Gymnopus foliiphilus R.H. Petersen, 2016

Petersen, Ronald H. & Hughes, Karen W., 2016, Micromphale sect. Perforantia (Agaricales, Basidiomycetes); Expansion and phylogenetic placement, MycoKeys 18, pp. 1-122 : 16-27

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Gymnopus foliiphilus R.H. Petersen

sp. nov.

2. Gymnopus foliiphilus R.H. Petersen sp. nov.


United States, Connecticut, Middlesex Co., vic. Salem, Devil’s Hopyard State Park, N41°28.937', W72°20.491', 1.IX.2013, coll RHP, TFB 14332 ( TENN-F-68183).


folius (Latin) = leaf; phil- (Greek) = to love; preference for broad-leafed leaves.


Similar to Gymnopus (Mi.) perforans : differing in: 1) fruiting substrate of dead deciduous leaves, most commonly Quercus ; 2) unique phylogenetic placement (based on ITS sequences); 3) apparent geographic range in eastern North America.


Basidiomata (Fig. 10 View Figure 10 ) diminutive, scattered to (rarely) gregarious. Pileus 3-22 mm diam, shallowly to strongly convex with downturned margin when young, becoming applanate to slightly depressed centrally by maturity (and then with small central dot of “drab” 6D3 or mouse gray), sometimes with small umbo, subtuberculate, matt to minutely plushy (35 ×) especially outward, when dried commonly sublaccate (glistening with reflected light rather than matt); disc when fresh "pinkish buff" 6A3, "vinaceous buff" 9B2, near "light pinkish cinnamon" 7A2, "Mikado brown" 7C6, to “drab” 6D3; limb "pale pinkish cinnamon" 6A2, "pale ochraceous buff" 4A2, "pale cinnamon pink" 5A2, "light buff" 3A2, "pinkish buff" 6A3, grayish orange 5B3; margin somewhat thick, entire to uplifted, vaguely sulcate-striate to not striate, usually mellowing to entirely tan to pallid brown. Lamellae adnate-adnexed or occasionally attached to a weak pseudocollarium (especially visible when dried and seceded), subdistant to distant, total lamellae = 30-32; through lamellae = 13-16, arcuate, thickish, narrow (not more than 1 mm broad) with no anastomoses or interveining, with dark brown ring around stipe apex, off-white to "pale pinkish cinnamon" 6A2, near “chamois” 4B4 or "pale ochraceous salmon" 3A3, mellowing to "light buff" 3A2, and perhaps with slight tint of necropigment in storage to "light ochraceous buff" 5A4; lamellar edge entire, never marginate nor fimbriate, occasionally minutely laccate. Stipe 12-30 × 0.8-1.2 mm, terete, equal, insititious, at junction with lamellae "vinaceous russet" 8D4, “bister” 5F8, upward concolorous with gills, "cinnamon buff" 6B4, “avellaneous” 7B3 to "tilleul buff" 7B2, soon downward "wood brown" 5A4, "buffy brown" 6D4, "mummy brown" 6F8, "Verona brown" 6E5, “Rood’s brown" 6D5, "clove brown" 6F5, "chaetura black" 2F3 to "bone brown" 7F8, weakly to densely vestured throughout, variably minutely flocculose, especially upward, to barbed with setoid vesture, hollow, downward becoming stuffed; vesture at stipe apex (30 ×), hyaline, downward becoming pigmented to dull yellow then dull straw-colored, but never black. Rhizomorphs usually present but widely scattered and inconspicuous, filiform (0.2-0.4 mm thick), resupinate on leaf surface (especially more sclerophyllous leaves), and there branching and anastomosing, sometimes orange-brown and diffuse, otherwise black and meandering, short (never more than 6 mm long), unbranched, straight to somewhat curly apically, tapering to flagelliform terminus. Taste usually reported as negligible, occasionally very weak of garlic; odor usually reported as negligible, occasionally resembling boiled cabbage after drying or mildly fetid.

Habitat and phenology.

On dead broad-leafed leaves, most often Quercus leaves, fruiting especially on midribs and petioles of both red and white oak complexes; other adventitious substrates include Acer (at least A. rubrum ), Cornus , Magnolia , Rhododendron , 2-needle Pinus ; Appalachian Mountain chain from New England through northern South Carolina and northern Georgia, west to Arkansas and south to Gulf Coast; late Spring through early Autumn.

