Restingomyces reticulatus
Restingomyces reticulatus Sulzbacher, B.T. Goto & Baseia 2016, in Sulzbacher et al., Mycologia 108(5): 959 (2016).
Etymology: The epithet reticulatus (adj. A) refers to the ornamentation of the basidiospores resembling a net-like surface.
Diagnosis: Basidiomata hypogeous, globose to subglobose, 5–17 mm 6 7–16 mm, with distinct rhizomorphs at the base, orange white, grayish orange or yellowish white, turning white near the base, exterior tomentose to glabrous; gleba firm to cartilaginous, brown, locules not gel-filled; columella percurrent, gelatinized; rhizomorphs white, branched, tomentose; peridium composed of two layers, crystals adhering to the outer surface, peridial hyphae with clamp connections; basidiospores 7–10 6 4–7 mm (ornamentation excluded), ellipsoidal, wall irregularly reticulate (<3 mm diam.).
Basidiomata 5–17 mm diam., 7–16 mm high, globose to subglobose, becoming depressed or misshapen in age, with a distinct rhizomorph at the base. Peridium <1 mm thick, in youth orangish white (5A2) turning white (1A1) near the base when fresh, becoming greyish orange (5B3), yellowish white (4A2), and at full maturity greyish yellow (4B5), gradually turning light brown (5D4) when dried; exterior surface finely tomentose to glabrous, covered by sandy and organic particles. Gleba firm and cartilaginous; structure of small, roundish to extended locules, when observed under a stereomicroscope, united in groups by translucent tramal layer originating from an evident, percurrent and gelatinized central dendroid columella, yellowish brown (5F6) at younger stages to dark brown (6F5, 6F7, 7F5) at maturity. Rhizomorphs white (1A1), thin 0.1–0.3 mm diam., short and branched, easily snapping off from the base of basidiomata, tomentose, forming a base in the basidiomata. Basidiospores 7–10 × 4.5–7 µm (ornamentation excluded), L = 10 μm, W = 6.4 μm, Q = 1.28–1.8 (–2), Qm = 1.5, n = 30; ellipsoid, apex and base tapered, some with a short mucronate apex; sterigmal attachment persistent at maturity; hyaline or pale yellowish when young but becoming pale yellowish brown at maturity (in 3% KOH); wall smooth when young, becoming irregularly reticulate at maturity and with variable diameter (<3 µm diam.). Under SEM the surface is irregularly reticulate. Basidia 14–21 × 4–7 µm, cylindric to cylindric-clavate, but collapsing soon after maturity, hyaline or frequently encrusted with a pale yellowish pigment, 2-spored, thin to thick-walled (up to 2 µm diam.). Peridium not separable from the gleba, 2-layered: a) external layer formed by hyaline to pale yellowish hyphae, 0.5–4 µm diameter, thin to thick-walled (up to 1.5 µm diam.), with or without short crystal-like spiny projections along the wall (1–8 × 0.5–2 µm), crystals also adhering to the surface (1–3 µm diam.), crystals dissolving in 3% KOH; hyphae in the external peridial layer are clamped (not frequently); b) internal layer composed of hyaline and numerous oleoacanthohyphae with yellowish content, smooth, thin to thick-walled hyphae (up to 1 µm diam.), non-gelatinized, compactly parallel to interwoven, 19–152 × 3–20 µm. Hymenophoral trama 30–120 µm thick, not gelatinized in young and mature specimens, formed by parallel to subparallel, hyaline, smooth, thin-walled hyphae, 1–6 µm diam., clamp connections rare. Rhizomorphs composed of hyaline, thin-walled hyphae, 2–10 µm diam., smooth or encrusted with numerous crystal-like spines and angular crystals 1–5 µm diam., dissolving in 3% KOH. Numerous oleoacanthohyphae present, with yellowish internal contents, 3–6 µm diam., smooth, thin to thick-walled (up to 1.5 µm diam.), non-gelatinized hyphae.
Index Fungorum Number: IF815515
Figures 1. Phylogram based on Maximum Likelihood analysis of concatenated atp6 and nuc 28S rDNA genes using two specimens of Restingomyces reticulatus and sequences of Phallales from Hosaka et al. (2006). Hysterangium album and H. cistophilum were used as outgroups. Bootstrap support values (MP/ML) are based on 1000 bootstrap replicates.
Figure 2A–D. Restingomyces reticulatus, holotype. A. Sectioned and entire sporocarps among excavated roots. B. Sporocarps in situ. C. Globose sporocarps entwined in roots. D. Close up image of fresh gleba showing a well-developed columella. Photographs by Jomar Jardim.
Figure 3. Restingomyces reticulatus, holotype. Basidiospores mounted in 5% KOH. Immature spores with smooth wall, becoming irregularly reticulate at maturity.
Figure 4A–D. Restingomyces reticulatus, holotype. A, B. Scanning electron microscope images of mature basidiospores showing clear irregularly reticulate surface. C, D. External peridium layer formed by hyphae 0.5–4 mm diam, with or without short crystal-like- spine projections along the wall (1–8 6 0.5–2 mm) and crystals (arrows) adhering to the surface (1–3 mm diam).
Figure 5A–D. Restingomyces reticulatus, holotype. A. Peridium showing differentiation of the outer and inner peridial layers. B. Details of the exoperidium showing spiny hyphae and crystals projecting from the hyphal walls. C. Basidiospores. D. Basidia.
Reference:
Sulzbacher, M. A., Grebenc, T., Cabral, T. S., Giachini, A. J., Goto, B. T., Smith, M. E., & Baseia, I. G. (2016). Restingomyces, a new sequestrate genus from the Brazilian Atlantic rainforest that is phylogenetically related to early-diverging taxa in Trappeaceae (Phallales). Mycologia, 108(5), 954-966.
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