Collybiopsis prolapsis, Petersen & Hughes, 2024

Petersen, Ronald H. & Hughes, Karen W., 2024, Two new species of Collybiopsis (Agaricales, Omphalotaceae) from Eastern North America, MycoKeys 107, pp. 95-124 : 95-124

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.

Figures

Figure 12. Collybiopsis prolapsis A basidioma B basidiospores, Scale bars: 8 mm (A); 5 µM (B).

Figure 13. Collybiopsis prolapsis. Dermatocystidia. Scale bars: 10 µM.

Figure 14. Collybiopsis prolapsis. Repent pileipellis hyphae. Scale bars: 5 µM.

Figure 15. Collybiopsis prolapsis. Smooth, repent hyphae with ‘ Subfumosae ’ side branches. Scale bars: 5 µM.

Figure 16. Collybiopsis prolapsis. Dermatocystidia, thick-walled, inflated, often ornamented. Scale bars: 7.5 µM.

Figure 17. Collybiopsis prolapsis. Pleurocystidia. Scale bars: 30 uM.

Figure 18. Collybiopsis prolapsis. Basidia. Scale bars: 30 uM.

Figure 19. Collybiopsis prolapsis. Cheilocystidia. Clusters with diverticula (A, B) Individual Cheilocystidia (C – G). Scale bars: 16 uM (A, B).