Pileipellis a thin tissue involved in a slime matrix, composed of the following: 1) pileal hairs (Fig. 11 View Figure 11 ) -120 × 2-3.5 µm, smooth, occasionally clamped internally, with telltale evidence of superficial mucoid deposit; 2) repent hyphae slender [3.5-5.5(-13) µm diam], firm-walled (wall -1 µm thick, often somewhat gelatinized), generally radially oriented, conspicuously clamped, mostly smooth, occasionally vaguely ornamented (Fig. 12A-C View Figure 12 ) with minute flakes in slime next to hyphal wall, commonly very vaguely striped with some profile flakes (PhC), rarely significantly encrusted, hyaline, embedded in a thin layer of mucoid material (amorphous debris expressed in paradermal squashes, PhC); 3) common secondarily septate hyphal segments (Fig. 12D View Figure 12 ); small, peg-like, small lobes (Fig. 12F, G View Figure 12 ) common. Subpellis hyphae broader (5-7 µm diam), thick-walled (wall -1.0 µm thick), conspicuously clamped, hyaline, interwoven, with evidence of a mucoid or gelatinous deposit. Pileus tramal hyphae 5-21 µm diam, thin- to firm-walled, with minimal slime matrix, clamped. Lamellar trama loosely interwoven, of uninflated cells (2-)3.5-10 µm diam, firm- to thick-walled (wall -0.7 µm thick), lightly encrusted or with evidence of insoluble mucoid matrix, conspicuously clamped. Hymenium dense, with basidia becoming diaphanous after spore discharge but not disappearing ( “husking”). Pleurocystidia (Fig. 13A-D View Figure 13 ) 25-33 × 6-9 µm, fusiform, conspicuously clamped, serially produced from subhymenial clamp connections. Basidioles clavate; Basidia (Fig. 13E-H View Figure 13 ) (21-)27-32 × (5-)6-9 µm, clavate to narrowly clavate, clamped, 4-sterigmate (occasional individuals, always semicollapsed, observed with two prolonged sterigmata), obscurely to conspicuously clamped; contents minutely multigranular, not guttulate. Subbasidial cells appearing catenulate, lobose but hyphal (not as lobose as in G. perforans ). Basidiospores (Fig. 14 View Figure 14 ) (4.5-)6.5-7(-8) × 2.5-3.5(-4) µm (Q = 1.33-2.80; Qm = 1.92; Lm = 6.85 µm), gymnopoid to pip-shaped (ellipsoid, not tapered proximally), smooth, thin-walled, inamyloid. Cheilocystidia observed only in rare specimens, clavate, 28-34 × 9-10 µm, broadly clavate, not longer than basidia but broader, hyaline, clamped. Stipe medullary hyphae 4-9 µm diam, irregularly thick-walled (wall -1.5 µm thick) as though encrusted in bands (but not so), hyaline, conspicuously clamped; outer medullary hyphae 3-6 µm diam, hyaline, thick-walled (wall -2 µm thick), free (not adherent), strictly parallel, conspicuously clamped, commonly anastomosed in “H” connections. Stipe cortical hyphae 3.5-8 µm diam, smooth, thick-walled (wall -1.0 µm thick), pigmented in cytoplasm, producing caulocystidia as side branches. Caulocystidia (Fig. 15 View Figure 15 ) 25->150 × (2.5-)6-9 µm, arising from a tangled thatch of dry, interwoven, very thick-walled (occluding cell lumen), clamped hyphae, a combina tion of straight and setoid, mixed with other gnarled or curled individuals, densely scattered, thick-walled, usually arising as hyphal terminus or commonly with short abortive branch below, pigmented in cytoplasm (wall subhyaline), usually somewhat broader near origin than at mid-point (6-10 µm diam). Lower stipe caulocystidia (Fig. 16 View Figure 16 ) setoid, 4-7 µm diam, thick-walled (occluding cell lumen), arising as side branches from stipe surface hyphae, gathered into rough synnematal spines.


Gymnopus foliiphilus is the most commonly collected North American taxon in sect. Perforantia . Preliminary field identification attempts to distinguish several taxa with similar basidiomata. Substrate segregates G. androsaceus and G. perforans (conifer needles, usually Picea and/or Abies ), from G. foliiphilus . Geographic distribution is less secure. Both G. androsaceus and G. perforans are found in Europe and temperate North America, while G. foliiphilus seems limited to eastern North America. From all these taxa, a mimic, Marasmius pallidocephalus , is separated from G. androsaceus with difficulty in the field, based almost solely by lack of clamp connections of the former and phylogenetic placement.

