New species, new taxon report and biogeography of the diatom genus <i>Gomphoneis</i> Cleve (Bacillariophyceae) in Patagonia, Chubut Province, Argentina

Abstract

The presence of three <i>Gomphoneis</i> species from Chubut Province in Argentina is documented with light and scanning electron microscopy. Two of the taxa, <i>G. patagoniana</i> and <i>G. eriense var. variabilis</i>, are part of the Herculeana subgroup of <i>Gomphoneis. Gomphoneis patagoniana</i> is a newly discovered species and <i>G. eriense var. variabilis</i> is reported from Argentina for the first time. These two species have evident axial plates, differentiated apical pore fields (APFs), a stigmal opening that is round externally and slit-like internally, and areolae that are mostly triradiate in shape. The third species, <i>G. frenguellii</i>, is also newly discovered and described. Presence of four isolated stigmoids, undifferentiated APFs and lack of an axial plate indicates <i>G. frenguellii</i> is a member of the Elegans subgroup of the genus. Presence of these newly described species, and the previously unreported taxon, may also be associated with the invasive species <i>Didymosphenia geminata</i>. Given there is no long history of reports of <i>Gomphoneis</i> in the country and, in the case of <i>G. eriense var. variabilis</i>, its previously known distribution, it is possible that the origin of this <i>Gomphoneis</i> taxon is from western North America.