The genus Leccinum in Western and Central Europe

INTRODUCTION / CHARACTERS/ KEY / DESCRIPTIONS / REFERENCES

DIAGNOSTIC CHARACTERS OF LECCINUM

This page gives an overview of the species of Leccinum in Western Europe, based upon the recent work of Henk den Bakker during his succesfully ended PhD project at the National Herbarium of the Netherlands under my supervision.
The genus Leccinum is easily identifiable in the field, at least in the Northern Temperate regions of Europe and North America, on account of the stipe surface, which is ornated with fine to rather coarse squamules, which often have a colour contrasting with the surface of the stipe.
Most species are rather variable in colour and in the way the context stains or not when cut. This has lead to the description of rather many species. Morphological studies, combined with modern molecular methods have proved that the number of species is much lower than reflected in recent literature. The present key and description are based on these studies.

Key tot the species

1. Context usually clearly staining grey to black when cut

2

1. Context not staining grey or black when cut, or at most after many hours

9

2. Pores yellow

L. crocipodium

2. Pores whitish or with a greyish of brownish colour

3

3. Margin of pileus, especially in young fruiting bodies, overhanging with disrupted flaps; colour of pileus usually reddish or orange, more rarely pink or yellowish-ochre

4

3. Margin of pileus entire, rarely somewhat overhanging; colour of pileus brown, yellow-brown or grey-brown

8

4. Ornamentation of stipe white, brown or reddish, in mature fruiting bodies often almost black; caulocystidia with reddish brown pigment ; associated with deciduous trees

5

4. Ornamentation of stipe brown or black, caulocystidia with greyish pigment; associated with conferous trees or Betula

6

5. Stipe with reddish squamules already when young, darkening with age; pileus reddish brown, becoming dark brown in exsiccates

L. aurantiacum

5. Stipe with white squamules when young, which turn only slightly darker with age; pileus orange, becoming pale bornwin exsiccates

L. albostipitatum

6. Pielus orange to brown-orange; the larger caulocystidia utriform or fusiform, often also lageniform; associated with Betula

L. versipelle

6.Pileus brown to reddish brown; larger caulocystidia clavate; associated with coniferous trees (Pinaceae)

7

7. Pileus reddish brown; associated with Pinus, rarely Picea

L. vulpinum

7. Pileus dull brown; with Picea

L. piceinum

8. Surface of pileus in young fruiting bodies rugulose; pileipellis a palisade-like trichoderm of broad, clavate elements; associated with Corylus or Carpinus

L. pseudoscabrum

8. Surface of pileus in young fruiting bodies smooth; pileipellis a cutis with cylindrical elements; associated with Populus

L. duriusculum

9. Pileipellis with cylindrocysts; stipe base often with blue-green stains

10

9. Pileipellis usually without distinct cylindrocysts; stipe base with or without blue-green stains

11

10. Stipe surface with rather coarse squamules,giving the stipe surface an almost woolly appearance; pileus uniformly coloured; elements of pileipellis often rather broad; Q-value of spores in average > 3.0

L. cyaneobasileucum

10. Squamules on stipe small, contrasting with paler background; pileal surface variegate with lighter and darker stripes and patches; pileipellis a cutis, often with chains of cylindrocysts; Q value of spores in average < 2.8

L. variicolor

11. Surface of stipe dark greyish brown to almost black with similarly coloured squamules

L. melaneum

11. Surface of stipe pale, contrasting with dark squamulose covering; or otherwise with pale coloured squamules;

12

12. Q value of spores in average > 3.0; caulocystidia large, clavate; stipe base without blue stains

L. scabrum

12. Q value of spores in average < 3.0; without clavate caulocystidia; with or without blue stains in the base of stipe

13

13. Caulocystidia clavate to lageniform; base of stipe without blue stains

L. rotundifoliae

13. Caulocystidia narrowly lageniform with a flexuous neck or utriform, rarely clavate; blueish colourations in stipe base present or absent.

14

14. Stipe with rather coarse warty or floccose squamules; caulocystidia often lageniform with flexuous neck; elements of pileipellis with intracellular pigment; pileus white or pale brown, often with bluish greenish tinges when old

L. holopus

14. Stipe with fine, blackish or brownish squamules; caulocystidia utriform or more rarely lageniform with flexuous neck; pileipellis incrusted with plague-like patches; pileus usually brown or grey

L. schistophilum

DESCRIPTIONS

 Leccinum aurantiacum (Bull.) Gray

Icons: Lannoy & Estades, Mon. Lecc. Europe: pl. 37 (as L. quercinum). 1995; Korhonen in Karstenia 35: p. 54, ?g. 1 & 2 (as L. populinum and L. quercinum respectively). 1995.

Description

 

Pileus 30-150(-280) mm, truncate-conical to conico-convex or hemispherical when young, expanding to truncate conico-convex, convex or planoconvex when mature, with involute then deflexed margin, extending over tubes with distinct triangular or irregularly shaped flaps, up to 6 mm long, very evident in young specimens, and generally also in mature specimens, rarely disappearing with age; vivid red to red-brown (Mu. 2.5 YR 4/6 -5/8; 10 R 4/4, 4/6, 3,6, towards margin sometimes more orange-yellow (7.5 YR 7/8), initially ?nely tomentose, breaking up with age in small adpressed squamules all over. Tubes adnexed to adnate, segmentiform to venticose, 9-30 mm long, creamy-white to very pale brown (Mu 10 YR 6/4). Pores ca 0.2-0.5 mm in diameter, yellowish white to very pale brow (Mu 10 YR 7/4), discolouring brownish when bruised. Stipe 50-270 mm x 15-50, cylindrical to clavate to fusiform, whitish, often with a distinct blue discolouration at base, especially when handled, entirely covered with scabers, which are small and isolated at apex, coarse and more dense and sometimes agglutinated towards base, initially reddish, darkening to red-brown or reddish black with age. Context white, turning violaceous-grey, grey or blackish when bruised; in stipe base often turning blue-green.

Spores 12.5-18.5 (-22.5) x 3.6-5.1 (-6.1) µm, Q = 2.8 - 4.1, Qav= 3.5; fusiform with conical apex, with distinct suprahilar depression, pale, purplish brown in water. Basidia 18.5 -25.0 x 6.5-10.5 µm, clavate. 2- or 4-spored. Hymenocystidia 20-45 x 5-8 µm, narrowly lageniform and hyaline in tubular hymenium, clavate or utriform with reddish brown content on pore surface. Pileipellis a intricate trichoderm of narrowly cylindrical and cylindrical elements, terminal elements often conical or cylindrical with a mucronate apex, 31.5-99.0 x 3.0-15.5 µm, elements in suprapellis 50-68 x 5.5-12.5 µm, pigment in water vacuolar or in globules, larger elements often intracellularly granular incrusted, red-brown. Caulocystidia 33.0-60.0(-89.5) x (6.5-) 12.5-20.5µm, clavate with acute or obtuse apex to almost spheropedunculate, rarely urtriform or fusiform, often also small lageniform cystidia present, large cystidia usually with reddish brown content in KOH, small lageniform cystidia usually hyaline. Clamp connections absent.

Habitat and distribution -Solitary or gregarious in grass and mosses on mesotrophic, sandy or loamy soils. Mycorrhizal with Populus, Quercus and Betula, rarely with Salix, Fagus, Castanea and Tilia. Fairly common in the Netherlands and widespread in Europe.

