Biddulphia alternans (Bailey) Van Heurck, 1885 accepted as Trigonium alternans (Bailey) A.Mann, 1907 accepted as Triceratium alternans f. alternans J.W. Bailey, 1851
Biddulphia bailey W. Smith, 1856 accepted as Biddulphia mobiliensis (J.W.Bailey) Grunow, 1882 accepted as Trieres mobiliensis (J.W.Bailey) Ashworth & E.C.Theriot in Ashworth, Nakov & E.C.Theiriot, 2013
Biddulphia biddulphiana (J.E.Smith) Boyer, 1900
Biddulphia mobiliensis (J.W.Bailey) Grunow, 1882 accepted as Trieres mobiliensis (J.W.Bailey) Ashworth & E.C.Theriot in Ashworth, Nakov & E.C.Theiriot, 2013
Biddulphia obtusa (Kützing) Ralfs, 1861 accepted as Odontella obtusa Kützing, 1844
Biddulphia pulchella S.F.Gray, 1821 accepted as Biddulphia biddulphiana (J.E.Smith) Boyer, 1900
Biddulphia reticulum (Ehrenberg) Boyer, 1900 accepted as Triceratium reticulum f. reticulum Ehrenberg, 1844
Biddulphia sinensis Greville, 1866 (uncertain > unassessed )
Isthmia enervis Ehrenberg, 1838
Isthmia nervosa Kützing, 1844
Trigonium alternans (Bailey) A.Mann, 1907 accepted as Triceratium alternans f. alternans J.W. Bailey, 1851