Pulveroboletus bembae
Encyclopedia
Pulveroboletus bembae is a species of fungus
in the Boletaceae
family that was first described in 2009. It is known only from the rainforest
of northern Gabon
, a region known for its high level of species diversity
. Like all bolete
s, P. bembae has fleshy fruit bodies
that form spore
s in tubes perpendicular to the ground on the underside of the cap
. These yellowish tubes form a surface of pores, each about 1–2 mm in diameter. The brownish caps may reach up to 3.5 cm (1.4 in) wide, and rest atop pale brown stems up to 5.5 cm (2.2 in) long. The stems have a woolly, whitish yellow ring
of tissue that is short-lived, and may be absent in older specimens. The spore
s of P. bembae are spindle- or fuse-shaped, and have rough surfaces—a detail observable when viewed with scanning electron microscopy. The fungus grows in a mycorrhiza
l relationship with Gilbertiodendron dewevrei, the dominant
tree species of the Guineo-Congolian rainforest. Other similar Pulveroboletus species in the area include P. annulus and P. croceus, which may be differentiated from P. bembae by a combination of macro- and microscopic characteristics.
: in Ogooue-Ivindo Province at the Ipassa-Makokou Research Station; in the Minkébé National Park
near Minvoul
, and in Bitouga, both locations in the northerly province of Woleu-Ntem
. Until the report of this species and the related Pulveroboletus luteocarneus, 12 species of Pulveroboletus
had been reported in tropical Africa
. According to Degreef & De Kesel, who described the species in a 2009 publication, P. bembae belongs to the section Pulveroboletus of the genus Pulveroboletus. This section, defined by Singer in 1947, is characterized by the presence of a pulverulent-arachnoid veil (covered with fine, powdery wax granules and cobwebby) and fruit bodies that are sulphur-yellow, greenish, or yellowish-brown in color.
The specific epithet is derived from the word bemba, a name used by the Baka people
for the tree Gilbertiodendron dewevrei that is associated with the fungus.
is initially convex—sometimes with a small rounded elevation in the center—and flattens out in maturity. It reaches 30–35 mm (1.2–1.4 in) in diameter, and the color is almost uniformly rust-brown to reddish brown, although young specimens have a slightly paler margin (edge). The cap surface is dry and dull, but develops a sheen with age. In older specimens, the texture of the margins is described as rimulose—a condition in which a surface is cracked, but the cracks do not intersect one another to form a network and mark out areas. The cap cuticle
extends slightly over the edge of the cap and curves downward, and is partly covered with remnants of the universal veil
. The flesh
at the center of the cap is less than about 5 mm (0.196850393700787 in) thick, and gradually becomes very thin towards the margin. It is cream-colored to pale yellow with pale reddish-brown to light brown shades under the cuticle and down the stem
.
The yellowish tubes on the underside of the cap are slightly swollen on one side, slightly depressed around the area of attachment to the stem. They are fused to the stem, in an adnate
attachment; rarely, some tubes will have a decurrent "tooth" (tissue that runs slightly down the length of the stem) that is less than 5 mm (0.196850393700787 in) long. The pores formed by the tube ends are angular to round, and are more elongated near the stem. Their diameters are typically less than 1–2 mm in diameter, and are they are the same color as the tubes, or slightly greener. The stem
is 37 – by 4–5 mm (0.15748031496063–0.196850393700787 in) thick, cylindrical, with a narrow base measuring 2–4 mm, and sometimes attached to yellow mycelia. It is solid, but as it ages it becomes stuffed (as if filled with cotton) and eventually almost completely hollow. The stem surface is dull, dry, pale brown, and entirely covered with tiny brown to reddish brown squamules (small scales). The flesh of the stem is cream-colored, streaked with pale reddish brown to light brown from the upper third towards the base, while the base is light brown. The ring
is located on either the stem or the margin of the cap. This woolly, whitish yellow ring of tissue is fragile and short-lived, and has usually weathered away in older specimens. The odor of the mushroom is described as "mildly fungoid to earthy", and the taste "mildly fungoid".
