Heimioporus fruticicola (Berk.) E.Horak
E. Horak gen. nov.--replacing Heimiella
Boedijn (1951, syn. post., Boletales, Basidiomycota).
This name is currently accepted.
Diagnosis: Pileus red to red brown and dry. Flesh pale yellow. Tubes yellow, unchanging. Stipe yellow, red subpruinose ridged. Spores olive brown, elongate fusoid, subrugulose and with crater-like pits.
Registration number: MB368304
Macroscopic description: Pileus (2.5-)4.5-8(-9.5) cm broad, convex to plano-convex to plane, viscid when wet, soon dry, matted
subtomentose, red to lake red (10C8, 9C–D8,7), fading to near greyish red (7B4), somewhat blotchy with age; flesh pale yellow when young, white with age, not blueing, or very rarely with a hint of pale blue, with mild odour and taste. Tubes 10–13 mm deep, adnexed to depressed around the stipe, pale yellow to yellow becoming greenish yellow, (3A6 to 3E6) or dull yellowish green to olive, not blueing, or only slightly with injury; pores concolorous, 1–2 per mm, rarely blueing, and eventually staining pale brown. Stipe (3-)5.5-8 cm long, 1-1.5(-2) cm broad, dry, straight or curved, teret or flattened, ±equal to broadly subclavate, or tapering downward, usually pinched at the base, white to pale yellow to pale greenish yellow at apex, yellow at base, pseudo-reticulate to subpruinose-ridged to subscabrous with scabrosity confined to ridges; these red or pink on pale yellow to yellow ground color; interior solid, pale yellow to yellowish white, unchanging; basal mycelium white.
Microscopic description: Basidiospores 11.2-16.1 × 5.6-7.7 µm, (n = 16; x = 13.87 × 7.08; Q = 1.96), subfusoid to ellipsoid, rugulose with crater-like pits, inamyloid (rarely lightly dextrinoid), honey brown in KOH. Basidia 25-35 × 12-15 µm, clavate, 4-sterigmate, hyaline. Hymenophoral trama bilateral, of the Boletus-subtype, with cells 4.2-8,4 µm broad, hyaline. Pleurocystidia rare, up to 60 µm long, fusoid-ventricose, hyaline, thin-walled. Cheilocystidia subclavate, 25-35 µm long, hyaline, thin-walled. Pileipellis a collapsed trichodermium, with cells 3.5-6.3 µm broad, cylindrical to narrolwy clavate-subcapitate, smooth, thin-walled, inamyloid, hyaline or with golden yellow content in KOH, with an amorphous, soluble, reddish brown, plasmatic pigment. Stipitipellis hyphae hyaline, smooth, thin-walled, with caulocystidia 15-40 × 10-13 µm, subclavate to clavate or short-clavate to oblong or subrectangular. Clamp connections absent (sparse, fide Watling & Gregory 1986).
Ecology: Solitary to gregarious on soil, in the vicinity of Allocasuarina littoralis (Salisb.) L.A.S. Johnson, Eucalyptus camaldulensis Dehnh., Eucalyptus sp., Acacia sp. (known mycorrhizal plants), and Hibbertia riparia (R.Br. ex DC.) Hoogland.
Distribution: Austrlalia: Queensland, Victoria, Tasmania.
Commentary: This species was first described by Berkeley (1848) based on a collection from Tasmania. The locality was published as 'Penguite' but this is clearly a typographical error for 'Penquite' near Launceston, where the collector R.C. Gunn lived and worked for some time. Horak (1980) examined the type specimen, provided some modern details on microscopic features, and transferred the species to Austroboletus. Our examination shows that the spores are finely and irregularly rugulose with occasional and scattered, shallowly cratered pits; the rugulosity is continuous over the apex. In optical section with bright field optics, the spores appear to have peg-like warts and have been described as Ganoderma-like (Watling & Gregory, 1986). Watling & Gregory (1986) had examined material from the Cooloola portion of the Great Sandy National Park, which extended the range beyond the type locality in Tasmania. They were able to provide only some sparse details from the field data lodged with those specimens, but specifics outlining the macromorphology were still lacking. Until 2011, a habit image has not been available. The dry, basically red colors overall, yellowish hymenophore, a typical lack of cyanescence, non-reticulate (but not unornamented) stipe, and medium stature can be distinguishing macroscopic features in the field. Superficially similar, Boletellus obscurecoccineus has more conspicuous scales on the stipe and is of less substantial stature. In H. fruticicola, the finely rugulose spore ornamentation with cratered pits appears unique in the boletes. In our experience, some Austroboletus spores can be rugulose and will become pitted with maturity, but these lack the rim around the pit. Furthermore, the spore colors are different (pinkish vinaceous in Austroboletus, olivaceous in Heimioporus). References to this species in lists and catalogues have been compiled by May & Wood (1997). A gasteroid form from Victoria (MEL 2264992) is known to have similar spore morphology, but further studies are needed to ascertain its relationship to H. fruticicola.