Ascobolus michaudii and Ascobolus albidus
These fungi live as decomposers on the droppings of large herbivore mammals. Within the National Park area, Ascobolus albidus has been found only on bear droppings. Its survival depends on the survival of large mammals.

Golden Cup (Caloscypha fulgens)
In Croatia, golden cup is found only in fir forests and is closely associated with fir. This fungus living on forest ground is included in the Red List of Threatened Fungi of Croatia, under the Vulnerable category, and is strictly protected by law.

Chlorencoelia versiformis
It is a decomposer living on decaying wood remains of deciduous trees. The specimens found in Northern Velebit are the first find of the Chlorencoelia genus in Croatia. It is extremely rare, and is most widespread in the boreal (northern) and sub-arctic zones of North America, Asia and Scandinavia. It is also found as a very rare species in most mountain ranges of the northern and southern hemisphere temperate zone.

Entoloma catalaunicum
Entoloma catalaunicum is a decomposer living on mountain meadows and high mountain vegetation. Its fruiting bodies develop in summer and autumn. In Croatia, it has been found only in two localities within the Northern Velebit National Park. It is included in the Red List of Threatened Fungi of Croatia, under the Endangered category, and is strictly protected by law.

True Tinder Polypore (Fomes fomentarius)
It is a parasite and decomposer living on deciduous trees, typically beech, with perennial fruiting bodies. It is very common in old beech forests, and its large grey hoof-shaped fruiting bodies are easily spotted.

Galerina marginata
A decomposer of large and small coniferous and deciduous tree debris, this fungus develops its fruiting body between spring and late autumn. It is commonly found on fallen trees in the Park. Galerina marginata belongs to one of the most poisonous species of fungi. It develops a relatively small fruiting body which is not interesting to most mushroom pickers so the risk to be mistaken for edible groups of mushrooms is small.

Gymnopilus picreus
This fungus is a decomposer living on large coniferous tree debris (fallen trees, logs and stumps). It develops its fruiting body in autumn. Gymnopilus picreus is a rare and endangered species in managed forests due to removal or large tree remains. The forests that are not managed, such as national parks, are a refuge for this and other fungal species that depend on naturally dead wood. It is included in the Red List of Threatened Fungi of Croatia, under the Vulnerable category, and is strictly protected by law.

Discina montana
This very rare species of fungi lives as decomposer on large coniferous tree remains. Discina montana is most commonly found at high altitudes where it develops its fruiting body during the cold season at the time and in the area of melting snow. The find within the National Park is the third known locality in which this fungus was identified in Croatia. As the survival of this species depends on the forest being protected from any deforestation, it is not surprising that one of localities in which it was found is within the National Park. Discina montana is included in the Red List of Threatened Fungi of Croatia, under the Vulnerable category, and is strictly protected by law.

Heyderia abietis
This fungus is a decomposer living exclusively on fallen spruce and fir needles. Veliki Lubenovac, in the Northern Velebit National Park, is the fourth known locality in which this fungus was identified in Croatia. This relatively rare species is included in the Red List of Threatened Fungi of Croatia, under the Near Threatened category.

Kuehneromyces lignicola
This decomposer living on coniferous tree remains in mountainous regions is scarce throughout Europe, and the only known locality in Croatia is within the Northern Velebit National Park. It develops its fruiting body only in spring and early summer. Kuehneromyces lignicola is included in the Red List of Threatened Fungi of Croatia, under the Data Deficient category, and is strictly protected by law.

Stone milkcap (Lactarius salmonicolor)
This fungus lives exclusively in mycorrhiza – a symbiotic relationship with fir, and develops its fruiting body in late summer and autumn. It is a very common species in fir forest, and its bright orange fruiting body is easily spotted from a distance.

Weeping slimecap (Limacella guttata)
Found in different types of forest, this decomposer develops its fruiting body during the autumn. It is very rare in Croatia, where it has been identified in only three localities, one of which is Northern Velebit. The species is included in the Red List of Threatened Fungi of Croatia, under the Vulnerable category, and is strictly protected by law.

Garlic Parachute (Marasmius alliaceus)
A decomposer living on smaller beech remains (leaf litter and twigs), its fruiting bodies develop from late spring to late autumn. It is one of the most common fungal species in beech forests. It is easily identified for its blackish brown stem and characteristic smell of garlic.

Porcelain Fungus (Oudemansiella mucida)
Porcelain fungus is a parasite and decomposer living on deciduous trees, mostly on beech. It is very common in old beech forests, and its white fruiting bodies are easily discernible from a distance.

Pseudoomphalina kalchbrenneri
This fungus lives as a decomposer in coniferous forests. It is very rare throughout Europe, and its only known locality in Croatia is within the Northern Velebit National Park. Pseudoomphalina kalchbrenneri develops its fruiting body in late summer and autumn. It is included in the Red List of Threatened Fungi of Croatia, under the Data Deficient category, and is strictly protected by law.

Scutellinia cejpii
The distribution of this fungus is limited to alpine and sub-alpine regions where it is found in coniferous and mixed forests. It lives as a decomposer on large wood debris of fir and spruce trees.

Beechwood Goblet (Tatraea dumbirensis)
A decomposer living on bulky beech deadwood, it is found in old forests and old-growth forests containing beech. Numerous finds within the Park area indicate that large areas with this type of forest are still, more or less, maintained in their natural state. On vast tracts of land throughout Croatia and the rest of Europe, where this type of forest is subject to great economic pressure, this species is either completely absent or is extremely rare. It is included in the Red List of Threatened Fungi of Croatia, under the Vulnerable category, and is strictly protected by law.

Wood Mulberry (Bertia moriformis)
A decomposer living on fallen, rotten branches and other remains of woody plants, mostly deciduous trees, it is widely spread throughout Europe.

Brunnipila clandestina
This fungus is as decomposer living on fallen rotten twigs of brambles and stems of tall herbaceous plants from the daisy, carrot or parsley, buttercup and other plant families. It is commonly found only in alpine regions and some areas north of the Alps. In Croatia this species was first identified within the Park.

Vibrissea decolorans
A decomposer of rotten branches, more rarely cones, this fungus lives in sub-alpine and alpine regions in an aquatic environment of fast moving waters, in the waterfall spray zone and in environments where the air is permanently saturated with moisture. The find in a snow pit within the Park area is the only find of this species in Croatia.

Redleg Jellybaby (Cudonia circinans)
This species lives in a mycorrhiza, relationship in spruce, larch and birch forests in mountain, alpine, boreal (northern) and arctic regions. Three out of the four known localities in Croatia are within the Northern Velebit National Park. All specimens were identified in a natural spruce forest. Redleg jellybaby is included in the Red List of Threatened Fungi of Croatia, under the Vulnerable category, and is strictly protected by law.

Peziza exogelatinosa
A decomposer living on limestone soils in the forests of north Europe and the mountainous areas of the Dinarides. Apart from Croatia, its habitats have been identified in the coastal regions of Denmark, south Sweden and north Germany. It is probably more widespread and common in its habitat than believed as it resembles some other cup fungus species.

Trichopezizella relicina
This decomposer lives on dead stems of tall herbaceous plants from the carrot and buttercup families. It is relatively common in the Alps region. This species was first identified in Croatia within the Northern Velebit National Park.

Carbon Cushion (Ustulina deusta)
Carbon cushion lives as a parasite on beech trees. It first attacks and parasitizes the plant, and after killing it, decomposes the dead remains. It is widely spread and quite common in beech forests and mixed beech forests throughout Europe.