Heimioporus japonicus (Hongo) E.Horak
E. Horak gen. nov.--replacing Heimiella
Boedijn (1951, syn. post., Boletales, Basidiomycota).
This name is currently accepted.
Diagnosis: Red overall, dry, with a slightly lacerate-ridged stipe beset with a heavy pruina. Spores are alveolate-reticulate.
Registration number: MB368253
Macroscopic description: Pileus 4.5-5 cm broad, plano-convex, dry, finely subvelutinous, deep red to pale red, with some hints of olive at margin from fading; flesh pale yellow, unchanging, with mild odor and taste. Tubes adnexed, bright yellow to yellow with a hint of pale greenish, unchanging; pores 1-2 per mm, yellow, unchanging. Stipe 7.5 × 1.5 cm, barely subclavate, straight, dry, dark dull red, pale yellow near base, white at base, coarsely and shallowly lacerate ridged with a dense red pruina overlaying the ridges, pseudoscabrous; flesh pale yellow above, white toward and at base, unchanging.
Microscopic description: Basidiospores 10.5-14.7 × 6.3-8.4 µm (n = 16; x = 12.95 × 7.78 µm; Q = 1.66), ellipsoid to subamygdaliform, reticulate to alveolate-reticulate, honey brown in KOH. Basidia 26-34 × 11-14 µm clavate, 4-sterigmate, hyaline. Hymenophoral trama bilateral, of the Boletus-subtype, fleetingly amyloid in Melzer's, hyaline in KOH, with cells 4-9 µm broad. Pleurocystidia absent. Cheilocystidia 20-33 × 10-16 µm, broadly clavate to sphaeropedunculate, smooth, thin-walled. Pileipellis a hymeniform epithelium, with cells 7-14(-17) µm broad, broadly clavate to napiform, sometimes isodiametric, hyaline in KOH, subtended with subpellis elements containing an amorphous, soluble, reddish brown, plasmatic pigment. Pileus trama interwoven, with hyphae 5-10 µm broad, thin-walled, hyaline in KOH, inamyloid. Stipitipellis hyphae smooth and thin-walled, with caulocystidia 14-30 × 10-20 µm, clavate to short-clavate to subcylindrical or oblong and subrectangular. Clamp connections absent.
Distribution: Japan, China, Australia (SE Queensland).
Ecology: Solitary to gregarious; associated with pine and oak in Japan; with Melaleuca, Allocasuarina, Eucalyptus, and Leptospermum in Australia; China (associate unknown).
Commentary: The material from Cooloola cited by Watling & Gregory (1986, p. 117) as Heimiella sp. is the earliest collection of the species from Australia. Although Hongo (1969) described the stipe as reticulate, the type, as well as the other material examined, possess the coarsely and shallowly lacerate-ridged stipe surface that is overlain with a dense, red pruina. This could be construed as a reticulum of sorts, but is not a reticulum as exemplified by Boletus edulis Bull. or Tylopilus felleus (Bull.) P. Karst., for example. The finely subvelutinous nature of the pileus surface would hint at the hymeniform configuration of the cells forming that surface. With these surface features and alveolate-reticulate spores, the species is distinctive in the Australian mycota.
The broad geographic distribution and the association with a range of mycorrhizal partners are not unique for H. japonicus. Clinal distributions on continental scales and switching of mycorrhizal partners have been documented before (Halling 1989; Mueller & Strack 1992; Halling & Mueller 2002, 2005; Halling et al. 2008). Notwithstanding Watling & Gregory's (1986) initial synopsis of the neighboring Cooloola boletes, it is reasonable to expect that our intensive survey for macrofungi on Fraser Island would reveal novel or little known distribution patterns.