New species, new taxon reports and biogeography of the diatom genus Gomphoneis Cleve (Bacillariophyceae) in Patagonia, Chubut Province, Argentina

PATRICK KOCIOLEK; SILVIA SALA; NOELIA UYUA; ADRIÁN CEFARELLI; NORMA SANTINELLI

Quebec

Simposio; 24th International Diatom Symposium; 2016

The diatom genus Gomphoneis Cleve was initially established with 3 species, G. elegans (Grunow) Cleve, G. herculeana (Ehrenberg) Cleve and G. mammilla (Ehrenberg) Cleve, and has grown to currently be comprised of over 75 species worldwide. Kociolek and Stoermer suggested there were two subgroups within the genus, one, including the generic type G. elegans, has either multiple stigmoids or lacks isolated pores in the central area. In addition, the ?Elegans? subgroup has undifferentiated apical pore fields and, if longitudinal lines are present, they are formed by laminae of silica covering the margins and mantle area of the valve. The other subgroup, the Herculeana subgroup, has a single stigma, longitudinal lines formed by an axial plate and differentiated apical pore fields.Gomphoneis has not previously been widely reported in South America. Rivera and colleagues reported G. ?herculeana?, G. herculeana var. robusta (Grunow) Cleve and G. herculeana var. septiceps M. Schmidt from several rivers in Chile, and G.? herculeana? and ?G. minuta?, both from the Herculeana subgroup, have been previously reported from Argentina. Aside from the cosmopolitan species G. olivacea no other species from the Elegans subgroup have previously been reported. Among the diatoms reported from Argentinean Patagonia, no species of Gomphoneis have been previously reported.A recent (November 2015) expedition to Chubut province, Patagonia, to document the presence of the invasive diatom Didymosphenia geminata (Lyngbye) M. Schmidt, resulted in collections in the western portion of the province, and along the Chubut River. We report the presence of 3 species of Gomphoneis from this region, 2 of the Herculeana subgroup, one of which is new to science, and a new species from the Elegans subgroup. Gomphoneis species may be introductions into the region, potentially associated with Didymosphenia, another alien species in the Patagonia region.