Collybiopsis prolapsis Petersen & Hughes 2024
Creators: name: Petersen, Ronald H.
name: Hughes, Karen W.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Agaricales
Omphalotaceae
Collybiopsis
Collybiopsis prolapsis

description: Collybiopsis prolapsis
Figs 12, 13, 14, 15, 16, 17, 18, 19
Holotype.
United States, Georgia, Rabun Co., vic. Clayton, Warwoman Dell Picnic Area, 34 ° 52 ' 57.81 " N, 83 ° 20 ' 57.99 " W, 15. VI. 1992, coll. Scott A. Gordon, TFB 4800 (TENN-F- 051101).
Diagnosis.
1) Basidiomata diminutive, collybioid or marasmielloid, saprophytic on hardwood litter; 2) clamp connections ubiquitous; 3) cheilocystidia “ prolapsed, ” similar to “ ramealis ” type, with an abrupt bouquet of branched diverticula; 4) stipe without vesture (i. e. not similar to Gymnopus sect. Vestipedes; 5) resupinate patch significant, with diminutive, white hyphal ropes; 6) necropigment weak over hymenophore; 7) nrITS sequence unique, but quite similar to that of C. complicata and C. minor.
Etymology.
Pileo- and cheilocystidia structures with swollen, subspherical excrescences, reminiscent of a prolapse.
Description.
Basidiomata diminutive (Fig. 12). Pileus 8–12 mm broad, when fresh rich deep brown (6 E 6-7, “ Brussels brown, ” “ Sudan brown ”), shallowly convex to plane, very vaguely finely sulcate, minutely radially fibrillose; drying grayish brown, more or less unicolorous. Lamellae subdistant, adnate (with very slight non-lamellate hymenium decurrent on stipe apex for less than a millimeter), not ventricose (straight from stipe to margin), total lamellae 30–40, through lamellae 4–10, “ off-white ” to “ cream ” to “ brown orange ”, 6 C 4 in age; lamellulae rudimentary. Stipe when fresh reported as concolorous with pileus, when dried more or less concolorous with lamellae, terete, hardly twisted, glabrous-shining to somewhat wispy very near base; stipe base with extensive (– 1.5 sq cm) resupinate patch, now creamy off-white and appearing varnished and with a few small, off-white synnematoid mycelial ropes. Odor and taste not recorded.
Pileipellis a repent layer of free (with no evidence of slime matrix or individual slime sheath), filamentous hyphae of the following types: 1) dermatocystidia (Fig. 13) clavate to fusiform to inflated and tapering distally, 7–11.5 μm diam, smooth (Fig. 13 A, B) to ornamented in annular pattern (Fig. 13 C, E), apparently arising at a clamp connection; contents homogeneous to heterogeneous with scattered inclusion (Fig. 13 D); 2) repent hyphae 3.5–8 μm diam, thin- to firm-walled, varying as follows: a) minutely roughened (Fig. 14 A); b) ornamented with individual scabs, flattened in flake-like scales, individual lumps – 2 μm high (Fig. 14 B), spiculate structures (Fig. 14 C) and / or annular ornamentation with profile calluses (Fig. 14 D); 3) smooth, repent hyphae 3.5–7.5 μm diam, with occasional filamentous side branches (Fig. 15 A – C); branches simple, lobate to branched, not arising from clamp connections; and 4) thick-walled, usually somewhat inflated hyphae 5.5–10.5 μm diam, with thick-walled cog-like warts, 1.5–2.5 × 1–2.5 μm (Fig. 16 A, B); intermediate forms (Fig. 16 C) occasional. Pileal and lamellar tramae interwoven; hyphae 3–8.5 μm diam, firm-walled, frequently and conspicuously clamped, in lamellar trama with slender hyphae 2–3.5 μm diam. Pleurocystidia (Fig. 17) 24–34 × 7–11 μm, abundant, stalked-fusiform, near lamellar edge ampulliform with rounded apex, conspicuously clamped; contents homogeneous to heterogeneous with crystal-like inclusions. Basidia (Fig. 18) more or less stalked-columnar (not urniform, not clavate), 27–35 × 8–12 μm, 4 - sterigmate (sterigmata slender, slightly curved), conspicuously clamped; contents homogeneous to minutely heterogeneous. Basidiospores (Fig. 12 B) (9 –) 9.5–10.5 × 4–4.5 (– 5) μm (Q = 2.10–2.50; Q m = 2.05; L m = 9.75 μm), elongate-ellipsoid, somewhat tapered proximally, thin-walled, hyaline; contents homogeneous to heterogeneous-subrefringent. Cheilocystidia (Fig. 19 A – G) ventricose-rostrate to stalked-globose, hyaline, firm- to thick-walled (wall – 1 μm thick, especially laterally, smooth), conspicuously clamped, apically producing a cluster of diverticula; diverticula – 16 × 1–2.5 (– 4) μm, repeatedly dichotomously branched, often inflated somewhat apically (Fig. 19 A, B). Stipe medullary hyphae thick-walled, occasionally conspicuously clamped, of two types: 1) 4.5–8.5 μm diam, seldom branched; contents heterogeneous (multigranular); and, 2) 2–3.5 μm diam, occasionally branched; contents homogeneous. Stipe cortical hyphae similar to slender medullary hyphae. Resupinate patch composed of tightly interwoven hyphae in a slime matrix; hyphae of two types, both inconspicuously clamped: 1) 3–5.5 μm diam, thick-walled (wall – 1 μm thick, refringent; PhC); and 2) 2.5–4 μm diam, thick-walled (wall – 0.7 μm thick, non-refringent), frequently branched.
Commentary.
Specimen notes on undried specimens for the holotype specimen, TENN-F- 051101, report lamellae as brownish-orange (6 C 4) in age. Similar pigmentation is currently evident on dried material, presumably a necropigment (approximately “ Light ochraceous salmon, ” “ Light salmon orange, ” more or less characteristic of the Collybiopsis ramealis complex.)
The pileipellis is a poorly developed Gymnopus structure (Hughes and Petersen 2015), with only a few “ diverticulate ” hyphal termini as described by Halling (1983); typical of section Subfumosae. Conversely, the typical Ramealis pileipellis structure is quite different. There, the typical diverticula are cog-like (not wart-like) and the surrounding hyphal walls thickened (vaguely similar to those shown in Fig. 16 A, B). Clamp connections are common and conspicuous throughout. The thick walls of stipe medullary hyphae appears to be laminate, often peeling into narrow shards (as in peeling a banana).
Cheilocystidia, while highly distinctive, are not totally unique. Collybiopsis straminipes cheilocystidia are similar, but the specimens examined (Desjardin and Petersen 1989, including the type) were clampless and from spruce-fir zone. A clamped variety (Marasmius straminipes var. fibulatus Desjardin & R. H. Petersen) is from lower elevation and hardwood (Quercus litter) substrate.
description: Published as part of Petersen, Ronald H. & Hughes, Karen W., 2024, Two new species of Collybiopsis (Agaricales, Omphalotaceae) from Eastern North America, pp. 95-124 in MycoKeys 107 on pages 95-124, DOI: 10.3897/mycokeys.107.122634