**New and poorly known species of the genus Cytherissa Sars, 1925 (Ostracoda, Podocopida, Cytherideidae) endemic to Lake Baikal**

TATYANA M. ALEKSEEVA, ROMAN S. KRIVOROTKIN, OLEG A. TIMOSHKIN — Thu, 07 May 2026 00:00:00 +1200

The authors examined morphological features of 17 species of the genus Cytherissa Sars, 1925 from a collection of endemic Baikal ostracods assembled by the outstanding researcher of Baikal Prof. G.F. Mazepova. Specimens of six little-known species, Cytherissa tuberculata Bronstein, 1930, Cytherissa anisoptera Mazepova, 1990 stat. nov., Cytherissa burchani Mazepova, 1990, Cytherissa puschkarevi Mazepova, 1990, Cytherissa pterygota Bronstein, 1947 and Cytherissa florensovi Mazepova, 1990 were redescribed based on syntypes and other non-type material. The first two species were previously classified as subspecies of one species, C. tuberculata Bronstein, 1930, but analysis of their morphological variations allowed us to reclassify them at a higher taxonomic level as two separate species. All the species were redescribed following ICZN requirements, and for some of them, we designated neotypes, lectotypes and paralectotypes. Careful examination of the collection revealed Cytherissa species unknown to science. Consequently, we prepared descriptions of eleven new species, endemics of Lake Baikal: Cytherissa bondarenkoae Alekseeva & Krivorotkin sp. nov., Cytherissa costata Alekseeva & Krivorotkin sp. nov., Cytherissa gigantea Alekseeva & Krivorotkin sp. nov., Cytherissa koptyugi Alekseeva, Krivorotkin & Timoshkin sp. nov., Cytherissa martensi Alekseeva, Krivorotkin & Timoshkin sp. nov., Cytherissa mazepovae Alekseeva & Krivorotkin sp. nov., Cytherissa obtusa Alekseeva & Krivorotkin sp. nov., Cytherissa pygmaea Alekseeva & Krivorotkin sp. nov., Cytherissa ranaformis Alekseeva & Krivorotkin sp. nov., Cytherissa sagittata Alekseeva & Krivorotkin sp. nov. and Cytherissa schonae Alekseeva & Krivorotkin sp. nov. For eight species, their descriptions are supplemented with illustrations of the valves of juvenile stages. For a detailed morphological analysis of all species, we used light and scanning electron microscopy and provide brief notes on their distribution and ecology.

Zootaxa

New and poorly known species of the genus Cytherissa Sars, 1925 (Ostracoda, Podocopida, Cytherideidae) endemic to Lake Baikal

**New and poorly known species of the genus Cytherissa Sars, 1925 (Ostracoda, Podocopida, Cytherideidae) endemic to Lake Baikal**