Abstract
Ampharetid polychaetes adapted to live in chemosynthetic environments are well known from the deep Pacific and Atlantic Oceans, but to date no such species have been reported from the Arctic Ocean. Here, we describe two new species, Paramytha schanderi gen. et sp. nov. and Pavelius smileyi sp. nov., from the Arctic Loki’s Castle vent field on the Knipovich Ridge north–east of the island of Jan Mayen. The new species are both tube-builders, and are found in a sedimentary area at the NE flank of the vent field, characterized by low-temperature venting and barite chimneys. The new genus, Paramytha, is characterized by a prostomium without lobes or glandular ridges, smooth buccal tentacles, four pairs of cirriform branchiae arranged as 2+1+1 without median gap dorsally on segments II–IV, absence of chaetae (paleae) on segment II, and absence of modified segments. P. smileyi sp. nov. is placed in the previously monotypic genus Pavelius, primarily based on the presence of a rounded prostomium without lobes and four pairs of branchiae arranged in a single transverse row without median gap dorsally on segment III. Pavelius smileyi sp. nov. differs from the type species, Pavelius uschakovi, in the number of thoracic and abdominal chaetigers, and the absence of chaetae (paleae) on segment II. The phylogenetic position of the two new species from Loki’s Castle is further explored by use of molecular data. New sequences of mitochondrial (16S rDNA and cytochrome c oxidase subunit 1, COI) and nuclear (18S rDNA) markers have been produced for both species from Loki’s Castle, as well as for specimens identified as Paramytha sp. from Setùbal Canyon off Portugal, and for the following species: Pavelius uschakovi, Grassleia cf. hydrothermalis, Sosane wireni, Amphicteis ninonae and Samythella neglecta. Results from phylogenetic analysis, including 22 species and 12 genera of Ampharetidae, recovered Paramytha gen. nov. as monophyletic with maximum support, and a close relationship between the genera Pavelius and Grassleia which together form a well supported monophyletic clade.
Highlights
The family Ampharetidae is the second largest family within the order Terebellida with more than 300 species and 100 genera described (Jirkov, 2011)
We formally describe two new species of Ampharetidae from the Loki’s Castle vent field
c oxidase subunit I (COI) intraspecific genetic distances for Pavelius smileyi sp. nov. was o0.3%, while the closest related species, Grassleia cf. hydrothermalis, differed by 13.1%
Summary
The family Ampharetidae is the second largest family within the order Terebellida with more than 300 species and 100 genera described (Jirkov, 2011). Recent identification of fauna samples from the Arctic Loki’s Castle hydrothermal vent field at 2350 m depth on the Mohn–Knipovich ridge north–east of Jan Mayen has documented a total of 14 species of polychaetes, including two ampharetids. Unlike the more shallow water hydrothermal vent sites in the Arctic (Fricke et al, 1989; Schander at al., 2010), the fauna at Loki’s Castle has been shown to be endemic and highly adapted to the chemosynthetic environment (Pedersen et al, 2010; Tandberg et al, 2012). Only the two dominating polychaetes, the siboglinid Sclerolinum contortum Smirnov, 2000 and the maldanid Nicomache lokii Kongsrud and Rapp, 2012 have been reported
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