Discussion:
After intensive molecular and morphological studies of collections (including holo-types) that were associated with Populus, Quercus and Betula, we could not find any clear support for the recognition of L. populinum and L. quercinum as distinct species. Therefore we merge these taxa into one species, L. aurantiacum, with a broad host range. Our measurements did not indicate there is a significant difference in spore-size nor in spore-dimensions between collections that were associated with either Populus or Quercus. For more details is referrend to our paper (see literature)

L. aurantiacum: photo M.E. Noordeloos

 Leccinum albostipitatum Den Bakker & Noordeloos

Iceons: Lannoy & Estades, Mon. Leccinum: pl. 34. 1995; Korhonen in Karstenia 35: p. 55, ?g. 3 (as L. aurantiacum), 1995.

Description

Pileus 80-250 mm, hemispherical when young, convex to planoconvex when mature, margin especially in young fruit bodies inflexed, with appendiculate flaps, exceeding up to 4 mm, in mature fruit bodies margin often seemingly entire and marginal flaps absent, vivid orange (Mu. 7.5 YR 7/6 -7/8); surface minutely tomentose to ?brillose squamulose. Tubes adnexed to adnate, venticose, 9-30 mm long, pale brownish (Mu 10 YR 6/4), yellowish white. Pores ca 0.5 mm in diameter, yellowish white to very pale brownish (Mu 10 YR 7/4), discolouring brownish when bruised. Stipe 50-270 x 15-50 mm, cylindrical to subclavate, whitish, often with a clear blue discolouration in the stipe base when handled, lightly to densely covered with ?ne (sometimes on the stipe base more coarse) whitish (when young) to reddish brown (in older specimens). Context white, when bruised often discolouring ?rst vinaceous, than greyish, blackish, often discolouring bluish in the stipe base.

Spores (9.5-) 11-17. x 3.9-5.1 (-5.6) µm, Q=2.3-3.6 (-4.0), Q= 3.1; fusiform with a conical apex, with a distinct suprahilar depression, pale, purpilish brown in water. Basidia 23.5-35.0 x 7.5-11.0 µm, clavate, 2- or 4-spored. Hymenocystidia 20-45 µm x 7- 10µm, lageniform in tubular hymenium, form cystidia of hymenium pore surface not clearly observed. Pileipellis an intricate (ixo-)trichoderm of narrowly cylindrical and cylindrical elements, terminal elements often conical, 34-81.5 x 4.0-15.5 µm, pigment in water often intracellularly granular incrusted, yellowish brown. Caulocystidia 16.0-63.0 x 16-63.0 µm, clavate to fusiform, rarely lageniform, largest cystidia often fusiform, apex usually obtuse, content pale sepia to hyaline in KOH. Clamp connections absent.

Habitat and distribution - Mycorrhizal with Populus. Probably a boreal and sub-alpine species, common in Scandinavia and the mountainous areas of central Europe, rare at lower altitudes.

Discussion:
The main difference between L. aurantiacum and L. albostipitatum is found in the colour of the stipe ornamentation and the cap colour both in fresh and dried carpophores. L. aurantiacum generally has a brownish reddish stipe ornamentation that is already reddish coloured in young carpophores. L. albostipitatum starts with an completely white stipe ornamentation, that colours slightly darker in older carpophores. Care should be taken in using this character when the carpophores are found in high vegetation. We observed that the stipe ornamentation of L.aurantiacum can be almost white when the stipe is covered with grass. In these cases the cap colour provide a better character to discriminate the two species. L. aurantiacum has a vivid red to reddish brown cap, and when dried the cap has a reddish brown colour. The cap colour of L. albostipitatum is generally vivid orange and changes to a dull light brown in dried carpophores.

 Leccinum vulpinum Watling

Iceons: Lannoy & Estades, Mon. Lecc. Europe: pl. 36. 1995.

Description

Pileus 70-92 mm, hemispherical when young, convex to planoconvex when mature, margin especially in young fruitbodies involute or inflexed, with appendiculate flaps, exceeding up to 6 mm, in mature fruit bodies margin often seemingly entire and marginal flaps absent; usually dark reddish brown (Mu. 2.5 YR 6-3/6, 10 R 3/6), with patches of a slightly lighter colour; tomentose to ?brillose squamulose. Tubes adnate to sinuate, venticose, 10-16 mm long, pinkish brown (7.5 YR 7/4) pale greyish brown (10 YR 7/3-4), slightly darker when bruised. Pores ca 0.5 mm in diameter, concolorous with tubes. Stipe 70 -150 x 14 - 31 mm, cylindrical to subclavate, sometimes fusiform, whitish, near the apex lightly covered and towards the base more densely covered with ?ne (sometimes on the stipe base more coarse) dark brown or greyish to blackish coloured scabers. Context white, when bruised almost unchanging, slowly discolouring greyish, blackish with a violet hue in the cap and upper half the stipe, sometimes with bluish discolorations in the stipe base.

Spores (9.5-) 11-15.5 x 3.6-4.7 µm, Q=2.5 - 3.8, Qav= 3.2; fusiform with conical apex, with a distinct suprahilar depression, pale, purplish brown in water. Basidia 20.5- 26.5 x 7.5-10.5 µm, clavate. Hymenocystidia 20 - 45 x 5 - 10 µm, lageniform, hyaline in tubular hymenium, pleurocystidia often clavate or narrowly utriform with a reddish brown content. Pileipellis cutis-like, elements 18.5 - 34.0 x 3.0 - 3.5 µm, elements in suprapellis 50.0 - 68 x 5.5 - 12.5 µm, pigment in water vacuolar or in globules, bigger elements often intracellularly granular incrusted, red-brown. Caulocystidia 20.5 - 42.5 x 9.5 - 16.0 µm, generally clavate with an obtuse or acuminate apex, content usually brownish in KOH, larger cystidia usually hyaline. Clamp collections absent.

Habitat & distr. - Solitary or in clusters in coniferous forests. Associated with Pinus and Picea. Known from Scotland, Scandinavia and Central Europe. Probably widespread in coniferous forests in subalpine and boreal regions throughout the Northern Hemisphere.

Discussion:
Leccinum vulpinum can readily be recognized in the ?eld on account of its dark reddish brown pileus and distinct black squamules on the stipe. The intensity of the blackish discoloration of the context is only a fraction of the intensity of the discoloration as seen in L. versipelle and L. aurantiacum, which, together with its association with conifers, can help to facilitate the identification.

 Leccinum piceinum Pilát et Dermek

Discussion:

Leccinum piceinum Pilát and Dermek is another species that has been described from coniferous forests in Europe. This species is associated with Picea and was originally described from central Europe. Most collections from Sweden that were collected in Picea forest and therefore identi?ed as L. piceinum did not differ in their pileus coloration and other morphological characters from L. vulpinum. The collections in central Europe differed from L. vulpinum mainly by a duller cap colour, a character that is also used by Lannoy and Estades (1995) to distinguish L. piceinum from L. vulpinum. The original holotype of L. piceinum was not suf?ciently well preserved to make a morphological study possible, however, material from the locus typicus did not differ from our concept of L. vulpinum, except for the cap colour. Whether the central European collections associated with Picea with an aberrant cap colour represent a genetically distinct taxon remains to be investigated.

