Aquatic remnant of ancient Mediterranean flora: Discovery of Callitriche lenisulca (Plantaginaceae) on the Black sea coast of Russia

Abstract

The subcosmopolitan genus Callitriche is comprised of 50–75 species that can usually be reliably distinguished only by their reproductive characters, a problem that leads to frequent misindentifications. Barcoding of the Callitriche samples, stored in the herbarium of Lomonosov Moscow State University (MW), allowed discovery C. lenisulca on the north-eastern coast of the Black sea in Russia. It is a new species for flora of Russia that was previously known only from the Mediterranean. The revealed locality belongs to the relic ecosystem of arid sub-Mediterranean forests. The observed genetic difference between the Russian sample and the Mediterranean samples suggests independent evolution of Russian population after fragmentation of a more or less continuous ancient Mediterranean vegetation. We also report a new locality for C. lenisulca in Lebanon where the species is a novelty to the Lebanon flora too.