Heimioporus species are primarily confined to eastern Asia (Japan and China), Indo-malaya to eastern Australia (so far) and Tasmania (9 species, 1 variety). Two species (three names) are only known from the Americas (H. alveolatus, H. betula, H. ivoryi). Horak (2005) provided the necessary nomenclatural updates from Heimiella to Heimioporus in a list of taxa. He recognized two subgenera based on spore morphology:
subg. Heimioporus — spore surface alveolate-reticulate
subg. Punctisporus — spore surface pitted
Heimioporus alveolatus from Mexico (Heim & Perreau, 1964) is virtually identical, both macro- and microscopically, to H. betula and is undoubtedly a later synonym. Unfortunately, alveolatus was only known from the type specimen (Natural History Museum of Paris), and is apparently no longer extant.
Likewise, H. anguiformis, described by R. Heim (1963) from Papua New Guinea, appears to be known only from the type specimen (Paris) and is also apparently no longer extant. However, published photomicrographs of spores and an exquisite color plate of the macroscopic appearance of the species leave little doubt as to its uniqueness (Heim 1965).
While spore color has been used traditionally as a distinguishing character for bolete genera, the definitiveness of this feature appears not as rock-solid as previously thought (Boletus 'austroseparans' in ed.). However, the olive brown spores of Heimioporus will readily distinguish the few punctate-spored taxa from those of Austroboletus (vinaceous pinkish to pinkish flesh colored spores) with generally similar ornamentation. Perforate/punctate or alveolate-reticulate spores do not occur in Boletellus, and this latter genus appears distinct from Heimioporus inferred from gene sequence data. In this latter analysis by Halling et al. (2015), it is not demostrable that H. betula is a Heimioporus.
Key to Known Species
1. Pileus some shade of red (crimson, scarlet, rhubarb, etc.) [retisporus, ivoryi, mandarinus, betula, fruticicola, australis, cooloolae, japonicus, subretisporus, xerampelinus]
2. Japan (NE Asia) to Australia [retisporus, mandarinus, japonicus, fruticicola, australis, cooloolae, subretisporus, xerampelinus, also possibly betula]
3. Pileus conic-umbonate, alveolate - - - H. mandarinus
3. Pileus convex [retisporus, japonicus, fruticicola, australis, cooloolae, xerampelinus]
4. Spores ellipsoid or rarely subglobose - - - H. retisporus (with var. levipedes)
4. Spores fusoid, subfusoid to elongate-ellipsoid [japonicus, fruticicola, australis, cooloolae, xerampelinus]
5. Spore surface finely rugulose with crater-like ornamentation [cooloolae, fruticicola]
6. Pileus bright red; stipe lacking colored tomentum at base - - - H. fruticicola
6. Pileus dull red; stipe with scattered olive-mustard colored tomentum at base - - H. cooloolae
5. Spores alveolate-reticulate [japonicus, australis, xerampelinus]
7. Stipe shallowly lacerate ridged with a red pruina; Australia - - - H. australis
2. America [ivoryi, betula]
8. Spores alveolate-reticulate - - - H. ivoryi
8. Spores perforate- - - H. betula
1. Pileus not red (brown, fawn, pale tan to ochraceous or black) [anguiformis, kinabaluensis, punctisporus, rubropunctus, subretisporus.]
9. Pileus surface cerebriform; stipe apex pinkish orange - - - H. anguiformis
9. Pileus surface even to somewhat rugulose to rugulose-tuberculate to shallowly subalveolate, but NOT cerebriform; stipe apex some other color [kinabaluensis, subretisporus, punctisporus, rubropunctus.]
10. Spores punctate - - - H. punctisporus
10. Spores reticulate, not punctate
11. Pileus even - - - H. subretisporus
11. Pileus rugulose to rugulose-tuberculate
12. Stipe with red scurfy ornamentation; tubes and pores cyanescent - - - H. rubropunctus
12. Stipe with fawn then blackening scurfy ornamentation; tubes and pores unchanging - - - H. kinabaluensis
Halling, R.E., et al. 2015. Evolutionary relationsnhips of Heimioporus and Boletellus (Boletales), with an emphasis on Australian taxa including new species and new combinations in Aureoboletus, Hemileccinum and Xerocomus. Austral. Syst. Bot. 28: 1-22.
Heim, R. 1963. Diagnoses latines des espèces de Champignons, ou nonda, associé à la folie du komugl taï et du nadaadl. Rev. Mycol. (Paris) 28: 277-283.
Heim, R. 1965. Les champignons associés a la folie de kuma: étude descriptive et iconographie. Cahiers du Pacifique 7: 7-65.
Heim, R. & J. Perreau. 1964. Les genres Porphyrellus et Strobilomyces au Mexique. Bull. Soc. Mycol. France 80: 88-101.
Horak, E. 2005. Heimioporus E. Horak gen. nov. - replacing Heimiella Boedijn (1951, syn. post., Boletales, Basidiomycota). Sydowia 56: 237-240.