Fottea X:X | DOI: 10.5507/fot.2026.001

Cryptic diversity in the marine diatom genus Climaconeis (Berkeleyaceae, Bacillariophyta) with description of Climaconeis aucklandensis sp. nov.

Rinat M. Gogorev1, Olga Davidovich2, Nickolai Davidovich2, Yekaterina Bedoshvili3, Vyacheslav Yu. Nikulin4, Arthur Yu. Nikulin4
1 Laboratory of Algology, Komarov Botanical Institute, Russian Academy of Sciences, St. Petersburg, 197022, Russia
2 T.I. Vyazemsky Karadag Scientific Station - Nature Reserve of RAS - Branch of A.O. Kovalevsky Institute of Biology of the Southern Seas, Russian Academy of Sciences, Feodosia, 298188 Russia
3 Limnological Institute, Siberian Branch, Russian Academy of Sciences, Irkutsk, 664033, Russia
4 Federal Scientific Center of the East Asia Terrestrial Biodiversity, Far Eastern Branch of the Russian Academy of Sciences, Vladivostok, 690022, Russia

Clonal cultures of the diatom genus Climaconeis from the Black Sea (Crimea), Mediterranean Sea (Anatolia), Atlantic Ocean (Canary Islands), and Southwest Pacific Ocean (Auckland, New Zealand) were investigated. The Auckland population is described as Climaconeis aucklandensis sp. nov., distinguished by 4-12 H-shaped plastids per cell, a larger valve size range, and different stria density. We used morphological (LM, SEM, TEM, LSM), molecular (rbcL), and ecophysiological (salinity tolerance) analyses to characterize C. aucklandensis, C. scalaris, and Climaconeis cf. scalaris. Black Sea and Atlantic specimens resembled C. scalaris but differed diagnostically. New Zealand strains were morphologically close to C. undulata but genetically distinct. Sexual compatibility was confirmed between Black Sea and Mediterranean populations. Three species delimitation methods (ASAP, PTP, GMYC) identified six genetic lineages, supporting significant cryptic diversity within the genus.

Keywords: Climaconeis aucklandensis, Climaconeis scalaris, morphology, plastids, raphid naviculoid diatoms, rbcL phylogeny, taxonomy

Received: July 30, 2025; Revised: November 18, 2025; Accepted: January 19, 2026; Prepublished online: September 9, 2026 

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