is unknown. The spore
s are somewhat spindle-shaped, boletoid (long, lean, and fuse-shaped), with a pronounced suprahilar depression (a surface indentation formed where the spore was attached to the spore-bearing cells, the basidia), and typically measure 9.3–11.3 by 3.9–4.7 µm
. They are weakly pigmented, and their rough surfaces can be seen under scanning electron microscopy. The spores are inamyloid
, meaning they will not absorb iodine
stain from Melzer's reagent
. The basidia are 26.9–39.3 by 9.0–12.0 µm, cylindrical to narrowly club-shaped, hyaline
(translucent), and have four sterigmata (extensions that attach the spores). The pleurocystidia (cystidia on the gill face) are 57.4–92.6 by 9.4–17.4 µm, spindle-shaped, moderately frequent, and extend beyond the surface of the hymenium
. They have thin, hyaline walls, and are colored the same as the hymenium, without any crystals or encrustations. The cheilocystidia (cystidia on the gill edge), which measure 50.6–75.1 by 12.2–16.1 µm, are more abundant than the cheilocystidia, but otherwise share the same characteristics. The cap cuticle is made of a thin physalo-palisadoderm—a type of tissue where the ends of the hypha
e reach the same length and form a palisade of cells; these short anticlinal hyphae are 20–40 by 5–8 µm, and support one or two inflated, brownish, spherical to spheropedunculate (somewhat spherical with a stem) terminal elements that are 25–45 µm wide, non-amyloid, thin-walled, and do not have any encrustations. The cuticle of the stem is made of smooth parallel hyphae. The squamules on the cap surface have a physalo-palisadodermic arrangement made of short anticlinal hyphae that support elongated inflated elements of 15–30 by 10–15 µm and some scattered basidia. The flesh is made of hyaline, thin-walled hyphae, measuring 10–15 µm wide, and organized in a parallel fashion. These hyphae do not have an associated mediostratum—a central strand of parallel hyphae from which other hyphae diverge sideways. Clamp connection
s are absent in the hyphae of P. bembae.
, species in this genus do not have the powdery veil characteristic of P. bembae. Two similar species in the same area include P. annulus and P. croceus, described in 1951 by Belgian mycologist Paul Heinemann, based on specimens collected in the Congo. Although the identity of these two species is not fully clarified because of insufficient collections, P. bembae differs from both in its larger cystidia, its cream-colored flesh with pale reddish-brown to light brown tones under the cap cuticle (compared to white in P. annulus and P. croceus), its yellow mycelium (white in P. annulus and P. croceus), and differences in ecology.
by the single canopy tree species Gilbertiodendron dewevrei. Not only does this tree provide food in the form of edible seeds for a wide variety of large mammals, it forms mycorrhiza
l relationships with P. bembae. This is a mutually beneficial relationship where the hyphae of the fungus grow around the roots of the plant, enabling the fungus to receive moisture, protection and nutritive byproducts of the tree, and affording the tree greater access to soil nutrients. The ectomycorrhizal symbiosis is thought to contribute to the success of the dominant species, by allowing it access to nutrients otherwise unavailable. The Congolian forests
encompass an ecoregion
known for its species richness
and endemism, which is spread across four countries: Cameroon
, Gabon
, Republic of Congo, and the Central African Republic
.
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
in the Boletaceae
Boletaceae
Boletaceae are a family of mushrooms, primarily characterized by developing their spores in small pores on the underside of the mushroom, instead of gills, as are found in agarics. Nearly as widely distributed as agarics, they include the Cep or King Bolete , much sought after by mushroom hunters...
family that was first described in 2009. It is known only from the rainforest
Rainforest
Rainforests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm...
of northern Gabon
Gabon
Gabon , officially the Gabonese Republic is a state in west central Africa sharing borders with Equatorial Guinea to the northwest, Cameroon to the north, and with the Republic of the Congo curving around the east and south. The Gulf of Guinea, an arm of the Atlantic Ocean is to the west...
