Public Description of Hebeloma riparium A.H. Sm., V.S. Evenson & Mitchel

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Name: Hebeloma riparium A.H. Sm., V.S. Evenson & Mitchel
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Description status: Unreviewed

General Description:

This species illustrates one reason why mature specimens should be used for study of the cheilocystidia. At a certain stage in the development of the fruiting bodies the cystidia apparently elongate rather rapidly. One would expect them to agglutinate in age. The ixotrichodermium of the pileus, narrow close gills, and absence of a distinctive odor and taste distinguish this species.

Diagnostic Description:

Pileus 1-3.6 cm broad, obtuse to convex, the margin incurved, becoming plane or nearly so, or margin finally uplifted, ± evenly “Prout’s Brown” to “Buckthorn Brown” (dark to medium yellow- brown), opaque at all times, slowly becoming pale “Sayal Brown” in aging, canescent at first and avellaneous over marginal area. Context thin watery brown, fragile, odor and taste mild, FeS04 staining base of stipe gray (very slowly); KOH on cuticle of pileus no reaction.
Lamellae narrow, close, adnate, pallid becoming a pale vinaceous- buff, near “Sayal Brown” in age, not beaded and not stained.
Stipe 2-3 cm long, 4-6 mm thick, equal, pallid from a thin coat- ing of veil fibrils, becoming bister from the base up, solid, surface fibrillose from the thin veil but no annular zone evident.
Spores 8-10 × 5-5.5 j.1m, elliptic to ovate in face view, bean- shaped to very obscurely inequilateral in profile, pale snuff brown in KOH and about the same in Melzer’s, appearing smooth under a high-dry objective.
Hymenium.-Basidia 4-spored, 6-7 (8) j.1m broad. Pleurocystidia none. Cheilocystidia fusoid-ventricose, at first 33-46 × 9-12 j.1m but becoming 50-67 x by 7-10 j.1m by the elongation of the neck, apex obtuse, not branched or forked, lacking secondary septa.
Lamellar and pilear tissues.-Lamellar trama typical for the ge- nu~ but hymenium and subhymenium reddish to orange in Melzer’s. Cuticle of pileus a tangled ixotrichodermium collapsing to an ixolat- tice, hyphae 2-3.5 j.1m diam and with refractive walls, in Melzer’s reagent copious dextrinoid debris forming; clamps present. Hypoder- mium of yellow-brown inflated cells (as seen in KOH mounts of fresh material), tawny as revived in KOH. Tramal hyphae of pileus typical of the genus (no red content in Melzer’s).
Habit, habitat, and distribution.-On soil on an overflow area of a stream, Lincoln Creek, Pitkin County, Colorado, spruce nearby, July 16, 1978 (type, MICH).

Description author: Excited delirium [EXD]▼ (Request Authorship Credit)