Achnantheiopsis Lange-Bert., 1997 accepted as Planothidium F.E. Round & L. Bukhtiyarova, 1996 (original description)
Achnantheiopsis apiculata (R.M.Patrick) Lange-Bert., 1997 accepted as Planothidium apiculatum (R.M.Patrick) Lange-Bertalot, 1999 (new combination reference)
Achnantheiopsis aueri (Krasske) Lange-Bert., 1997 † accepted as  † (new combination reference)
Achnantheiopsis biporoma (M.H.Hohn & Hellerman) Lange-Bertalot, 1997 accepted as Planothidium biporomum (M.H.Hohn & Hellerman) Lange-Bertalot, 1999 (new combination reference)
Achnantheiopsis borneolanceolata Lange-Bert., 1997 accepted as  (original description)
Achnantheiopsis chilensis (Hust.) Lange-Bert., 1997 † accepted as Planothidium chilense (Hustedt) Lange-Bertalot, 1999 † accepted as Achnanthes chilensis Hustedt, 1927 † (new combination reference)
Achnantheiopsis daui (Foged) Lange-Bert., 1997 accepted as Planothidium daui (Foged) Lange-Bertalot, 1999 accepted as Achnanthes daui Foged, 1962 (new combination reference)
Achnantheiopsis delicatula (Kütz.) Lange-Bert., 1997 accepted as Planothidium delicatulum (Kützing) Round & Bukhtiyarova, 1996 accepted as Achnanthidium delicatulum f. delicatulum Kützing, 1844 (new combination reference)
Achnantheiopsis distincta (Messik.) Lange-Bert., 1997 accepted as Planothidium distinctum (Messikommer) Lange-Bertalot, 1999 accepted as Achnanthes distincta Messikommer, 1954 (new combination reference)
Achnantheiopsis dubia (Grunow) Lange-Bert., 1997 accepted as Planothidium dubium (Grunow) Round & Bukhtiyarova, 1996 (new combination reference)
Achnantheiopsis engelbrechtii (Cholnoky) Lange-Berta., 1997 accepted as Planothidium engelbrechtii (Cholnoky) Round & L.Bukhtiyarova, 1996 accepted as Achnanthes engelbrechtii var. engelbrechtii Cholnoky, 1955 (new combination reference)
Achnantheiopsis fonticolanceolata (Lange-Bert. & Schim.) Lange-Bert., 1997 accepted as Planothidium fonticolanceolatum (Lange-Bertalot & Schimanski) Lange-Bertalot, 1999 accepted as Achnanthes fonticolanceolata Lange-Bertalot & Schimanski, 1989 (new combination reference)
Achnantheiopsis fragilarioides (J.B.Petersen) Lange-Bert., 1997 accepted as Planothidium fragilarioides (J.B.Petersen) Round & Bukhtiyarova, 1996 accepted as Achnanthes fragilarioides J.B.Petersen, 1924 (new combination reference)
Achnantheiopsis frequentissima (Lange-Bert.) Lange-Bert., 1997 accepted as Planothidium frequentissimum (Lange-Bertalot) Lange-Bertalot, 1999 (new combination reference)
Achnantheiopsis frequentissima var. magna (F.Straub) Lange-Bert., 1997 accepted as Planothidium frequentissimum var. magnum (F.Straub) Lange-Bertalot, 1999 accepted as Achnanthes rostrata var. magna F.Straub, 1985 (new combination reference)
Achnantheiopsis frequentissima var. minor (Schulz-Danzig) Lange-Bert., 1997 accepted as Planothidium frequentissimum var. minus (Schulz-Danzig) Lange-Bertalot, 1999 accepted as Achnanthes lanceolata f. minor Schulz, 1926 (new combination reference)
Achnantheiopsis grana (M.H.Hohn & Hellerman) Lange-Bert., 1997 accepted as Planothidium granum (M.H.Hohn & Hellerman) Lange-Bertalot, 1999 accepted as Achnanthes grana Hohn & Hellerman, 1963 (new combination reference)
Achnantheiopsis hauckiana (Grunow) Lange-Bert., 1997 accepted as Planothidium hauckianum (Grunow) Round & Bukhtiyarova, 1996 (new combination reference)
Achnantheiopsis haynaldii (Schaarschm.) Lange-Bert., 1997 accepted as Planothidium haynaldii (Schaarschmidt) Lange-Bertalot, 1999 (new combination reference)
