Neoboletus luridiformis: The Ultimate Mushroom Guide
About The Neoboletus luridiformis Mushroom
Neoboletus luridiformis is a yellow stem well-coated mushroom with orange-brown powder/spots, blues when bruised. Blue-bruising yellow baby pores soon age to orange/red. Yellow to greenish flesh quickly blues.
It is found in Northern Europe and North America and is commonly known as the scarletina bolete, for its red pores (yellow when young).
Whilst edible when cooked properly, it can cause gastric upset if raw. Where the two species coincide it can be confused with the poisonous Rubroboletus satanas, which has a paler cap.
The European species are formerly known as Boletus discolor, and Boletus luridiformis, Boletus erythropus, and Boletus queletii have been merged into a single species that is now called Suillellus (maybe Neoboletus) queletii.
Boletes of Eastern North America follows this by merging the American “discolor” into “luridiformis” (using Neoboletus as the genus) and then continuing to use the European name until a replacement is settled. The bottom line is this: it is a beautiful mushroom with massive flexibility in how it appears.
Other names: Red Foot Bolete, Dotted Stemmed Bolete, Dotted Stem Bolete, Slender Red-Pored Bolete.
Neoboletus luridiformis Identification
The cap color of this often massive bolete is very variable. It can be dark chocolate brown, pale brown, or even, as in this fine specimen, coppery bronze. The cap flesh is yellow, rapidly bluing when cut or bruised.
Caps of Neoboletus luridiformis are initially downy and convex, becoming flatter, smooth, and shiny as the fruitbody matures. The diameter at maturity varies between 8 and 20 cm.
Tubes and Pores
Orange at first, the round, crowded pores soon become bright red and then rusty brown with age.
The spore tubes are lemon yellow, but they very quickly turn blue-green when cut or bruised.
Apart from a pale area near the apex, a pattern of tiny red dots covers most of the stem of Neoboletus luridiformis. (A hand lens may be necessary to distinguish the separate dots on some specimens.)
Typically 2 to 4cm in diameter and more or less parallel-sided, stems of the Scarletina Bolete range between 7 and 15cm tall and have yellow flesh that instantly turns blue-green when cut or bruised.
Sub-fusiform (broadly spindle-shaped) to broadly ellipsoidal, 12-16 x 4.5-6µm.
Neoboletus luridiformis Look-Alikes
Similar but has a red net pattern on its stem.
Has a chalky white cap and a bulbous stem covered in a bright red net pattern on a yellow background; it is poisonous.
Has a reticulate stipe, and is larger.
Has a reddish cap.
Prefers neutral soil.
Neoboletus luridiformis Taxonomy & Etymology
In 1796 Christian Hendrik Persoon described Boletus erythropus, deriving its specific name from the Greek ερυθρος ("red") and πους ("foot"), referring to its red-colored stalk. During the next 200 years or so, this name was used extensively for the species which is the subject of this article, and which (as well as a red stalk) has red pores. Recently it was discovered however that Persoon's mushroom had orange pores, and was a different species (actually thought to be Suillellus queletii). So the use of this name for the red-pored mushroom was invalid.
In 1844 Friedrich Wilhelm Gottlieb Rostkovius independently defined the red-pored species under the name Boletus luridiformis. That is now the first valid description of the taxon and is the basis of the current name (the basionym).
The genetic analysis published in 2013 showed that B. luridiformis and many (but not all) red-pored boletes were part of a dupainii clade (named for Boletus dupainii), well-removed from the core group of Boletus edulis and relatives within the Boletineae. This indicated that it needed to be placed in a new genus. It became the type species of the new genus Neoboletus in 2014.
To avoid confusion, the name Boletus erythropus should now be avoided if possible. It is not a valid synonym of Neoboletus luridiformis, and that can be indicated by using the term sensu auct. in place of the author name (that is, Boletus erythropus sensu auct. = Neoboletus luridiformis (Rostk.) Gelardi, Simonini & Vizzini).
The generic name Boletus comes from the Greek bolos, meaning 'lump of clay', while the prefix neo- means new or young, and in taxonomy it is used to indicate a recent cladistic branch.
The specific epithet luridiformis suggests that this species is similar in form to Suillellus luridus.
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