Subgenus (Mactromeris) T. A. Conrad, 1868

(3-4-4-0-21-3-2-92-4-0-0-0-0)
Ref. Lindner, 1977 p 111
Wagner, 1984 p 66
Syn. (Mactrodesma) T. A. Conrad, 1869
Ref. Abbott, 1974 p 490
[see also as Genus]

hemphilli (W. H. Dall, 1894)
(3-4-4-0-21-3-2-92-4-1-0-0-0)
Hemphill Surfclam, Hemphill's Mactra
Ref. Abbott & Dance, 1982 p 335 c
Amer. Fish. Soc., 1988 p 40
Lindner, 1977 pl 62 c

polynyma (W. Stimpson, 1860) [T]
(3-4-4-0-21-3-2-92-4-2-0-0-0)
Stimpson's Mactra, Stimpson's Surf Clam
Ref. Abbott & Dance, 1982 p 335 c
Syn. Mactra (Mactra) ovalis A. A. Gould [not G. B. Sowerby, 1817]
Ref. Abbott, 1974 p 490
Syn. Mactra (Mactra) ovalis A. A. Gould, 1840 [not G. B. Sowerby, 1817];
Mactra (Mactra) polynyma W. Stimpson, 1860;
Spisula polynyma alaskana W. H. Dall, 1894
Ref. Wagner, 1984 p 66

polynyma (Stimpson, 1860) (3-4-4-0-21-3-2-92-4-2-1-0-0)

Form alaskana (W. H. Dall, 1894) [f]
(3-4-4-0-21-3-2-92-4-2-1-1-0)
[may be a synonym of Spisula (Mactromeris) polynyma (W. Stimpson, 1860)]
Ref. Abbott, 1974 p 490

voyi (W. M. Gabb, 1868) [f]
(3-4-4-0-21-3-2-92-4-2-2-0-0)
[Miocene or Pliocene]
Ref. Abbott, 1974 p 490

voyi W. M. Gabb, 1868
(3-4-4-0-21-3-2-92-4-3-0-0-0)

korolevae Zhidkova in R. L. Merklin, 1972
(3-4-4-0-21-3-2-92-4-3-1-0-0)
[=Mact
romeris polynyma (W. Stimpson, 1860)]
Ref. Bernard, 1983 p 40