Tubariomyces inexpectatus (M. Villarreal, Esteve-Rav., Heykoop & E. Horak) Esteve-Rav. & Matheny, in Alvarado et al., Mycologia 102(6): 1393 (2010)
Pileus 4–16 mm, convex, hemispherical to planoconvex or slightly depressed at maturity, without umbo, margin incurved when young, later straight and usually somewhat sinuose, not striate, without any remnants of veil, surface dry, velutinous, furfuraceous to slightly squamulose or floccose, brown-argillaceous, sienna to beige-brown or yellowish-brown (7.5YR 6/8, 5/6–5/8 to 10YR 6/8, 5/6–5/8), not or slightly hygrophanous. Lamellae arquate-decurrent to triangular when young, deeply decurrent at maturity, close to moderately close (L = [20–]24–28, l = 1), first beige to cream-brownish, finally nearly ochraceous, edge floccose, white or paler than the surface. Stipe 11–23 3 1–2 mm, cylindrical, central, more rarely somewhat subeccentric, usually sinuose, solid, at first whitish to pale beige, then becoming beige-brownish, finally darker but always paler than the pileus, surface finely fibrillose-pruinose throughout. Cortina present in young specimens, fugacious. Context whitish to ochraceous in the pileus, concolorous to the surface in the stipe, unchanging. Odor and flavor none.
Basidiospores (9.5–) 10.3–12.2–14 × 3.4–4–4.8 (–5.2) µm, Q = (2.3–) 2.4–3.1–3.7 (n = 36), cylindrical to suballantoid (‘‘boletoid’’), sometimes with central constriction, smooth, thin-walled, not dextrinoid, without germ pore, yellowish in KOH. Basidia 25–37 × 5–11 µm, subcylindrical to narrowly clavate, predominantly four-spored, sterigmata up to 7(–8) µm in those scarcely two-spored, with yellowish necropigment. Cheilocystidia (29–) 40–76 × 7–13(–18) µm, forming a nearly sterile band, variable in shape and size, predominantly cylindrical, flexuose, sublageniform to narrowly clavate, with obtuse rounded apex, exceptionally subcapitate, rarely septate, hyaline or with yellowish content, often covered apically by a refringent resinous matter. Pleurocystidia absent. Caulocystidia present, abundant throughout the sometimes septate. Pileipellis a trichoderm with abundant caulocystidioid cylindrical to claviform terminal cells, 25–75 × 6.5–13 µm, sometimes packed in clusters, usually covered apically by amorphous yellow deposits, encrusting yellowish pigments in the hardly differentiated subpellis, sometimes intracellular pigment also present. Clamp connections present.
Habitat: In open areas, on acid sandy soil, gregarious (more than 50 specimens in the holotypic collection), near Tuberaria guttata (Cistaceae), in Mediterranean evergreen oak forest (Quercus ilex subsp. ballota), Spain, spring (April).
Index Fungorum number: IF518325
Notes: Tubariomyces inexpectatus is known from two abundant collections that were made in the same locality fruiting among Tuberaria guttata (Cistaceae), a herbaceous annual plant that occurs in acidic sandy soils in open Mediterranean woodlands. This plant is known to form ectomycorrhizae with some truffles such as Terfezia spp., among others, and was known as Helianthemum guttatum (Comandini et al. 2006). It also is known that some agarics (e.g. Cortinarius, Inocybe) may establish ectomycorrhizae with some Helianthemum spp. in subalpine areas of Europe, but these plants (like Cistus or Halimium), are biannual or perennials.
Tubariomyces inexpectatus originally was considered an Inocybe species (Villarreal et al. 1998), although the authors considered its inclusion in this genus as debatable on account of the deviating macro- and microscopical characters, which were ‘‘unexpected’’ for this genus. It then was compared with I. malençonii R. Heim, which also has similar long and narrow spores. However this species belongs to the Mallocybe clade (Matheny et al. 2009).
T. inexpectatus can be recognized morphologically by the strongly decurrent lamellae in mature specimens (sometimes suggesting an ‘‘omphalinoid’’ habit), the mucoid yellow deposits that cover the apex of the cystidia, and the typical trichodermoid pileipellis.
Figure 1. Maximum likelihood (ML) phylogram from RAxML software. Sequences of rpb2 and LSU produced for this study were added to a previous alignment of rpb1, rpb2 and LSU sequences from Matheny et al. (2009). Provisional names from Matheny (2009) for the seven major clades or lineages in Inocybaceae are provided with Auritella and now Tubariomyces indicated as genera. Numbers above branches represent ML bootstrap proportions.
Figure 2. Neighbor joining cladogram of a 500 bp alignment of the complete 5.8S nuclear ribosomal subunit and partial ITS1 and ITS2 from the different samples in Tubariomyces included in this study: T. inexpectatus AH25500 (GU907095), Tubariomyces sp. RFS0805 (GU907096), T. hygrophoroides PAM05112008 (GU907097) and T. hygrophoroides CEH2885 (GU907098). Tree reconstruction was performed with MEGA4 software (Tamura et al. 2007). Numbers above branches represent bootstrap proportions from 5000 replicates. Only values .70% are shown. Inocybe cf. dulcamara (AM882860) and I. malenc¸onii (AM882867) from Ryberg et al. (2008) were used as outgroups.
Figure 3. A. Tubariomyces inexpectatus (AH25500, photo by Fernando Esteve-Raventós). Bar 5 15 mm. Scale bar = 10 mm.
Alvarado P., Manjón J.L., Matheny P.B., Esteve-Raventós F. 2010. Tubariomyces, a new genus of Inocybaceae. Mycologia. 102(6): 1389–1397
Comandini O, Contu M, Rinaldi AC. 2006. An overview of Cistus ectomycorrhizal fungi. Mycorrhiza 16: 381–395.
Villarreal M, Esteve-Raventós F, Heykoop M, Horak E. 1998. Inocybe inexpectata, a new and unusual species of subgenus Mallocybe. Mycological Research 102: 479–482.
Matheny PB. 2009. A phylogenetic classification of the Inocybaceae. McIlvainea 18(1): 11–21.