Trieres Ashworth and E.C. Theriot

Sims, Pat A., Williams, David M. & Ashworth, Matt, 2018, Examination of type specimens for the genera Odontella and Zygoceros (Bacillariophyceae) with evidence for the new family Odontellaceae and a description of three new genera, Phytotaxa 382 (1), pp. 1-56 : 5

Trieres Ashworth and E.C. Theriot

Synonym: Microtheca Ehrenberg 1838: 164 , pl. 11, fig. 10a–d, nom. rej. prop.

Although grouped amongst other species that today would be placed in the desmids, Ehrenberg’s genus Microtheca seems to have never been clearly understood. First properly described in his Infusionsthierchen ( Ehrenberg 1838: 164, pl. 11, fig. 10a-d, the text erroneously refers to pl. 12; figure 10b is reproduced as figure 7, 1(1) in Kutorga 1841; Ehrenberg’s figure 10b and d are reproduced in Pritchard 1852: pl. 2, figs 119, 120), Ehrenberg first mentioned the name Microtheca in a short piece on the ‘Leuchtinfusorien’ ( Ehrenberg 1835a: 130, 132, which is an offprint of Ehrenberg 1836: 538, 540). Here Ehrenberg referred to an earlier account when he introduced the name Anuraea? octoceras in connection with Microtheca octoceras ( Ehrenberg 1836: 540) ; Anuraea? octoceras was the name he used when he first thought his specimens to be a rotifer ( Ehrenberg 1834: 55; Ehrenberg 1835b: 199). The question mark and accompanying text indicate he had plenty of reservations. He quickly revised his opinion and determined that these specimens should really be in the ‘Bacillarien’, placed in a genus of their own, within the ‘Desmidiacea’ cluster of genera, rather than a rotifer (which happened to include the genus Odontella, Ehrenberg 1836: 538 , 540; Ehrenberg 1838: 164). There is not much subsequent mention of the genus.

If Microtheca octoceras is synonymous with any particular Odontella -like species then it is probably with something that is now in the genus Trieres . If so, then Microtheca octoceras would have priority for that species’ name. If Microtheca octoceras is synonymous with Biddulphia mobiliensis then it would have priority for both the genus and species name. This is not the best of situations, primarily because no original specimens of Microtheca octoceras have been found or does it seem likely there ever will be. Therefore, we have submitted a proposal to reject the name Microtheca to save any future nomenclatural issues with this genus (Williams, et al. 2017).