Re-examination of type material of Melosira perpusilla Frenguelli (Bacillariophyta) and description of two new Aulacoseira species from Santa Cruz Province (Argentina).

MAIDANA, N. I.; GARCÍA, MARÍA LUJÁN; MORALES, E. A.; GUERRERO, JOSE M.

Berlin

Simposio; 25th International Diatom Symposium ? Berlin 2018; 2018

Botanic Garden and Botanical Museum Berlin Freie Universität Berlin

During analyses of lacustrine sediments for palaeoenvironmental reconstructions, the occurrence of new species with unknown ecological requirements become a challenge for an accurate interpretation of the diatom record. Working on diatom taxonomy in an isolated region such as southern Patagonia is a complicated task due to lack of supporting bibliography. The use of references for the Northern Hemisphere has caused identification errors since southern taxa have been force-fitted into European and North American concepts. In the case of the genus Aulacoseira, there is a long history of misidentifications due to use of literature for other continents and a renewed interest in this group has produced a number of new taxa and the documentation of known taxa (Tremarin et al. 2014, Morales et al. 2015, Casa et al. 2017). In the present work, we examine the type material of Melosira perpusilla Frenguelli, analyse its transfer to Aulacoseira and provide the basis for the description of two new small species of Aulacosiera found in sediment samples from Laguna Verde (49.20°S; 72.98°W) located in southern Santa Cruz province (Patagonia, Argentina). We present light and scanning electron microscopy data for the three taxa and a comparison with similar species.