Encounters with the rare genus Helicosalpa (Chordata, Thaliacea, Salpida), using citizen science data

Species within the genus Helicosalpa are pelagic tunicates with keg-shaped solitary zooids and aggregate zooids in chains (not whorls). They are also among the most rarely collected salps, with most observations from subtropical and tropical regions. Pictures and videos of live, aggregate helicosalp species in situ are rare. As a pilot study, we present material (images and videos) showing previously poorly described characteristics for live, aggregate Helicosalpa virgula, H. cf. komaii and H. cf. younti (e.g. shape and colours of gonads with projections). Our material is based on citizen science data from both Atlantic and Pacific Oceans. Helicosalpa virgula is the only helicosalp species recorded from the Atlantic Ocean, and is considered a circum-(sub) tropical species, with a few recordings in the temperate zone, off the NW coast of Scotland and the NW coast of Spain. We report on Helicosalpa virgula for the first time north to Norway (60–63°N), between Bømlo and Kristiansund. Salp species are seldom reported from nearshore Norwegian waters, although a few salp species are occasionally reported offshore. Some of these nearshore encounters may be due to climate variability, e.g. influx of warmer water mass and/or changing of ocean currents.