 

 Leccinum versipelle (Fr. & Hök) Snell

Icons: Lannoy & Estades, Mon. Lecc. Europe: pl. 24, pl. 31, pl. 32, pl. 33. 1995; Estades & Lannoy, Bulletin Mycologique et Botanique Dauphiné-Savoie 174 (3): p. 74 (top)

Description:

Pileus 80-180 mm, hemispherical when young, convex to planoconvex when mature, with inflexed margin especially in young fruitbodies, with appendiculate flaps, exceeding the tubes up to 4 mm, in mature fruit bodies marginal flaps often absent and margin entire, yellowish brown (Mu. 10 YR 7/8), orange (.2.5 YR 6/8) to brown (. 5 YR 5/6), sometimes whitish or whitish with pinkish or apricot tinges; minutely tomentose to ?brillose squamulose. Tubes adnexed to emarginate, segmentiform to venticose, 8 - 22 mm long, yellowish white to brownish grey, violacious/greyish when bruised. Pores ca 0.5 mm in diameter, greyish white to grey ochre (10 YR 7/3), discolouring brownish when bruised. Stipe 70 - 200 x 10 - 45 mm, cylindrical to clavate, whitish, greyish white or yellowish white, sometimes with a clear blue discolouration in the stipe base when handled, lightly to densely covered with ?ne (sometimes on the stipe base more coarse) greyish to blackish, sometimes whitish squamules. Context white, when bruised often discouloring greyish, blackish with a violet hue in the cap and upper half the stipe, often discolouring bluish in the stipe base.

Spores (9.0-) 11.5-16.5 x 3.6-4.0 (-5.2) µm, Q = 2.6-3.8, Qav = 3.2; fusiform with a conical apex, with a distinct suprahilar depression, pale, purplish brown in water. Basidia 22.0 - 34.0 x 6.5-11.0 µm, clavate, generally 4-spored. Hymenocystidia 22-45µm x 7-11µm, often lageniform and hyaline in tubular hymenium, narrowly utriform or clavate (sometimes with an obtuse, acuminate apex), hyaline or with a brownish content on the pore surface. Pileipellis an intricate cutis of cylindrical elements, terminal elements observed obtuse, 42.0-87 x 5.0-17.5 µm, pigment granular encrusted, sometimes forming small globules, pale yellowish brown. Caulocystidia (26.5-) 39.0-70.5x 8.5- 70.5 µm, fusiform to utriform, sometimes conical or clavate, largest cystidia generally fusiform or utriform, apex usually obtuse, sometimes acute, pale brownish, greyish content in KOH. Clamp-connections absent.

Habitat & distr.-Solitary or gregarious on sandy, slightly acidic, loamy soils, mycorrhizal with Betula. Rare and endangered in the Netherlands (Red List 2: Arnolds and Van Omering, 1997), more common in Scandinavia and other parts of Europe.

Discussion:
The number of species around Leccinum versipelle has steadily grown in the past decades. Several related or similar species have been described, such as L. percandidum with a white or whitish pileus that becomes pale brownish when mature, and L. roseotinctus, with an initially white pileus that changes to pinkish when mature, L. cerinum with a paler orange to yellowish pileus and pale, yellowish white pores in young basidiocarps, and L. callitrichum with a more or less ochre pileus and dark brown elements in the pileipellis. The outcome of the molecular studies (Den Bakker 2004a and 2004b) indicate, however, that a broad morphological species concept of Leccinum versipelle fits better with these results. No consistent morphological and molecular characters support the recognition of species species like L. cerinum and L. callitrichum. The collections of Leccinum. roseotinctum and L. percandidum showed sequences that were identical or almost identical to the sequences of collections of normally pigmented L. versipelle. These taxa must therefore be considered less pigmented forms of L. versipelle without formal taxonomic status.

Various forms of Leccinum versipellei: top figure: form descrbied as L. cerrinum; middle: typical L. versipelle; lower left: L. roseotinctum; lower right L. percandidum. All these taxa are now considered mere colour forms of L.versipelle.

 Leccinum duriusculum (S. Schulz.) Singer

Icons: M. Bon, Mushr. Toadst.: 41. 1987; Breitenb. & Kränzl., PIlze Schweiz 3: 70, pl. 32. 1991; Engel, Rauhstielröhrlinge: pl. 5a. 1978; Muñoz, Fungi non del. 13: pl. 11, 12 (as f. robustum). 2000; R. Phillips, Paddest. Schimm.: 212. 1981; Pilát & Dermek, Hrívobité Huby: pl. 75 1974.

Description:

Pileus 40-150(-220) mm, hemispherical then convex, finally sometimes with slightly flattened centre, very variably in color from rather pale grey-brown with slight violaceous tinge to rather dark grayish or reddish brown (Mu. 10 YR 7/4-4/4; 7.5 YR 7/4-4/2), minutely fibrillose-felted to very minutely adpressedly squamulose all over, often very finely cracked with age in form of very small fibrillose-felted patches, initially concolorous with context, but later on contrasting with paler context. Tubes adnexed to almost free, broadly ventricose, up to 25 mm long, creamy white then with grayish-buff colour; pores rounded, about 0.3-0.5 mm in diameter, beige (5Y 7-6/3) turning brown when bruised. Stipe 80-170 x 14-20 mm, cylindrical with slightly tapering apex and rounded to subclavate base, solid, entirely minutely squamulose with fine grayish to blackish squamules, which become larger towards base, often arranged in longitudinal rows or ridges, sometimes, especially in upper part of stipe, merging into a reticulate pattern, strongly contrasting with pallid, almost white stipe surface. Context white in pileus and upper part of stipe, frequently tinged yellow-green in lower part of stipe, slowly turning violaceous pink when cut, then spots wise turning darker grayish-violaceous black; in base of stipe locally turning yellow-green to blue-green. Spore print olivaceous-yellow brown (2.5 Y 6/6 tending to 10 YR 5/6).

Spores (120.5) (11.5-)12-15.5 x 4.5-6.0 µm, av. 13-14 x 4.8-5.1 µm, Q = 2.3-3.3, Qav = 2.4-2.7; fusiform with conical apex, with distinct suprahilar depression, relatively thick-walled, pale brown in water. Basidia 19-37 x 6.0-9.0 µm, clavate, 4-spored. Hymenial cystidia abundant on edge and sides of the pores, 20-75 x 5.5-17 x 2.0-4.0 µm, lageniform, often with rather long, tapering neck, colorless or with brown, intracellular-granular pigment. Pileipellis intricate trichoderm of septate hyphae, terminal elements 12-90(-120) x 2.5-7.5 µm, irregularly cylindrical with intracellular pigment. Stipitipellis a cutis of narrow, cylindrical, 3.0-9.0 µm wide hyphae, with small to fairly large caulohymenial clusters of basidia and cystidia, forming the squamules on the stipe surface. Caulocystidia 25-110 x 5.0-12 x 2.0-6.5 µm, lageniform or fusiform, thin- or thick-walled, colourless or with brown granular intracellular pigment. Clamp-connections absent.

Habitat & distr. - Mycorrhizal, associated with Populus, esp. with P. alba and P. tremula, but also with various Populus cultivars, preferably on calcareous clay, sometimes on sand or loam; locally not uncommon, elsewhere rare, mainly in N and F, very rare in L, E, Z, D en K. rare, but widespread in Europe.

Discussion:
Leccinum duriusculum f. robustum, which is said to differ by the more robust basidiocarps, is not recognized here, since a continuum has been observed, well covering the size and shape of f. duriusculum and f. robustum. The last-mentioned form, however, seems to prefer hybrid Populus, whereas the more slender form often grows with Populus tremula. But this is not always the case, hence the forms are not given a formal status here.

