ИСТИНА

The results of our phylogenetic reconstructions of the tribe Polygoneae based on nuclear ITS 1-2 sequences are compared with morpholological data, with special attention to Atraphaxis L. Incuding in the analysis 161 sequences of the tribe Polygoneae we clarified the phylogenetic relationships of Atraphaxis and Polygonum. Phylogenetic trees were constructed by a maximum likelihood (ML) method with RAxML-7.2.6. using the GTRGAMMA model of nucleotide substitution and 500 bootstrap replications. Polygonum ovczinnikovii is a sister to the clade of Atraphaxis while four more species previously attributed to Polygonum took their places among typical members of Atraphaxis. Polygonum ovczinnikovii, P. toktogulicum, P. atraphaxiforme, P. tortuosum, and P. arianum have perianths typical for Polygonum, divided to ½-3/4 in 5 ovate, elliptical or oblong tepals, keeled and expanded at ends in P. arianum. Both variants of perianth structure can be treated as intrageneric polymorphism. Pollen grains of P. arianum, P. atraphaxiforme, P. tortuosum and P. toktogulicum are very similar to pollen of Atraphaxis. All of them have striato-perforate or striato-reticulate sporoderm/Sporoderm sculpture of Polygonum ovchinnikovii is similar to P. toktogulicum, but striae are indistinct – the surface is foveolate with foveola of different size and forms, mostly 4-5-6-angular, sometimes perforated at the bottom. Taking into account similarity of growth form, inflorescence structure, perianth and pollen morphology, the sister position to Atraphaxis in ITS 1-2 tree, we consider P. ovchinnikovii as Atraphaxis ovczinnikovii (Czuk.) Yurtseva, probably representing a new section Ovczinnikovia (Czuk.) O.V.Yurtseva.