Trial key to the species of XEROMPHALINA in the Pacific Northwest

Prepared for the Pacific Northwest Key Council
By Ian Gibson, South Vancouver Island Mycological Society

Copyright © 2008, 2017 Pacific Northwest Key Council

Photo copyright held by each photographer
Do not copy photos without permission

TABLE OF CONTENTS

 Introduction

 Acknowledgements

 Table of Selected Characters

 Key to Species

 Glossary

 References

 Index

INTRODUCTION

Xeromphalina campanella is familiar in the Pacific Northwest to those who have found clusters of small, orange-brown, gilled mushrooms with a central depression in the cap, attached by tough, dark stipes to conifer logs. There are at least seven other species of this genus in the Pacific Northwest.

The genus Xeromphalina was erected for omphalinoid species in the Tricholomataceae with amyloid spores, and wiry to corneous stipes with golden colored mycelium at the base. In 1953 A.H. Smith added the genus Heimiomyces, a similarly defined, but collybioid genus that included the species known here as Xeromphalina fulvipes.

The differentiation of Xeromphalina from other gilled species is usually not difficult. They are small mushrooms with reddish brown to yellowish brown caps at most about 5 cm across. The caps are convex or have a depressed center, and do not generally appear conical like most Mycena species. They are not prominently translucent-striate like many Galerina species, although they are often striate near the margin. The surface is dry to moist (never viscid) and bald to pruinose. The stipe is slender to thread-like, and yellowish to red-brown or dark brown. There may be fine tawny hairs on the stipe which can appear pruinose. In the Pacific Northwest, they fruit on conifer wood or conifer litter. Most of the species produce short wiry rhizomorphs. Spore deposit is white to pale buff or pale yellow. Mycena picta is similar enough to a Xeromphalina, because of its wiry stipe, that it used to be known as Xeromphalina picta, but microscopically it fits Mycena better. The stipe of Mycena picta is swollen at the top and the gills are attached to the swelling by their inner margins.

Microscopically the species of Xeromphalina here are divided into three groups. Xeromphalina fulvipes is in subgenus Heimiomyces and has a duplex cap trama with the upper half gelatinized in KOH, the lower half of thick-walled, glassy hyphae. Subgenus Xeromphalina on the other hand lacks the duplex cap trama, and the remaining species are divided between two of its sections. Xeromphalina campanella and X. brunneola are in section Xeromphalina in which the cap trama remains ochraceous or brown, or becomes vinaceous in KOH, and cystidia on the stipe and cap margin are typically ventricose, fusoid, or cylindric. The remaining species are in section Mutabiles, in which the cap trama turns reddish in KOH and cystidia on the mid-stipe and around the cap margin are irregular, usually with some branched. These features can be useful when macroscopic features and spores are not enough to separate species; consequently, more microscopic data is given than for most PNW Key Council keys. Xeromphalina species have thin-walled, smooth, amyloid spores borne on 4-spored basidia.

The analysis in this key depends on monographs by A.H. Smith (1953) and by O.K. Miller (1968), but depends even more on Scott Redhead’s 1988 article in the Canadian Journal of Botany, "Notes on the genus Xeromphalina (Agaricales, Xerulaceae) in Canada: biogeography, nomenclature, taxonomy". As is usual with Pacific Northwest Key Council keys, macroscopic characters are used as far as possible, but microscopic characters are used when ambiguity persists.

Descriptions are derived (except where noted) from Redhead (1988) for Xeromphalina campanelloides, X. cauticinalis, X. cirris, X. cornui, and X. parvibulbosa, from Miller (1968) for Xeromphalina brunneola and Xeromphalina campanella and from Smith (1953) for X. fulvipes. The SIMILAR sections and REMARKS are the comments of the author, although their content is usually also from the same sources.

The most obvious macroscopic characters separating the Xeromphalina species are gill attachment, taste, and habitat, summarized in the following table. Spore sizes are given in the table, and further microscopic features are mentioned in the key and descriptions.

ACKNOWLEDGEMENTS

I am grateful to Dr. Scott Redhead for reviewing the draft key leads and summary chart.

TABLE OF SELECTED CHARACTERS

1. Smith and Arora both give mild taste but these were both before Redhead’s 1988 clarification that Xeromphalina cauticinalis sensu Smith is mostly Xeromphalina cornui. Their gill description is also different.

