Mycena nivicola B.A. Perry & Desjardin, 2016

Perry, Brian A. & Desjardin, Dennis E., 2016, New species of Mycena (Basidiomycota, Agaricales) from California, Phytotaxa 269 (1), pp. 33-40 : 34-36

Mycena nivicola B.A. Perry & Desjardin , sp. nov. ( Figs. 1a , 2 )

MycoBank No. 563354

Previous references:

Mycena nivicola B.A. Perry & Desjardin , nom. prov., A Taxonomic Investigation of Mycena in California, M.S. Thesis, San Francisco State University, San Francisco, p. 186 (2002).

Mycena nivicola , nom. inval., The Laws Field Guide to the Sierra Nevada, p. 22 (2007).

Mycena nivicola R.M. Davis, R. Sommer & J.A. Menge , nom. inval., Field Guide to Mushrooms of Western North America, p. 179 (2012).

Mycena nivicola B.A. Perry & Desjardin , nom. prov., California Mushrooms, p.198 (2016).

Diagnosis:—Pileus olivaceous to olivaceous brown, with or without yellow tones, lacking a conspicuously white-pruinose surface, covered with a separable gelatinous pellicle. Lacking strong farinaceous taste. Lamellae white to grayish white or pale yellowish white, lacking green coloration. Basidiospores 9.6–12 × 5.6–7.2 μm. Basidiomes fruiting on wood and woody debris of conifers in association with moisture produced by snow melt, April to June.

Holotype:— UNITED STATES. California: Sierra Co., 3 June 1991, Gold Lake Rd., north of Gold Lake , gregarious on woody debris in deep conifer duff, near melting snow, DED 5075 ( SFSU).

Description:— Pileus 7–32 mm diam., conical to campanulate; the margins incurved in young specimens, pellucidstriate; surface viscid but occasionally becoming dry with exposure (in such cases the surface becoming viscid to tacky when moistened), smooth, glabrous, covered with a separable gelatinous pellicle, hygrophanous, pale yellow with olivaceous tones when young and buried in substrate, becoming olivaceous to olivaceous brown and with or without yellow tones (4–5E3–6), the disc often darker, occasionally developing more yellow tones or rarely becoming reddish olivaceous with moisture loss. Context up to 3 mm thick under disc, white to pale yellow or yellowish green.

Lamellae ascending-adnate, with a small decurrent tooth, close with 1–2 series of lamellulae (25–29 reaching the stipe),

moderately broad (up to 2 mm), white to grayish white or pale yellowish white; edges concolorous, not separable as an elastic thread. Stipe 40–140 × 1–5 mm, central, terete, ±equal, hollow; surface viscid but quickly drying with exposure,

shiny or dull, entirely to apically covered with a white pruinosity or canescence, glabrescent below, the base white-

tomentose, typically covered with adhering substrate, surface when young pale yellow to lemon yellow (1–3A2–5)

centrally, the apex often paler to off-white, becoming dark reddish brown (8E6–8) from the base upwards in age. Odor indistinct; taste indistinct to mildly farinaceous.

Basidiospores ( Fig. 2a ) (9.2–)9.6–12(–12.8) × (5.2–)5.6–7.2(–7.6) μm [x m = 10.9 ± 0.8 × 6.2 ± 0.5 μm, Q = 1.4–2.2, Q m = 1.8 ± 0.1, n = 223 spores], ellipsoid to broadly ellipsoid, thin-walled, smooth, amyloid. Basidia ( Fig. 2c ) 31–44(–58) × 8.0–9.6(–11.2) μm, 4-spored, clavate, clamped, with sterigmata 3.2–4.4 μm in length; basidioles similar.

Cheilocystidia ( Fig. 2b ) 24–58 × 5.5–8.0 μm, commonly with a clavate to bulbous base and apically extending into one, occasionally two, short to long, tapered, often rather pointed excrescences, more rarely ±lageniform, the lower portion often with one to several, short, cylindrical excrescences, occasionally lacking excrescences altogether and then

±clavate, thin-walled, clamped, mixed with basidia, embedded in a gelatinous layer. Pleurocystidia absent. Pileipellis an ixocutis ( Fig. 2e ); hyphae 1.2–4.0 μm diam., embedded in a gelatinous layer, thin-walled, clamped (clamps often loop-like), smooth, rarely with a few scattered diverticula; terminal cells typically enlarged somewhat, much branched and/or covered with cylindrical to slightly coarse excrescences, 1.2–9.6 × 1.2–3.2 μm. Hypodermium composed of inflated cells up to 24.8 μm diam., dextrinoid. Lamellar trama composed of interwoven hyphae (subregular), dextrinoid. Stipe cortical hyphae 1.2–3.2 μm diam., embedded in gelatinous matter, thin-walled, clamped (clamps often loop-like), often appearing coiled, smooth, rarely with a few scattered, cylindrical excrescences; terminal cells (caulocystidia– Fig. 2d ) 21–88 × 5–12 μm, lageniform or with a bulbous to ±clavate or irregular basal portion, typically extending apically into one, occasionally two, long, tapered excrescences, the lower portion frequently with one to several, relatively short, cylindrical to coarse excrescences, clamped.

Habit, habitat, and known distribution:—Gregarious to subcespitose on wood or woody debris of conifers (typically buried) near melting snow banks. Common to the Abies / Pinus forests of the High Sierra Nevada and Cascade Ranges of California, April to June.

