Russula neoelpidensis S.L. Mill. & Cotter, 2025

Miller, Steven L. & Cotter, Henry Van T., 2025, Russula neoelpidensis, a new sequestrate species and member of the Badia subclade within the Integrae clade, Phytotaxa 704 (2), pp. 187-195 : 189-191

Russula neoelpidensis S.L. Mill. & Cotter sp. nov. ( Figs. 2 , 3 )

MycoBank: 854612

Diagnosis: Russula neoelpidensis is characterized by a sequestrate basidiome morphology, cream to pale yellow translucent pileus, pale yellow gleba, percurrent to nearly percurrent stipe-columella, suprapellis and incrustations on the subglobose cells that give rise to pileocystidia that stain pink in Sulfovanillin, basidiospores ellipsoid to narrowly ellipsoid, heterotropic, bimodal in size and shape, ornamentation of isolated, blunt, broadly conical elements, occasionally interconnected with low faintly amyloid bands, suprahilar plage absent. Associated with oaks in the southeastern United States.

Etymology: Latin “neo” meaning “new” and Greek “elpida” meaning “hope” in reference to the New Hope Creek Bottomlands in North Carolina where the fungus was collected.

Macroscopic description:— Basidiomata russuloid, partially pseudoangiocarpic, stipitate. Pileus 2.2–4.4 cm wide, subglobose to hemispherical, smooth, shiny to mat, translucent, white to yellowish white (4A2), mottled in patches with pale yellow (4A3) where handled; margin closed or laterally open, sublamellate where exposed. Hymenophore loculate, yellowish white (3A2–4A2) to pale yellow (4A3), darkening to greyish orange (5B5) to golden yellow (5B8) or so where insect larvae have traveled, locules 0.7–1.8 × 0.15–1 mm (1–3 per mm), larger and more sinuous toward the base and where exposed, irregular, elongated, sinuous, deeply interdigitating with pileus cuticle; fresh spore mass in locules pale yellow to yellow (4A2–A3). Stipe-columella 1.5–2.6 × 0.6–1.1 cm, well developed, cylindrical, central, curved, mostly percurrent to percurrent, not branched, white with low rugulose texture on the surface, context white, translucent pale grey or mottled with white and translucent pale grey patches, darker where insect larvae have traveled, irregularly solid, minutely lacunose. Odor and taste not noted.

Microscopic description:— Basidiospores bi-modal in size, smaller spores 9.6–10.4 x 7.6–8 µm, x=10.2 x 7.8, Q=1.2–1.4. Qm=1.3, larger spores more numerous 11.2–13.2 x 8–9.6, x=11.9 x 8.6, Q=1.3–1.5, Qm=1.4, ellipsoid to narrowly ellipsoid, heterotropic, ornamentation of isolated, blunt, broadly conical elements, 1–1.5 μm high, occasionally interconnected with low faintly amyloid bands, in Melzer’s reagent larger spores staining darker with thicker-walls, hilar appendix 1.3–1.8 × 1.2 μm, conical or cylindrical, straight, frequently with tear-marks at the apex; suprahilar plage absent or indistinct. Basidia 2 or 4-spored with 2-spored basidia more abundant, 25–35 × 8–15 μm, broadly clavate; sterigmata 4–7 x 1.3–1.5 μm, basidioles 20–35 × 8–15 μm, clavate. Hymenial cystidia common, 40–90 × 7–12 μm, cylindrical, lanceolate or fusiform, rostrate or irregular. Subhymenium composed of isodiametric cells 10–20 μm diam. Hymenophoral trama 30–50 μm wide, composed of hyaline hyphae 3–8 μm diam, with nests and columns of sphaerocytes 20–36 μm diam. Pileipellis two-layered, suprapellis consisting of a pseudoepithelium of loosely arranged subglobose and inflated cells 6–25 μm diam, and hyaline, pileocystidia near the disk cylindrical or clavate 30–80 × 6–10 μm with sand-colored grainy contents in KOH, heavily incrusted but not acid resistant in BF, purplish grey to grey with sparce pink incrustations in SV, entire suprapellis turning pink and spherical cells that give rise to pileocystidia with pink incrustations, hyphal terminations near the margin filamentous, obtuse, scarcely branching, 1–3 celled, 30–60 x 1–3 µm; subpellis consisting of tightly compacted, thick-walled subglobose cells, 8–40 µm diam, not colored or incrusted in SV. Pileus context 200–300 μm thick, heteromerous with hyaline hyphae 2–8 μm diam inflated hyphae and sphaerocytes up to 15 μm diam. Stipitipellis with numerous large clavate to subclavate dermatocystidial elements, 80–160 x 5–12 µm, medium brownish grey not incrusted in SV, incrusted but not colored in BF, sublayers strongly pink in SV.

Habit, habitat, and distribution —On the ground in mixed bottomland hardwood forest including oaks. Known only from North Carolina, USA.

Material examined:— USA. Durham County, North Carolina. Along Bottomlands Trail, New Hope Creek Preserve ; Latitude: 35.952747, Longitude : -78.981247 ; collected by H. Van T. Cotter and Meriel Goodwin, 11 October 2021, VC 2318 (holotype DUKE 0378456 ). GenBank ITS PP905596 ; same region, Latitude: 35.951033, Longitude :—78.9786 ; collected by H. Van T. Cotter and Meriel Goodwin, 11 October 2021, VC 2319 ( DUKE 0378457 ). GenBank ITS PP905597 .

Figures

FIGURE 2. Macroscopic features of Russula neoelpidensis. A. Mature basidiomata sectioned vertically showing the gleba and stipecolumella (left) and outer surface (right) (holotype VC 2318); B. Mature basidiomata sectioned vertically showing outer surface (left) and gleba and stipe-columella (right), VC 2319; C–D. Macroscopic features of mature basidiomata, VC 2319, C. showing a ventral view of exposed hymenophore, D. Showing a dorsal view of the surface of basidioma. Scale bars = 1 cm.

FIGURE 3. Microscopic characteristics of Russula neoelpidensis (holotype VC 2318). A. Diagram of a section of the pileipellis taken from near the disc; B. Pileocystidia in KOH taken from near the disc. C. Subglobose cells of the suprapellis showing incrustations in Sulfovanillin. D. Hymenial cystidia. E. Basidia; F. Elements of the stipitipellis in Sulfovanillin; G. Basidiospores in Melzer’s reagent. Scale bars = 10 µm.