, 1921) Dollfus, 1922 (original description)
Plagiorchis anacondae MacCallum, 1921 accepted as Telorchis clava (Diesing, 1850) Lühe, 1899 (original description)
Renifer ancistrodontis MacCallum, 1921 accepted as Ochetosoma ancistrodontis (MacCallum, 1921) (original description)
Renifer natricis MacCallum, 1921 accepted as Ochetosoma natricis (MacCallum, 1921) Leao, 1945 (original description)
Renifer ophiboli MacCallum, 1921 accepted as Ochetosoma ophiboli (MacCallum, 1921) Leao, 1945 (original description)
Renifer septicus MacCallum, 1921 accepted as Ochetosoma septicum (MacCallum, 1921) Leao, 1945 (original description)
Spirorchiidae MacCallum, 1921 accepted as Spirorchiidae Stunkard, 1921 (original description)
Spirorchis emydis MacCallum, 1921 accepted as Spirorchis innominatus Ward, 1921 (original description)
Spirorchis eustreptos MacCallum, 1921 accepted as Spirorchis innominatus Ward, 1921 (original description)
Styphlodora lachesidis MacCallum, 1921 (original description)
Taenia rosaeformis MacCallum, 1921 accepted as Scalithrium rankini (Baer, 1948) Ball, Neifar & Euzet, 2003 (original description)
Telorchis angusta Stafford of MacCallum (1921) accepted as Telorchis angustus MacCallum, 1921 (basis of record)
Telorchis angusta Stafford of MacCallum (1921) accepted as Telorchis angustus MacCallum, 1921 (original description)
Zoogonoides boae MacCallum, 1921 accepted as Paradistomum boae (MacCallum, 1921) Viana, 1924 (original description)

Australia for Cephalogonimus trachysauri MacCallum, 1921 
Brazil for Zoogonoides boae MacCallum, 1921 
Floridian for Lecithaster anisotremi MacCallum, 1921 
Georgia (US State) for Renifer natricis MacCallum, 1921 
Gulf of Mexico for Allocreadium priacanthi MacCallum, 1921 
Massachusetts Continental Shelf for Anisocoelium hippoglossi MacCallum, 1921 
New York for Diplostomum minimum MacCallum, 1921 
New York for Eurostomum micropteri MacCallum, 1921 
New York for Eustomos MacCallum, 1921 
New York for Eustomos chelydrae MacCallum, 1921 
New York for Paragonimus trachysauri MacCallum, 1921 
New York for Renifer ancistrodontis MacCallum, 1921 
New York for Renifer septicus MacCallum, 1921 
New York Harbor for Globoporum moronis MacCallum, 1921 
Ohio for Spirorchis emydis MacCallum, 1921 
Philippines for Cyclocoelum halcyonis MacCallum, 1921 
South America for Plagiorchis anacondae MacCallum, 1921 
Southwestern U.S.A. for Renifer ophiboli MacCallum, 1921 
Trinidad for Diplostomum cinosterni MacCallum, 1921 
Trinidad for Styphlodora lachesidis MacCallum, 1921 
Virginian for Cotylogaster chaetodipteri MacCallum, 1921 
Virginian for Monostoma sphargidis MacCallum, 1921 

 Nomenclature

 for Telorchis angusta Stafford of MacCallum (1921)

It is not clear why MacCallum changed the suffix to feminine. Perhaps an assumption that Telorchis is based on ... [details]