2. Spore measurements from Redhead.

KEY TO SPECIES

1a Growing in clusters on conifer logs, taste mild

................................................................................Xeromphalina campanella

CAP 0.3-2.5 cm across, convex to broadly convex, usually depressed in center when old, inrolled at first; orange-brown (in age cinnamon-brown), yellowish ocher on the margin; moist, bald, striate near margin when fresh. GILLS short decurrent to decurrent, subdistant, yellowish to dull orange, (Miller), arcuate-adnate at first, becoming deeply decurrent, (Smith). STIPE 1-4(5) cm x 0.05-0.25 cm, nearly equal, widening somewhat toward base, horny, cartilaginous, curved; yellowish just at apex, reddish brown in lower part, ending in a basal bulb that is covered with strigose tawny hairs. ODOR not distinctive (Smith, Miller), may have faint odor of household geranium, may have carrot odor, (Redhead). TASTE mild. HABITAT gregarious to cespitose "on decaying conifer sticks, logs and stumps often long after they are moss covered, usually not on newly fallen wood or fresh stumps", "usually found in gregarious to caespitose clusters on the sides of logs or stumps", summer, fall, and (where mild) winter, (Miller), very rarely on hardwoods, one on a burnt oak log, (Redhead(2)), common throughout the Pacific Northwest. MICROSTRUCTURES spores 5.8-7.8 x 3.1-4 um, cylindric to ellipsoid, (Redhead), spores 5-7(9.5) x 3.0-3.5(4.0) um, ellipsoid; pleurocystidia "the same as cheilocystidia but infrequently found, usually near gill edge", cheilocystidia protruding 1/3 to 1/2 of total length beyond hymenium, 29-55 x 6.0-13.5 um, "fusoid, ventricose, subventricose, narrowly fusiform to clavate", colorless in KOH and in Melzer's reagent, thin-walled, usually numerous; cap trama of erect hyphae 4.2-21.0 um wide, walls thickened (0.5-1.0 um), yellow-brown with incrustations on the walls in KOH, red-brown in Melzer's reagent; pileipellis composed of occasional pileocystidia 33-50 x 10-15 um, narrowly clavate, clavate to fusiform, colorless to yellow-brown in KOH, embedded in the cap trama; stipitipellis of hyphae 3-15 um wide, thick-walled (1-1.5 um thick), with little pigment, usually light yellowish in KOH, caulocystidia 25-40(75) x (8.5)11-15 um, clavate, subventricose, fusiform, colorless, thin-walled, often with clamp connection at base, protruding 1/3 of length, single or in small fascicles, (Miller). SIMILAR Xeromphalina brunneola has somewhat darker more reddish brown cap, disagreeable odor and taste (when fresh), smaller more elongated spores, and dark pigmentation of caulocystidia (older X. campanella specimens may have this); Xeromphalina campanelloides has a convex cap, gills that are adnate with short tooth or arcuate, bitter taste, and subglobose to broadly ellipsoid spores. Xeromphalina cornui grows on coniferous debris or in Sphagnum bogs, and cap trama becomes reddish in KOH as opposed being yellow brown. Other species inhabit conifer litter or debris.

Xeromphalina campanella © (Tim Zurowski)

1b Not growing in clusters on conifer logs, or taste unpleasant to bitter when fresh

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2a Growing on conifer logs, taste unpleasant to bitter when fresh

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2b Growing on conifer debris, taste mild or bitter

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Note: If a Xeromphalina is found growing on hardwood leaf litter and twigs, and has mild taste, consider Xeromphalina fraxinophila. It has never been found in the Pacific Northwest but has been found in Alberta next to the BC border and in Colorado. A full description is found in Redhead (1988). Xeromphalina fulvipes, with bitter taste, usually fruits on conifer debris but is said by Smith to fruit "more rarely on alder". Xeromphalina campanella has been confirmed once on a burnt oak log from Oregon. Xeromphalina kauffmanii grows on hardwoods, but has not been found in western North America. Microscopic confirmation would be needed.

