Pholiotina rugosa Identification Guide

The First Impression

The setting is usually domestic or semi-domestic: a wood-chip mulch bed in a park, a garden border topped up with bark, a mossy lawn edge, the shoulder of a woodland path where chippings have been spread. Among the chips are small tawny mushrooms, 2–3 cm across, with slim stems — at first glance one of the thousand small brown mushrooms that make experienced recorders sigh. What stops you is a detail you can see at arm's length: a small but unmistakably membranous ring partway up the stipe. A genuine skirt-like ring on something this slight and this brown is unusual, and it is where the identification of Pholiotina rugosa begins.

Reading the Cap

The cap is 1–2.5 cm and occasionally 4 cm across. It starts ovoid to conical, then becomes convex and finally broadly convex to almost flat, often keeping a low, broad umbo. The surface is smooth and bald — no scales, no fibrils, no veil flecks — but very frequently wrinkled or rugulose over the disc, especially as it dries, and that puckered central zone is what the epithet rugosa refers to.

Colour is the other half of the cap story. It is strongly hygrophanous: rich rusty tawny, cinnamon or date-brown when moist, drying out paler ochre-tan from the centre outward, so a drying cap often shows a distinctly two-tone pattern with a pale disc and a darker moist rim, then reverses as the whole thing pales. When moist, the margin is faintly translucent-striate, and you can see the shadow of the gills through it if you hold the cap to the light.

The Gills

Adnate to narrowly adnexed, close, moderately narrow, with several tiers of shorter gills between the full-length ones. They begin pale ochre to clay-buff and darken steadily to rusty cinnamon-brown as the spores mature — the colour change is a direct preview of the spore print. Under a hand lens the gill edge is paler than the face and finely fringed.

Stipe, Ring and Base

The stipe is 2–6 cm long and only 1.5–4 mm thick, equal or barely enlarged at the base, hollow and fragile — it snaps rather than tearing. Colour is whitish to pale brown at the top, darkening to brown from the base upward with age. The apex is finely pruinose; below the ring the surface is silky-fibrillose, often with a faint whitish sheen.

The ring itself deserves careful handling. It is thin but genuinely membranous, sits in the upper half of the stipe, and flares outward as a small collar; the upper surface is often finely grooved or striate. In many collections it is loose enough to slide on the stalk. It catches falling spores and consequently turns rusty brown, which makes it easier to see on older specimens than on young ones. In wet weather it can collapse flat against the stipe or wash away entirely, so examine several fruit bodies, including young ones, before deciding a collection is ringless.

There is no volva and no bulb. The extreme base is usually bound to the mulch by fine white mycelial threads and a scatter of adhering chips.

Flesh

Cut the fruit body lengthways. The flesh is thin, pale watery brown in the cap and slightly darker in the stipe base, and it shows no colour change on exposure — no reddening, no blueing, no darkening beyond ordinary drying. The smell is faint and indistinct.

Taking a Spore Print

Small caps drop sparse prints, so use two or three of the largest mature caps, set them gills down on white paper, cover them with a glass, and give them four to eight hours rather than the usual two. The print is rusty brown to cinnamon-brown, warm-toned, quite unlike the chocolate or purple-brown of Psathyrella or the sooty black of Panaeolus, and obviously not white.

That single result eliminates a great many small brown mushrooms at a stroke. Microscopically, the spores are smooth, ellipsoid, moderately thick-walled and rusty in deposit, with a distinct truncate germ pore at the apex; the cheilocystidia on the gill edge are not the bowling-pin (lecythiform) shapes that characterise Conocybe in the strict sense, which is the standard microscopic separation between the two genera.

Substrate, Season and Ecology

Pholiotina rugosa is a saprotroph of woody debris in disturbed, nutrient-rich ground. Wood-chip and bark mulch is the classic substrate, but it also fruits on decaying woody fragments in soil, in mossy lawns, along path edges, in greenhouse beds and in garden borders. It is very much a fungus of managed landscapes, and freshly laid mulch can produce a flush within a week or two of the first good rain.

The season runs from late spring through autumn, driven by rainfall. Fruit bodies come up solitary, scattered or in small loose troops; they do not form the tight tufted clusters typical of wood-inhabiting Galerina and Kuehneromyces.

Separating It from the Look-Alikes

Conocybe and ringless Pholiotina species share the slim build, tawny hygrophanous cap and rust-brown print, but have no membranous ring at all; they are usually more sharply conical and more strongly striate.

Galerina marginata is the most important morphological comparison, because it also combines a rust-brown print with a ring. It grows in tufts directly on wood — stumps, buried logs, especially conifer — is usually larger and more uniformly tawny date-brown, has a smoother cap, and carries a whitish fibrillose bloom on the stipe below the ring. Microscopically its spores are ornamented and wrinkled with a smooth suprahilar plage, not smooth with a truncate pore.

Kuehneromyces mutabilis is tightly clustered on hardwood stumps, has a two-toned cap with a hygrophanous marginal band, and a stipe conspicuously covered in dark recurved scales below the ring.

Agrocybe praecox and A. putaminum are considerably larger (3–8 cm), pale clay to buff, with a dull tobacco-brown print and a rooting stipe base bound by white cords.

Tubaria furfuracea shares the mulch habitat and cinnamon colouring, but has broad distant gills, whitish veil flecks scattered along the cap margin instead of a true ring, and a paler ochre-brown print.

Psathyrella candolleana carries veil teeth on the cap margin rather than a ring, has extremely fragile whitish flesh, and prints dark purple-brown.

A Quick Field Sequence

Wood-chip or mulch substrate; small tawny hygrophanous cap, often wrinkled over the disc; adnate close gills going rusty; slim fragile hollow stipe; a true membranous, often striate, sometimes movable ring; no volva; no colour change; rusty cinnamon-brown spore print.