Leccinum duriusculum: top from the Netherlands, typical form under cultivated Populus hybrids on clayey soil; lower figure represents "forma"robustum from a dune grassland in Ravenna, Italy, growing under Populus alba.

 Leccinum scabrum (Bull.: Fr.) Gray

Icons: Lannoy & Estades, Monogr. Leccinum: pl. 4. 1995; Marchand, Champ. Nord Midi 2: pl.169. 1973; R. Phillips, Paddest. Schimm: 213. 1993; Rymann & Holmåsen, Pilze: 231. 1992. Lannoy & Estades, Monogr. Leccinum: pl. 16 (as L. rigidipes). 1995; R. Phillips, Paddest. Schimm: 213 (als L. oxydabile). 1993.

Description:

Pileus 52 -130 mm, convex at ?rst, expanding to planoconvex, with entire, deflexed or inflexed margin, not or only very slightly (< 1mm) extending over tudes, yellowish brown to dark brown (Mu. 7.5 YR 6/4 to 5/4, 10 YR 6/6); minutely tomentose, breaking up in minute, adpressed squamules with age, somewhat viscid when moist. Tubes broadly adnexed, 8 -1.9 mm long, segmentiform to subventricose when mature, whitish when young, brownish grey when mature. Pores greyish white, often with brownish spots, discolouring brownish when bruised. Stipe 82 - 145 x 12 - 55 mm, cilindrical to clavate, whitish, often more brownish towards apex, entirely covered with blackish to greyish, sometimes pale brownish scabers, ?ne at apex, becoming gradually coarser towards base, sometimes agglutingating and almost forming a network. Context whitish, not changing colour when bruised or at most discolouring pinkish or reddish (9A2), ?nally often brownish or slightly greyish after several hours.

Spores 14.5-19.0 x 5.0-6.5 µm, Q = 2.5-3.5, Qav = 3.0, fusiform with a suprahilar depression. Basidia 31.0-37.5 x 10.5-12.5 µm, 4-spored (sometimes 3-spored). Hymenocystidia 28.5-50.0 x 5.5-7.5 µm, fusiform lageniform, cylindrical to clavate or lageniform, apex obtuse or accuminate. Caulocystidia (34.5-) 41.0-69.0 (-92.5) x 9.0-18.5 µm, lageniform to clavate, hyaline or with a greyish brown content when mounted in KOH. Pileipellis an dense to lose, intricate cutis, composed of slender, hyaline to brownish intracellularily pigmentated, or granular incrusted hyphal-elements, 3.5-7.0(-8.0) µm in diameter and broadly elongated hyphal elements, (7.5-) 8.0-14.0(-16.0) µm in diameter, sometimes also with broad, clearly articulated, hyaline hyphal elements, (8.0-) 9.0-13.5(-17.0) µm in diameter, terminal elements conical. Clamp-connections absent.

Habitat & distr. - Associated with Betula. Often found in lawns or oligotrophous Festuca rubra /Deschampsia flexuosa vegetations on slightly acidic, dry sandy soils. Widespread and common in Western Europe. Probably a species with a circum boreal distribution.

Discussion:
Leccinum scabrum can usually be distinguished from other species of subsection Scabra by a combination of the following characters: -the stipe ornamentation is usually coarse in the lower part of the stipe and changes to fine, sometimes almost 'glandular' squamules in the upper half of the stipe. -bluish discolorations of the context are always absent. -the presence of remarkably big (up to 92µm long), usually clavate caulocystidia. -the pileipellis which is a loose cutis composed of a mixture of slender and broad, sometimes elliptical, elements. Leccinum scabrum occurs generally in drier habitats than other species of subsection Scabra. Thanks to monographs like that of Lannoy & Estades (1995) there generally is a consensus about the identity of Leccinum scabrum. The current concept, however, of Leccinum scabrum is wider than that Lannoy & Estades, and includes also Leccinum roseofractum, L. avellaneum and L. rigidipes, thus including also forms with discolouring context. As such, Leccinum scabrum is a fairly variable species, and L. avellaneum and L. roseofractum may be considered the extremes in a series of lighter to darker forms. Gradual differences were also found in the discoloration of the context when bruised, ranging from not reacting to discolouring pinkish to almost reddish. To consolidate the taxonomic status of Leccinum scabrum an epitype originating from the neighbourhood of Paris is designated here. In Europe, the slender spores (Qav ³ 3.0) can help to dicriminate it from from Leccinum rotundifoliae. However, the average Q-value of collections identified as Leccinum scabrum from eastern North America is lower than the average Q value in Europe, viz., 2.8 instead of 3.0. Therefore the average Q value can probably not be used in Northern America to discriminate this species from L. rotundifoliae. According to Watling (1968) L. roseofractum differs from L. scabrum by the more robust habit, dark coloured pileus, the dense black stipe ornamentation and flesh changing distinctly red. Collections were made of L. roseofractum in Scotland, Norway and Canada. The European collections matched all of Watlings criteria for L. roseofractum, the Canadian collection, however had a slender habit, but a strong reddish discoloration, an almost blackish pileus and dark blackish stipe ornamentation. The three collections did not form a separate clade in our molecular phylogenetic analysis, but were found dispersed between accessions of L. scabrum. Microscopically these collections were not different either from collections identified as L. scabrum. Therefore L. roseofractum is considered a synonym of L. scabrum. The type material and original description of Orton (1988) of L. rigidipes is reminiscent to L. scabrum in almost every morphological character, except for the presence of short hyphal elements (interpreted as 'cylindrocysts' by Lannoy & Estades, 1995) in the pileipellis. Specimens with abundant 'cylindrocysts', identified as L. rigidipes, were molecularly identical with collections without 'cylindrocysts'. Moreover, we found cylindrocysts, though in low numbers, are often present in the pileipellis of L. scabrum. In conclusion, Leccinum rigidipes is also considered synonymous with L. scabrum. The name Leccinum subcinnamomeum is validly published, since Pilat and Dermek refer to Krombholzia scabra f. cinnamomea Vasilkov being the basionym of this taxon. Kromholzia scabra f. cinnamomea Vaslikov is validly published and is not the basionym of L. cinnamomeum Smith, Thiers and Watling. No type material of L. subcinnamomeum seems to be designated. Material of this species in PRM fits perfectly in our morphological concept of L. scabrum. Most descriptions and plates in literature (Engel 1978, Bresinsky 1996, Dähnke 1993) also refer to a taxon close to Leccinum scabrum with a reddish brown cap colour.

Leccinum scabrum. Note the dramatic differences in colour and also the context which may not change colour when cut, or turn bright pinkish red.

 Leccinum melaneum (Smotl.) Pilát & Dermek

Icons: Dähncke, 1200 Pilze: pl.98. 1993.

Description:

Pileus 50 - 130 mm, convex at ?rst, expanding to planoconvex with age, often irregularly shaped, brown to dark brown (Mu. 7.5 YR ¾), sometimes with lighter coloured spots; very ?nely tomentose, becoming subviscid with age. Tubes narrowly to broadly adnexed, 8-1.9 mm long, whitish when young, greyish to brownish at maturity. Pores greyish white, often with brownish spots, brownish when bruised. Stipe 90-145 mm x 21-55 mm, cylindrical to (broadly) clavate, greyish to blackish, entirely covered with squamules (scabers), ?ne near the apex of the stipe, gradually becoming coarser towards base, in basal part often agglutinated and forming a sort of reticulum. Context white, when bruised often discoloring pinkish (9A2), then often brownish after several hours.

