Kurtkrammeria, a new genus of freshwater diatoms (Bacillariophyta, Cymbellaceae) separated from Encyonopsis

Abstract

The new genus Kurtkrammeria is erected to include 13 species assigned to Encyonopsis that have (1) slit-like or crescent-shaped areolae aligned lengthwise along the apical axis, (2) striae convergent at the apices, and (3) internal proximal raphe ends hooked strongly towards the dorsal side of the valve. Some species of Kurtkrammeria also have dorsal stigmata, apical pore fields and internal anastomosing costae at both poles, and lateral papilla-like projections from intercostae into internal areola openings. Species of Kurtkrammeria are reported infrequently from fossil deposits and from recent diatom assemblages. Kurtkrammeria is a genus of remote and undeveloped regions from the Arctic to the Tropics, in both the Old World and New World. Most species are local or regional endemics and only four species -K. aequalis, K. neoamphioxys, K. recta, and K. subspicula -appear to be widely distributed. Kurtkrammeria species consistently occur in oligotrophic or dystrophic waters with very low specific conductance and circumneutral pH. An extant population of the very rare Kurtkrammeria stodderi is described from Montana, USA. Living cells of K. stodderi were observed to be motile and to have plastids similar to those of Encyonema species. Examination under SEM reveals that K. stodderi also has apical pore fields at both poles.

Valve ultrastructure of two species of the diatom genus Gomphonema Ehrenberg (Bacillariophyta) from Yunnan Province, China

“…Diversity of internal stigma openings of a magnitude similar to Gomphonema is shown in the genus Cymbella, another genus, like Gomphonema, with over 2,000 named taxa (Kociolek et al 2019). The diversity of features demonstrated in Gomphonema by a wide range of authors seems to suggest that genus is ripe for a major revision, as was done for Cyclotella sensu lato (Lowe 1975;Theriot et al 1987;Hakansson & Khursevich 1997;Khursevich & Kociolek 2002;Houk & Klee 2004;Khursevich & Kociolek 2012;Kociolek et al 2016b;Acs et al 2016;), Navicula sensu lato (Lange-Bertalot 2001), Eunotia sensu lato (Metzeltin & Lange-Bertalot 2007;Taylor et al 2014;Burliga et al, 2013;Wetzel et al 2012;Wetzel & Kociolek 2018) and Cymbella Krammer 1997Krammer , 1999Krammer , 2003Metzeltin et al 2009;Bahls 2015;Kapustin et al 2017).…”

Periphytic diatoms from an oligotrophic lentic system, Piraquara I reservoir, Paraná state, Brazil

“…Diatom identification was performed up to the lowest level of taxonomic hierarchy based on recent and classic literature (e.g. Lange-Bertalot 1993, 1999, 2001, 2005, Bahls 2015. For each taxon, we included information on morphometry, remarks on the autoecology (when available in literature) as well as on the occurrence in the samples (see also table 2).…”

Analysis and critical evaluation of structural features in four Cymbellaceae taxa from New Caledonia

“…Manguin (1962) and Maillard (1978) included all biraphid taxa showing a dorsiventral symmetry within the genus Cymbella. In the past 20 years however, the genus has been split into several new or resurrected genera (Krammer 1997a(Krammer ,b, 2002(Krammer , 2003Jüttner et al 2010;Kulikovskiy et al 2012;Bahls 2015;Kulikovskiy & Kuznetsova 2016;Kaspustin et al 2017). Recently, Wynne (2018) found out that one of the newly described genera, Delicata Krammer, was invalidly described and replaced it by the genus Delicatophycus Wynne.…”