3a Gills decurrent, (spores small and elongate)

................................................................................Xeromphalina brunneola

CAP 0.6-15 cm across, convex-depressed to nearly flat-depressed; evenly dull orange (dull and darker colored than X. campanella); bald, moist, margin opaque when moist. GILLS decurrent, close, narrow, dull evenly orange-buff. STIPE 3-6 cm x 0.1-0.25 cm, narrowing somewhat towards base, tubular, cartilaginous, base nearly bulbous; orange-buff at top, dark rusty brown downward; smooth at top, base covered with ochraceous pubescence. ODOR disagreeable at first. TASTE usually disagreeable (bitter), (Redhead), persistently disagreeable (chew thoroughly), (Miller). HABITAT in densely cespitose clusters on debarked conifer logs, late September and early October. MICROSTRUCTURES spores 5-6.6 x 2.1-3 um, cylindric to kidney-shaped or allantoid (not ellipsoid); context hyphae with thickened, refractive, brownish walls, (Redhead), spores 5.5-6.6 x 2.5-3.0 um, ellipsoid; pleurocystidia and cheilocystidia protruding about 1/3 of their length beyond hymenium, 44-82 x 5.5-8.5 um, subcylindric to fusiform, colorless in KOH and Melzer's reagent; cap trama of interwoven hyphae 5.5-1.1 um wide, cylindric or somewhat inflated, slightly thickened walls, yellow-brown in KOH, light yellow in Melzer's reagent; pileipellis "of radially arranged rectangular, square, or irregularly shaped, thick-walled cells" 5-12 um in diam, dark red-brown in Melzer's reagent and KOH, cell walls somewhat incrusted, pileocystidia rare, 50-60 x 16-20 um, "clavate to broadly fusiform, yellow-brown in KOH"; stipitipellis at apex reddish brown in KOH, hyphae 3.5-15 um wide, thick-walled (0.9-1.2 um), with caulocystidia (17)20-60 x (5)8.0-16 um, clavate, subventricose to fusiform, with thin or slightly thickened walls (up to 1.0 um), yellow-brown to occasionally light yellow-brown or colorless in KOH, single or in small fascicles; clamp connections mentioned as frequent for cap trama and base of caulocystidia, (Miller). REMARKS Redhead says taste is "usually disagreeable (bitter)" (italics mine) and notes that the taste in herbarium specimens is not reliable. Identification of a mild Xeromphalina with decurrent gills and growing on wood as something other than the common X. campanella would require microscopic confirmation.

3b Gills adnate to short-decurrent, (spores subglobose or broadly ellipsoid)

................................................................................Xeromphalina campanelloides

CAP 0.35-1.2 cm across, convex, obtuse to subumbonate, with incurved margin at first; fulvous to sienna brown or ochraceous-tawny, sometimes with dark brick-colored umbo and pale luteous [pale yellow] or maize yellow margins; dry, frosted yellow, margin obscurely translucent-striate. GILLS adnate with short decurrent tooth or arcuate, moderately spaced, narrow, with 2 tiers of lamellulae; pallid to straw-colored. STIPE 1.6-3.0 cm x 0.07-0.1 cm, honey to buff at top, fulvous to umber centrally, and dark brick-colored to blackish in lower part; finely powdered overall, cinnamon-colored mycelium at base, associated with dark brick-colored rhizomorphs in the wood. ODOR not distinctive. TASTE bitter. HABITAT coniferous wood. MICROSTRUCTURES spores 4.5-5 x 3-4.8 um, subglobose to broadly ellipsoid; cheilocystidia 25-32 x 3.5-4 um, narrowly cylindric, colorless, thin-walled, refringent, usually with 2-5 finger-like processes at top; cap trama duplex, the subpellis about 50 um thick, composed of hyphae (3)8-14 um wide, with subgelatinized walls, incrusted with red to reddish brown pigments in KOH, this subtended by a layer of more filamentous hyphae (3)4-9 um wide, with non-gelatinized walls, incrusted with reddish pigments in KOH; pileipellis a thin layer of smooth, thin-walled hyphae that are colorless in KOH or water, mostly 4-6 um wide, "on some basidiomes giving rise to diverticulate ends over the entire surface, on others only a sparse layer, marginally giving rise to thin-walled, diverticulate cystidia or cystidioform ends"; stipitipellis hyphae 4-5 um wide, filamentous, colorless in the apical region, smooth, thick walled, "with thickened reddish brown walls lower down", "bearing scattered caulocystidia apically, and hairs on lower portions"; caulocystidia 45-60 x 10-12 um, "irregularly shaped, thin walled to only slightly thickened, inflated apically, often obscurely angular, obtusely lobed, often a few subcircinate [somewhat coiled], golden yellow in water, yellow to pale reddish brown in KOH, very conspicuous against the colorless stipitipellis hyphae in scalp sections of the stipe apex"; clamp connections present. SIMILAR Young specimens of Xeromphalina brunneola might be confused if gills were adnate, but spores are quite different. Xeromphalina cauticinalis ssp. cauticinalis is similar apart from favoured habitat, but X. campanelloides has relatively short, curved stipe and thin-walled, inflated caulocystidia, and (unlike most fruitbodies of X. cauticinalis ssp. cauticinalis) yellow granules in medulla of stipe that turn reddish in KOH. Xeromphalina fulvipes has adnate gills, habitat on conifer debris, and narrower spores. Xeromphalina parvibulbosa has gills that are arcuate to adnate with short tooth to short-decurrent, mild to astringent or bitter taste, habitat on conifer debris, and longer spores.