Spores 14.0 - 19.0 x 5.0 - 6.0 µm, Q = 2.5 - 3.5, `Q = 2.9, fusiform with a suprahilar depression. Basidia 20.5 - 27.5 x 11.5 - 13.0 µm, 4-spored, sometimes 2-spored. Hymenocystidia 25.0 - 52.5 x 7.5 - 11.5 µm, lageniform, clavate with a mucronate apex or utriform. Pileipellis a loose intricate cutis of cylindrical, sometimes bifurcate, elements 9.0 - 11.5 ( - 15.0) µm wide with dark brown intracellular pigment. Caulocystidia 34.0 - 60.5 x 12.5 - 18.5 µm, fusiform, utriform and clavate. Clamp-connections absent.

Habitat & distr. - Known from four localities in the Netherlands (Boekweitveentje, Gieten, Drenthe; Boswachterij Gees, Drenthe; Amsterdamse Waterleiding Duinen, Noord Holland, Wisselsche Veen, Epe, Gelderland). Distribution in Europe unclear, because of confusion with dark forms of L. scabrum.

Discussion:
Leccinum melaneum does not differ morphologically much from L. scabrum, except for the fact that the stipe surface generally is coloured greyish or blackish in this species, opposed to whitish to brownish in L. scabrum. Three of the four collections further show an unusually broad stipebase (giving the stipe a broadly clavate form) and slightly malformed pileus. Molecular data indicate L. melaneum might be a taxon of hybridogen origin as explained above in the paragraph ' hybridization and introgression' in the introduction.

 Leccinum rotundifoliae(Singer) Smith, Thiers and Watling

Icons: Lannoy & Estades, Mon. Leccinum: pl. 2 (as L. pulchrum), pl. 3 (as L. pulchrum f. fuscodiscum), pl. 7. 1995; Estades and Lannoy, Bull. Mycol. Bot. Dauphiné-Savoie 174: 62 (as L. pulchrum).

Description

Pileus 25-90 mm, hemispherical) to convex, expanding with age, with inflexed, entire margin, not exceeding the tubes or at most up to 1 mm, pale yellowish brown, light brown (Mu. 10 YR 5/2) to very dark brown or grey brown (10 YR 6/4), then often mottled; surface ?brillose tomentose, sometimes appearing to be velutinous ,frequently irregularly cracked; slightly viscid when old.Tubes adnexed to narrowly adnate, 8 - 21 mm long, broadly convex to ventricose, creamy white to greyish white. Pores yellowish white to brownish white, discolouring brownish when bruised. Stipe 40 - 100 x 7-25 mm, sub-clavate to clavate, whitish; entirely covered with squamules, squamules either whitish and changing to brownish with maturity or blackish, ?ne near the apex, gradually becoming more coarse/flocculose towards towards stipe base. Context whitish, when bruised unchanging or discolouring pinkish, especially in apex of stipe.

Spores (11.5-) 13.5-17.5 (-20) x 4.5-6.8 (-7.0) µm, Q=2.2-3.2, Qav= 2.8. Basidia 23.5-33.0 x 11.0-12.5 µm, clavate. Pileipellis a rather regular intricate, cutis-like trichoderm, elements 31.5-94.5 x 3.0-8.5 µm, narrowly cylindrical, hyaline and granular incrusted or brownish and than often granular incrusted. Caulocystidia 37.5-59.5 x 11.0-20.5, utriform, lageniform or fusiform, content hyaline or pale greyish brown when mounted in KOH. Clamp collections absent.

Habitat& distr.-Solitary or gregarious in wet to dry habitats, mycorrhizal with Betula. Widespread in boreal and arctic regions, probably following a circum polar distriburion. Exact distribution in subalpine regions at lower latitudes unclear because unsuf?ciently known morphologic variability (see chapter 3)

Discussion:
L. rotundifoliae is a species of arctic, alpine, boreal and sub alpine habitats. Light colored carpophores can be discriminated from L. holopus by the absence of bluish discolorations in the context of the stipe base, and the absence of greenish bluish tinges in the cap of older carpophores. Next to differences in colour there seems to be an ecological difference in arctic regions, L. rotundifoliae being a species of dry habitats, whereas L. holopus prefers wet habitats. In subalpine and boreal regions L. rotundifoliae can also be found in wetter habitats.
L. rotundifoliae is generally considered to be a pale brown to almost whitish species. However, specimens with a dark cap and dark stipe squamules were also sequenced. The first of these specimens (a collection from Borgsjö, Jämtland, Sweden) to be sequenced was eroniously called L. scabrum (Den Bakker et al. 2004a) based on the minor sequence divergence in ITS between L. scabrum and L. rotundifoliae. Analysis of an additional gene (Gapdh), however supported the existence of L. rotundifoliae as a separate species. When type material of L. pulchrum was sequenced, these accessions surprisingly appeared in the L. rotundifoliae-clade. Upon closer inspection of the morphology and a comparison of photographs of dark specimens of L. rotundifoliae from Greenland and Sweden with the picture of L. pulchrum in Estades & Lannoy (2004, p. 62) these show a perfect resemblance. Leccinum pulchrum is therefore reduced to the synonymy of L. rotundifoliae. This demontrates that Leccinum rotundifoliae not only occurs in Northern Europe, but also in the Alps. One accession from the French lowlands that was identified as Leccinum pulchrum, appeared in the L. scabrum clade, which was confirmed with morphological data, and must therefore be considered a misapplication. In their description of Leccinum pulchrum, Lannoy and Estades (1995) state that occasionally bluish discolorations can be found in the stipe base. One collection from a marshy birch forest in the Netherlands fitted their discription well with respect to this character. But, the molecular and microscopic characters placed this collection in the current concept of Leccinum holopus. This, normally pale-coloured species, usually has bluish discolorations in the stipe base. It has been collected in the same locality as the above mentions " L. pulchrum" and ended up in the same clade. Apparently the concept of Leccinum pulchrum by Lannoy and Estades is merely based on non-diagnostic macroscopical characters, and represents a mixture of different species, including L. scabrum, L. rotundifoliae and L. holopus.

 Leccinum schistophilumM. Bon

L. palustre M. Korhonen
Icons: Lannoy & Estades, Mon. Leccinum: pl. 30. 1995; Korhonen in Karstenia 35: p. 62, Fig. 11 (as L. palustre). 1995.

Description:

Pileus 25-110 mm, convex expanding to planoconvex, with inflexed margin, not markedly exceeding the tubes, light yellowish brown (Mu 10 YR 6/4), greyish brown (Mu 10 YR 5/2 ), to dark brown (Mu 10 YR 3/2 4/2), often evenly coloured, but sometimes with light spots; minutely tomentose, matt.Tubes narrowly to broadly adnate, 9-25 mm long, ventricose to broadly ventricose, yellowish white at ?rst, in later stages greyish with a pinkish hue. Pores ca 0.5 mm in diameter, whitish, yellowish white, discolouring brownish when bruised. Stipe 46-150 mm x 9-25 mm, cilindrical to clavate, greyish white to brownish, lightly to densely covered with ?ne squamules, usually not markedly differing between base and apex stipe. Scabers initially brownish, in later stages greyish to blackish, sometimes dark brown. Context (greyish) white, when bruised discoloring pinkish (9A2) in the pileus and upper half of the stipe, sometimes discoloring bluish green (25A4) in lower half of stipe; sometimes not discoloring at all, rarely discolouring greyish after several hours.