Often in collections of G. foliiphilus , evidence of some bleaching of substrate can be detected. This is not dramatic - not to pale off-white - but distinct nonetheless. The phenomenon cannot be compared to M. perforans because fallen needles of Picea / Abies naturally bleach over time.

In G. folliiphilus , stipes are almost always bicolor , upward with some avellaneous to pinkish shade, downward to dark brown and finally black toward the base (note that the very junction of stipe and lamellae is always dark brown). The relative stipe length of these colors varies considerably, with the upward avellaneous shades from only the uppermost 10% to as much as the upper 50%. To some extent, the density and quality of the stipe vesture also varies, with upper surfaces producing shorter, less setoid, hyaline caulocystidia, often with long, slender, hyaline hyphae producing a sparsely silky or wispy appearance (40 ×) rather different from the hispid or barbed appearance of the lower stipe caused by setoid caulocystidia often gathered into synnematous sheaves.

A seductive artifact in microscope mounts of hymenial structures are the subbasidial cells. As is typical, basidioles and basidia are produced in “bouquets” by subbasidial hyphae, which usually are tightly packed but which retain hyphal characteristics. In G. foliiphilus , subbasidial hyphae are catenulate or congestedly lobose. The result are structures which mimic the cheilocystidia of numerous Gymnopus taxa, especially in sect. Vestipedes . In G. foliiphilus (as in G. perforans ), cheilocystidia are difficult to interpret, and when present, are consummately basidiiform.

Traditional generic characters are not consistent in sect. Perforantia and sect. Androsacei . For example, the pileipellis of G. androsaceus resembles a rameales structure of repent but diverticulate hyphae. Such a pileipellis is also present in Marasmiellus , taxa of which seem to belong to several relatively distantly related clades. In Micromphale , a gelatinous layer within the pileus trama can usually be demonstrated (i.e. M. foetidum , etc.), but in Micromphale sect. Perforantia the gelatinous layer is absent, but “replaced” by a thin slime matrix over and within the pileipellis.

A paper by Farnet et al. (1999) employed an agar medium reputed to promote production of rhizomorphs. For the present study, this medium (whole wheat flour 20 g/L; agar, Bacto 20 g/L; H2O 1 L) was used for numerous dikaryon isolates of various Marasmius and Micromphale collections. Ancillary to production of rhizomorphs, aerial mycelium of isolates of M. foliiphilus slowly changed from white to bright yellow ("empire yellow" 3A6), while aerial mycelium of M. perforans remained white.

Desjardin (pers. comm.) indicated the possibility that Marasmius insititius Fr. (1838. Epicrisis: 386), fruiting on Quercus leaves in Sweden, might be similar to M. foliiphilus . Marasmius insititius has seen a checkered history. Recently, Antonín and Noordeloos (2010) excluded the epithet from Marasmius because: 1) no type specimen exists; 2) Fries’s description is less than explicit; 3) in spite of Fries’s physical location in central Sweden in 1838, a habitat on Quercus leaves might indicate his exposure to the organism in southern Sweden; and 4) Orton (1960): 303) had dismissed the epithet as a later heterotypic synonym of Marasmius calopus . Desjardin (1989) did not include M. insititius in his type specimen studies, presumably based on the above and its extralimital status for Marasmius of the southeastern United States. Svengunnar Ryman (UPS; pers. comm.) indicates that M. insititius is an unknown entity. It is not the purpose of this paper to attempt to exhume M. insititius , especially as this name was not taken up in the Scandinavian mycota by Noordeloos in Funga Nordica ( Knudsen and Vesterholt 2012).

Once informed of our intention to propose a new species to represent the oak-loving relative of Mi. perforans , Desjardin (pers. comm.) graciously supplied extensive notes on three specimens [DED 4329 (TN), DED 4449 (SC), DED 4477 (NC)] and numerous citations of herbarium specimens chiefly listed under Ma. epiphyllus and Ma. insititius from AL, OH, PA, VA (not represented in "specimens examined" below).

Specimens examined.