4a (2b) Fruitbodies collybioid, taste bitter, gills adnate or adnexed, (cap trama duplex, the upper half gelatinized in 2% KOH, the lower half of thick-walled, glassy hyphae, coralloid pileocystidia present)

................................................................................Xeromphalina fulvipes

CAP 1-2.5(5) cm across, with collybioid aspect, convex to flat, the margin incurved at first and often remaining downcurved; bright yellow brown on disc, ochraceous tawny on margin, cap at times orange, fading very slowly; smooth, bald, moist. GILLS adnate, close (24-30 reaching stipe), narrow to moderately broad, 3 tiers of lamellulae; warm buff or more brownish (whitish only when very young). STIPE 2-8 cm x 0.1-0.25 cm, "reddish brown to black at base; tomentose, hairy at base", (Phillips), hairs at base orange (Arora), 2-8 cm x 0.1-0.25 cm, equal, tough, stuffed with tawny fibrils; 'ferruginous to blackish brown and covered over its entire length with "zinc-orange" tomentum, base tawny strigose and often deeply buried in the debris, extreme apex yellowish and pruinose pubescent', (Smith), rhizomorphs present (Redhead). ODOR none. TASTE "bitterish". HABITAT single to scattered or in clusters of a few fruitbodies on debris of conifers, more rarely on alder, spring and fall, (Smith) a common species along the west coast and in the interior wet belt in BC and ranges as far south as California, (Redhead). MICROSTRUCTURES spores 4.5-6 x 1.7-2 um, cylindric or in side view slightly curved, smooth, pale bluish in Melzer's reagent; pleurocystidia rare to abundant, 20-32 x 3-9 um, fusoid-ventricose at first, soon elongating greatly and with a flexuous hair-like prolongation projecting from hymenium, thin-walled, colorless in KOH, cheilocystidia similar to pleurocystidia; cap trama with surface pellicle of subgelatinous hyphae about 2 um wide, "but this layer easily obliterated and often not demonstrable, beneath it a hypoderm of enlarged yellow-brown cells, the remainder of compactly interwoven hyphae similar to those of the gill trama"; clamp connections present, (Smith), pileocystidia coralloid; based on the subgenus the upper part of the cap trama would be gelatinized and the lower part of thick-walled, glassy hyphae, (Redhead). SIMILAR Xeromphalina campanelloides found on rotting conifer wood, has wider spores, and has other microscopic differences. Xeromphalina cauticinalis ssp. cauticinalis has short-decurrent gills, wider spores, and other microscopic differences. Xeromphalina parvibulbosa has gills that are arcuate to adnate with short tooth to short-decurrent, mild to astringent or bitter taste, and larger spores.

Xeromphalina fulvipes © Kit Scates Barnhart

4b Fruitbodies collybioid or omphalinoid, taste various, gills arcuate to decurrent (if adnate then taste not bitter), (cap trama lacking a gelatinized upper half in KOH)

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5a Taste mild, gills decurrent, (growing on coniferous debris or in sphagnum bogs)

................................................................................Xeromphalina cornui