Etymology:— nivicola = snow dweller

Additional Specimens Examined:— UNITED STATES. California: Amador Co., SR 88 , Silver Lake Campground, in soil near melting snow, 18 May 1985, HDT 49040 ( SFSU). Calaveras Co. , Poison Creek Picnic Ground, gregarious in humus near melting snowbank, 8 May 1976, R. Halling 1334 ( SFSU). El Dorado Co. , Highway 50, Crystal Basin, gregarious to scattered on conifer debris, 6 May 1972, HDT 28801 ( SFSU). Madera Co. , Beasore Rd. , Bass Lake area , gregarious or subcespitose in woody soil debris near melting snowbanks, 25 April ; 1997, BAP 118 ( SFSU). Sierra Co., SR 49 , Yuba Pass , gregarious in woody debris near rotting log, in red fir forest, 2 June 1996, BAP 040 ( SFSU) ; SR 49 , Yuba Pass , gregarious or cespitose on woody debris, 4 June 1996, BAP 046 ( SFSU) ; Weber Lake Rd., approx. 4.5 miles from junction with SR 49 at Yuba Pass , gregarious to subcespitose in woody debris near melting snowbanks, 2 June 1997, BAP 120 ( SFSU) ; Weber Lake Rd., gregarious in woody debris, June 2001, M. G. Wood s.n. (personal collection). Siskiyou Co., Mt. Shasta , gregarious in debris near snow, 29 May 1972, HDT 28886 ( SFSU) ; Mt. Shasta, Red Fir Flat , gregarious in soil from beneath rotten log, in red fir forest near melting snow, 16 May 1976, R. Halling 1354 ( SFSU). Tuolumne Co., Pinecrest Lake , gregarious on conifer wood near melting snow, 22 May 1970, HDT 25328 ( SFSU) .

Comments:— Mycena nivicola is herein proposed as a new species of section Hygrocyboideae (Fr.) Singer. For years investigators have collected this taxon, commonly identified as M. griseoviridis A.H. Sm. (= M. epipterygia var. griseoviridis sensu Maas Geesteranus 1992 ), at higher elevations in the Sierra Nevada of California during the spring months. Based upon our investigations, we have chosen to segregate this taxon from M. griseoviridis due to macroscopic, microscopic, and habitat differences that exist between the material found in California and that found growing in eastern North America. The holotype specimen of M. griseoviridis was collected under Quercus sp. during the Fall in Michigan. The California taxon is found only in the Spring growing at high elevations on or near decaying wood of Abies spp ., and associated with the moisture produced by melting snow near which it is commonly encountered. In addition to these habitat and seasonal differences, M. nivicola differs from M. griseoviridis in that M. nivicola lacks a “conspicuously white-pruinose” pileus surface, lacks greenish coloration to the lamellae, lacks a strong farinaceous taste and odor, and forms larger basidiospores (see below).

It was suspected at the outset of this investigation that M. griseoviridis var. cascadensis A.H. Sm. , described from Baker Lake, Washington as a summer (spring at higher elevations) fruiter on Abies logs, was possibly the same taxon commonly encountered in the Sierra Nevada and Cascade ranges of California. Investigations of the holotype specimen of M. griseoviridis (AHS 15498; MICH!), several additional collections from Michigan (AHS 6159, AHS 6165, AHS 15516, HDT 512; all at MICH), numerous collections of the California taxon, and the holotype specimen of M. griseoviridis var. cascadensis (AHS 16656; MICH!) revealed that with the exception of spore size, the micromorphology of all three taxa is much too similar to be useful in delimiting these species. Mycena griseoviridis has smaller spores overall (x m = 9.5 × 6.0 μm) than does M. nivicola (x m = 10.9 × 6.2 μm). The holotype specimen of M. griseoviridis var. cascadensis has spores within the same size range as the type variety. Additionally, Smith’s (1947) description of M. griseoviridis var. cascadensis indicates that this taxon has a more gray to yellow colored pileus than M. nivicola , and lacks the reddish brown coloration that develops on the stipe base in mature basidiomes of M. nivicola . Until further specimens from Baker Lake, Washington matching the protologue of M. griseoviridis var. cascadensis are collected and studied, we recognize the latter taxon as distinct from M. nivicola .

Pairwise comparison of ITS sequence data for the holotype collection of M. nivicola (KX513843) with sequences of Mycena epipterygia (of which M. griseoviridis is considered a variety by Maas Geesteranus) from California, Washington, Tennessee, British Columbia, Italy and Sweden (KX513842, KP406534, FJ596884, DQ384586, EF530946, EU486451, HQ604771, HQ604772, KP454034, HM240533, JF908458, JF908460, JF908468, AY781261, GU234008), indicate 5.6%–6.8% difference between this taxon and M. nivicola in aligned, overlapping regions. However, among the ITS sequences of those collections identified as M. epipterygia , pairwise comparisons recover differences of 0%–10.3%, suggesting that the taxon is highly variable for this marker and likely represents multiple cryptic taxa at the species level. Pairwise comparison of the more conserved nLSU region for an additional M. nivicola specimen (KX13847) with sequences of M. epipterygia specimens from California and Germany (KX13846, AY207249) indicate 0.7–3.6% difference between aligned, overlapping regions, respectively. Comparison of nLSU sequences from the two M. epipterygia specimens reveal a difference of only 0.3%.

Figures

FIGURE 1. a. Mycena nivicola (MGW s.n., photo by Michael G. Wood). b. Mycena bulliformis (BAP 547, photo by Brian A. Perry) Scale bars = 10 mm.

FIGURE 2. Micromorphological features of Mycena nivicola (HOLOTYPE–DED 5075). a. Basidiospores. b. Cheilocystidia. c. Basidia and basidiole. d. Caulocystidia. e. Pileipellis hyphae. Scale bar = 10 μm. Drawings by Brian Perry.