Rare colour morphs in the slow worm Anguis fragilis in Norway

The frequency of melanism in Natrix natrix and Vipera berus is known to be high in the Nordic countries. However, melanism in the slow worm Anguis fragilis has previously never been documented in Norway. Here, for the first time, melanism, amelanism, and erythrism in the slow worm in Norway is docu...

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Main Authors: Beate Strøm Johansen, Pål Sørensen
Format: Article
Language:English
Published: Norwegian University of Science and Technology 2025-06-01
Series:Fauna Norvegica
Online Access:https://www.ntnu.no/ojs/index.php/fauna_norvegica/article/view/6274
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author Beate Strøm Johansen
Pål Sørensen
author_facet Beate Strøm Johansen
Pål Sørensen
author_sort Beate Strøm Johansen
collection DOAJ
description The frequency of melanism in Natrix natrix and Vipera berus is known to be high in the Nordic countries. However, melanism in the slow worm Anguis fragilis has previously never been documented in Norway. Here, for the first time, melanism, amelanism, and erythrism in the slow worm in Norway is documented by photographs. There are several observations of erythristic or partly erythristic slow worms with various degrees of red colour as this depends on the amount of erythrocytes in the skin. This leaves some uncertainty about what could be named an erythristic slow worm based on field observations. We used the software CorelDRAW Graphics Suite for the RGB colour profile at the photographs of the slow worms as an extra support for the assessment of reddish colour. Because the photographs were taken under different light conditions and with different cameras, we could not make a defined threshold value to separate normal coloured brown and grey slow worms from erythristic slow worms using this RGB system. However, the RGB values support our visual observations.
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issn 1502-4873
1891-5396
language English
publishDate 2025-06-01
publisher Norwegian University of Science and Technology
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series Fauna Norvegica
spelling doaj-art-1fd468ca16aa4fb3abc74709afdfdaaa2025-08-20T03:10:46ZengNorwegian University of Science and TechnologyFauna Norvegica1502-48731891-53962025-06-014410.5324/fn.v44i0.6274Rare colour morphs in the slow worm Anguis fragilis in NorwayBeate Strøm Johansen0Pål SørensenUniversity of Agder The frequency of melanism in Natrix natrix and Vipera berus is known to be high in the Nordic countries. However, melanism in the slow worm Anguis fragilis has previously never been documented in Norway. Here, for the first time, melanism, amelanism, and erythrism in the slow worm in Norway is documented by photographs. There are several observations of erythristic or partly erythristic slow worms with various degrees of red colour as this depends on the amount of erythrocytes in the skin. This leaves some uncertainty about what could be named an erythristic slow worm based on field observations. We used the software CorelDRAW Graphics Suite for the RGB colour profile at the photographs of the slow worms as an extra support for the assessment of reddish colour. Because the photographs were taken under different light conditions and with different cameras, we could not make a defined threshold value to separate normal coloured brown and grey slow worms from erythristic slow worms using this RGB system. However, the RGB values support our visual observations. https://www.ntnu.no/ojs/index.php/fauna_norvegica/article/view/6274
spellingShingle Beate Strøm Johansen
Pål Sørensen
Rare colour morphs in the slow worm Anguis fragilis in Norway
Fauna Norvegica
title Rare colour morphs in the slow worm Anguis fragilis in Norway
title_full Rare colour morphs in the slow worm Anguis fragilis in Norway
title_fullStr Rare colour morphs in the slow worm Anguis fragilis in Norway
title_full_unstemmed Rare colour morphs in the slow worm Anguis fragilis in Norway
title_short Rare colour morphs in the slow worm Anguis fragilis in Norway
title_sort rare colour morphs in the slow worm anguis fragilis in norway
url https://www.ntnu.no/ojs/index.php/fauna_norvegica/article/view/6274
work_keys_str_mv AT beatestrømjohansen rarecolourmorphsintheslowwormanguisfragilisinnorway
AT palsørensen rarecolourmorphsintheslowwormanguisfragilisinnorway