CAP 0.7-1.7 cm across, flat-convex or rarely pulvinate [cushion-shaped], "depressed or flattened centrally"; pale yellow to amber or ochreous with reddish brown to umber center; becoming finely cracked or eroded marginally when old, "translucent-striate when moist, becoming polished and opaque when partially dried", often with gold-yellow frosting at margin and centrally (under hand lens). GILLS decurrent to arcuate-decurrent, subdistant, moderately narrow, 1-2 tiers of lamellulae; pale yellow becoming umber. STIPE 1.5-6 cm x 0.05-0.1 cm, horny; 'bay to chestnut, dark brick or black'; dry, with yellow to ochraceous powder at top, otherwise smooth and polished, with conspicuous, tomentose, ochreous to amber hairs at base. ODOR and TASTE not distinctive. HABITAT in sphagnum bogs or on coniferous debris. MICROSTRUCTURES spores 5-7.5 x 3-4.5 um, narrowly ovoid to ellipsoid to broadly ellipsoid or even subglobose; pleurocystidia rare, scattered, inconspicuous, 30-35 x 2.7-3 um, thread-like, subacute, colorless, thin-walled; cheilocystidia scattered, rare to abundant, 23-27 x 3.5-6.5 um, mostly irregularly clavate with 1-5 swollen irregular processes at top; cap trama duplex, the subpellis a conspicuous layer of broad, heavily incrusted hyphae 4.5-16.5 um wide, "composed of barrel-shaped hyphae often forming a layer of textura prismatica as viewed in scalp sections, usually dark reddish brown in KOH", below this the tramal hyphae 3.5-5.5 um wide, "filamentous, finely to moderately incrusted with pigments, which are red to reddish brown in KOH"; pileipellis a thin layer of repent, filamentous hyphae mostly 4.5-5 um wide, "heavily incrusted with yellowish to orangish brown pigments, which become red to reddish brown in KOH", giving rise to cystidia largely confined to the cap margin at maturity, occasionally on the disc; pileocystidia around cap margin 30-50 x 4-7 um, broader in branched parts, "often twice or more dichotomously or irregularly branched forming ascending, irregular, finger-like, rarely subglobose processes, the walls slightly thickened except at the apices of some, smooth, yellow, becoming reddish in KOH at least in the thickened portions"; stipitipellis hyphae 2.7-3.5 um wide, filamentous, thick-walled, smooth to incrusted, dark reddish brown in KOH; caulocystidia abundant at top of stipe, 25-38 x 3-8 um, similar to those around cap margin. SIMILAR Xeromphalina cirris has broadly adnate to short-decurrent gills, habitat on conifer needles, usually in the mountains, and characteristic pileocystidia. Xeromphalina parvibulbosa has gills that are arcuate to adnate with short tooth to short-decurrent, mild to astringent or bitter taste, and cystidia around cap margin are colorless in KOH as opposed to becoming reddish in KOH. REMARKS Note that some specimens under Smith’s and Miller’s concept of X. cauticinalis key out here, but Redhead says those concepts are really Xeromphalina cornui for the most part, and the same may be true for David Arora’s concept that likely follows Smith’s or Miller’s. Microscopic confirmation is desirable.

Xeromphalina cornui © Steve Trudell

5b Taste immediately or slowly bitter OR gills adnate to short decurrent

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6a Fruiting in mountains, typically on conifer needles, taste mild when fresh, spores 5.5-8.5 x 4-5 um

................................................................................Xeromphalina cirris

CAP 0.7-2.6 cm across, convex and subumbonate to flat and umbilicate; hygrophanous, orange to "argus brown" [a Ridgway(1912) color] towards center and orange marginally; margin translucent-striate. GILLS broadly adnate to short decurrent, close to subdistant; light orange-yellow to orange buff with paler margins. STIPE 1.5-2.5 cm x 0.1-0.25 cm, horny; pale at top, dark brown below; dry, pubescent, with orangish hairs, becoming bald, basal mycelium colored raw sienna. TASTE mild. HABITAT type on conifer needles; found mostly in the mountains. MICROSTRUCTURES spores 5.5-8.5 x 3.8-5 um, broadly ellipsoid to broadly ovoid; cheilocystidia scattered, sometimes inconspicuous, 31-36 x 3-4 um, "broader in branched area, with thin but refringent walls"; prominent bundles of elongated pileocystidia not confined to marginal area (along with "relatively smooth, yellowish to orangish pileipellis and subpellis hyphae as seen in KOH") help distinguish X. cirris from X. campanelloides, X. cauticinalis, X. cornui, and X. parvibulbosa: cap cystidia are 28-50 x 4-5 um, broader in branched part, sometimes dichotomously lobed, golden in KOH, refractive, smooth, with long pedicels, the pileocystidia "very conspicuous against the nonrefractive, nearly colourless, filamentous hyphae when viewed in scalp sections"; pileipellis a thin layer of repent, mostly smooth, filamentous hyphae 4-4.5 um wide, giving rise to repent fascicles on thick-walled, obtusely lobed cystidia or cystidioform ends scattered over the entire surface of the cap; cap trama distinctly duplex, the subpellis a broad layer 1/3 to 1/2 the thickness of the cap, golden brown in KOH, the hyphae smooth to vaguely incrusted, mostly 7-11 um wide, the walls slightly thickened, "this subtended by a densely compact zone, which becomes less compact towards the hymenium", the hyphae filamentous, thin-walled, prominently incrusted, 4-5 um wide or occasionally wider, "the incrustations red to vinaceous brown in KOH"; stipitipellis hyphae dark reddish brown in KOH, 4-5 um wide, roughened, "with slightly thickened walls, bearing fascicles of caulocystidia mostly concentrated near the apex"; caulocystidia 35-45 x 4-10 um, broader in branched part, often narrowly clavate to somewhat strangulate-fusoid, often with one or more growths at tip, the walls thickened, reddish brown in KOH; clamp connections present. SIMILAR Xeromphalina campanella has decurrent gills, habitat on logs and stumps, and narrower spores. Xeromphalina fulvipes has bitter taste and smaller spores. Xeromphalina cornui has decurrent to arcuate decurrent gills and habitat on conifer debris or in sphagnum bogs. Xeromphalina cauticinalis var. cauticinalis has bitter taste, habitat on conifer litter, and smaller spores. Xeromphalina parvibulbosa has mild to astringent or bitter taste, habitat on conifer debris, and somewhat smaller spores. In addition, Xeromphalina cirris is distinguished from X. cornui, X. cauticinalis ssp. cauticinalis, and X. parvibulbosa microscopically by its prominent fascicles of elongated pileocystidia that are not confined to the marginal areas and that remain yellowish in KOH, and the relatively smooth, yellowish to orangish pileipellis and subpellis hyphae in KOH. REMARKS Mycena picta could key out here. The cap is yellowish brown and umbilicate. The wiry stipe is swollen at the top and the gills are attached to the swelling by their inner margins, with the gill margin almost horizontal as if the cap has not expanded. In addition it has cheilocystidia with rod-like projections.