, a region known for its high level of species diversity
Species diversity
Species diversity is an index that incorporates the number of species in an area and also their relative abundance. It is a more comprehensive value than species richness....
. Like all bolete
Bolete
A bolete is a type of fungal fruiting body characterized by the presence of a pileus that is clearly differentiated from the stipe, with a spongy surface of pores on the underside of the pileus...
s, P. bembae has fleshy fruit bodies
Basidiocarp
In fungi, a basidiocarp, basidiome or basidioma , is the sporocarp of a basidiomycete, the multicellular structure on which the spore-producing hymenium is borne. Basidiocarps are characteristic of the hymenomycetes; rusts and smuts do not produce such structures...
that form 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 in tubes perpendicular to the ground on the underside of the cap
Pileus (mycology)
The pileus is the technical name for the cap, or cap-like part, of a basidiocarp or ascocarp that supports a spore-bearing surface, the hymenium. The hymenium may consist of lamellae, tubes, or teeth, on the underside of the pileus...
. These yellowish tubes form a surface of pores, each about 1–2 mm in diameter. The brownish caps may reach up to 3.5 cm (1.4 in) wide, and rest atop pale brown stems up to 5.5 cm (2.2 in) long. The stems have a woolly, whitish yellow ring
Annulus (mycology)
An annulus is the ring like structure sometimes found on the stipe of some species of mushrooms. The annulus represents the remaining part of the partial veil, after it has ruptured to expose the gills or other spore-producing surface. An annulus may be thick and membranous, or it may be cobweb-like...
of tissue that is short-lived, and may be absent in older specimens. 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 of P. bembae are spindle- or fuse-shaped, and have rough surfaces—a detail observable when viewed with scanning electron microscopy. The fungus grows in a mycorrhiza
Mycorrhiza
A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....
l relationship with Gilbertiodendron dewevrei, the dominant
Dominance (ecology)
Ecological dominance is the degree to which a species is more numerous than its competitors in an ecological community, or makes up more of the biomass...
tree species of the Guineo-Congolian rainforest. Other similar Pulveroboletus species in the area include P. annulus and P. croceus, which may be differentiated from P. bembae by a combination of macro- and microscopic characteristics.
Discovery and classification
The specimens of Pulveroboletus bembae upon which the species description is based were collected in April, 2008 from three locations in GabonGabon
Gabon , officially the Gabonese Republic is a state in west central Africa sharing borders with Equatorial Guinea to the northwest, Cameroon to the north, and with the Republic of the Congo curving around the east and south. The Gulf of Guinea, an arm of the Atlantic Ocean is to the west...
: in Ogooue-Ivindo Province at the Ipassa-Makokou Research Station; in the Minkébé National Park
Minkébé National Park
Minkébé National Park is a national park in the extreme northeast of Gabon. It covers an area of 7,570 km². The WWF recognized it as an area needing protection as early as 1989 and has been actively working towards protecting the forest since 1997...
near Minvoul
Minvoul
- External links :*...
, and in Bitouga, both locations in the northerly province of Woleu-Ntem
Woleu-Ntem
Woleu-Ntem is one of Gabon's nine provinces. It covers an area of 38,465 km². The provincial capital is Oyem.As Woleu-Ntem is the most northerly province of Gabon, it is the only province that borders Cameroon, as well as bordering the Republics of Equatorial Guinea and of the Congo...
. Until the report of this species and the related Pulveroboletus luteocarneus, 12 species of Pulveroboletus
Pulveroboletus
Pulveroboletus is a genus of fungi in the Boletaceae family. The genus has a cosmopolitan distribution and contains 25 species.-Taxonomy:The genus was first described by American mycologist William Alphonso Murrill in 1909...
had been reported in tropical Africa
Tropical Africa
Although tropical Africa is most familiar in the West as depicted by its rain forests, this region of Africa is far more diverse. While the tropics are thought of as regions with warm to hot moist climates caused by latitude and the tropical rain belt, the geology of areas, particularly mountain...