Achnantheiopsis heteromorpha (Grunow) Lange-Bert., 1997 accepted as Planothidium heteromorphum (Grunow) Lange-Bertalot, 1999 accepted as Achnanthes heteromorpha var. heteromorpha Grunow in Cleve & Grunow, 1880 (new combination reference)
Achnantheiopsis holstii (Cleve) Lange-Bert., 1997 accepted as Planothidium holstii (Cleve) Lange-Bertalot, 1999 accepted as Achnanthes holstii var. holstii Cleve, 1881 (new combination reference)
Achnantheiopsis joursacensis (Hérib.) Lange-Bert., 1997 accepted as Planothidium joursacense (Héribaud-Joseph) Lange-Bertalot, 1999 accepted as Achnanthes joursacense Héribaud-Joseph, 1903 (new combination reference)
Achnantheiopsis lanceolata (Bréb. ex Kütz.) Lange-Bert., 1997 accepted as Planothidium lanceolatum (Brébisson ex Kützing) Bukhtiyarova, 1999 (new combination reference)
Achnantheiopsis lanceolatoides (Sovereign) Lange-Bert., 1997 (new combination reference)
Achnantheiopsis linkei (Hustedt) Lange-Bert., 1997 accepted as Planothidium linkei (Hustedt) Lange-Bertalot, 1999 accepted as Achnanthes linkei var. linkei Hustedt, 1939 (new combination reference)
Achnantheiopsis magnifica (Hustedt) Lange-Bert., 1997 accepted as Planothidium magnificum (Hustedt) Lange-Bertalot, 1999 accepted as Achnanthes magnifica Hustedt, 1952 (new combination reference)
Achnantheiopsis marina (Hust.) Lange-Bertalot, 1997 accepted as Planothidium marinum (Hustedt) Lange-Bertalot, 1999 accepted as Achnanthes marina Hustedt, 1937 (new combination reference)
Achnantheiopsis minutissima (Krasske) Lange-Bert., 1997 accepted as Achnanthes lanceolata var. minutissima Krasske, 1938 accepted as Planothidium minutissimum (Krasske) Lange-Bertalot, 1999 (new combination reference)
Achnantheiopsis miota (J.R.Carter & Denny) Lange-Bert., 1997 accepted as Planothidium miotum (Carter & Denny) Lange-Bertalot, 1999 accepted as Achnanthes miota Carter & Denny, 1982 (new combination reference)
Achnantheiopsis oestrupii (Cleve-Euler) Lange-Bert., 1997 accepted as Planothidium oestrupii (A.Cleve) Round & L.Bukhtiyarova, 1996 (new combination reference)
Achnantheiopsis peragalloi (Brun & Hérib.) Lange-Bert., 1997 accepted as Planothidium peragalloi (J.Brun & Héribaud-Joseph) Round & L.Bukhtiyarova, 1996 (new combination reference)
Achnantheiopsis pericava (J.R.Carter) Lange-Bert., 1997 accepted as Planothidium pericavum (J.R.Carter) Lange-Bertalot, 1999 accepted as Achnanthes pericava J.R.Carter, 1966 (new combination reference)
Achnantheiopsis pseudotanensis (Cleve-Euler) Lange-Bert., 1997 accepted as Planothidium pseudotanense (Cleve-Euler) Lange-Bertalot, 1999 accepted as Achnanthes pseudotanensis A.Cleve-Euler, 1953 (new combination reference)
Achnantheiopsis pungens (Cleve-Euler) Lange-Bert., 1997 accepted as Planothidium pungens (Cleve-Euler) Lange-Bertalot, 1999 accepted as Achnanthes elliptica var. pungens Cleve-Euler, 1934 accepted as Skabitschewskia pungens (Cleve-Euler) Kulikovskiy & Lange-Bertalot, 2015 (new combination reference)
Achnantheiopsis robusta (Hustedt) Lange-Bert., 1997 accepted as Planothidium robustum (Hustedt) Lange-Bertalot, 1999 (new combination reference)
Achnantheiopsis robustior Lange-Bertalot, 1997 accepted as Planothidium robustius Lange-Bertalot, 1999 (original description)
Achnantheiopsis rostrata (Østrup) Lange-Bert., 1997 accepted as Planothidium rostratum (Østrup) Lange-Bertalot, 1999 (new combination reference)
Achnantheiopsis salvadoriana (Hustedt) Lange-Bert., 1997 accepted as Planothidium salvadorianum (Hustedt) Lange-Bertalot, 1999 (new combination reference)
Achnantheiopsis septentrionalis (Østrup) Lange-Bert., 1997 accepted as  (new combination reference)