Sebacina
Encyclopedia
Sebacina is a genus
of fungi in the family Sebacinaceae. Its species are mycorrhizal, forming a range of associations with trees, orchids, and other plants. Basidiocarps (fruit bodies) are produced on soil and litter, sometimes partly encrusting stems of living plants. The fruit bodies are cartilaginous to rubbery-gelatinous and variously effused to coral-shaped. The genus has a cosmopolitan distribution
, but less than a dozen species are currently recognized worldwide.
and Charles Tulasne
who had discovered that two species (Sebacina incrustans and S. epigaea) previously referred to Corticium
or Thelephora
possessed septate
basidia, similar to those found in the genus Tremella
. Although it was unusual at that time to separate fungal genera on purely microscopic characters, Sebacina was erected for effused, Corticium-like fungi with tremelloid basidia.
Many additional species were added to the genus by subsequent authors. Most, however, proved to be unrelated to Sebacina and were removed in 1957 by Ervin, who shuffled some species to Heterochaetella (for example, Heterochaetella dubia, now Stypella dubia (Bourdot & Galzin) P. Roberts), Bourdotia and Exidiopsis
. In 1961, Wells also transferred many species to the genus Exidiopsis. The type species
, S. incrustans, has a variable morphology
, which has led to it being assigned a number of names.
Recent molecular research has shown that Sebacina is far more diverse than previously assumed, though this genetic diversity may not be reflected in morphological characters (in other words, species may be impossible to distinguish except by DNA analysis). The same research also shows that the genus splits into two groups, one clustered with the type species, the other clustered with a species sometimes referred to as "Sebacina vermifera" (though this is a misidentification). This latter species is distinct in forming thin, waxy fruit bodies and the group may not be part of Sebacina in the strict sense. Even in the strict sense, Sebacina is artificial, not being clearly distinct from related genera such as the coral-like Tremellodendron
.
s in a gelatinous matrix. In one species the hyphal system is dimitic. The spore
-bearing surface is initially covered in a layer of weakly branched hyphidia below which the basidia are formed. The basidia are tremelloid (ellipsoid and vertically septate), giving rise to long, sinuous sterigmata or epibasidia on which the basidiospores are produced. These spores are typically ellipsoid to oblong, but allantoid (sausage-shaped) in one species and vermiform (worm-shaped) in another.
showed that they were plant associates. They are now known to be ectomycorrhizal associates of forest trees as well as endomycorrhizal
associates of orchids. They also form mycorrhizas with ericoid
plants. Recent research has additionally revealed their presence on a range of non-mycorrhizal plant roots, suggesting they may be common root endophyte
s.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of fungi in the family Sebacinaceae. Its species are mycorrhizal, forming a range of associations with trees, orchids, and other plants. Basidiocarps (fruit bodies) are produced on soil and litter, sometimes partly encrusting stems of living plants. The fruit bodies are cartilaginous to rubbery-gelatinous and variously effused to coral-shaped. The genus has a cosmopolitan distribution
Cosmopolitan distribution
In biogeography, a taxon is said to have a cosmopolitan distribution if its range extends across all or most of the world in appropriate habitats. For instance, the killer whale has a cosmopolitan distribution, extending over most of the world's oceans. Other examples include humans, the lichen...
, but less than a dozen species are currently recognized worldwide.
Taxonomy
The genus was first published in 1871 by LouisLouis René Tulasne
Louis René Tulasne, aka Edmond Tulasne was a French botanist and mycologist who was born in Azay-le-Rideau. He originally studied law at Poitiers, but his interest later turned to botany. As a young man he accompanied botanist Auguste de Saint-Hilaire to South America to study the flora of Brazil...
and Charles Tulasne
Charles Tulasne
Charles Tulasne was a French physician and mycologist who was born in Langeais in the département of Indre-et-Loire. He received his medical doctorate in 1840 and practiced medicine in Paris until 1854. Afterwards he worked with his older brother Louis René Tulasne in the field of mycology...
who had discovered that two species (Sebacina incrustans and S. epigaea) previously referred to Corticium
Corticium
Corticium is a genus of crust fungi in the family Corticiaceae. According to a 2008 estimate, the genus contains 25 widely distributed species.-Species:*Corticium appalachiense*Corticium auberianum*Corticium boreoroseum...
or Thelephora
Thelephora
Thelephora is a genus of fungi within the Thelephoraceae family. The genus has a widespread distribution and contains about 50 species. Fruit bodies of species are leathery, usually brownish at maturity, and range in shape from coral-like tufts to having distinct caps...
possessed septate
Septum
In anatomy, a septum is a wall, dividing a cavity or structure into smaller ones.-In human anatomy:...
basidia, similar to those found in the genus Tremella
Tremella
Tremella is a genus of fungi in the family Tremellaceae. All Tremella species are parasites of other fungi and most produce anamorphic yeast states. Basidiocarps , when produced, are gelatinous and are colloquially classed among the "jelly fungi". Over 100 species of Tremella are currently...
