Chara lipkinii (Charales, Charophyceae): a new dioecious Mediterranean species under risk of extinction in the wild and some implications for the taxonomy of the genus Chara

A new species, Chara lipkinii, was described based on specimens from the Mediterranean, Israel. Dioecy, 10–13 branchlets in a whorl, complete tylacanthous to isostichous displostichous axial cortex with very short solitary spine cells, hardly visible diplostephanous bistipulate short obtuse stipulodes, frequently appearing as haplostephanous, in combination with completely ecorticate branchlets without cortex initials and with 1–3, mainly two nodes with unilateral bract cells distinguish it from species of Chara described to date. Its morphological traits, which are most important in the infrageneric taxonomy described by Wood, point towards its placement in the subsection Chara, rather than its distant clustering with both Chara and Grovesia. The oospore surface of C. lipkinii showed no features allowing identification based on oospore morphology only, but could be useful to distinguish it from some species. According to our analyses, the genetic affinity of species based on rbcL and ITS1 mostly does not support infrageneric division of the genus Chara based on morphological traits. Chara lipkinii is a freshwater and brackish water species, growing in small shallow inland water bodies and streams in the Eastern Mediterranean, i.e., in one of the most threatened water bodies of the region. The species faces a very high risk of extinction in the wild. It has disappeared from all previously discovered localities, which no longer support charophyte populations. The gradual decline and disappearance of living plants from one recently discovered locality of C. lipkinii were observed as a result of heavy sediment accumulation and eutrophication. Urgent action to restore the habitat needs to be taken.