Hide and seek on the central Kuril Island Simushir: Firstly recorded vascular plant species are confined to specific scattered habitats

The central part of the Kuril Archipelago (the Russian Far East) remains the least studied due to its poor accessibility. Such insufficient floristic data lead to uncertainties in the floristic subdivision of the Kuril Islands. We aimed to explore the vascular flora of the Simushir island, the largest one among the Middle Kurils. We revealed 24 new species for the flora of Simushir or Middle Kurils in general, including three species (Callitriche anceps, Carex meyeriana, and Ribes nigrum) that are new for the whole Kuril Archipelago. One-third of species new for Simushir are alien. Almost all the rest of the new species are associated with special types of habitats and can be found only after a detailed study of the island. We reported six new aquatic species for the Middle Kurils, refuting the earlier idea of extreme poverty of the Middle Kurils' aquatic flora. We found no grounds for drawing a floristic border within the Northern and Middle Kurils, as the floristic similarity between Onekotan (oceanic Northern Kurils), continental Northern Kurils, and Simushir has the same magnitude. (c) 2021 National Science Museum of Korea (NSMK) and Korea National Arboretum (KNA), Publishing Services by Elsevier. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

Researchers explored the vascular flora of the Simushir island in the central part of the Kuril Archipelago and discovered 24 new species, including three new species for the entire Kuril Archipelago. The study showed that one-third of the new species found on Simushir island are alien, and there is no distinct floristic border between the Northern and Middle Kurils. Additionally, the study revealed that the Middle Kurils' aquatic flora is not as impoverished as previously believed.