''Chaenotheca brunneola'', the brown-head stubble lichen, is a species of

pin lichen Lichens are symbiotic organisms made up of multiple species: a fungus, one or more photobionts (an alga and/or a cyanobacteria) and sometimes a yeast. They are regularly grouped by their external appearance – a characteristic known as their gro ...

in the family Coniocybaceae.

Taxonmomy

It was first

scientifically described A species description is a formal scientific description of a newly encountered species, typically articulated through a scientific publication. Its purpose is to provide a clear description of a new species of organism and explain how it diffe ...

Erik Acharius Erik Acharius (10 October 1757 – 14 August 1819) was a Swedish botanist who pioneered the Taxonomy (biology), taxonomy of lichens and is known as the "father of lichenology". Acharius was famously the last pupil of Carl Linnaeus. Life Ac ...

in 1816, as ''Calicium brunneolum''.

Johannes Müller Argoviensis Johann Müller (9 May 1828 – 28 January 1896) was a Swiss botanist who was a specialist in lichens. He published under the name Johannes Müller Argoviensis to distinguish himself from other naturalists with similar names. Biography Müller ...

transferred it to the genus ''

Chaenotheca ''Chaenotheca'' is a genus of lichenized fungi within the family Coniocybaceae. The sexual reproduction structures are a mass of loose ascospores that are enclosed by a cup shaped sitting on top of a tiny stalk, having the appearance of a dres ...

'' in 1862. A

common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often con ...

used for the lichen in North America is "brown-head stubble lichen".

Description

The

thallus Thallus (: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. A thallus usually names the entir ...

of ''Chaenotheca brunneola'' is immersed in its , whereas the extends to 1.5 mm, upon which rests a shiny black spherical . It makes that are colourless and spherical, measuring 3.5–4.5

μm The micrometre (Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a unit of length in the International System ...

. The

green alga The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ( ...

l photobiont partner for ''C. brunneola'' is from the genera ''

Trebouxia ''Trebouxia'' is a unicellular green alga. It is a photosynthetic organism that can exist in almost all habitats found in polar, tropical, and temperate regions.Erokhina, L. G., Shatilovich, A. V., Kaminskaya, O. P., & Gilichinskii, D. A. (2004 ...

'' or ''

Dictyochloropsis ''Dictyochloropsis'' is a genus of Unicellular organism, unicellular Green algae, green alga of the phylum Chlorophyta. This genus consists of Free-swimming, free-living algae which have a reticulate (net-like) chloroplast that varies slightly in ...

''. In a 2016 study, the authors show that ''Chaenotheca brunneola'' appears to comprise multiple distinct species that are morphologically similar but genetically different. Specimens growing on fruit bodies of the polypore fungus '' Trichaptum'' formed a separate evolutionary lineage from those growing on wood, despite looking very similar. The ''Trichaptum''-dwelling specimens had somewhat shorter stalks and occasional K+ (red) pigmentation compared to true ''C. brunneola''. This suggests there are

cryptic species In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

within what has been considered ''C. brunneola'', with substrate specificity (wood vs. fungal fruit bodies) corresponding to distinct genetic lineages. The authors consider this a case of

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...

leading to morphologically similar but genetically distinct species adapted to different substrates.

Habitat

The lichen typically grows on wood, particularly on

snags In forest ecology, a snag is a standing dead or dying tree, often missing a top or most of the smaller branches. In freshwater ecology the term ''snag'' refers to trees, branches, and other pieces of naturally occurring wood found sunken in riv ...

(standing dead trees) of pine (''

Pinus sylvestris ''Pinus sylvestris'', the Scots pine (UK), Scotch pine (US), Baltic pine, or European red pine is a species of tree in the pine family Pinaceae that is native plant, native to Eurasia. It can readily be identified by its combination of fairly s ...

''), spruce (''

Picea abies ''Picea abies'', the Norway spruce or European spruce, is a species of spruce native to Northern Europe, Northern, Central Europe, Central and Eastern Europe. It has branchlets that typically hang downwards, and the largest cones of any spruce, ...

''), and

birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech- oak family Fagaceae. The genus ''Betula'' contains 3 ...

. It has also been reported to occasionally grow on fruit bodies of

polypore Polypores, also called bracket or shelf fungi, are a morphological group of basidiomycete-like gilled mushrooms and hydnoid fungi that form large fruiting bodies called conks, which are typically woody, circular, shelf- or bracket-shaped, ...

fungi, particularly '' Trichaptum abietinum'' and '' T. fuscoviolaceum''.

References

{{Taxonbar, from=Q10713601 Coniocybaceae Lichen species Lichens described in 1816 Lichens of Europe Lichens of North America Taxa named by Erik Acharius