Description of Aneumastus Mongolotusculus Sp. Nov

Nova Hedwigia, Beiheft 148, p. 21–33 C Stuttgart, February 2019

Description of Aneumastus mongolotusculus sp. nov. (Bacillariophyceae, Mastogloiales) from Lake Hovsgol (Mongolia) on the basis of molecular and morphological investigations

Yevhen Maltsev1, Svetlana Andreeva1, Julia Podunay2 & Maxim Kulikovskiy1*

1 Institute of Plant Physiology, Russian Academy of Sciences, Moscow, 127276, Russia 2 Karadag Scientiﬁ c Station – Nature Reserve, Russian Academy of Science, Nauki 24, Kurortnoe, 298188 Feodosiya, Russia * Corresponding author: [email protected]

With 24 ﬁ gures and 1 table

Abstract: For the ﬁ rst time, the phylogenetic position of the genus Aneumastus D.G. Mann & Stickle is studied using molecular methods. In this manuscript we describe a new species, Aneumastus mongolotusculus Maltsev, Andreeva & Kulikovskiy sp. nov. from Lake Hovsgol in Mongolia, based on molecular and morphological investigations. The phylogenetic analysis (region V4 18S rDNA and partial rbcL gene) of the genus Aneumastus shows that the new taxon is closely related to the genus Mastogloia Thwaites and that Aneumastus should be included in the order Mastogloiales erected by Round et al. (1990).

Key words: diatoms, Aneumastus, morphology, phylogeny, Mongolia. Introduction After the description of Navicula Bory in 1822, many species were added to the genus. They were classifi ed there because they shared bilateral symmetry and had a central raphe system, but lacked other special diff erentiating characteristics (Cox & Williams, 2006). With the development of electron microscopy, as well as the study of live diatom cells, greater morphological diversity within this genus became evident, and numerous taxonomic revisions were carried out. Species previously assigned to Navicula sensu lato were transferred to new genera, such as Luticola D.G. Mann, Envekadea Van de Vijver, Gligora, Hinz, Kralj & Cocquyt, Mayamaea Lange- Bertalot, Fistulifera Lange-Bertalot, Ochigma Kulikovskiy, Lange-Bertalot & Metzeltin, Khursevichia Kulikovskiy, Lange-Bertalot & Metzeltin, Cavinula D.G. Mann & Stickle, and Lyrella Karayeva (Round et al., 1990; Lange-Bertalot, 1997; Gligora et al., 2009; Nevrova et al., 2013; Kulikovskiy et al., 2014; Kulikovskiy & Kuznetsova, 2016; Maltsev et al., 2017). At the same time, several forgotten genera were revived, including Sellaphora Mereschkowsky and Placoneis Mereschkowsky (Cox, 1987; Mann, 1989). The genus Aneumastus D.G. Mann & Stickle was described in 1990 with the type species, Aneumastus tusculus (Ehrenberg) D.G. Mann & Stickle (= Navicula tuscula Ehrenberg). Aneumastus is a small freshwater or brackish genus, which possesses two fore and aft chloroplasts that are H-shaped in girdle view, open porous girdle bands and complex areolae occluded by cribra, but not hymenes (Round et al., 1990; Spaulding et al., 2003; Cox, 2006). Aneumastus was considered to be closely related to species of Mastogloia Thwaites, because of chloroplast type and some aspects of valve morphology, with the exception of partectal chambers on the valvocopulae like in Mastogloia (Round et al., 1990). Therefore, in their diatom classifi cation scheme, Aneumastus was placed together with Mastogloia within the family Mastogloiaceae, order Mastogloiales (Round et al., 1990). However, the phylogenetic position of Aneumastus using molecular approaches has not yet been studied.