Bythotrephes arcticus Lilljeborg, 1901

Korovchinsky, Nikolai M., 2020, Description of a new species in the genus Bythotrephes Leydig, 1860 (Crustacea Cladocera: Onychopoda), supplements to selected species, and concluding remarks on the genus, Zootaxa 4789 (2), pp. 441-465 : 449-450

Bythotrephes arcticus Lilljeborg, 1901

Material examined: Russia ( Kola Peninsula , Murmansk Region): 1) samples ( SMNH N 156548 and N 158654

labeled “ Bythotrephes , Russia, Kola Peninsula, Lumbowski, lakes in the tundra, leg. Sandebergska Exp. 1877, sta. 68” (old label: “N 2467, Sandebergs Exp., Lumbowski, sjoarpåtundran, 11/8 1877, Bythotrephes …? Lilljeborg”, 2 ad and 1 juv. and 1ad, respectively; 2) sample SMNH N 156571 labeled “ Bythotrephes , Russia, Kola peninsula, Karabella on Ribatski, leg. Sandebergska Exp. 1877” (old label: “N 2468, Sandebergs Exp., Karabella på Rebatochki, 1/9 1877, Bythotrephes n. sp. Lilljeborg”), 1 ad; 3) sample SMNH N 158285 labeled “ Bythotrephes ” (old label: “N 2863 Sandebergs Exp., Karabella, 30–31/7 1877 ”), 11ad, 1 juv; 4) sample SMNH N 158645 labeled “Russia, Karabella, Kola, så sötvattensjöar på Tundran, 31/7 1877, Sandeb. Exp. Trybom”, 2 ad; Sweden (Norrbotten): 5) sample SMNH N 158372 labeled “Torneträsk, E of Ortojokk mouth, 28/7 1920, O. Wettsbein”, 8 ad, 1 gam.

Remarks. All these specimens, except those of the latter sample, were certainly used by Lilljeborg (1901) for investigation and description of B. arcticus (“ B. longimanus var. arcticus ”) and therefore they can be considered as belonging to the type series of the taxon (ICZN, 72.4.1., 72.5.), named syntypes (ICZN, 73.2.) (see Korovchinsky 2016), and further can be designated paralectotypes (ICZN, 74.1.3).

It is necessary to note that initially Lilljeborg considered the taxon a new species (see label of sample 2) but later he downgraded its status to a variety of B. longimanus (see Lilljeborg 1901).

In total, the studied specimens originated from the regions where the species was recorded before (see Korovchinsky 2016) on the Kola Peninsula (North-Western Russia) and in the north of Sweden.