Conocybe sp. “olivaceobrunnea”
Common Name: none
Cap 5-20 (25) mm broad, conic, conic-umbonate to campanulate; margin decurved, translucent-striate when moist; surface hygrophanous, at first dark olivaceous brown, the disc rivulose, becoming medium brown and rugulose, faintly tan orange at the margin; context thin, approximately 1 mm, pallid, soft; odor and taste not distinctive.
Gills close, narrowly attached, up to 3 mm broad, pallid, maturing buff rusty brown, edges pallid; lamellulae in 2-3 series.
Stipe 30-60 x 1.5-3 mm in width, central, hollow, fragile, equal to enlarged towards the apex and base; surface buff orange, longitudinally striate to twisted striate from gill edges ornamented with a white pubescence (use hand lens); lower stipe and in age similar, less conspicuous, partial veil absent.
Spores 13.5-18.5 x 7.5-10 µm, smooth, moderately thick-walled, ellipsoid, slightly inequilateral in profile, apex truncate, germ pore central; basidia two-spored to occasionally 4 spored; spores rusty brown in deposit; cheilocystidia lecythiform scattered, pleurocystidia not seen.
In small groups on disturbed ground, e.g. soil, grass, and woody debris along paths and roadways; fruiting spring and fall at low elevations of the Sierra Nevada and Coast Ranges; occasional; easily overlooked unless the olive, fresh stage is seen.
Unknown.
Conocybe “olivaceobrunnea” the descriptive, non-taxonomic name used here for this Conocybe is an outlier in a group known for brown to rusty brown caps. When fresh the caps are olivaceous, albeit only briefly, as they soon become brown with age and drying. A DNA-ITS sequence of specimens from the Bullards Bar area (Yuba Co.) indicates a close relationship (99% similarity) with Conocybe gigasperma, a European taxa. Arguing against conspecific status, however, are significant morphological differences, notably the nature of the cap and spores. Local material possess a rivulose to rugulose cap, a character not described for C. gigasperma; spores have a central germ pore vs eccentric germ pore in Conocybe gigasperma, and the spores of the local species are shorter, up to 18 µm versus 27 µm long in C. gigasperma. More collections and sequences are needed to clarify the taxonomic status of this possibly undescribed Conocybe. It should be noted in addition to Conocybe gigasperma, at least 3 other greenish capped Conocybe species are known from Europe and Russia. Conocybe aeruginosa differs with a cap that is described as bluish green, not olive. Conocybe cyanopus has blue green tints that are restricted to the stipe, and a recently described Russian species, Conocybe olivaceopileata when fresh, has a ochre brown, olivaceous tinged, glabrous, not rivulose or rugose cap, slightly wider spaced gills, and narrower spores.
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Hausknecht, A, Krisai-Greilhuber, I. (2004) Type studies in north American species of Bolbitiaceae belonging to the genera Conocybe and Pholiotina. Österr Z Pilzk 13:153–235
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Malysheva, E.F. (2017). Five new species of Conocybe (Agaricomycetes, Bolbitiaceae) from Russia. Mycological Progress 16(6): 625-636.
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