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Astraeus (genus)
Encyclopedia
Astraeus is a genus
of fungi in the Diplocystaceae
family. The genus, which has a cosmopolitan distribution
, contains five species of earthstar mushrooms. They are distinguished by the outer layer of flesh (exoperidium
) that at maturity splits open in a star-shape manner to reveal a round spore
sac. Additionally, they have a strongly hygroscopic character—the rays will open when moist, but when hot and dry will close to protect the spore sac. Species of Astraeus grow on the ground in ectomycorrhizal associations with trees and shrubs.
of immature specimens is fibrous, and originates from all parts of the surface. The peridium
is roughly spherical, and made of two distinct tissue layers. The outer layer, the exoperidium, is thick, leathery, and initially inseparable from the inner layer (endoperidium). At maturity, the exoperidium bursts open into several pointed "rays". The inner layer of tissue, the endoperidium, is thin, like a membrane. The spore case enclosed by the endoperidium has no stalk (sessile
), and a opened at the top by a tear or pore. Microscopically, sterile cells, long-threaded cells called capillitium originate from the inner surface of the peridium; they are highly branched and interwoven. The spore
s are large, spherical, minutely warted, and brown.
Astraeus species are strongly hygroscopic, and absorb moisture from the environment, so that the rays are closed over the spore case when dry, but open up flat when moistened.
in 1885. The outward resemblance of Astraeus species with those from genus Geaster (Geastraceae
family) has led several authors to place them in that genus.
Phylogenetic analyses proved that the genus Astraeus together with the genera Boletinellus
, Phlebopus
, Pisolithus
, Calostoma
, Gyroporus
, Scleroderma
, and Veligaster, form a distinct phylogenetic lineage in the Boletales
; these genera collectively form the suborder Sclerodermatineae. The similarity between Geastrum and Astraeus species is an example of convergent evolution. Astraeus is currently classified in the Diplocystaceae
family.
s of the ITS
region of the ribosomal DNA
from a number of Astraeus specimens from around the world has helped to establish the phylogenetic relationships within the genus. Currently, five species are recognized:
-type triterpene
s were isolated and identified from the fruit bodies of A. pteridis; two of these compounds had an inhibitory effect on the growth of the pathogen Mycobacterium tuberculosis
.
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 Diplocystaceae
Diplocystaceae
Diplocystaceae is a family of fungi in the Boletales order. The family was described by mycologist Hanns Kreisel in 1974....
family. The genus, which 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...
, contains five species of earthstar mushrooms. They are distinguished by the outer layer of flesh (exoperidium
Peridium
The peridium is the protective layer that encloses a mass of spores in fungi. This outer covering is a distinctive feature of the Gasteromycetes.-Description:...
) that at maturity splits open in a star-shape manner to reveal a round 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...
sac. Additionally, they have a strongly hygroscopic character—the rays will open when moist, but when hot and dry will close to protect the spore sac. Species of Astraeus grow on the ground in ectomycorrhizal associations with trees and shrubs.
Description
The myceliumMycelium
thumb|right|Fungal myceliaMycelium is the vegetative part of a fungus, consisting of a mass of branching, thread-like hyphae. The mass of hyphae is sometimes called shiro, especially within the fairy ring fungi. Fungal colonies composed of mycelia are found in soil and on or within many other...
of immature specimens is fibrous, and originates from all parts of the surface. The peridium
Peridium
The peridium is the protective layer that encloses a mass of spores in fungi. This outer covering is a distinctive feature of the Gasteromycetes.-Description:...
is roughly spherical, and made of two distinct tissue layers. The outer layer, the exoperidium, is thick, leathery, and initially inseparable from the inner layer (endoperidium). At maturity, the exoperidium bursts open into several pointed "rays". The inner layer of tissue, the endoperidium, is thin, like a membrane. The spore case enclosed by the endoperidium has no stalk (sessile
Sessility (botany)
In botany, sessility is a characteristic of plants whose flowers or leaves are borne directly from the stem or peduncle, and thus lack a petiole or pedicel...
), and a opened at the top by a tear or pore. Microscopically, sterile cells, long-threaded cells called capillitium originate from the inner surface of the peridium; they are highly branched and interwoven. 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...
s are large, spherical, minutely warted, and brown.
Astraeus species are strongly hygroscopic, and absorb moisture from the environment, so that the rays are closed over the spore case when dry, but open up flat when moistened.
History
The genus Astraeus was first described by the American mycologist and botanist Andrew Price MorganAndrew Price Morgan
Andrew Price Morgan was an American botanist. He investigated the flora of the Miami Valley in Ohio. While his interest included flowering plants, as noted by his Flora of the Miami Valley, Ohio, his special interest was in fungi. Morgan worked as a teacher in Dayton...
in 1885. The outward resemblance of Astraeus species with those from genus Geaster (Geastraceae
Geastraceae
The earthstars are the family Geastraceae of gasterocarpic basidiomycetes . It includes the genera Geastrum and Myriostoma. About sixty-four species are classified in this family, divided among eight genera....
family) has led several authors to place them in that genus.
Phylogenetic analyses proved that the genus Astraeus together with the genera Boletinellus
Boletinellus
Boletinellus is a genus of fungi in the family Boletaceae . The genus was first described by American mycologist William Alphonso Murrill in 1909....
, Phlebopus
Phlebopus
Phlebopus is a genus of fungi in the family Boletinellaceae . The genus has a widespread distribution in subtropical and pantropical regions, and contains 12 species. The species are saprobic, with some possibly able to form mycorrhizae with exotic trees in certain conditions...
, Pisolithus
Pisolithus
Pisolithus is a genus of fungi within the Sclerodermataceae family . The type species, P. arenarius, is now known to be synonymous with P. arhizus.-Species:*Pisolithus abditus*Pisolithus albus...
