Diversity and distribution of Arctic Echinoderes species (Kinorhyncha: Cyclorhagida), with the description of one new species and a redescription of E. arlis Higgins, 1966

Abstract

The kinorhynch fauna from Svalbard and the Arctic Ocean north of Svalbard was explored, and a total of nine species of Echinoderes was identified. Two species were new to science, and one, Echinoderes balerioni sp. nov., is described. Echinoderes balerioni sp. nov. is characterized by the presence of short middorsal spines on segments 4, 6, and 8, and in lateroventral positions on segments 6 to 9. Tubes are present in laterodorsal, sublateral, and ventrolateral positions on segment 2, lateroventral positions on segment 5, and lateral accessory positions on segment 8, and tergal extensions conspicuously long and spiniform. The collected material also offered the first chance to examine specimens of Echinoderes arlis with scanning electron microscopy, which prompted a redescription of the species. The recorded species are compared with all other known records of Echinoderes in the Arctic region, and the summarized data suggests that at least some species show a circumpolar distribution.

Echinoderes pterus sp. n. showing a geographically and bathymetrically wide distribution pattern on seamounts and on the deep-sea floor in the Arctic Ocean, Atlantic Ocean, and the Mediterranean Sea (Kinorhyncha, Cyclorhagida)

“…Species with a geographically wide distribution are e.g., Ce. barbanigra found in the Gulf of Mexico, the Caribbean Sea, Bermuda, and the Dominican Republic at a depth ranging from 2 m to 57.5 m, E. ohtsukai found on both the eastern and western coasts of the Pacific Ocean in the intertidal zone, and E. tchefouensis found in the East China Sea, South China Sea, Celebes Sea, Singapore Strait, and Mariana Islands at a depth ranging from 0 m to 140 m (Sørensen et al 2012b, 2016; Yamasaki and Kajihara 2012; Neuhaus et al 2014; Herranz and Leander 2016). Species from a bathymetrically wide range are e.g., Echinoderes arlis Higgins, 1966, Echinoderes drogoni Grzelak & Sørensen, 2018, Echinoderes eximus Higgins & Kristensen, 1988, Echinoderes peterseni Higgins & Kristensen, 1988, and Echinoderes rhaegali Grzelak & Sørensen, 2018, all found in the Arctic Ocean, at depths ranging from 236 m to 940 m ( E. arlis ), 78 m to 2,200 m ( E. drogoni ), 60 m to 940 m ( E. eximus ), 24 m to 940 m ( E. peterseni ), and 78 m to 940 m ( E. rhaegali ) (Grzelak and Sørensen 2018b). However, their distribution records are not both geographically and bathymetrically wide like those of E. pterus sp.…”

“…To date, more than 260 kinorhynchs species are known from around the world (Grzelak and Sørensen 2018a, b; Yamasaki et al 2018). Many ecological studies on meiofauna from various regions and environments often report the presence of Kinorhyncha, but unfortunately provide only phylum-level identification (e.g., Grzelak and Kotwicki 2012; Nomaki et al 2016; Riera et al 2018).…”

New mud dragons from Svalbard: three new species ofCristaphyesand the first Arctic species ofPycnophyes(Kinorhyncha: Allomalorhagida: Pycnophyidae)

“…16 ). This shows that Pycnophyidae is just as diverse in the Arctic as Echinoderidae, which currently is represented with 13 species in the Arctic ( Grzelak & Sørensen, in press ). Interestingly, Pycnophyidae and Echinoderidae are so far the only two kinorhynch families that have been recorded from the Arctic Region.…”

“… Grzelak & Sørensen (in press) suggested that at least some species of Arctic Echinoderes appeared to show a circumpolar distribution. A similar distribution pattern is not really clear for any of the recorded pycnophyids.…”

“…The kinorhynch fauna of Svalbard has recently been explored during annual meiofauna samplings in the fjords and surrounding waters, through a period from 2013 to 2017. The studies have so far resulted in the description of four new species of Echinoderes ( Grzelak & Sørensen, 2018 , in press ), a redescription of Echinoderes arlis Higgins, 1966 ( Grzelak & Sørensen, in press ), and the finding of four species of Echinoderes that otherwise are only known from West Greenland and Eastern Canada ( Grzelak & Sørensen, 2018 , in press ). The latter finding, together with the record of the Alaskan species E. arlis , prompted ( Grzelak & Sørensen, in press ) to suggest that Arctic Echinoderes species may show a circumpolar distribution.…”