Epithet “albicantipes” refers to having a whitish base of the stipe.

The Republic of Korea, Jeollanam-do: Yeosu-si, Dolsan-eup, Hyangiram, 34°35'27"N, 127°47'55"E, alt. 183 m, 25 July 2017, Jae Young Park, Komsit Wisitrassameewong, SFC20170725–35 (GenBank accession no. ITS: OL467272; nrLSU: OL462811).

This species notably has hemispherical to convex, 4–23 mm pileus, distant lamellae, central to eccentric, tomentose, 5–15 × 0.5‒1.5 mm stipe with a white base; ellipsoid to ovoid, 5.8–7.4 × 2.8–4 μm basidiospores, clavate (often constricted), 25.5–34.8 × 4.8–6.7 μm basidia, broadly clavate, irregular, sometimes lobed, 26–49 × 5.4–10.6 μm cheilocystidia, and a habit of fruiting on branches.

Pileus: 4‒23 mm, eccentric, convex to hemispherical when young, becoming depressed and undulating with age; Surface smooth, brownish orange (5C3 to 6D4) at the center, becoming paler to the margin (4A3 to 3A2). Lamellae: distant, L = 10–16, l = 3–7, adnate, whitish to yellowish white (3A2). Stipe: 5–15 × 0.5‒1.5 mm, central to eccentric, cylindrical, tomentose, apex brownish orange (5C3) to light brown (6D4), gradually becoming paler downwards (5B2 to 6C2), with whitish basal tomentum. Basidiospores: 5.8–7.4 × 2.8–4 μm (average 5.5 × 3.2 μm), Q = 1.6–2.1 (mean = 1.97), ellipsoid to ovoid, amygdaliform, smooth, hyaline, non-dextrinoid, with drops. Basidia: (23) 25.5–34.8 × 4.8–6.7 (7) μm, 4-spored, clavate, often constricted. Cheilocystidia: 26–49 × 5.4–10.6 (14) μm, broadly clavate, irregular, sometimes lobed. Pleurocystidia: 25.8–56.4 (62) × 6.2–12.5 μm, clavate, subulate, sometimes lobed. Trama hyphae: cylindrical, often sub-inflated, smooth, non-dextrinoid 1.7–9 (12) μm wide. Pileipellis: a cutis made up of cylindrical, often sub-inflated, with weak annular ornamentation, 2.0‒7.5 μm wide hyphae; terminal elements adpressed, cylindrical, clavate, sometimes constricted or curved, 2.0‒5 μm wide. Stipitipellis: a cutis of cylindrical, smooth, 2.7‒9.7 (11) μm wide hyphae. Caulocystidia: 21.7–90 × 3.9–11.7 μm, cylindrical, flexuose, sometimes curved. Clamp connections: present in all tissues.

The Republic of Korea, Jeollanam-do: Jindo-gun, Maenggoldo island, 34°12'21"N, 125°51'41"E, alt. 24 m, 4 July 2018, Jae Young Park, SFC20180704–86.

Scattered to gregarious on the branch in mixed forest dominated by Camellia japonica Linne, in summer.

The Republic of Korea.

Collybiopsis albicantipes is similar to Co. ramulicola and Co. koreana when comparing macro-morphological characteristics. Collybiopsis ramulicola is distinguishable from Co. albicantipes by a reddish pileus, fewer and buff lamellulae (1–4), a shorter and thinner stipe (12–23 × 2–3 mm), shorter and slightly elongated basidiospores (6.6–8.4 × 3.5–4.5 μm), shorter basidia (23–27 × 3.8–5.5 μm), and shorter cheilocystidia (23–27 × 3–6 μm) (Deng et al. 2016). Collybiopsis koreana differs from Co. albicantipes by having a larger pileus (27–60 mm), more lamellae (15–20) and lamellulae (2–3), longer and thicker stipe (14–70 × 2–3.5 μm), bigger and elongated basidiospores (7.5–10 × 4–5 μm), cheilocystidia with different shapes and sizes (25–55 × 4–10 μm), and incrustation dark brown in KOH (Antonín et al. 2010).

