Identificaciones de marinaandreeva

Photos 1-4 - Coregonus albula was caught in Plesheevo Lake 24.07.2020 in the course of research work of Papanin Institute for Biology of Inland Waters (Russian Academy of Sciences) staff.
Picture 5 - Coregonus albula from Plesheevo (Pereslavskoe) Lake (marked as Coregonus albula pereslavicus) 166 mm long, dated 02.12.1931. The picture is from the book of L.S. Berg "Freshwater Fishes of the USSR and the Neighboring Countries" (Part 1, Pages 326-329 (Academy of Sciences of the USSR Publications, 1948).

Plesheevo Lake isolated relict population of Coregonus albula in some sources is described as subspecies of Coregonus albula - Coregonus albula pereslavicus Borisov, 1924 (Coregonus albula pereslavicus Webpage of A.N. Severtsev Institute of Ecology and Evolution of the Russian Academy of Sciences (in Russian): http://www.sevin.ru/redbooksevin/index.html?content/188.html)

Biotope info: http://life-on-earth.ru/evropejskaya-chast-rossii/ozero-pleshcheevo-yaroslavskaya-obl

Our iNaturalist colleague Gianmarco Virga (https://www.inaturalist.org/people/gianvir) looking through my photos of Cobitis of Plesheevo Lake could identify two species: Cobitis taenia and Cobitis melanoleuca. He also informed me about differences in morphology of these two Cobitis species and his hypothesis concerning possibility of introgression between them:
“One of the unique morphological features of each Cobitis species are the "Gambetta's zone", a.k.a. the dark stripes areas which compose the flanks livery pattern: in C. melanoleuca the Gambetta's zone Z4 (the one near the ventral area) is composed of large and wide dark spots almost making a continuous dark line, while in C. taenia in this zone there are small, separated and well defined dark spots. In addition these two species can be easily identified looking at the dark spots position near the caudal peduncle. Since C. melanoleuca range include Volga and Don drainage basins, I think that there can be the chance of introgression between these two Cobitis species, but actually nobody as described a C. melanoleuca x C. taenia hybrid in scientific literature”.

Additional info - FishBase (a global species database of fish species): https://www.fishbase.de/summary/Cobitis-taenia.html

Videos of Cobitis in this location:
https://youtu.be/sEAujZ7gZXY

https://youtu.be/yG0lJIPsu7s

Biotope info: http://life-on-earth.ru/evropejskaya-chast-rossii/ozero-pleshcheevo-yaroslavskaya-obl