Xerocomellus porosporus: The Ultimate Mushroom Guide
About The Xerocomellus porosporus Mushroom
Xerocomellus porosporus is an unspectacular Bolete that can be difficult to identify to species, particularly as it ages. When fully expanded, the caps are up to 8 cm (3.15 in) in diameter and are soon cracked or fissured. Varying in color from putty beige to dull brown, or olivaceous. The pores are narrow, angular, lemon yellow, and darken later. They also bruise blue.
Although edible, this mushroom is rather tasteless and has a very spongy texture.
Other names: Sepia Bolete.
Xerocomellus porosporus Identification
Boletus porosporus, the Sepia Bolete, has a shallow, convex sepia brown to orange-brown cap with a subtomentose (finely velvety) surface that soon cracks extensively in a crazy-paving pattern. The soft flesh that shows through the wide cracks is pale cream.
4 to 8 cm in diameter when fully expanded, the caps become almost flat when fully mature.
Tubes and Pores
The yellow tubes terminate in large, angular pores that are lemon yellow at first but darken with age. When bruised, the pores of mature specimens turn blue.
The stem of Boletus porosporus has no ring, is greyish sepia with a slight reddish flush near the apex and is covered in longitudinal brownish fibrils. 1 to 2cm in diameter and 3 to 6cm tall, the stem is more or less constant in diameter throughout its length apart from usually having a slightly bulbous base.
Subfusiform, truncate at one end, smooth; 11.5-17 x 4.5-6.5µm.
Odor and Taste
Habitat & Ecological Role
This ectomycorrhizal mushroom is most likely to be found beneath oak trees.
Xerocomellus porosporus Look-Alikes
Has a yellow stem that is flushed red in the lower part and blues when cut or bruised near the stem base; its spores are finely striated.
Pseudoboletus parasiticus (synonyms Xerocomus parasiticus and Boletus parasiticus)
Has a dirty yellow stem without red fibrils, and it occurs only with the Common Earthball (Scleroderma citrinum) upon which it may be slightly parasitic.
Also has truncate smooth spores, but it has a reddish cap and blueing flesh.
Another European bolete with truncate spores, but these are clearly striate. It also has a reddish cap.
Xerocomellus porosporus Taxonomy & Etymology
This bolete was described and given the scientific name Xerocomus porosporus in 1958 by Louis Imler (1900 - 1993), who was the founder of the Antwerp Mycological Circle. The currently-accepted scientific name Xerocomellus porosporus dates from a 2008 publication by Czech mycologist Josef Å utara, whose studied in detail morphological character of this and other closely-related boletes - since further supported by DNA studies.
Synonyms of Xerocomellus porosporus include Xerocomus porosporus Imler and Boletus porosporus Imler ex G. Moreno and Bon.
The generic name Boletus comes from the Greek bolos, meaning 'lump of clay', while the new genus name Xerocomellus indicates a (rather distant, actually) relationship with the genus Xerocomus. The prefix Xero- means dry.
The meaning of the specific epithet porosporus comes from the prefix poro- meaning 'a cavity, opening, passage or pore' and sporus, 'relating to spores'. This is a reference to the shape of the spores, which have a noticeable germ pore at the truncate end.
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