. According to Degreef & De Kesel, who described the species in a 2009 publication, P. bembae belongs to the section Pulveroboletus of the genus Pulveroboletus. This section, defined by Singer in 1947, is characterized by the presence of a pulverulent-arachnoid veil (covered with fine, powdery wax granules and cobwebby) and fruit bodies that are sulphur-yellow, greenish, or yellowish-brown in color.
The specific epithet is derived from the word bemba, a name used by the Baka people
Baka (Cameroon and Gabon)
The Baka, known in the Congo as Bayaka , are an ethnic group inhabiting the southeastern rainforests of Cameroon, northern Republic of Congo, northern Gabon, and southwestern Central African Republic. They are sometimes called a subgroup of the Twa, but the two peoples are not closely related...
for the tree Gilbertiodendron dewevrei that is associated with the fungus.
Description
The capPileus (mycology)
The pileus is the technical name for the cap, or cap-like part, of a basidiocarp or ascocarp that supports a spore-bearing surface, the hymenium. The hymenium may consist of lamellae, tubes, or teeth, on the underside of the pileus...
is initially convex—sometimes with a small rounded elevation in the center—and flattens out in maturity. It reaches 30–35 mm (1.2–1.4 in) in diameter, and the color is almost uniformly rust-brown to reddish brown, although young specimens have a slightly paler margin (edge). The cap surface is dry and dull, but develops a sheen with age. In older specimens, the texture of the margins is described as rimulose—a condition in which a surface is cracked, but the cracks do not intersect one another to form a network and mark out areas. The cap cuticle
Pileipellis
thumb|300px||right|The cuticle of some mushrooms, such as [[Russula mustelina]] shown here, can be peeled from the cap, and may be useful as an identification feature....
extends slightly over the edge of the cap and curves downward, and is partly covered with remnants of the universal veil
Universal veil
In mycology, a universal veil is a temporary membranous tissue that fully envelops immature fruiting bodies of certain gilled mushrooms. The developing Caesar's mushroom , for example, which may resemble a small white sphere at this point, is protected by this structure...
. The flesh
Trama (mycology)
In mycology trama is a term for the inner, fleshy portion of a mushroom's basidiocarp, or fruit body. It is distinct from the outer layer of tissue, known as the pileipellis or cuticle, and from the spore-bearing tissue layer known as the hymenium....
at the center of the cap is less than about 5 mm (0.196850393700787 in) thick, and gradually becomes very thin towards the margin. It is cream-colored to pale yellow with pale reddish-brown to light brown shades under the cuticle and down the stem
Stipe (mycology)
thumb|150px|right|Diagram of a [[basidiomycete]] stipe with an [[annulus |annulus]] and [[volva |volva]]In mycology a stipe refers to the stem or stalk-like feature supporting the cap of a mushroom. Like all tissues of the mushroom other than the hymenium, the stipe is composed of sterile hyphal...
.
The yellowish tubes on the underside of the cap are slightly swollen on one side, slightly depressed around the area of attachment to the stem. They are fused to the stem, in an adnate
Adnation
Adnation in plants is the "union of unlike parts; organically united or fused with another dissimilar part, e.g. an ovary to a calyx tube, or stamens to petals". This is in contrast to connation, the fusion of similar organs....
attachment; rarely, some tubes will have a decurrent "tooth" (tissue that runs slightly down the length of the stem) that is less than 5 mm (0.196850393700787 in) long. The pores formed by the tube ends are angular to round, and are more elongated near the stem. Their diameters are typically less than 1–2 mm in diameter, and are they are the same color as the tubes, or slightly greener. The stem
Stipe (mycology)
thumb|150px|right|Diagram of a [[basidiomycete]] stipe with an [[annulus |annulus]] and [[volva |volva]]In mycology a stipe refers to the stem or stalk-like feature supporting the cap of a mushroom. Like all tissues of the mushroom other than the hymenium, the stipe is composed of sterile hyphal...
