ИСТИНА

Genus Cyanea includes some of the most conspicuous and majestic representatives of megaplankton, and throughout the last century its taxonomy has been revised repeatedly due to high morphological plasticity of Cyanea species. Until recently all Cyanea from European Arctic have been identified as C. capillata. Here, we describe a new Cyanea species sympatric to C. capillata. Morphologically Cyanea sp. nov. is easily distinguishable from all described Cyanea species by an eye-spot-bearing bulb in the basal part of each of the eight rhopalia upon the subumbrellar side of the bell, as well as by a unique combination of other morphological traits (the shape of bell margin, structure of gastrovascular system, color and nematocysts clusters on the exumbrellar surface). All the collected specimen of C. tzetlinii sp. nov. were somewhat smaller than C. capillata from the White Sea collected in the same time in the same place. This well-recognizable morphological characteristic is supported at the molecular level by a substantial genetic distance in mitochondrial (CO1: 9.6%-10.6%, 16S RNA: 3.1%-3.5%) as well as nuclear (ITS: 5.0%, 18S RNA: 0.1%) loci, making it the sister species to Cyanea capillata. In the ecological aspect we can note that mature C. tzetlinii sp. nov. form accumulations a bit later, than C. capillata. Taking into account the young geological age of the White Sea and a substantial genetic divergence between C. tzetlinii sp. nov. and the nearest sister species, we suppose that C. tzetlinii sp. nov. has been advected to the White Sea from elsewhere and may also inhabits other Arctic seas.