, Calostoma
Calostoma
Calostoma is a genus of 29 species in the Sclerodermataceae family of fungi. Like the other Sclerodermatacae species, Calostoma do not have the spore discharge mechanism associated with typical gilled fungi , and instead have enclosed spore-bearing structures...
, Gyroporus
Gyroporus
The Gyroporaceae are a family of fungi in the order Boletales. The family is monotypic, containing the single genus Gyroporus, which, according to a 2008 estimate, contains ten widely distributed species....
, Scleroderma
Scleroderma (genus)
Scleroderma is a genus of fungi, commonly known as earth balls, now known to belong to the Boletales order, in suborder Sclerodermatineae.. The best known species are S. citrinum and S. verrucosum...
, and Veligaster, form a distinct phylogenetic lineage in the Boletales
Boletales
The Boletales are an order of Agaricomycetes, containing over 1300 species with a diverse array of fruiting body types. The boletes are the best known members of this group, and until recently, the Boletales were thought to only contain boletes...
; these genera collectively form the suborder Sclerodermatineae. The similarity between Geastrum and Astraeus species is an example of convergent evolution. Astraeus is currently classified in the Diplocystaceae
Diplocystaceae
Diplocystaceae is a family of fungi in the Boletales order. The family was described by mycologist Hanns Kreisel in 1974....
family.
Species
For a long time, the genus Astraeus was thought to contain at most two species. However, studies in the 2000s showed that species collected from around the world and labelled under the specific epithet hygrometricus were actually considerably variable in a number of macroscopic and microscopic characteristics. A molecular study of the DNA sequenceDNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
s of the ITS
Internal transcribed spacer
ITS refers to a piece of non-functional RNA situated between structural ribosomal RNAs on a common precursor transcript. Read from 5' to 3', this polycistronic rRNA precursor transcript contains the 5' external transcribed sequence , 18S rRNA, ITS1, 5.8S rRNA, ITS2, 28S rRNA and finally the 3'ETS...
region of the ribosomal DNA
Ribosomal DNA
Ribosomal DNA codes for ribosomal RNA. The ribosome is an intracellular macromolecule that produces proteins or polypeptide chains. The ribosome itself consists of a composite of proteins and RNA. As shown in the figure, rDNA consists of a tandem repeat of a unit segment, an operon, composed of...
from a number of Astraeus specimens from around the world has helped to establish the phylogenetic relationships within the genus. Currently, five species are recognized:
- Astraeus asiaticusAstraeus asiaticusAstraeus asiaticus is a species of false earthstar in the family Diplocystaceae. Described as a new species in 2007, it was originally found in north and northeastern areas of Thailand, where it grows in sandy or laterite-rich soil in dry lowland dipterocarp forests. The species has a wide...
Phosri, M.P. Martín & Watling
- This species, thought to be an Asian version of A. hygrometricus, is found in the northern areas of Thailand. Its glebaGlebaGleba is the fleshy spore-bearing inner mass of fungi such as the puffball or stinkhorn.The gleba is a solid mass of spores, generated within an enclosed area within the sporocarp. The continuous maturity of the sporogenous cells leave the spores behind as a powdery mass that can be easily blown away...
has a purplish-chestnut color when mature, and a granulate outer peridium. The range of its spore sizes are generally larger than A. hygrometricus (upper diameter of 15.2 μmMicrometreA micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
).- Astraeus hygrometricusAstraeus hygrometricusAstraeus hygrometricus, commonly known as the hygroscopic earthstar, the barometer earthstar, or the false earthstar, is a species of fungus in the Diplocystaceae family. Young specimens resemble a puffball when young and unopened...
(Pers.) Morgan - Astraeus koreanusAstraeus koreanusAstraeus koreanus is a species of false earthstar in the family Diplocystaceae. Described as a new species in 1976, it is found in Korea. The species was originally named as a variety koreanus of Astraeus hygrometricus in 1958....
(V.J.Staněk) Kreisel - Astraeus odoratusAstraeus odoratusAstraeus odoratus is a species of false earthstar in the family Diplocystaceae. Described as a new species in 2004, it was originally found in Thailand growing in sandy or laterite-rich soil in dry lowland dipterocarp forests. The species is found in Southeast Asia.-Description:Fruit bodies begin...
Phosri, Watling, M.P.Martín & Whalley
- Astraeus hygrometricus
- Discovered in ThailandThailandThailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
, fresh species have a strong odor, and a smooth outer surface.- Astraeus pteridisAstraeus pteridisAstraeus pteridis is a species of false earthstar in the family Diplocystaceae. It was described by American mycologist Cornelius Lott Shear in 1902 under the name Scleroderma pteridis. Sanford Myron Zeller transferred it to Astraeus in a 1948 publication. It is found in North America....
(Shear) Zeller
- Astraeus pteridis
Bioactive compounds
In 2008, five lanostaneLanostane
Lanostane or 4,4,14-trimethylcholestane is a chemical compound with formula . It is a polycyclic hydrocarbon, specifically a triterpene...
-type triterpene
Triterpene
Triterpenes are terpenes consisting of six isoprene units and have the molecular formula C30H48.The pentacyclic triterpenes can be classified into lupane, oleanane or ursane groups.Animal- and plant-derived triterpenes exist, such as:*squalene...
s were isolated and identified from the fruit bodies of A. pteridis; two of these compounds had an inhibitory effect on the growth of the pathogen Mycobacterium tuberculosis
Mycobacterium tuberculosis
Mycobacterium tuberculosis is a pathogenic bacterial species in the genus Mycobacterium and the causative agent of most cases of tuberculosis . First discovered in 1882 by Robert Koch, M...
.