Spores (13.0--) 13.5-17.0 x 5.0--6.5 (-7.5) µm, Q = 2.3-3.1 (-3.4), `Q = 2.8, subcylindrical to fusifrom. Basidia 24.0-27.5 x 10.0-11.5 µm, 4-spored. Hymenocystidia 32.0-43.5 x 7.5-9.0 µm, lageniform. Pileipellis a dense cutis-like trichoderm composed of cylindrical, brownish to dark brownish elements, (3.5-)4.5-8.0 µm wide, sometimes also with broad (7.0-11.5 µm), clearly articulated, elements. Caulocystidia 33.0-70.5 x 11.0-20.5 µm, fusiform clavate or lageniform. Clamp-connections absent.

Habitat& distr. - Gregarious or solitary on mossy, humid, alkaline, sandy soils. Mycorrhizal with Betula. Distribution insufficiently known, probably widespread and uncommon throughout northern and western Europe.

Discussion: The typical form of Leccinum schistophilum that can be readily identified in the field is characterized by a small, slender habit, light greyish brown pileus, white stipe with contrasting fine, greyish to blackish squamules and a greenish-blue discolouring context in the lower half of the stipe. However, basidiocarps with a brown cap and a non-discolouring context may occur, which accordingly can only be distinguished from L. scabrum by their different ecology (L. schistophilum usually grows in wet habitats, L. scabrum in dryer habitats) combined with microscopic differences (caulocystidia, average Q-value of spores and differences in pileipellis structure). Large specimens of Leccinum schistophilum may be confused with L. variicolor, especially when the discoloration of the context is clearly observable. Microscopically it can be easily distinguished, however, by the structure of the pileipellis, which is composed of long, cylindrical elements, while generally in the pileipellis of L. variicolor has chains of short, cylindrical elements ('cylindrocysts'). Furthermore lageniform, septate caulocystidia are abundant in L. variicolor, while these are only occasionally observed in L. schistophilum. This taxon was erroneously placed in the subsection Leccinum by Bon (1981), because of he over-emphesized the importance of the grey tinges that may appear in the context several hours after it has been bruised. Den Bakker et al. (Chapter 3) showed that Leccinum schistophilum is nested in the subsection Scabra-clade.

 Leccinum variicolor Watling

Icons: Cetto, Fungi Vero 4: 1566 (als L., 1200 Pilze: pl.97. 1993. Lannoy & Estades, Monogr. Leccinum: pl. 13 to 15. 1995; R. Phillips, Paddest. Schimm: 213. 1993.

Description

Pileus 35-95 mm, convex expanding to planoconvex or sometimes broadly conical when mature, with entire margin, not markedly exceeding the tubes, at most up to 1 mm, dark brown (Mu. 5 YR 3/1 to3/4, 10 YR 3/2 to 3/3) with a radial patttern of lighter spots, sometimes almost whitish with dark spots or entirely dark brown; very ?nely tomentose all over, often subviscid with age. Tubes narrowly to broadly adnate, venticose to broadly ventricose, 7-18 mm long, greyish or creamy white, discolouring brownish when bruised. Pores ca 0.5 mm in diameter, creamy white, often with yellowish brown spots, discolouring brownish when bruised Stipe 70-157 mm x 350, cylindrical to clavate, whitish of greyish white, often with a distinct greenish blue discolouration in the lower half of the stipe, entirely covered with brown to black scabers, ?ne at apex, gradually becoming coarser towards base. Context white, when bruised often staining pinkish (9A3, 9A4) in pileus and apex of upper half of the stipe, often discolouring greenish blue (24A5, 25A5) in the lower half of the stipe (in some collections limited to the cortex of the stipe only); when dried the discoloration in the lower half of the stipe often turns yellow (3A7) which remains visible in the herbarium specimens.

Spores (10-) 13.5-17.5 (-20) x 5.0-6.5 µm, Q = 2.4-3.1, Qav = 2.8, fusiform with a suprahilar depression or without a suprahilar depression. Basidia 23.0-34.2 x 8.5-11.0 µm, 2- and 4-spored. Hymenocystidia 26.0-44.5 x 8.0-10.5 µm, lageniform to clavate with a mucronate or obtuse apex. Pileipellis an lose cutis of cilindrical, hyaline or brownish intracellularly pigmentated elements, 4.5 - 9.0( - 12.6) µm wide, elements in suprapellis often arranged in a moniliform fashion and clearly cylindrical ('cylindrocytes'), terminal elements generally conical. Caulocystidia (20.5-) 34.5-86.5 x 7.5-22.0 µm, clavate or irregular cylindrical to lageniform with a flexuose, sometimes forked neck, which often is separated from body of the cystidium by a septum. Clamp-connections absent.

Habitat & distr. - Associated with Betula in mossy, acidic environments. (Betula swamps with Sphagnum, mossy places, on peaty and sandy soil. In the Netherlands uncommon in the pleistocene district and in the coastal dunes. Widespread, but not common in Europe, probably with a circumboreal distribution. Probably unnoticed before in North America (see comments).

Discussion:
Leccinum variicolor can readily be recognized in the ?eld on account of its variegated pileus and distinct blue-green discoloration of the context of the stipe. Although it occurs in North America (pers. observation) and is probably quite common there, it has long been unnoticed because it was confused with Leccinum snellii. Both species have a similar discoloration of the context, and also the septate caulocystidia, that were thought to be diagnostic for L. snellii, (Smith, Thiers and Watling, 1967) are found in L. variicolor. Molecularly, however the two species cannot even be considered closely related (see Chapter 3). Based on a limited number of herbarium collections and the original description of L. snellii, the most important differences are found in the pileipellis, in particular in the shape of the terminal elements. The pileipellis of Leccinum snellii is characterized by the presence of 8-10 µm broad cylindrical elements and clavate to conical, terminal elements with dark brown intravacuolair pigment. The pileipellis of L. variicolor is also characterized by the presence of short, cylindrical hyphal elements, but usually they are less broad (4.5 - 9.0) and the terminal elements are conical. Particularly the clavate terminal elements are distinctive for Leccinum snellii, and never found in L. variicolor. There may also be an ecological difference between the two taxa. In the great lake region of Canada the first author generally found L. variicolor in the same habitat as in Europe, viz. in humid, acidic habitats. Leccinum snellii was found only once, and in a completely dfferent habitat, viz. a rich, slightly humid forest on alkaline soil. The locality of the specimens on which the original description of L. snellii is based can also be interpreted as a rich forest, consisting of beech, maple and yellow birch. More study is needed to delimitate these two species more thoroughly. Lannoy and Estades (1995) recognise three infraspecic taxa within L. variicolor, viz. var. bertauxii differing from var. variicolor by a evenly coloured blackish cap and the absence of pinkish discolorations of the context in stipe and cap, f. atrostellatum, differing from the typical form by dark a star-shaped pattern on the pileus, and f. sphagnorum, a form with uniformly coloured brownish pileus. Since all of these character states fall well into the normal range of variability of Leccinum variicolor examined during this study, they are considered of no taxonomic value.

 Leccinum cyaneobasileucum Lannoy et Estades

Icons: Courtecuisse & Duhem, Champ. France Eur.: pl. 1713. 1994; Lannoy & Estades, Monogr. Leccinum: pl. 18. 1995.