6b Fruiting on conifer litter at various altitudes, taste mild to bitter when fresh, spores different in size from the sp. above

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7a Immediately to slowly bitter, spores 4.8-5.5(7.5) x 3-4 um, marginal areas of pileipellis having relatively smooth, non-incrusted hyphae

................................................................................Xeromphalina cauticinalis ssp. cauticinalis

CAP 1-2 cm across, convex with incurved margin, becoming flat-convex to flat and centrally depressed with recurved margin; ochreous with fulvous disc and amber to pale yellow edges; moist, margin obscurely translucent-striate. GILLS short decurrent, moderately spaced, 2-3 tiers of lamellulae; pale luteous to yellowish ochreous. STIPE 2.5-7.2 cm x 0.06-0.1 cm, straight except for the base, horny; ochreous to luteous at top, dark brick to chestnut in lower part, with ochreous to fulvous base; tomentose, powdered at top with ochreous-colored cystidia. ODOR not distinctive. TASTE immediately to tardily bitter. HABITAT colonizes litter on soil in coniferous and mixed forests. MICROSTRUCTURES spores 4.8-5.5(7.5) x 3-4 um [this is the measurement used in Redhead’s key, but in his description given as 4.8-5.5 (on the coast), 5-6.8 (interior western mountains) x 3-3.5 um wide], broadly ellipsoid to broadly ovoid; cheilocystidia "usually conspicuous, abundant", 29-39 x 6-8 um, fusoid to clavate, usually undulate, with 1-3 irregular finger-like processes at top; cap trama duplex, "the subpellis composed of swollen, orangish to reddish brown or yellowish (in KOH) hyphae" (2)2-22(40) um wide, "with smooth to tardily incrusted, slightly thickened walls", subtended by a layer of finely to moderately incrusted, more filamentous hyphae 3-7 um wide, "yellowish to orangish or reddish in KOH"; pileipellis a thin layer of repent, smooth, filamentous hyphae 3-4 um wide, "embedded in a thin ephemeral gelatinous layer", giving rise to circumcystidia [cystidia around the margin] or cystidioform ends; pileocystidia around cap margin "initially filamentous, although in older specimens they can swell considerably", thin-walled, sometimes refringent, colorless, smooth, with a few obtuse diverticula at top, 22-55 x 3-4 (expanding to 8) um; stipitipellis hyphae 3-4 um wide, colorless in apical region, reddish brown in lower stipe with roughened thickened walls, "bearing dense clusters of caulocystidia apically and scattered or clustered cystidia and hairs below"; caulocystidia 45-55 x 5-6 um, "filamentous, substrangulate to subfusoid or occasionally lobed or forked", thick-walled. SIMILAR Xeromphalina campanelloides has relatively short, curved stipe, habitat on rotting conifer wood as opposed to conifer litter, thin-walled inflated caulocystidia, and (unlike most fruitbodies of ssp. cauticinalis) yellow granules in medulla of stipe that turn reddish in KOH. Xeromphalina fulvipes has adnate gills and narrow spores. Xeromphalina parvibulbosa has mild to astringent or bitter taste, longer spores, and hyphae of marginal areas of pileipellis with reddish brown incrustation in 2% KOH. REMARKS Redhead (1988) says that Xeromphalina cauticinalis sensu A.H. Sm.(1953) is mainly Xeromphalina cornui, and moreover that Xeromphalina cauticinalis var. cauticinalis sensu O.K. Miller (1968) is mainly Xeromphalina cornui and that Xeromphalina cauticinalis var. acida O.K. Miller is Xeromphalina parvibulbosa (Kauffman & A.H. Sm.) Redhead.

