The theme of this year's EUROPA stamps is "Underwater Fauna & Flora". Slovenia has issued 2 stamps for this years Europa showing a Nobel Pen Shell and a Water Beetle.
Noble pen shell (Pinna nobilis)
The noble pen shell (Pinna nobilis) is a Mediterranean endemic species and the largest bivalve mollusc in the Mediterranean Sea. Its shell rate growth is among the fastest of any species and its shell can reach a length of more than a metre. It is generally found in sedimentary seabed habitats, most frequently in areas of seagrass, since the survival rate of fragile young shells is highest when they are hidden among grasses. Pinna nobilis plays a key ecological role by filtering water and retaining organic matter, which contributes to water clarity. By offering a habitat to numerous organisms, it also increases biodiversity. It is also important in human culture, since it is a source of sea silk and pearls and its shell is used as a receptacle. Its flesh is also prized.
The noble pen shell population began to recover significantly after 2000 when the species was listed as endangered and granted protected status. In 2016 mass mortality events were recorded in the western Mediterranean, mainly caused by the parasite Haplosporidium pinnae, which in 2020 also arrived in the Gulf of Trieste. Today the noble pen shell is listed among critically endangered species.
Water beetle (Graphoderus bilineatus)
The water beetle Graphoderus bilineatus is a member of the Dytiscidae family. It grows to a length of between 14 and 16 mm and can be distinguished from the other members of the Graphoderus genus by its dorsally flattened body and the very broad yellow transverse band on the pronotum. Both as a larva and as an adult it lives in water, in most cases in large, standing freshwater bodies with gently sloping banks and good conservation status. It only leaves the water for a short time to pupate and transform to the adult stage.
It is found across a large part of Europe but is generally rare and populations are patchy. Because of its rarity and the endangered status of its habitats, it is recognised as a species of European conservation importance. It is also extremely rare in Slovenia. The handful of recorded sightings to date are limited to the north-eastern part of the country, most recently the Mura basin.