is 37 – by 4–5 mm (0.15748031496063–0.196850393700787 in) thick, cylindrical, with a narrow base measuring 2–4 mm, and sometimes attached to yellow mycelia. It is solid, but as it ages it becomes stuffed (as if filled with cotton) and eventually almost completely hollow. The stem surface is dull, dry, pale brown, and entirely covered with tiny brown to reddish brown squamules (small scales). The flesh of the stem is cream-colored, streaked with pale reddish brown to light brown from the upper third towards the base, while the base is light brown. The ring
Annulus (mycology)
An annulus is the ring like structure sometimes found on the stipe of some species of mushrooms. The annulus represents the remaining part of the partial veil, after it has ruptured to expose the gills or other spore-producing surface. An annulus may be thick and membranous, or it may be cobweb-like...
is located on either the stem or the margin of the cap. This woolly, whitish yellow ring of tissue is fragile and short-lived, and has usually weathered away in older specimens. The odor of the mushroom is described as "mildly fungoid to earthy", and the taste "mildly fungoid".
Microscopic characteristics
The color of the spore printSpore print
thumb|300px|right|Making a spore print of the mushroom Volvariella volvacea shown in composite: mushroom cap laid on white and dark paper; cap removed after 24 hours showing pinkish-tan spore print...
is unknown. 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 somewhat spindle-shaped, boletoid (long, lean, and fuse-shaped), with a pronounced suprahilar depression (a surface indentation formed where the spore was attached to the spore-bearing cells, the basidia), and typically measure 9.3–11.3 by 3.9–4.7 µm
Micrometre
A 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...
. They are weakly pigmented, and their rough surfaces can be seen under scanning electron microscopy. The spores are inamyloid
Amyloid (mycology)
In mycology the term amyloid refers to a crude chemical test using iodine in either Melzer's reagent or Lugol's solution, to produce a black to blue-black positive reaction. It is called amyloid because starch gives a similar reaction, and that reaction for starch is also called an amyloid reaction...
, meaning they will not absorb iodine
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
stain from Melzer's reagent
Melzer's Reagent
Melzer's reagent is a chemical reagent used by mycologists to assist with the identification of fungi.-Composition:...
. The basidia are 26.9–39.3 by 9.0–12.0 µm, cylindrical to narrowly club-shaped, hyaline
Hyaline
The term hyaline denotes a substance with a glass-like appearance.-Histopathology:In histopathological medical usage, a hyaline substance appears glassy and pink after being stained with haematoxylin and eosin — usually it is an acellular, proteinaceous material...
(translucent), and have four sterigmata (extensions that attach the spores). The pleurocystidia (cystidia on the gill face) are 57.4–92.6 by 9.4–17.4 µm, spindle-shaped, moderately frequent, and extend beyond the surface of the hymenium
Hymenium
The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores. In some species all of the cells of the hymenium develop into basidia or asci, while in others some cells develop into sterile cells called cystidia or...
. They have thin, hyaline walls, and are colored the same as the hymenium, without any crystals or encrustations. The cheilocystidia (cystidia on the gill edge), which measure 50.6–75.1 by 12.2–16.1 µm, are more abundant than the cheilocystidia, but otherwise share the same characteristics. The cap cuticle is made of a thin physalo-palisadoderm—a type of tissue where the ends of the hypha
Hypha
A hypha is a long, branching filamentous structure of a fungus, and also of unrelated Actinobacteria. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium; yeasts are unicellular fungi that do not grow as hyphae.-Structure:A hypha consists of one or...
