Cliff Mining Bee vs Cliff Scalewort

Andrena thoracica compared with Porella cordaeana

Key Differences

Cliff Mining Bee is Extinct while Cliff Scalewort is Least Concern.

Taxonomic Classification

Rank	Cliff Mining Bee	Cliff Scalewort
Kingdom	Animalia (Animals)	Plantae (Plants)
Phylum	Arthropoda (Arthropods)	Marchantiophyta (liverwort)
Class	Insecta (Insects)	Jungermanniopsida (Jungermanniopsida)
Order	Hymenoptera (Ants, Bees & Wasps)	Porellales (Porellales)
Family	Andrenidae	Porellaceae
Genus	Andrena	Porella
Species	Andrena thoracica	Porella cordaeana

Conservation Status

Cliff Mining Bee

EX — Extinct

Cliff Scalewort

LC — Least Concern

Physical Characteristics

Attribute	Cliff Mining Bee	Cliff Scalewort
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Cliff Mining Bee

Habitat

Typically found in virtually all terrestrial and freshwater habitats.

Range

Distributed across Denmark, Luxembourg, Norway, and Sweden.

Cliff Scalewort

Habitat

Native to Europe and North America, inhabiting ecosystems characteristic of the region.

Range

Found across Europe (6 countries) and North America (United States).

Cliff Mining Bee

The Cliff Mining Bee, Andrena species in the family Andrenidae, is a solitary ground-nesting bee that excavates tunnels in cliff faces, earthen banks, and compacted sandy or loamy soils, where the loose or friable substrates exposed in cliff profiles provide ideal nesting conditions. Mining bees in the genus Andrena are among the most species-rich solitary bee genera in the world, with hundreds of species across the Holarctic region, many narrowly specialized in their choice of pollen host plants. Female cliff mining bees construct vertical or angled burrows in cliff faces, with lateral cells off the main shaft, each containing a pollen ball and a single egg. Males are typically smaller and emerge before females to establish territories near nesting sites. Many Andrena species are oligolectic, collecting pollen from only a small number of plant species, making their populations sensitive to the availability of specific flowering plants in the landscape surrounding nesting areas. Cliff and bank nesting habitats provide well-drained, sun-warmed substrates essential for brood development. The loss of natural cliff faces and earthen banks to development, vegetation succession, and quarrying reduces available nesting habitat for cliff mining bees.

Cliff Scalewort

Cliff Scalewort, Porella obtusata, is a leafy liverwort in the family Porellaceae found on cliff faces, shaded rock surfaces, and the bark of trees in moist, humid environments across Europe and North America. Porella is one of the most diverse and widely distributed leafy liverwort genera, with species adapted to a range of substrates from bark and rock to soil in forests and coastal habitats. Cliff Scalewort forms flat, overlapping mats of small, scale-like leaves arranged in two lateral rows and a row of smaller underleaves, creating a texture that gives the plant its common name. The green to brownish-green plants are tightly appressed to the surface, extracting moisture from rainfall and condensation. Liverworts in this family reproduce sexually when conditions are favorable, producing small capsules on delicate setae, as well as vegetatively through fragmentation. Porella species on cliff faces are sensitive to air pollution, particularly sulfur dioxide, and have declined in many industrial regions of Europe, recovering more recently as air quality has improved. They serve as indicators of habitat continuity and air quality in ecological assessments. Cliff Scalewort is not globally threatened but may be locally rare in heavily polluted or drought-prone areas.