7b Mild to astringent or bitter, spores 5.5-7.3 x 3.1-4 um, marginal areas of pileipellis with reddish brown incrustation in 2% KOH

................................................................................Xeromphalina parvibulbosa

CAP 0.6-2.6 cm across, convex to subumbilicate or funnel-shaped; somewhat hygrophanous, light cinnamon to ochraceous-tawny or fulvous to sienna brown, with pale yellow margin, when drying becoming yellower; bald, translucent-striate. GILLS "arcuate to adnate with short tooth to short decurrent", close, moderately narrow (up to 0.3 cm broad); buff-yellow or amber to ochreous or light ochreous. STIPE 1.8-7 cm x 0.1-0.15 cm, swollen at base; amber or light cinnamon to cinnamon brown at top, darkening from base up to chestnut or bay when wet, "drying with a yellowish hoar", base with orange tomentum. TASTE "mild to astringent (not bitter) or bitter". HABITAT "on coniferous debris, often in low wet areas, or in subalpine forests". MICROSTRUCTURES spores 5.5-7.3 x 3.1-4 um, ellipsoid; cheilocystidia 23-33 x 3.8-5 um, scattered, inconspicuous, smooth, colorless, refringent, undulate-filamentous to narrowly clavate with 1-3 processes at top; cap trama somewhat duplex, the subpellis region with hyphae 3-15 um wide, "with slightly thickened walls, reddish brown incrustations in KOH", this subtended by more filamentous hyphae 3-10 um wide, "with thin walls and conspicuous red to reddish brown incrustations"; pileipellis "a thin layer of finely to moderately incrusted, filamentous hyphae, the incrustations yellowish in water, reddish brown in KOH", 3-4 um wide, giving rise to circumcystidia [cystidia around cap margin], these pileocystidia 21-45 x 4-5 um, "coralloid, sometimes submoniliform, usually repent, with lobes or finger-like projections arising from the surface", thin-walled to thick-walled, colorless in water or KOH, "usually relatively inconspicuous among the incrusted surface hyphae"; stipitipellis hyphae 2-4 um wide, "roughened, thick-walled, reddish brown, giving rise to clustered apical cystidia and other scattered cystidia"; caulocystidia 22-65 x 4.5-7 um, mostly tapered cylindric, "often substrangulate, occasionally forked", thick-walled, reddish brown. SIMILAR Xeromphalina campanella has decurrent gills, mild taste, habitat on logs and stumps, and cap trama is yellow-brown in KOH rather than having red-brown incrustations in KOH. Xeromphalina campanelloides has bitter taste, habitat on rotting conifer wood, and shorter spores. Xeromphalina fulvipes has adnate gills, bitter taste, and narrower spores. Xeromphalina cornui has decurrent to arcuate-decurrent gills, mild taste, and cystidia around cap margin are well developed and become reddish in KOH. Xeromphalina cauticinalis ssp. cauticinalis has bitter taste, shorter spores, and marginal areas of pileipellis with hyphae faintly pigmented or colorless in KOH. REMARKS: Smith placed Omphalia parvibulbosa in synonymy with Xeromphalina cauticinalis which sensu Smith was mainly X. cornui, but the type of Omphalia parvibulbosa differs microscopically from both, according to Redhead. The online Species Fungorum synonymizes Xeromphalina parvibulbosa with Xeromphalina cauticinalis but the basis for the synonymy is unclear and MycoBank retains them as separate species (both accessed January 22, 2017).

