Kützing described Biddulphia septemlocularis Kützing (1844, p. 138, pl. 19, fig. II, 1, 2) also from Canary Island material (“Unter Algen von den canarischen Inseln”). The alternative name ‘ septemcostata ’ was used in Eulenstein’s Catalogue of Kützing’s collection, this name being found only in the herbarium; there is also the additional unpublished name ‘ Isthmosira [Isthmia] canariensis ’.

Eulenstein’s Catalogue indicates ‘Kützing 823’ (BM 19390, “Ins Canar.”) was also the source for the original material of Biddulphia septemlocularis. Inspection of the mica for ‘Kützing 823’ reveals only a few complete frustules so no SEM study was attempted.

The images on which this description is based are from BM 19390 (‘Kützing 823’) (Figs 2–6). Inspection of BM 19343 (‘Kützing 766’) yielded no whole specimens of Diatoma liber, the sample being dominated by Grammatophora marina (Lyngbye) Kützing (1844, p. 128, pl. 17, fig. XXIV, 1–6, pl. 18, fig. I, 1–5). The specimens figured are all confirmed as a species of Biddulphia.