UNITED STATES, Arkansas, Baxter Co., vic. Big Flat, Ozark National Forest , Leatherwood Wilderness , N36°02.4', W92°23.2', 23.X.2013, coll RHP (as M. perforans var. quercophilus ), TFB 14422 View Materials (ITS, TENN-F-69084) GoogleMaps . Connecticut, Middlesex Co., vic. Salem, Devil's Hopyard State Park , 41°28.937'N, 72°20.491'W, 1.ix.2013, coll RHP, TFB 14332 View Materials (ITS, TENN-F-68183, holotype) . Georgia, Rabun Co., vic. Clayton, Warwoman Dell picnic area, 15.VI.1992, coll SA Gordon, TFB 4902 (ITS, TENN-F-51221) . Mississippi, Stone Co., Ramsey Springs, Red Creek Wildlife Management Area , N30°46.572', W88°54.815', coll. RHP, TFB 14291 View Materials (ITS, TENN-F-68145) GoogleMaps . North Carolina, Macon Co., vic. Highlands, Rte 106, Blue Valley Overlook , north side of road, N35°01'45.15", W83°16'57.09", 20.VII.1n989, coll RHP, TFB 2800 ( TENN-F-49363); vic. Highlands , Bull Pen Rd. at Slick Rock , 29.VI.1992, coll SA Gordon, TFB 4928 (ITS, TENN-F-51244); vic. Highlands, Nantahala Nat. For., Blue Valley , Trail to Pickelseimer's Falls , 23.VII.1994, coll RHP, TFB 7243 ( TENN-F-56223); same location, Road 79, 14.VIII.1999, coll RHP, TFB 10364 View Materials (ITS, TENN-F-57923); same location, Forest Rd. 79, N35°01.103', W83°14.697', 1.VIII.2012, coll. RHP, TFB 10463 View Materials ( TENN-F-67809); same location, Blue Valley Campground , N35°00'45.23", W83°09'29.33", 11.VIII.2014, coll. RHP, TFB 14508 View Materials ; same location, FR 77 gate area, N35°00.243', W83°14.151', 14.VIII.2014, coll RHP, TFB 14531 View Materials ( TENN-F-69226); same location, start of FR 79, at picnic area, N35°01.085', W83°14.715', coll RHP (as Mi. perforans var. quercophilus ), TFB 13875 View Materials (ITS, TENN-F-65571); same location, FR 79, N35°01.103', W83°14.697', 1.VIII.2012, coll RHP (as Mi. perforans var. quercophilus ), TFB 14063 View Materials ( TENN-F-67809); Cliffside Lake Rd. , N34°04.749', W83°14.150', 30.VIII.2012, coll RHP, TFB 14048 View Materials (ITS, TENN-F-65977) GoogleMaps . South Carolina, Oconee Co., Oconee State Park, Nature Trail , N34°52'07", W83°06'20", 17.V.1991, coll SA Gordon, TFB 3612 ( TENN-F-50731); TFB 3615 ( TENN-F-50734); Oconee State Park , N39°52'07", W83°06'19", 18.VIII.1992, coll SA Gordon, TFB 5051 ( TENN-F-51454); Rte 107 circ. 12 m south of Cashiers , N34°59'37", W83°03'09", 16.VIII.1992, coll RHP, TFB 5435 ( TENN-F-51753); vic. Cashiers (NC), Walhalla Fish Hatchery, N34°59.155', W83°04.374', 7.VIII.1996, coll RHP, TFB 8782 (ITS, TENN-F-55210) GoogleMaps . Tennessee, Blount Co., GSMNP, Spruce Flats, N35°37'18.4", W83°40'26.3", 24.VI.1991, coll RHP & V. Antonín, TFB 3659 ( TENN-F-50778); GSMNP, Metcalf’s Bottoms, picnic area, 9.VI.1997, coll RHP, TFB 9166 (ITS, TENN-F-55764); GSMNP, vic Crib Gap, N35°36'45.8", W83°44'42.1", 22.VII.1991, coll & det DE Desjardin (as Micromphale perforans var. quercophilus ), DED 5272 (ITS, TENN-F-50013; SFSU); GSMNP, Greenbrier at trailhead to Ramsay’s Cascades, 20.VI.1991, coll SA Gordon, RHP, V. Antonín, TFB 3642 (ITS, TENN-F-50761); Foothills Parkway, Look Rock Campground, 10.VIII.2003, coll KWH & RHP, TFB 11608 View Materials ( TENN-F-59641); Cocke Co. , vic. Cosby, GSMNP, Gabes Mt. Trail , N35°12'33.0", 5.VII.2006, coll M. Padansee, E Lickey, TFB 13242 View Materials ( TENN-F-61274) GoogleMaps .