GLOSSARY

allantoid - sausage-shaped, tubular and slightly curved with rounded ends

arcuate - forming an arch, curved or arc-like; of gills, means that the middle of the lower edge of the gill is higher than its ends

ascending - refers to gills that curve upwards from the margin of the cap to the attachment at the stem, as in a conic or unexpanded cap

cartilaginous - of tissue, tough, like cartilage, not fibrous; of stems: firm, tough and pliant (flexible)

cheilocystidium - cystidium on edge of gill

collybioid - resembling in general form a mushroom of the genus Collybia (in the old wider sense), typically with expanded caps (convex to broadly convex to flat), often with downcurved to incurved margin, cartilaginous or brittle stems not more than two or three times in length the diameter of the caps, without annulus or volva

coralloid - much branched; like coral in form

corneous - horn-like in texture

cystidium - a sterile cell frequently of distinctive shape, at any surface of a sporocarp

dichotomous - repeatedly dividing or forking into pairs

diverticulum (plural diverticula) - peg-like protuberance or small branch scattered over the surface of hyphae or cystidia

diverticulate - having diverticula

embedded - of hymenial elements such as cystidia, neither reaching the surface formed by other elements (such as basidia) nor projecting beyond it

equal - of a stem, the same diameter throughout its length

fascicle - bundle

filamentous - thread-like, long and slender

flexuous - of the stipe, or of cystidia, curving alternately in opposite directions

fusiform - spindle-shaped, fairly slender and narrowing from middle to both ends

fusoid - spindle-shaped

horny - hard and brittle in texture, homogeneous in texture and difficult to section

hygrophanous - surface changing color markedly as it dries, usually having a water-soaked appearance when wet and turning a lighter opaque color on drying

lamellula (plural lamellulae) - the short gills that do not span the entire distance from margin to stem

medulla - the part internal to the cortex (internal to the surface layer)

moniliform - having swellings at regular intervals like a string of beads

omphalinoid - of general form of the genus Omphalina, with broadly convex to depressed cap, decurrent or subdecurrent gills, cartilaginous stem, and no annulus or volva

pedicel - of cystidia, a slender stalk

pellicle - an upper surface layer on cap surface that can undergo gelatinization

pileipellis - the outer cellular layer of the cap (pileus), excluding veils

pileocystidium - cystidium on cap

pleurocystidium - cystidium on side (face) of gill

pruinose - looking finely powdered or finely granular

pubescent - covered with soft short downy hairs

recurved - curved back: when used of cap margin or scales means curved back upward

refractive - of hyphal or cystidial contents, light-deflecting

refringent - refractive

reniform - kidney-shaped

repent - of hyphae, prostrate, lying flat

rhizomorph - cordlike strand of twisted hyphae present around base of stem

short-decurrent - of gills, not extending far down the stem

stipitipellis - outer cellular layer of the stem, excluding veils

strangulate - constricted; constricted and expanded in an irregular manner

strigose - having long stiff hairs

sub- nearly, more or less, somewhat, slightly; below or under

subdecurrent - of gills, meaning short decurrent or nearly decurrent or somewhat decurrent (i.e. intermediate between adnate and decurrent, when attachment extends slightly further down stem than when adnate)

subglobose - of spores, nearly spherical

subpellis - the layer that separates the outermost cellular layer from the trama

textura prismatica - short-celled tissue of rectangular cells

tomentose - covered with soft hairs, often soft densely matted hairs, like a woollen blanket

tomentum - a covering of densely matted woolly hairs

trama - the interior tissue beneath the surface cellular layers of cap, stem, or gills

translucent-striate - of a cap or cap margin, with gills showing through to give a radially lined appearance

um - abbreviation for micron, one thousandth of a millimeter

ventricose - wider in the middle

REFERENCES

1. Johnson, J.E. 1997. "Mating Systems in Xeromphalina species" Mycologia 89: 393-399.
2. Miller, Orson K. 1968. "A Revision of the genus Xeromphalina" Mycologia 60: 156-188.
3. Redhead, S.A. 1988. "Notes on the genus Xeromphalina (Agaricales, Xerulaceae) in Canada: biogeography, nomenclature, taxonomy" Can. J. Bot. 66: 479-507.
4. Smith, Alexander H.. 1952, published 1953. "New and rare agarics from the Douglas Lake region and Tahquamenon Falls State Park, Michigan, and an account of the North American species of Xeromphalina" Papers from the Michigan Academy of Science, Arts and Letters 38: 53-87.

INDEX

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