Desarmillaria (Herink) R.A. Koch & Aime, in Koch et al., BMC Evolutionary Biology 17(no. 33): 11 (2017)
Basidiomata stipitate, usually in caespitoseclusters on wood. Pileus convex to applanate, usually some shade of brown. Lamellae pallid, adnexed to adnate to subdecurrent with lamellulae. Stipe central, various colorations but often concolorous with cap, longitudinally striate, usually with fibrils on upper third. Annulus absent. Basidiospores ellipsoid to spherical, smooth, hyaline, inamyloid. Basidia clavate, foursterigmate, hyaline. Cheilocystidia clavate, usually resembling basidioles. Pileipellis suprapellis composed of round, ellipsoid, cylindric, utriform, brown to hyaline, verrucose cells; subpellis composed of a layer of compact, shortened hyphae. Clamp connections absent. Rhizomorph production not observed in nature, while unmelanized production in culture has been observed. Saprotrophic to parasitic. Known only from the northern hemisphere.
Index Fungorum number: IF819124
Type species: Armillaria socialis (DC. ex Fr.) Herink, Sympozium o václavce obecné (J. Hasek). 1972 September. Lesnicka fakulta VSZ Brno: 44. 1973.
Notes: Desarmillaria includes mushroom forming armillarioid species that lack an annulus. This difference in morphology led Singer (1951; 1986) to divide Armillaria (as Armillariella) into two sections based on the presence or absence of an annulus at maturity. Herink (1973), then, recognized Armillaria as an annulate subgenus and Desarmillaria as an exannulate subgenus. Additionally, members of this genus have not been observed producing rhizomorphs in the field (Zolciak et al. 1997; Guillaumin et al. 1993), which is in contrast to most Armillaria species, most of which do produce rhizomorphs in the field (see Table 2). Rhizomorph production in nature appears to be a lost trait in this genus, as species are still able to form them in culture. Desarmillaria was elevated to genus-level for two reasons. First, the absence of an annulus in Desarmillaria species and the presence of one in Armillaria species is a reliable characteristic to differentiate the two genera. Second, the phylogenetic and molecular clock analyses show Desarmillaria is on a separate evolutionary trajectory compared to Armillaria, meriting a separate genus.
Figure 1. Phylogram generated from the analysis of six gene regions (28S, EF1α, RPB2, TUB, gpd and actin-1) from 58 taxa. Guyanagaster is the earliest diverging lineage and is sister to the mushroom-forming armillarioid species. The exannulate armillarioid species are the next to diverge, and compose Desarmillaria. The annulate armillarioid species form a monophyletic lineage and compose Armillaria sensu stricto. The major lineages within Armillaria are indicated in bold text at the corresponding node. The exannulate armillarioid species are sister to the annulate armillarioid species. Strobilurus esculentus and Oudemansiella mucida were selected as outgroup taxa. Black circles represent support of 90% (maximum likelihood bootstrap values, shown as percentages) and 0.95 BPP (Bayesian posterior probabilities) or greater, grey circles represent support of 0.95 BPP or greater and white circles represent support of 75% or greater.
Figure 2. Time-calibrated phylogeny generated from Bayesian analysis of three gene regions (28S, EF1α, RPB2) from 19 Armillaria species, two Desarmillaria species and two Guyanagaster species. Geographic origin of each specimen is indicated by the box to the left of the name: red = Neotropics, blue = Australasia, brown = temperate South America, lime green = Eurasia, purple = North America, and turquoise = Africa. Boxes at ancestral nodes correspond to the most probable ancestral range at that node. Geologic epochs are noted above the time scale. Dark grey bars correspond to the 95% HPD. The map in the lower left hand corner represents the proposed dispersal pattern.
Guillaumin J-J, Mohammed C, Anselmi N, Courtecuisse R, Gregory SC, Holdenrieder O, et al. Geographical distribution and ecology of the Armillaria species in western Europe. Eur J Forest Pathol. 1993;23:321–41.
Herink J. Taxonomie václacky obecné—Armillaria mellea (Vahl ex Fr.) Kumm. In: Hasek J, editor. Sympozium o václavce obecné: Armillaria mellea (Vahl ex Fr.) Kumm. Brno, Czechoslovakia: Vysoká Skola Zemĕdĕlská v Brné; 1973. p. 21–48.
Koch R.A., Wilson A.W., Sene O., Henkel T.W., Aime M.C. 2017. Resolved phylogeny and biogeography of the root pathogen Armillaria and its gasteroid relative, Guyanagaster. BMC Evolutionary Biology. 17(33):1-16
Singer R. 1951. Agaricales in modern taxonomy. Lilloa. 22:5–832.
Singer R. 1986. The Agaricales in modern taxonomy. 4th ed. Königstein: Koeltz Scientific Books
Zolciak A, Bouteville R-J, Tourvieille J, Roeckel-Drevet P, Nicolas P, Guillaumin J-J. 1997. Occurrence of Armillaria ectypa (Fr.) Lamoure in peat bogs of the Auvergne—the reproduction system of the species. Cryptogamie Mycologie 18(4):299–313.