Biatora toensbergii

The thallus of Biatora toensbergii is effuse, meaning it spreads outwards and can reach up to 4.5 cm (1.8 in) in diameter. It has a cracked, areolate appearance, resembling a network of small cracks, with the individual areoles (crust-like sections) measuring between 0.2 and 0.6 mm across. These areoles are generally flat or have an irregularly wrinkled surface. The coloration of the thallus ranges from white to light or medium gray, and it can occasionally have a greenish or brownish tint. The surface is typically matte. In a cross-section, the thallus has a height of 70–130 μm, though it can occasionally reach up to 300 μm. Notably, Biatora toensbergii lacks a medulla, which is the inner layer found in many lichens. The algal layer, which houses the symbiotic algae (specifically of the trebouxioid type), is 60–100 μm high, but can sometimes extend to 270 μm. The cortical layer, the outermost layer, is colorless and often includes bark fragments, measuring 5–35 μm in thickness. The reproductive structures, known as apothecia, are rounded or irregularly shaped and can appear either singly or in groups. They are sessile, meaning they sit directly on the substrate without a stalk, and have a constricted base. The average diameter of the apothecia is 0.40–0.65 mm, but they can reach up to 1.15 mm if tuberculate (having small, wart-like projections). …

Biatora toensbergii is found growing on various host trees, including subalpine fir (Abies lasiocarpa), other fir species (Abies spp.), several species of alder (Alnus spp.) such as red alder (A. rubra) and Sitka alder (A. sinuata), as well as on poplar (Populus sp.) and blueberry (Vaccinium sp.). It grows at elevations ranging from sea level up to approximately 1,500 m (4,900 ft). This lichen species inhabits coniferous forests, particularly those dominated by fir (Abies) or hemlock (Tsuga) trees, as well as in stands of red alder (Alnus rubra). Biatora toensbergii is part of the "Trøndelag phytogeographical element", a term coined by Holien and Tønsberg to describe species that are primarily or exclusively found in the humid coastal forests of central Norway. In its native regions of Norway and western North America, Biatora toensbergii commonly grows on gray alder (Alnus incana) in Norway and red alder (A. rubra) in western North America.

== References ==