CRCritically Endangered

gotlandsknagglav

Porpidinia tumidula

The gotlandsknagglav (Porpidinia tumidula) is a small, distinctive marine gastropod endemic to the Baltic Sea region, characterized by its translucent shell with prominent ridged knobs and pale blue-green coloration. This specialized mollusk plays a crucial role in its ecosystem as both a grazer of microscopic algae and biofilms, and as a key food source for various fish species and seabirds.

01Classification

Taxonomy & Classification

Kingdom

Fungi

Phylum

Ascomycota

Class

Lecanoromycetes

Order

Lecideales

Family

Porpidiaceae

Genus

Porpidinia

gotlandsknagglav belongs to the family Porpidiaceae, order Lecideales, within the Lecanoromycetes class.

02Description

Species Profile

The gotlandsknagglav (Porpidinia tumidula) is a small, distinctive marine gastropod endemic to the Baltic Sea region, characterized by its translucent shell with prominent ridged knobs and pale blue-green coloration. This specialized mollusk plays a crucial role in its ecosystem as both a grazer of microscopic algae and biofilms, and as a key food source for various fish species and seabirds.

Porpidinia tumidula faces severe population decline due to habitat destruction from coastal development and pollution in its limited range around Gotland and the Baltic Sea region. Climate change-induced alterations to marine ecosystems and overfishing of prey species have further compromised the species' survival prospects.

Key Facts

IUCN StatusCritically Endangered (CR)
GroupFungi
03Habitat

Habitat & Distribution

Inhabits shallow coastal waters, rocky intertidal zones, and kelp forests around limestone cliffs and coastal areas of Gotland and adjacent Baltic Sea regions. Requires clean, well-oxygenated waters with abundant algae and small invertebrate prey.

TERRESTRIALMajor
04Threats

Threats

!

IUCN Red List: Critically Endangered

Porpidinia tumidula faces severe population decline due to habitat destruction from coastal development and pollution in its limited range around Gotland and the Baltic Sea region. Climate change-induced alterations to marine ecosystems and overfishing of prey species have further compromised the species' survival prospects.

Climate change impacts on marine ecosystems

HighOngoing

Coastal habitat destruction from development

HighOngoing

Marine pollution and eutrophication

HighOngoing

Depletion of prey species from overfishing

MediumOngoing

Limited geographic range vulnerability

MediumOngoing
Community

Community Sightings

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07Sources

Sources & Attribution

How to Cite

IUCN: IUCN (2025). The IUCN Red List of Threatened Species. Version 2025-1. Available at: https://www.iucnredlist.org. doi:10.2305/IUCN.UK.2025-1.RLTS

GBIF: GBIF.org (2025). GBIF Home Page. Available at: https://www.gbif.org

This page: SpeciesRadar (2025). gotlandsknagglav (Porpidinia tumidula). SpeciesRadar: Intelligence for Earth's Biodiversity. Available at: https://speciesradar.org/species/gotlandsknagglav

Full citation guide & data usage terms