Boletellus obscureococcineus, known as the rhubarb bolete, is a species of fungus

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 family 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...

, found in Australia, New Guinea, Java, Borneo, Japan, Korea, and Taiwan. It is a distinctive and colourful 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...

 of the forest floor.

Boletellus obscureococcineus was originally collected in Java and described by Franz Xaver Rudolf von Höhnel

Franz Xaver Rudolf von Höhnel

Franz Xaver Rudolf von Höhnel was an Austrian bryologist, mycologist, and algologist. He obtained his PhD in Strasbourg in 1877, and was a professor of botany in the Vienna University of Technology from 1884 to 1920...

 in 1914, and placed in the genus

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...

 Boletellus

Boletellus

Boletellus is a genus of fungi in the family Boletaceae. The genus has a widespread distribution, especially in subtropical regions, and contains about 50 species. The genus was first described by American mycologist William Alphonso Murrill in 1909...

 by Singer

Rolf Singer

Rolf Singer was a German-born mycologist and one of the most important taxonomists of gilled mushrooms in the 20th century....

 in 1945.

Description

A brightly coloured and distinctive bolete, Boletellus obscureococcineus has a rose-red or rhubarb

Rhubarb

Rhubarb is a group of plants that belong to the genus Rheum in the family Polygonaceae. They are herbaceous perennial plants growing from short, thick rhizomes. They have large leaves that are somewhat triangular-shaped with long fleshy petioles...

-coloured, hemispherical to convex 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...

 to a diameter of 7 cm (3 in), with an overhanging margin when young. The cap may crack in older specimens, and reveal the yellow flesh beneath. The adnexed pores are five- or six-sided and yellow. They bruise blue in some specimens (although not generally in Western Australia). The narrow stipe

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...

 lacks a 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...

, and may reach 9.5 cm (3.7 in) tall with a diameter of 2 cm (0.78740157480315 in). It is reddish and scaled overall, fading to yellow under the cap. The spore print

Spore 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 a dark brown. The mycelium

Mycelium

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...

 is white. There is no significant odour and the taste is mild. Under the microscope, the elongated pale yellow spores

Basidiospore

A basidiospore is a reproductive spore produced by Basidiomycete fungi. Basidiospores typically each contain one haploid nucleus that is the product of meiosis, and they are produced by specialized fungal cells called basidia. In grills under a cap of one common species in the phylum of...

 measure 14.5–19.5 by 6–7.5 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...

.

Habitat and distribution

The distribution includes Korea, New Guinea, Java, Borneo, Japan, and Taiwan. Within Australia, the rhubarb bolete has been recorded from southwestern Western Australia, and the southeast of New South Wales

New South Wales

New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

, and into Victoria

Victoria (Australia)

Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....

 and Tasmania

Tasmania

Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...

.

Similar-looking African collections initially reported as Boletellus obscureococcineus have been redescribed as Boletellus rubrolutescens.

The rhubarb bolete is an ectomycorrhizal species, found in the leaf litter of eucalyptus

Eucalyptus

Eucalyptus is a diverse genus of flowering trees in the myrtle family, Myrtaceae. Members of the genus dominate the tree flora of Australia...

 forests in Australia. Fruit bodies appear over the summer and autumn, from July to November.

Despite its English name, whether this mushroom is safe to eat is unknown; however, the boletes are not a deadly poisonous mushroom variety, although many individuals get gastrointestinal distress from certain species, particularly species with red pigmentation.