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Page number:73 
Remarks (internal):The original description of Hydnellum gracilipes was based on the material collected by Karsten in 1866 from Tammela, Mustiala, south western Finland. Karsten (1868,1881,1882) himself did not report further collections and described the species as very rare. Due to the rarity H. gracilipes remained enigmatic for a long time. The species was not mentioned by Nikolajeva (1961) but Maas Geesteraanus (1975) provided a description of the species on the basis type material and a collection from Sweden (Södermanland: Nacka, between mosses, under a fallen pine trunk, G. Haglund & R Rydberg 5. VIII. 1948; UPS, not studied). Strid (1997) reported the species from Denmark (Western Jylland), Finland (Uusimaa and Etela-Hame) and Sweden (Smaland). We here list five new finds from Finland and the first collection from Norway. Although H. gracilipes seems to be very rare, it will probably be collected increasingly during forthcoming years. The species should be sought especially in old-growth pine forests with charred wood in northern Fennoscandia and Russia.
According to the ten known localities Hydnellum gracilipes is a rare fungus with a more or less northern distribution pattern. Most of the collections derive from dry forests predominated by Pinus sylvestris. The Norwegian specimen, however, was found on a Populus log in a mature southern boreal forest of deciduous trees. The Finnish sites were dry old-growth forests characterized by pine snags of different sizes, a number of fallen pine trunks at different stages of decomposition and the presence of charred wood. The field layer was low-growing and scanty, being formed by the dwarf shrubs Calluna vulgaris, Empetrum nigrum s. lat., Vaccinium vitis-idaea, V. myrtillus, and V. uliginosum. Lichens, especially Cladina spp., predominate in the ground layer, intermixed with the mosses Dicranum fuscescens, D. scoparium, Pleurozium schreberi and Polytrichum juniperinum.
The habitat ecology of Hydnellum gracilipes exhibits some special features. The fungus was found five times on old, uprooted and strongly charred pine trunks. The basidiocarps could be detected only if the trunks were lifted or turned. They were found on the undersides of the trunks that were closely attached to the ground but always partly also on debris below the trunks. These trees had fallen long ago and had evidently died, become decorticated and dried while standing. After the fall-down they had experienced one or several forest fires. Evidently the two top thirds of the trees had burned or completely decomposed a long time ago but the hard, resin-rich and more voluminous basal parts, though heavily damaged by fire, had survived, at least partly, almost untouched. Therefore these remnants of trunks remind up-rooted natural stumps more than windblown trunks.
The species of Hydnellum are mycorrhizal fungi (Agerer 1991, 1993), and it is well supported that most resupinate tomentelloid fungi, closely related to stipitate Thelephorales, are mycorrhiza formers (K61jalg et al. 2000, K61jalg et al. submitted manuscript). Although found on charred wood it is therefore evident that also Hydnellum gracilipes has a life strategy of an terrestial mycorrhizal species. On the other hand the fungus may also contribute in decomposing the remnants of woody debris, particularly charred wood.
Description type:Non-original description 
Description:Hydnellum gracilipes (P. Karst.) P. Karst. - (Figs. 2-4)
Macromorphology: Basidiocarps annual, resupinate and loosely attached to substrate, with 1 (rarely 2 or 3) centric to lateral, 10-30 mm long and 2-5 mm diam., stipe-like rhizomorphs, very soft and fragile when fresh, brittle when dry. Hymenophore hydnoid, purplish brown when fresh, the red tint fade to more or less greyish brown during drying, near Fawn (7.5YR 5/4) when dry, concolorous with subiculum, spines more or less cylindrical, somewhat curved, tapering towards the sharp apex, 0.5-1.5 (up to-21.5) (2) mm long, 5-(6)/(nun. Resupinate areas 1-5 x 0.5-3 cm wide and up to 1.5 (2) mm thick.
Macromorphology: Hyphal system monomitic, all hyphae simple septate, dextrinoid and/or cyanophilous, subicular hyphae hyaline to yellowish, 2-3.5 µm in diam., thin-walled, gloeoplerous hyphae present, some hyphae with brownish, granular encrustation, hyphal cords absent in subiculum but present in rhizomorphs. Tramal hyphae 2-4 µm in diam, thin-walled, subparallel, some hyphae with brownish, granular encrustation, mostly hyaline to yellowish, in 3% KOH some hyphae turn first lilac and then rapidly greenish, finally the colour mostly fades away, subhymenial hyphae 2-4 µm in diam, thin-walled, hyaline in 3% KOH. Cystidia absent. Basididia cyanophilous and dextrinoid, clavate, with 4 sterigmata, simple-septate at base, without transverse septa, hyaline in 3% KOH, 20-24 x 4.5-6.5 µm. Basidiospores subglobose in frontal face, ellipsoid in lateral face, tuberculate, yellowish brown in 3% KOH, cyanophilous CB+, 3.1-4.3 µm long in frontal and lateral face (mean value 3.7 µm n=20/1), chlamydospores absent.
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