Silva Center for Phycological Documentation: Index Nominum Algarum

The INA is a card file and online reporting system maintained at the Silva Center for Phycological Documentation of the University Herbarium, University of California, Berkeley. It contains nearly 200,000 names of algae (in the broad sense). The BPU is a card file containing bibliographic references pertaining to algal taxonomy.
A working list of algal type specimens at UC is available here

Results from INA database

Navicula tusculaEhrenberg Ber. Bekanntm. Verh. Königl. Preuss. Akad. Wiss. Berlin 1840: 215 1840
Navicula tuscula f. angulataHustedt Arch. Hydrobiol. 39: 120, fig. 37 1942
Navicula tuscula f. intermediaKisselev Trudy Nauchno-Issl. Inst. Bot. 7: 87, 93, figs. 10-13 1932
Navicula tuscula f. longerostrataAnt. Mayer Denkschr. K.-Baier. Bot. Ges. Regensburg 19: 149, pl. I: fig. 9 1933
Navicula tuscula f. minorHustedt image
Navicula tuscula f. minorHustedt in Pascher Süssw.-Fl. 10, 2.Aufl.: 308, fig. 553 1930
Navicula tuscula f. minorSimonsen image
Navicula tuscula f. obtusa(Hustedt) Hustedt in Pascher Süssw.-Fl. 10, ed. 2: 309 1930
Navicula tuscula f. rostrata(Hustedt) Hustedt in Pascher Süssw.-Fl. 10, ed. 2: 308 1930
Navicula tuscula f. rostrataHustedt image
Navicula tuscula var. arata 'Grunow' image
Navicula tuscula var. arataGrunow image
Navicula tuscula var. dense-punctataCleve-Euler image
Navicula tuscula var. densistriataSkvortzov image
Navicula tuscula var. mediaJurilj image
Navicula tuscula var. obtusaHustedt Int. Rev. Hydrobiol. u. Hydrogr. 10: 242 1922
Navicula tuscula var. rostrataHustedt Abh. Naturw. Ver. Bremen 20: 287, pl. III: fig. 22 1911
Navicula tuscula var. schinziiLimanowska Arch. Hydrobiol. 7: 365, fig. 2 1912
Navicula tuscula var. stroesei ěstrup image
Navicula tuscula var. stroesei_(`strösei')Østrup Danske Diat.: 84 1910