Epithet “clavicystidiata” indicates that the new species has clavate cheilocystidia.

The Republic of Korea, Jeollanam-do: Jindo-gun, Jodo-myeon, Donggeocha island, 34°23'34"N, 125°93'84"E, alt. 70 m, 05 July 2018, Jae Young Park, Tae Heon Kim, SFC20180705–84, (GenBank accession no. ITS: OL467252; nrLSU: OL462817).

The prominent features of this species include a greyish orange to brownish, 6–45 mm pileus, whitish lamellae, a subinstitious, tomentose, whitish, 15–26 × 1.2‒1.6 mm stipe, oblong to subcylindrical, 6.7‒9.4 × 3.1‒4.6 μm basidiospores, utriform, clavate, 20.1–37.5 × 6.8–12.2 μm cheilocystidia, and cylindrical, flexuose, irregular, 17–50 × 3.5–7 μm caulocystidia.

Pileus: 6–45 mm, convex to hemispherical, becoming plano-convex to flat with an uplifted margin with age; Surface smooth, dull, hygrophanous, greyish orange (6B3) to brownish (7D8 to E8) at the center, being whitish at the margin (4A2 to 6C8), being paler with age. Lamellae: subdistant, L = 20–32, l = 1–7, adnexed, white. Stipe: 15–26 × 1.2‒1.6 mm, cylindrical, tomentose, subinsititious, whitish to reddish grey (9B2). Basidiospores: 6.7‒9.4 × 3.1‒4.6 μm, average 8.13 × 3.62 μm, Q = 2–2.4 (mean = 2.26), oblong to cylindrical, smooth, hyaline, non-dextrinoid, with drops. Basidia: 18.3–30 × 4.1–8.8 μm, 4-spored, narrowly clavate, narrowly utriform, often curved. Cheilocystidia: 20.1–37.5 × 6.8–12.2 μm, utriform, clavate, sometimes with mucronate apex. Pleurocystidia: absent. Trama hyphae: cylindrical, often subinflated, smooth, branched, non-dextrinoid, 2‒12 μm wide. Pileipellis: transition between cutis and trichoderm, composed of cylindrical, with heavy annular ornamentation, 4‒12 μm wide hyphae; terminal elements adpressed to suberect, cylindrical, clavate, often incrusted (often incrusted), thin-walled, 3‒6 μm wide. Stipitipellis: a cutis of cylindrical, smooth, 2‒7 μm wide hyphae. Caulocystidia: 17–50 × 3.5–7 μm, cylindrical, flexuose, irregular or curved. Clamp connections: present in all tissues.

The Republic of Korea, Jeollanam-do: Haenam-gun, Mt. Duryun, 34°29'6"N, 126°38'54"E, alt. 169 m, 5 July 2018, Young Woon Lim, Abel Severin Lupala, Jun Won Lee, SFC20180705–26. The Republic of Korea, Seoul: Gwanak-gu, Gwanak-ro 1, Seoul National University, 37° 27' 37"N, 126° 56' 59"E, alt. 80m, 13 July 2018, Jae Young Park, SFC20180713–09.

Solitary to scattered on dead wood debris of conifers, in summer.

The Republic of Korea

Collybiopsis clavicystidiata is morphologically similar to G. omphalodes and Co. menehune. Collybiopsis omphalodes differs in their larger pileus (2–30 mm), a darker colored stipe, smaller basidiospores (5–6 × 2.5–3 μm), and thinner hyphae in the pileipellis (5–8 μm wide). Collybiopsis menehune can be distinguished from Co. clavicystidiata by its larger pileus (8–30 mm), buff lamellae, longer stipe (15–60 mm), longer basidiospores (7.5–9.5 × 3.5–4.2 μm, Q = 2.2), and longer caulocystidia (16–67 × 3–5 μm) (Desjardin et al. 1999). Co. clavicystidiata is phylogenetically close to Co. pseudomphalodes. Collybiopsis pseudomphalodes has relatively few references for comparison, but differences can be found in the lengths of the stipe (3–4 mm) and cheilocystidia (40 × 3 μm) when compared with Co. clavicystidiata (Dennis 1961).

