Termitomyces is a paleotropical genus of agarics intriguing both to mycologists and entomologists. As the name might suggest the species are considered obligate symbionts of termites belonging to the subfamily Macrotermitinae. The termites culture the fungus - in much the same way as the attine ants culture members of the Agaricaceae. The Termitomyces mycelium grows on comb-like structures made from faecal pellets (see photo below). These pellets are made of digested plant material passed quickly through the termite gut. After some weeks the plant material is degraded so much by the fungus, that it is palatable to the termites.
Termitomyces titanicus (the largest mushroom in the world according to Guinness Book of Records) has a cap diameter of up to 1 meter, whereas Termitomyces microcarpus rarely exceeds 2 cm. Some species are annulate, some not. Some have large velar remains on the cap, others are smooth and viscid. Although the genus covers a wide macromorphological range, the species are not very distinct microscopically.
Termitomyces medius (00-027) with the termite nest, Ouagadougou, Burkina Faso (© JHP)
Delimitation and systematic placement
The unifying characters of the Termitomyces species are the pinkish spores, the termite association and the subterranean elongation of the stipe called a pseudorhiza, through which the fruitbodies of most species are connected to the comb in the termite nest. Furthermore most of the species have a pronounced umbo or papilla called a perforatorium, which is thought to play a role during the penetration of the soil.
Until Roger Heim (1942) appreciated these unifying characters, the species had been placed/described in widely diverse genera: Pluteus, Lepiota, Lentinus, Entoloma, Schulzeria, Collybia, Mycena, etc. Heim originally placed the genus in Amanitaceae. Jülich (1981) erected the monotypic family Termitomycetaceae and later Pegler (1986) placed the genus in Pluteaceae. According to Singer (1986) the cyanophilous spores, the bilateral lamellar trama of young carpophores, the siderophilous staining of basidia and the spore hilum of the open pore type, places the genus in Tricholomataceae next to Lyophyllae (Lyophyllum, Hypsizygus, Calocybe and Asterophora) in its own tribus, Termitomyceteae, due to complete absence of clamps. Molecular data (Moncalvo et. al 2000 and Hoffstetter unpubl.) support this classification of Termitomyces in Tricholomataceae within or near Lyophyllae (which is supposedly monophyletic). But the exact relationship is not clear.
Infragenereric systematics
The first to partition the genus was Heim, who placed the epigaeic species - i.e. T. microcarpus - in the subgenus Praetermitomyces and all the other species in the subgenus Eu-termitomyces (which includes the type of Termitomyces and of course should be named Termitomyces). This classification is followed by Pegler (1977, 1986, 1994), whereas Singer places T. microcarpus in the genus Podabrella together with five small, neotropical, non-termitophilous species. Gomez (1995) transferred Podabrella to Termitomyces.
Heim further devided Eu-termitomyces into 6 stirpes, more for convenience than to reflect relationship.
Sinotermitomyces was described by Mu (1981) based on collections from Yunnan, China. The genus is supposedly distinguished from Termitomyces on the presence of ornamentated pleurocystidia and hollow stipes. At present Mu has described 5 species of Sinotermitomyces. Whether these species are sufficiently distinct from Termitomyces as to warrant a separate generic status or indeed specific status is highly questionable.
At present 60 taxa have been described including 5 species of Sinotermitomyces, 5 neotropical species and a total of 8 forms/varieties. Of these 60 taxa three are old, well known synonyms. A much higher number have recently been synonymized by Pegler. Several species described from Asia are hard to interpretate and probably also represent synonyms. My estimate is that a third (20) of all the names in Termitomyces ss. lato are synonyms, and another third are badly circumscribed and difficult to identify based on available literature. Seen in another way I consider (from literature studies) 12-15 species (excl. varieties and forms and neotropical species) as more or less well known (and collected by people), and of these 12 are known from West Africa. These are: T. aurantiacus, T. clypeatus, T. entolomoides, T. fuliginosus, T. globolus, T. letestui, T. mammiformis, T. medius, T. microcarpus, T. robustus, T. schimperi and T. striatus.
Three speceis were seen on the visit to Burkino Faso, T. (cf) medius, T. (cf) fuliginosus and T. aurantiacus. In all instances the specimens were growing directly on the ground, rooting to underground termite nests. The far most common species in Ouagadougou was T. medius - a Termitomyces with unusally small fruitbodies.
Termitomyces fuliginosus (B00-047), Ouagadougou, Burkina Faso (© JHP)
Preliminary key
to species of Termitomyces registrered in Western Africa including the widespread T. eurhizus, the gigantic T. titanicus and the brownish T. singidensis from East Africa.
1. Pileus small, less than 4 cm or/and pileus bluish 2 Pileus medium to large, more than 4 cm 4 2. Fruitboby without pseudorhiza, pileus up to 2 cm. T. microcarpus (Berk. & Broome) Heim Fruitboby with pseudorhiza, pileus larger 3 3. Pileus with bluish colours. T. entolomoides Heim Pileus without bluish colours. T. medius Heim 4. Pileus with pronounced, scrobiculate (with indentations) perforatorium 5 Pileus without or with non-scrobiculate perforatorium 6 5. Perforatorium strongly spiniform. T. spiniformis Heim Perforatorium mammiform. T. mammiformis Heim 6. Perforatorium spiniform. T. clypeatus Heim Perforatorium not spiniform 7 7. Pileus with pronounced velar remains 8 Pileus without velar ramains 9 8. Pileus whitish, without perforatorium. T. schimperi (Pat.) Heim Pileus brownish, with perforatorium. T. singidensis Saarim. & Härk. 9. Pseudorhiza very dark, blackish. T. eurhizus (Berk) Heim Pseudorhiza lighter, not blackish 10 10. Pileus large, stipe annulate 11 Pileus smaller and/or stipe not annulate 12 11. Pileus very large (more than 30 cm) without pronounced perforatorium. T. titanicus Pegl. & Piearce Pileus large (usually not more than 30 cm) with cylindric-clavate perforatorium. T. letestui (Pat.) Heim 12. Pileus large, dark unicolor, concentric "scrobiculate" stipe not annulate 13 Pileus large or small, not scrobilulate, stipe annulate or not 14 13. Perforatorium differentiated, mammiliform. With numerous rhizomorphs. T. robustus (Beeli) Heim Perforatorium an continuation of the pileus, obtuse. No rhizomorphs. T. fuliginosus Heim 14. Pileus globose, large (15-20 cm), cystidia dimorphic, pseudorhiza brownish. T. globolus Heim & Goss.-Font Pileus not globose, smaller, cystidia not dimorphic, preudorhiza not brownish 15 15. Pileus orange, small (up to 8 cm). T. aurantiacus Heim Pileus brownish, larger (up to 12 cm) (T. striatus (Beeli) Heim 16 16. Stipe annulate. T. striatus (Beeli) Heim f. annulatus Heim Stipe not annulate 17 17. Pileus ochraceus brown. T. striatus (Beeli) Heim f. ochraceus Heim Pileus grey to greyish brown. T. striatus (Beeli) Heim f. griseus Heim
