Mychonastes frigidus sp. nov. (Sphaeropleales/Chlorophyceae), a new species described from a mountain stream in the Subpolar Urals (Russia)

Abstract

This paper describes a new species from the Class Chlorophyceae, Mychonastes frigidus sp. nov., isolated from a cold-water mountain stream in the north of Russia (Subpolar Ural). The taxon is described using morphological and molecular methods. Mychonastes frigidus sp. nov. belongs to the group of species of the genus Mychonastes with spherical single cells. Comparison of ITS2 rDNA sequences and its secondary structures combined with the compensatory base changes approach confirms the separation between Mychonastes frigidus sp. nov and other species of the genus. Mychonastes frigidus sp. nov. represents a cryptic species that can only be reliably identified using molecular data.

A New Cryptic Species of the Genus Mychonastes (Chlorophyceae, Sphaeropleales)

“…Mychonastes hindakii clustered with colonial M. jurisii and unicellular M. huancayensis on the unrooted ITS2 tree and formed an individual branch ( Figure 3 ). The clade, consisting of two morphologically different species, was also recovered in previous ITS2 analyses [ 11 , 15 ], which contradicts the importance of cell organization in the systematics of Mychonastes. Morphologically, Mychonastes hindakii is most similar to M. jurisii .…”

“…The CBC concept was successfully used for species delimitation in different and independent groups of algae such as cryptophytes [ 38 , 39 ], diatoms [ 40 ], eustigmatophytes [ 41 ] and green algae [ 42 ]. Comparing the secondary structure of ITS-2, compensatory base changes are found to discriminate new species in the Mychonastes clade too [ 11 , 15 ].…”

“…The ITS2 sequences were aligned according to the secondary structure by ClustalW algorithm [ 62 ] in 4SALE [ 63 ]. Delimitations of species secondary structures of Mychonastes strains were checked for compensatory base changes (CBCs) according to Coleman [ 34 , 35 ] and Müller et al [ 36 ] in comparison with species described by Krienitz et al [ 11 ] and Patova et al [ 15 ]. For the phylogenetic analysis, the sequence part from the sequence–structure alignment (as obtained by 4SALE) was further processed using the same programs and methods as described above for the 18S data, except for the model of nucleotide substitution—HKY+G+I.…”

“…Then, Krienitz et al [ 11 ] revised the genus based on morphological observations and SSU and ITS rRNA sequence analyses, described eight new species and transferred the species from the genus Pseudodictyosphaerium Hindák (= Dictyosphaeriopsis Hindák) to Mychonastes . Recently, Patova et al [ 15 ] described another new species from a cold-water stream in the subpolar Urals.…”