. Although it was unusual at that time to separate fungal genera on purely microscopic characters, Sebacina was erected for effused, Corticium-like fungi with tremelloid basidia.
Many additional species were added to the genus by subsequent authors. Most, however, proved to be unrelated to Sebacina and were removed in 1957 by Ervin, who shuffled some species to Heterochaetella (for example, Heterochaetella dubia, now Stypella dubia (Bourdot & Galzin) P. Roberts), Bourdotia and Exidiopsis
Exidiopsis
Exidiopsis is a genus of fungi in the family Auriculariaceae. The genus has a widespread distribution and contains about 30 species....
. In 1961, Wells also transferred many species to the genus Exidiopsis. The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
, S. incrustans, has a variable morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
, which has led to it being assigned a number of names.
Recent molecular research has shown that Sebacina is far more diverse than previously assumed, though this genetic diversity may not be reflected in morphological characters (in other words, species may be impossible to distinguish except by DNA analysis). The same research also shows that the genus splits into two groups, one clustered with the type species, the other clustered with a species sometimes referred to as "Sebacina vermifera" (though this is a misidentification). This latter species is distinct in forming thin, waxy fruit bodies and the group may not be part of Sebacina in the strict sense. Even in the strict sense, Sebacina is artificial, not being clearly distinct from related genera such as the coral-like Tremellodendron
Tremellodendron
Tremellodendron is a genus of fungi in the family Sebacinaceae. Its species are mycorrhizal, forming a range of associations with trees and other plants. Basidiocarps are produced on soil and litter. The fruit bodies are clavarioid and leathery to rubbery-gelatinous...
.
Description
Fruit bodies are typically cartilaginous or rubbery-gelatinous. In effused species (those that spread out loosely or flat), they are formed on the soil surface or in leaf litter, often encrusting fallen twigs and debris, sometimes encrusting the stem bases of living plants. In the type species, irregular or coral-like outgrowths may also be produced. In one species, bracket-like outgrowths are formed. In two other species, the fruit bodies are entirely coral- or net-like. Spores are white in mass.Microscopic characters
Fruit bodies are composed of hyphae lacking clamp connectionClamp connection
A clamp connection is a structure formed by growing hyphal cells of certain fungi. It is created to ensure each septum, or segment of hypha separated by crossed walls, receives a set of differing nuclei, which are obtained through mating of hyphae of differing sexual types...
s in a gelatinous matrix. In one species the hyphal system is dimitic. The spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
-bearing surface is initially covered in a layer of weakly branched hyphidia below which the basidia are formed. The basidia are tremelloid (ellipsoid and vertically septate), giving rise to long, sinuous sterigmata or epibasidia on which the basidiospores are produced. These spores are typically ellipsoid to oblong, but allantoid (sausage-shaped) in one species and vermiform (worm-shaped) in another.
Mycorrhizal associations
Sebacina species were assumed to be saprotrophic until DNA analysis of mycorrhizal rootsMycorrhiza
A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....
showed that they were plant associates. They are now known to be ectomycorrhizal associates of forest trees as well as endomycorrhizal
Mycorrhiza
A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....
associates of orchids. They also form mycorrhizas with ericoid
Ericaceae
The Ericaceae, commonly known as the heath or heather family, is a group of mostly calcifuge flowering plants. The family is large, with roughly 4000 species spread across 126 genera, making it the 14th most speciose family of flowering plants...
plants. Recent research has additionally revealed their presence on a range of non-mycorrhizal plant roots, suggesting they may be common root endophyte
Endophyte
An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life without causing apparent disease. Endophytes are ubiquitous and have been found in all the species of plants studied to date; however, most of these endophyte/plant relationships...
s.
Species
For older names, the list is based on species retained in Sebacina by Wells (1961).- Sebacina allantoidea (described from Germany)
- Sebacina alutacea (described from India)
- Sebacina concrescens (described from the USA)
- Sebacina dimitica (described from Germany)
- Sebacina epigaea (described from England)
- Sebacina helvelloides (described from the USA)
- Sebacina incrustans (described from Europe)
- Sebacina pileata (described from Belize)
- Sebacina sparassoidea (described from the USA)
- Sebacina spongiosa (described from the Bahamas)