New araphid species of the genusPseudostaurosira(Bacillariophyceae) from southern Patagonia

New and poorly known “araphid” diatom species (Bacillariophyta) from regions near Lake Titicaca, South America and a discussion on the continued use of morphological characters in “araphid” diatom taxonomy

“…In turn, P. zolitschkae M.L. García, S. Bustos, Maidana & E. Morales (in García et al 2021 , p. 11, figs 81–91, 103–109) has the widest range of morphological variability of all taxa included in Table 5 producing smaller valves with clearly biconvex sides and pointy ends. The areolae acquire an 8-shape configuration due to the thick origin of the volae that arise from the longer (transapical) axes of the areolae.…”

“…Due to their cruciform shape, P. australopatagonica M.L. García, L.A. Villacís, Maidana & E. Morales (in García et al 2021 , p. 3, figs 2–35), P. caballeroae V.H. Salinas, D. Mora, R. Jahn & N. Abarca (2020, p. 199, figs 36–50) and P. pseudoconstruens (Marciniak) D.M.…”

“…Frenguelli 1939 ; Servant-Vildary 1986 ; Rumrich et al 2000 ) and not always reflecting topographic, bioclimatic and ecosystem variability, resulting in an incomplete account that often manifests in skewed conclusions regarding the richness and composition of diatom communities in high and lowlands (see discussions in Morales et al 2012b , 2014c , 2020 ). For the existing literature, besides the shortcomings in sampling and geographic coverage, at least for small “araphids”, there is a history of taxonomic drift, misidentification and a severe lack of pictorial support for floristic surveys in different regions of the continent ( Morales et al 2014c ; García et al 2021 ). Misidentification and poor illustration are problems that we have also shown here in the case of P. vulpina appearing in the literature under Fragilaria brevistriata var.…”

“…Through the revision of type material, we have attempted the documentation of traditional and new diagnostic features, expanding original descriptions and confirming or re-ascribing taxa into newly erected genera (such as those in Williams and Round 1987 ). We have also discovered new taxa, described and documented them following the current standards ( Morales 2001 , 2002 , 2003a , b , 2005 , 2006 ; Morales and Edlund 2003 ; Edlund et al 2006 ; Morales and Manoylov 2006a , b ; Morales et al 2005 , 2009 , 2010a , b , c , 2012a , b , 2013a , 2014a , b , 2015 , 2019a , b , 2021 ; Siver et al 2006 ; Cejudo-Figueiras et al 2011 ; Wetzel et al 2013a , b ; Rioual et al 2014 ; Talgatti et al 2014 ; Van de Vijver et al 2014 , 2020a , b ; Almeida et al 2015 , 2016 , 2017 ; Grana et al 2015 , 2018 ; Wetzel and Ector 2015 , 2021 ; Wengrat et al 2016 ; García et al 2017 , 2021 ; Beauger et al 2019 ; Seeligmann et al 2018 ; Guerrero et al 2019 ; Marquardt et al 2021 ). The amalgamation of LM and SEM has been crucial in our work, even though type materials were not always in a good state of preservation.…”