e reach the same length and form a palisade of cells; these short anticlinal hyphae are 20–40 by 5–8 µm, and support one or two inflated, brownish, spherical to spheropedunculate (somewhat spherical with a stem) terminal elements that are 25–45 µm wide, non-amyloid, thin-walled, and do not have any encrustations. The cuticle of the stem is made of smooth parallel hyphae. The squamules on the cap surface have a physalo-palisadodermic arrangement made of short anticlinal hyphae that support elongated inflated elements of 15–30 by 10–15 µm and some scattered basidia. The flesh is made of hyaline, thin-walled hyphae, measuring 10–15 µm wide, and organized in a parallel fashion. These hyphae do not have an associated mediostratum—a central strand of parallel hyphae from which other hyphae diverge sideways. Clamp connection
Clamp 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 are absent in the hyphae of P. bembae.
Similar species
Although the fruit bodies of P. bembae are roughly similar to those in XerocomusXerocomus
Xerocomus is a genus of fungi which is closely related to Boletus. Many mycologists do not recognize the distinction.Most members of Xerocomus are edible.Ladurner and Simonini published a monograph on Xerocomus in 2003....
, species in this genus do not have the powdery veil characteristic of P. bembae. Two similar species in the same area include P. annulus and P. croceus, described in 1951 by Belgian mycologist Paul Heinemann, based on specimens collected in the Congo. Although the identity of these two species is not fully clarified because of insufficient collections, P. bembae differs from both in its larger cystidia, its cream-colored flesh with pale reddish-brown to light brown tones under the cap cuticle (compared to white in P. annulus and P. croceus), its yellow mycelium (white in P. annulus and P. croceus), and differences in ecology.
Habitat and distribution
The species has been found growing in small groups in the Guineo-Congolian rainforest. This forest is dominatedDominance (ecology)
Ecological dominance is the degree to which a species is more numerous than its competitors in an ecological community, or makes up more of the biomass...
by the single canopy tree species Gilbertiodendron dewevrei. Not only does this tree provide food in the form of edible seeds for a wide variety of large mammals, it forms mycorrhiza
Mycorrhiza
A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....
l relationships with P. bembae. This is a mutually beneficial relationship where the hyphae of the fungus grow around the roots of the plant, enabling the fungus to receive moisture, protection and nutritive byproducts of the tree, and affording the tree greater access to soil nutrients. The ectomycorrhizal symbiosis is thought to contribute to the success of the dominant species, by allowing it access to nutrients otherwise unavailable. The Congolian forests
Congolian forests
The Congolian forests are a broad belt of lowland tropical moist broadleaf forest which extends across the basin of the Congo River and its tributaries in Central Africa...
encompass an ecoregion
Ecoregion
An ecoregion , sometimes called a bioregion, is an ecologically and geographically defined area that is smaller than an ecozone and larger than an ecosystem. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural...
known for its species richness
Species richness
Species richness is the number of different species in a given area. It is represented in equation form as S.Species richness is the fundamental unit in which to assess the homogeneity of an environment. Typically, species richness is used in conservation studies to determine the sensitivity of...
and endemism, which is spread across four countries: Cameroon
Cameroon
Cameroon, officially the Republic of Cameroon , is a country in west Central Africa. It is bordered by Nigeria to the west; Chad to the northeast; the Central African Republic to the east; and Equatorial Guinea, Gabon, and the Republic of the Congo to the south. Cameroon's coastline lies on the...
, Gabon
Gabon
Gabon , officially the Gabonese Republic is a state in west central Africa sharing borders with Equatorial Guinea to the northwest, Cameroon to the north, and with the Republic of the Congo curving around the east and south. The Gulf of Guinea, an arm of the Atlantic Ocean is to the west...
, Republic of Congo, and the Central African Republic
Central African Republic
The Central African Republic , is a landlocked country in Central Africa. It borders Chad in the north, Sudan in the north east, South Sudan in the east, the Democratic Republic of the Congo and the Republic of the Congo in the south, and Cameroon in the west. The CAR covers a land area of about ,...
.