Achnanthes calamae Frenguelli, 1930 (additional source)
Achnanthes delicatula var. pacis Frenguelli, 1923 (additional source)
Achnanthes herteri Frenguelli, 1933 (additional source)
Amphiprora lata var. sinuosa Frenguelli, 1938 (additional source)
Amphora capitellata Frenguelli, 1938 (basis of record)
Amphora lybica f. major J.Frenguelli, 1923 (additional source)
Amphora oscitans Frenguelli, 1936 (status source)
Amphora rostrigera Frenguelli, 1936 (status source)
Anomoeoneis sphaerophora var. angusta Frenguelli, 1934 † (additional source)
Caloneis mendosina var. minor Frenguelli, 1934 † accepted as Caloneis mendosina Frenguelli, 1934 (additional source)
Cyclotella stipata Frenguelli, 1942 accepted as Guarreraea stipata (Frenguelli) Kociolek & Guerrero in Guerrero et al., 2018 (additional source)
Cymbella clericii Frenguelli, 1923 (additional source)
Cymbella rigida Frenguelli, 1942 accepted as Cymbella helvetica Kützing, 1844 (additional source)
Delphineis tiltilensis (Frenguelli) Sar & Sala, 2009 † (new combination reference)
Fragilaria brevistriata var. obtusa Frenguelli, 1933 (status source)
Fragilaria fonticola var. tetragona Frenguelli, 1942 (additional source)
Frustulia calamensis Vouilloud & Guerrero, 2021 (source of synonymy)
Gomphonema augur var. capitulata Frenguelli, 1923 (additional source)
Gomphonema frickei O.Müller, 1905 (additional source)
Gomphonema gallaudi var. araucaniana Frenguelli, 1934 † (additional source)
Gyrosigma neglectum Frenguelli, 1938 (additional source)
Hantzschia amphioxys var. inversa Frenguelli, 1942 (additional source)
Hantzschia araucaniana Frenguelli, 1934 † (additional source)
Luticola mutica var. lanceolata (Frenguelli) M.Aboal, 2003 accepted as Luticola lanceolata (Frenguelli) Levkov, Metzeltin & A.Pavlov, 2013 (additional source)
Mastogloia pumila var. tetramera Frenguelli, 1938 (additional source)
Navicula aperta Frenguelli, 1923 accepted as Pinnularia aperta var. aperta (Frenguelli) F.W. Mills, 1934 (additional source)
Navicula bacterium Frenguelli, 1923 (additional source)
Navicula capitulata var. punensis Frenguelli, 1939 (additional source)
Navicula clericii Frenguelli, 1923 accepted as Pinnularia Clericii (Frenguelli) Mills, 1934 (additional source)
Navicula cordillerae Frenguelli, 1942 (additional source)
Navicula craticularis Frenguelli, 1933 (additional source)
Navicula dicephala var. sannicoensis Guerrero & Vouilloud, 2021 (additional source)
Navicula fuegiana var. yberiensis Frenguelli, 1933 (status source)
Navicula grimmei var. producta Frenguelli, 1942 (additional source)
Navicula guayqueriae Frenguelli, 1934 (additional source)
Navicula helea Frenguelli, 1933 (status source)
Navicula mendosina Frenguelli, 1934 † (additional source)
Navicula miramaris Frenguelli, 1925 (additional source)
Navicula mutica var. constricta Frenguelli, 1941 (additional source)
Navicula peregrina var. curta Frenguelli, 1923 † (additional source)
Navicula pseudannulata Frenguelli, 1941 (additional source)
Navicula pseudocari var. minor Frenguelli, 1942 (additional source)
Navicula riojae var. punctata Frenguelli, 1941 (additional source)
Navicula rioplatensis Guerrero & Vouilloud, 2021 (additional source)
Navicula trolopensis Frenguelli, 1942 (additional source)
Navicula ventricosa var. elliptica Frenguelli, 1923 accepted as  (additional source)
Nitzschia levis Frenguelli, 1923 (additional source)
Nitzschia sublinearis var. major Frenguelli, 1942 (additional source)
Nitzschia vitrioides Frenguelli, 1923 (additional source)
Pinnularia andina Frenguelli, 1942 (additional source)
Pinnularia appendiculata var. major Frenguelli, 1942 (additional source)
Pinnularia bogotensis var. patagonia Frenguelli, 1942 (additional source)
Pinnularia cordillerae Frenguelli, 1942 (additional source)
Pinnularia crucicula Frenguelli, 1942 (additional source)
Pinnularia delicata Frenguelli, 1942 (additional source)
Pinnularia divergens var. subcapitata Frenguelli, 1942 (additional source)
Pinnularia gracilens Frenguelli, 1942 (additional source)
Pinnularia graciloides var. krasskei Frenguelli, 1942 accepted as Pinnularia lange-bertalotii K.Krammer, 1992 (additional source)
Pinnularia lamaroana Guerrero & Vouilloud, 2021 (additional source)
Pinnularia microstauron var. major Frenguelli & Cordini, 1937 † (additional source)
Pinnularia neuquina Frenguelli, 1942 (additional source)
Pinnularia streptoraphe var. subacuta Frenguelli, 1942 (additional source)
Pseudonitzschia australis Frenguelli, 1939 (additional source)
Scoliopleura lorami Frenguelli, 1928 † (additional source)
Tabularia platensis (Frenguelli) Sar & Sala, 2009 (source of synonymy)
Tabularia platensis var. obusa (Frenguelli) Sar & Sala, 2009 † (new combination reference)
Tryblionella rustica Frenguelli, 1953 (additional source)