New Arctic Gastrotricha — ThreeChaetonotus(Chaetonotidae) from Longyearbyen (Spitsbergen, Svalbard Archipelago)

Abstract

Gastrotricha is a cosmopolitan phylum of aquatic and semi-terrestrial invertebrates comprising over 820 described species. Virtually no taxonomic or faunistic data exist on freshwater Gastrotricha of the Arctic. So far, 10 studies have recorded Gastrotricha from the entire area of the Svalbard Archipelago; only in two were gastrotrichs determined to the genus and species levels. The remaining studies only reported the presence of Gastrotricha as a phylum. In this article, I present the results of research on freshwater Gastrotricha from the area of fjord Isfjorden (Spitsbergen, Arctic). The collected material contained representatives of 8 species, 2 subgenera of Chaetonotus namely Chaetonotus (Chaetonotus) Erhenberg, 1830 and Chaetonotus (Hystricochaetonotus) Schwank, 1990, two genera namely Chaetonotus Erhenberg, 1830 and Bifidochaetus Kolicka et Kisielewski, 2016, both belonging to the family Chaetonotidae Gosse, 1864 (sensu Leasi and Todaro, 2008). I describe 3 new species from the Chaetonotidae: Chaetonotus (Chaetonotus) jaceki sp. nov., C. (C.) gelidus sp. nov., and C. (C.) svalbardi sp. nov., together with data on the range, frequency and abundance of all noted species. Furthermore, a record abundance of Gastrotricha was noted, amounting to more than one thousand specimens per 1 cm3 of bottom sediment.