{"id":274,"date":"2011-12-01T22:54:50","date_gmt":"2011-12-01T21:54:50","guid":{"rendered":"http:\/\/26.405"},"modified":"2011-12-01T22:54:50","modified_gmt":"2011-12-01T21:54:50","slug":"polycera-quadrilineata-and-polycera-faeroensis","status":"publish","type":"post","link":"http:\/\/blogg.vm.ntnu.no\/nudibranchia\/2011\/12\/01\/polycera-quadrilineata-and-polycera-faeroensis\/","title":{"rendered":"Polycera quadrilineata and Polycera faeroensis"},"content":{"rendered":"

We have recently got requests to present some our posts in english, so we start of with this post about our species of Polycera<\/em>.<\/p>\n

During fieldwork at Hitra in October this year we observed an enormous abundance of one of our most common nudibranch species, Polycera quadrilineata<\/em>. Even though this nudibranch is a common sight, we must not forget Polycera faeroensis<\/em>, a similar species with only a handful of observations along the Norwegian coast.
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Polycera quadrilineata<\/em> (M\u00fcller, 1776) and Polycera faeroensis<\/em> Lemche, 1929, are two representatives of a small family of nudibranchs called Polyceridae, which comprises the genera Colga<\/em>, Limacia<\/em>, Palio<\/em> and Polycera<\/em> in norwegian waters. Within this family only Limacia clavigera<\/em> <\/a>and P. quadrilineata<\/em> can be considered to occur commonly here in Norway (north to Lofotoen). Colga<\/em> is a little known genus that has been found from Spitsbergen and the Barents Sea south to Bod\u00f8 along the norwegian coast. Palio<\/em> is represented with two species of which one can be considered rare.<\/p>\n

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Polycera quadrilineata. Photo: Jussi Evertsen<\/figcaption><\/figure>\n

The basis for the family Polyceridae is Polycera quadrilineata<\/em> which in 1776 was described by Otto Friedrich M\u00fcller from the Dr\u00f8bak Sound. This species reaches a length of 40 mm, and is characteristic with its translucent white body with yellow appendages. Firstly, note the 4-6 oral tentacles around the mouth in front of the rhinophores. Secondly, note the yellow blotches scattered around the dorsal side of the body and the yellow broad stripe that completes the tail from the gill bush. Sometimes the yellow blotches melt together forming several continuous stripes integrated with black stripes (zebra-stripes). The species epithet \u201cquadrilineata\u201d given by M\u00fcller is based on such pigmented individuals. Our observations of P. quadrilineata<\/em> from central Norwegian localities indicate that zebra-stripes individuals are rather rare. However, from the west coast of Sweden, Anita Tullrot wrote a PhD dissertation investigating any possible molecular differences between normally pigmented and zebra-striped individuals of P. quadrilineata<\/em>, but could not find species-specific differences.<\/p>\n

In 1929, the Danish malacologist Henning Lemche, found individuals of Polycera<\/em> from the Faroe Islands which did not fit the morphological variations in Polycera quadrilineata<\/em>, and described Polycera faeroensis<\/em>. This species differs in external morphology from P. quadrilineata<\/em> in the number of oral tentacles and the frequency of yellow blotches \u2013 P. faeroensis<\/em> normally has 8-12 oral tentacles while P. quadrilineata<\/em> has 4-6, and the yellow blotches on the dorsal side of the body seem to be absent in P. faeroensis<\/em>.<\/p>\n

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Polycera faeroensis. Photo: Nils Aukan<\/figcaption><\/figure>\n

For a long time Polycera faeroensis<\/em> was only known from the Faroe Islands and the west coast of Sweden, but has in recent times also been found around the British Isles. Here in norwegian waters it was missing until 2004, when we finally found this species from Bud at the coast of M\u00f8re and Romsdal after being informed by Nils Aukan who had taken very good photos of it. In our search of this species we also found specimens previously not published in the scientific collections at the NTNU Museum of Natural History and Archaeology here in Trondheim\u00a0identified by Henning Lemche himself, which showed a distribution from Hjeltefjorden near Bergen to the Trondheim fjord.<\/p>\n

Both species feed on bryozoans like Membranipora<\/em> and Electra<\/em>, and Polycera quadrilineata<\/em> is one of the most common species of nudibranchs you can find in our kelp forests. We assume that P. faeroensis<\/em> can be found in the same habitat as P. quadrilineata<\/em>, but Nils Aukan has informed us that his observations of this species are usually a bit deeper than where he observes P. quadrilineata<\/em>.<\/p>\n","protected":false},"excerpt":{"rendered":"

We have recently got requests to present some our posts in english, so we start of with this post about our species of Polycera. During fieldwork at Hitra in October this year we observed an enormous abundance of one of our most common nudibranch species, Polycera quadrilineata. Even though this nudibranch is a common sight, […]<\/p>\n","protected":false},"author":57,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[179],"tags":[209],"class_list":["post-274","post","type-post","status-publish","format-standard","hentry","category-in-english","tag-polycera"],"_links":{"self":[{"href":"https:\/\/blogg.vm.ntnu.no\/hovedside\/index.php?rest_route=\/wp\/v2\/posts\/274","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogg.vm.ntnu.no\/hovedside\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogg.vm.ntnu.no\/hovedside\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogg.vm.ntnu.no\/hovedside\/index.php?rest_route=\/wp\/v2\/users\/57"}],"replies":[{"embeddable":true,"href":"https:\/\/blogg.vm.ntnu.no\/hovedside\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=274"}],"version-history":[{"count":0,"href":"https:\/\/blogg.vm.ntnu.no\/hovedside\/index.php?rest_route=\/wp\/v2\/posts\/274\/revisions"}],"wp:attachment":[{"href":"https:\/\/blogg.vm.ntnu.no\/hovedside\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=274"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogg.vm.ntnu.no\/hovedside\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=274"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogg.vm.ntnu.no\/hovedside\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=274"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}