Current taxonomic studies on the diatom flora (Bacillariophyceae) of the Bolivian Altiplano, South America, with possible consequences for palaeoecological assessments

Abstract

Abstract. The present investigation is based on detailed taxonomical analyses combining light microscopy (LM), scanning electron microscopy (SEM) and critical reviews of publications and type material. This method revealed a higher number of diatom taxa than that reported for the Altiplano, reports that are based on LM and SEM, but force-fitting the taxa into their European relatives. It also became evident that some taxa often reported from the Altiplano do not occur or are less common in this region and that misidentifications are the consequence not only of force-fitting, but also of misinterpretation of the original protologues and illustrations (taxonomic concept drift). These findings have important repercussions on past palaeoecological assessments for the Altiplano, which have been based on ecological information for taxa developing in ecosystems of highly contrasting conditions. Here we present the case of three araphid diatoms, which were reported as known taxa from Europe and elsewhere, but in fact correspond to taxa described as new for the Altiplano or unpublished taxa. It is recommended that: (1) a flora for this region is developed utilizing sound microscopical data and reviewing pertinent type material, (2) key common taxa used for past palaeoecological studies in the Altiplano are reviewed using a taxonomically thorough and critical method, and (3) future palaeoecological studies for the Andes are supported by prior detailed taxonomical analysis.

Diatomeas holocenas del delta del río Colorado, Argentina. Una aproximación paleoambiental a partir del estudio de “fragilarioides pequeñas”

“…Los obstáculos mencionados constituyen una restricción metodológica para la utilización de estos microfósiles en reconstrucciones paleoambientales, donde las especies constituyen los proxy-data, y la precisión taxonómica es fundamental para extrapolar la información autoecológica a la interpretación (Díaz Pardo et al, 2008;Hermany et al, 2013;Morales et al, 2014). En el registro fósil, los estudios que aplican estos avances en la comprensión de la diversidad de la familia Fragilariaceae han sido escasos.…”

On the geographical distribution and ecology of Pseudostaurosira cataractarum (Bacillariophyceae): new findings in the Palearctic and Neotropic ecozones

“…Thus, they are regarded as good environmental indicators in research projects focused on paleo-and neolimnological conditions. However, investigations on these small araphid diatoms are still problematic and sometimes produce conflicting results (Morales et al , 2014. Some diagnostic characters have similar appearance when analysed only under light microscopy (LM), and this generates taxonomic uncertainties and mistakes regarding distributional and ecological ranges for many taxa identified based on current literature reports.…”

“…For this reason, it became necessary to review and re-examine type material of several taxa using detailed analyses encompassing LM and scanning electron microscopy (SEM) in order to discriminate diagnostic ultrastructural features. The results have generated significant taxonomic changes and a better understanding of the ecology and biogeography of some species (Williams and Round 1987;Round et al 1990;Flower et al 1996;Morales 2001;Morales et al 2001Morales et al , 2010Morales et al , 2014Schmidt et al 2004;Williams and Morales 2010).…”

Fragilariaceae (Bacillariophyta) en humedales de altura de Catamarca (Argentina).

“…Una gran parte de la diatomoflora andina es aún poco conocida y el número de endemismos y de nuevas especies podría ser mucho mayor que lo reportado hasta ahora en la literatura. A pesar de ello, se han descripto numerosos taxones, y se ha registrado un alto número de especies en algunos sitios de los Andes (Maidana & Seeligmann, 2006Maidana et al, 2011;Morales et al, 2009Morales et al, , 2014aRumrich et al, 2000;Seeligmann & Maidana, 2003;Seeligmann et al, 2008, entre otros).…”

“…Esta escasez de información se hace extensiva a Sudamérica donde la carencia es más notoria, especialmente para ambientes de alta montaña. A esto se superpone la deriva taxonómica, que ha llevado a la existencia de más de un concepto para un solo taxón (Morales et al, 2014a). Es por ello que, a pesar de la frecuente ocurrencia de este grupo, falta un análisis detallado que incorpore información tanto de microscopía óptica (MO) como de microscopía electrónica de barrido (MEB) (Morales, 2005) y permita resolver la taxonomía de muchas especies.…”