Description:

Pileus 48-80 mm, hemispherical, expanding to convex or planoconvex, with involute to deflexed margin, not markedly exceeding the tubes, greyish brown (10 YR 5/3) to light brown (10 YR 6/6), sometimes almost white; surface minutely squamulose tomentose, sometimes ?nely granulose, somewhat viscid when moist. Tubes broadly adnate, 12-16 mm long, ventricose to broadly ventricose, whitish with a brownish or greyish tinge. Pores ca 0.5 mm in diameter, whitish or light greyish, discolouring brownish when bruised. Stipe 72-110 mm x 11-23 mm, cilindrical to clavate; densely covered with confluent squamules, which hardly show the backgroud, giving the stipe an almost woolly appearance, squamules first whitish, greyish when mature. Context whitish, noy staining or discolouring pinkish (9A3) in pileus and apex of stipe only; staining bluish (23A7) in cortex and base of stipe, especially in places where eaten by snails or arthropods.

Spores (11.0-) 14.0-19.5(-21.0) x (3.5-) 4.0-6.5(-7.0) µm, Q = 2.6-4.0(-4.1), Qav = 3.2, fusiform to narrowly fusiform with a suprahilar deppression. Basidia 20.5-27.5 x 11.5-13.0 µm, 4-spored, soms 2-spored. Hymenocystiden 32.0-43.5 x 5.5-7.5 µm, lageniform to fusiform. Pileipellis an intricate trichoderm of easily detachable, wide, cilindrical, brownish (sepia) elements, terminal elements often conical, (7.0-)8.0-15.0(-17.0) µm wide and narrowly cilindrical, dark brown elements, 4.5-6.0 µm wide. Caulocystiden 32.0-61.5 x 4.5-10.5 µm, narrowly lageniform , utriform or fusiform, when lageniform often with a flexuose neck. Clamp connections absent.

Habitat& distr. - Gregarious or solitary on dry to humid sandy or peaty soil, sometimes in sphagnum bogs. Mycorrhizal with Betula. Not uncommon in large parts of Europe, however uncommon or probably absent in Scandinavia (with the exclusion of Danmark).

Discussion:
Leccinum cyaneobasileucum is easily recognised already in the ?eld by the generally dull-coloured greyish brown pileus and woolly stipe surface. Pale and albinistic forms may occur, which is con?rmed by phylogenetic comparison of ITS and Gapdh sequences of material of L. brunneogriseolum and L. cyaneobasileucum. These pale and albinistic forms can be confused with L. holopus in the field, but differ from this taxon by their slender spores (Qav = 3.0), and the abundant 'cylindrocysts' in the pileipellis. Due to the fact that the epithet cyaneobasileucum was published earlier than brunneogriseolum, that name has priority and must, unfortunately, replace the latter. Lannoy and Estades 1995 recognize two infraspecific taxa within L. brunneogriseolum, viz. var. pubescentium, a variety that differs from var. brunneogriseolum by a browner colour of the pileus and a robust stipe, and f. chlorinum a form that shows olivaceous colours in the margin in older fruitbodies and also olivaceous, greenish tinges in the stipe. These infraspecific taxa are not considered of any taxonomic value. L. brunneogriseolum falls within the variability of the species, and greenish tinges like in f. chlorinum can also be observed in other taxa when they fructificate during a continuous wet period or in a wet habitat.

 Leccinum holopus (Rostk.) Watling

Icons: Korhonen in Karstenia 35: 64: Fig. 12. 1995; Rymann & Holmåsen, Pilze: blz. 230. 1992.

Dscription:

Pileus 40-100 mm, convex expanding planoconvex with entire margin, exceeding the tubes over up to 1 mm, usually minutely tomentose when fresh, sometimes granular , often becoming more viscid with age, whitish to yellowish, greyish white, often with a greenish hue or bluish green in older fruitbodies, sometimes brown (Mu. 10YR 5/4);. Tubes 7-18 mm long narrowly to broadly adnate, segmentiform to broadly ventricose, greyish white, finally brownish pinkish. Pores ca 0.5 mm in diameter, whitish with yellowish brown spots, brownish when bruised. Stipe 59-140 x 10-23 mm, cilindrical to clavate, whitish, covered with coarse whitish, in mature fruitbodies ochre to greyish scabers, sometimes blackish scabers already present in young fruitbodies. Context whitish, discolouring pinkish in cap and stipe when bruised, bluish discolorations often visible in cortex stipe base, regularly not discolouring at all.

Sporen 15.5-18.0 x 5.5-7.0 µm, Q = 2.5-3.0, Qav = 2.7, broadly fusiform to fusiform with a shallow suprahilary deprision. Basidia 28.5-36.5 x 11.5-12.5 µm, generally 4-spored. Hymenocystidia 39.0-45.5 x 7.5-9.0 µm, lageniform to fusiform. Caulocystidia 39.0-54.5 x 9.1-13.5 µm, fusiform, clavate to cylindrical, often with a flexuose neck. Pileipellis a cutis composed of cylindrical elements, 3.5-5.0(-7.0) µm in diameter, often hyaline, granular incrusted, sometimes brownish intravacuolar pigmented; Terminal elements sometimes elipsoid, then 10.5-11.5 µm in diameter. Clamp-collections absent.

Habitat & distr. - Single or in groups in Sphagnum bogs or among grass and mosses on humid, peaty soil. Mycorrhizal with Betula. Common and probably widespread throughout the (circumboreal) distribution area of its host.

Habitat & distr. - Gregarious or solitary among grass and mosses on humid, peaty soil. Mycorrhizal with Betula. Common and probably widespread throughout the distribution area of its host.

Discussion:
The typical form of Leccinum holopus is a slender, pale, almost whitish bolete, without any clear discoloration of the context when bruised, occuring in Sphagnum-bogs in montane, sub-boreal and boreal regions. Another, sturdier form with a darker, sometimes brownish cap, darker stipe ornamentation and bluish discolorations in the stipe base, is found in wet, acidic birch woods. This last form has been described as a seperate species by Lannoy & Estades (1993) as Leccinum nucatum. No molecular evidence to support the existence of L. nucatum as a seperate species was found. Moreover, the differences between both forms are not always clearcut and intermediates occur. For this reason the nucatum-type populations do not deserve a formal taxonomic status and Leccinum. nucatum is placed into the synonymy of L. holopus. Leccinum holopus can be distinguished from related taxa by a combination of the following microscopic characters: a pileipellis that is composed of slender hyphal elements of relatively even diameter (3.5 - 5.0 µm), abundant cylindrical caulocystidia with a flexuose neck in the lower half of the stipe and an average Q value of spores = 2.8.
Smith and Thiers (1971) recognize two varieties of L. holopus: var. holopus and var. americanum. According to Smith and Thiers var. americanum mainly differs from var. holopus in the fact that the context of the stipe (mainly in the upper half) changes from white to pinkish/reddish when bruised, and the stipe ornamentation in var. americanum is usually blackish, while in var. holopus the stipe ornamentation is whitish, becoming brownish with age. Both varieties have been observed in the field by the first author in Canada, sometimes side by side on the same spot. Though no molecular differences that were congruent with these varieties could be found, no intermediates were observed in the field. In this case the absence of (morphological) intermediates justifies the recognition of var. americanum as an infraspecific taxon.

 Leccinum crocipodium Letell.) Watling

Icons: Breitenb. & Kränzl., Pilze Schweiz 3: 72. pl. 34. 1991; Galli, Boleti: 260-261. 1998 ; Muñoz, Fungi non del. 13: pl. 18. 2000; Pilát & Dermek, Hrívobité Huby: pl. 73 1974 (as L. nigrescens).

Description:

Pileus 40-75 mm broad, rounded hemispherical to convex with straight, appendiculate margin extending over tubes for about 1 mm, yellowish brown or reddish brown, sometimes with an olivaceous tinge, later on darker olivaceous-brown or blackening when strongly exposed (Mu. 2.5 Y 6-5/4-6; 5 Y 6/6, 3.75 5 Y 6/6, 3.75 5/6), dry, appressed tomentose becoming entirely cracked with age, breaking up in small irregular patches showing pale grey context in between. Tubes adnexed to adnate, narrowly to broadly ventricose, up to 15 mm broad, pale yellow (5 Y 8/6); pores small, 0.3-0.5 mm in diameter, rounded, rather bright yellow (K&W 3A7-3B7), turning reddish brown then black when bruised. Stipe 60-150 x 15-30 mm, straight, typically fusiform with broadest part below the middle, tapering at base, more rarely cylindrical, creamy-white at apex, pale chrome-yellow below, minutely squamulose in longitudinal rows of small yellow to dark brown floccose squamules which become coarser towards base. Context thick, firm, pale yellow or cream-colored, staining reddish brown to violaceous-grey when bruised, blackening in damaged parts. Smell indistinct. Taste mild.

Spores (80.4) (11.5-)12-15 x 5.0-6.5.0 µm, av. 13-14 x 5.5-6.0 µm, Q = 2.0-2.9, Qav = 2.4=3-2.4; fusiform with conical apex, often also almost amygdaliform, with slight to distinct suprahilar depression, relatively thin-walled, pale brown in water. Basidia 18-35 x 5.0-9.0 µm, clavate, 4-spored. Hymenial cystidia abundant on edge and sides of the pores, 20-55 x 4.5-11 x 2.0-4.0 µm, lageniform, often with rather long, tapering neck, colorless or with brown, intracellular-granular pigment. Pileipellis a rather regular trichoderm of septate hyphae, terminal elements 12-50(-50) x 6.5-17 µm, usually rather slender, cylindrical, clavate or conical, with intracellular, incrusting and extracellular pigment. Stipitipellis a cutis of narrow, cylindrical, 4.0-7.0 µm wide hyphae, with small to fairly large caulohymenial clusters of basidia and cystidia, forming the squamules on the stipe surface. Caulocystidia 25-120 x 7.0-15 x 2.0-4.5 µm, lageniform or fusiform, thin- or thick-walled, colourless or with brown granular intracellular pigment. Clamp-connections absent.

Habitat & distr.- Mycorrhizal, associated with Quercus and Carpinus on heavy loamy, often slightly calcareous soil. Very rare in the Netherlands (Schaelsberg, Limburg; Sterkenburg, Utrecht). Widespread, rare to locally more common in Central and Southern Europe, preferably in thermophilous deciduous forest on heavy loamy soil.

Discussion:
The most distinctive characters of Leccinum crocipodium are the rather yellow pores, combined with the blackening context. It is the only species with this combination of characters known from temperate regions in Europe, where it has a preference for thermophilous deciduous forests. The macroscopically similar Leccinum corsicum and L. lepidum have an exclusive Mediterranean distribution, and are associated with Cistus spp. and Quercus ilex respectively. Leccinum crocipodium has only recently been discovered in the Netherlands in 1999, with a second observation in 2001. Whether this may be due to climate changes, or that is has been overlooked in the past, is difficult to ascertain. Boletus rimosus Venturi, Stud. Micol.: 31, pl. 10, fig. 93-94. 1842, often cited as a synonym, is better considered a nomen dubium on account of the brown-olivaceous pileus and pale pores. See also Rauschert (Nova Hedwigia 45: 503. 1987) for nomenclatural comments.

 Leccinum pseudoscabrum (Kallenbach) Sutara
Syn: L. carpini

Icons: M. Bon, Mushr. Toadst.: 41. 1987; Breitenb. & Kränzl., Pilze Schweiz 3: 70, pl. 31. 1991; Engel, Rauhstielröhrlinge: pl. 2. 1978; Galli, Boleti : 254-255. 1998; Muñoz, Fungi non del. 13: 42-44. 2000; R. Phillips, Paddest. Schimm.: 212. 1981; Pilát & Dermek, Hrívobité Huby: pl. 74. 1974.

Description:

Pileus up to 30-70 (-100) mm broad, hemispherical to conico-convex at first, expanding to truncately convex or plano-convex, with involute margin, not or only slightly exceeding the tubes for about 1 mm, pale to moderately dark grey-brown (Mu. 10 YR (3/3) 4/3-4/3, 5/4=4/6), sometimes with slight olivaceous tinge, dry, dull, initially velvety yo minutely or strongly radially rugulose or veined, usually cracked with age with concentric fissures, particularly near margin showing pale pinkish context. Tubes adnate to adnexed, subventricose to ventricose, p to 25 mm long, yellowish to pinkish beige or grayish brown (10 YR 8/4, 2.5 8/4, 10 YR 3/3-4), with slight chocolate tinge when old. Pores very small, 1-2 per mm, rounded, pale beige, staining borwn-grey when bruised. Stipe 60-130- x 6-14 mm, cylindrical, slightly broadened towards base to subclavate, sometimes flexuous, whitish to pale grey ochre, entirely covered with brownish-black (10 YR 6-5/4, 4/3-3/3(-3/2), very small dot-like squamules arranged in longitudinal rows, which become somewhat coarser towards white tomentose base. Context dirty white at first with watery darker streaks, on cutting first slowly staining pink to purple then grayish-blackish with purple tinge.

Spores (110.5) (12.5-)13-18.5 x 4.5-6.0 µm, av. 14.5-15 x 4.8-5.31 µm, Q = 2.3-3.3, Qav = 2.7-2.9; slender, fusiform with conical apex, with distinct suprahilar depression, relatively thin-walled, pale brown in water. Basidia 18-36 x 6.0-8.0 µm, clavate, 4-spored. Hymenial cystidia abundant on edge and sides of the pores, 18-70 x 5.0-14 x 2.0-4.0 µm, lageniform, often with rather long, tapering neck, usually with dark brown, intracellular-granular pigment. Pileipellis an intricate trichoderm of septate hyphae, terminal elements 12-70(-90) x 3.5-10.5 µm, irregularly cylindrical or clavate with intracellular pigment. Stipitipellis a cutis of narrow, cylindrical, 3.5-8.0 µm wide hyphae, with small to fairly large caulohymenial clusters of basidia and cystidia, forming the squamules on the stipe surface. Caulocystidia 25-90 x 5.0-12 x 2.0-8.5 µm, lageniform, clavate or fusiform, thin- or thick-walled, colourless or with brown granular intracellular pigment. Clamp-connections absent.

Habitat & distr. - Mycorrhizal, associated with Carpinus in deciduous forest and road-sides on calcareous loam and clay (Stellario-Carpinetum; Alno-Padion). Rare, mainly in F, very rare in D, S, K, E en Z. Widespread in Europe, not uncommon in mixed deciduous forests on clayey or loamy soil.

Discussion
The name L. pseudoscabrum is the oldest available valid name for the species, and should be used instead for L. carpini. Another name often used for this species, viz. L. griseum, goes back on Gyroporus griseus Quél., a superfluus name for L. scaber.

Literatur

DEN BAKKER, H. C. & M. E. NOORDELOOS (2005): A revision of European species of Leccinum Gray and notes on extralimital species. Persoonia 18(4):511-587.