This species has a pale orange to brownish-colored, 4–20 mm pileus, an orange white colored to light brownish colored, 7–30 × 0.7–1 mm stipe with pubescence, spheropedunculate, pleurocystidia, oblong to subcylindrical, 6.8–9.2 × 3.1–4.9 μm basidiospore, lobed, clavate with rostrate apex, 24.8–38.4 × 6.5–11.8 μm cheilocystidia.

Epithet “fulva” referring to fox-colored pileus.

The Republic of Korea, Gyeonggi-do: Pocheon-si, Soheul-eup, Gwangneungsumogwon-ro 415, 37°45'17"N, 127°9'59"E, alt. 101 m, Sang Kook Han, 21 July 2015, KA15–0210 (GenBank accession no. ITS: OL467259; nrLSU: OL462795).

Pileus: 4–20mm, hemispherical, convex to plane, sometimes concave with slightly reflexed, wavy margin, hygrophanous, pale orange (6A3) to greyish orange, becoming more brownish to the center (5B4 to 7C4). Lamellae: distant, L = 16–28, l = 1–5, sinuate, broad, whitish to yellowish white (4A2) to brownish orange (6C4 to 7C4). Stipe: 7–30 × 0.7–1 mm, cylindrical, gradually widened towards the base, tomentose, apex orange white (5A2) to brownish orange (6C6), becoming dense downwards (6D8), covered with pubescence. Basidiospores: 6.8–9.2 × 3.1–4.9 μm (average 7.47 × 3.69 μm), Q = 2.05, oblong to cylindrical, smooth, colorless, non-dextrinoid, with drops. Basidia: 20.4–29.4 × 4.7–7.8 μm, 4-spored, narrowly clavate, sometimes constricted or curved. Cheilocystidia: (20.5) 24.8–38.4 × 6.5–11.8 μm, lobed, clavate, sometimes with rostrate apex. Pleurocystidia: 31.5–46.9 × 12–20.6 μm, spheropedunculate, obovoid, sometimes with mucronate apex. Trama hyphae: cylindrical to subinflated, irregular, thin-walled, smooth, branched, non-dextrinoid, 2.0‒15 μm wide. Pileipellis: a cutis of cylindrical, thin-walled, 4–15 μm wide hyphae; terminal elements adpressed to suberect, narrowly clavate, thin-walled, with heavy annular ornamentation, 3–8 μm wide. Stipitipellis: a cutis of cylindrical, thin-walled, smooth, 5‒15 μm wide hyphae. Caulocystidia: 45.6–108.3 (131) × 6.8–14.8 μm, cylindrical, irregular, curved. Clamp connections: present in all tissues.

The Republic of Korea, Gyeonggi-do: Pocheon-si, Soheul-eup, Gwangneung forest exhibition hall, 37°45'19"N, 127°9'58"E, alt. 99 m, 8 July 2016, Sang Kook Han, KA16–0428. The Republic of Korea, Gyeongsangnam-do: Geochang-gun, Mt. Gibaek, 35°43'6"N, 127°45'49"E, alt. 1095 m, 19 June 2013, Sang Kook Han, KA13–0216.

Scattered or gregarious on the bark of deciduous trees or on the rotting branch of both broadleaf trees and conifers, in summer.

The Republic of Korea.

Collybiopsis fulva morphologically resembles Co. menehune and Co. ramealis. They can be distinguished based on several morphological differences. Collybiopsis menehune has a longer stipe (15–60 mm length), denser lamellae, and larger basidiospores (7.5–9.5 × 3.5–4.2 μm) (Desjardin et al. 1999). Collybiopsis ramealis has a smaller basidiocarp (2–20 mm), shorter basidiospores (7.8–11 × 2.5–4 mm) and different type of pileipellis (Rameales-structure) (Noordeloos 1983; Desjardin et al. 1997). Phylogenetically, Co. fulva is closely related to Co. ramulicola. Collybiopsis ramulicola differs in having a more yellowish pileus, fewer lamellae (9–12) that are brighter in color, a more reddish and thicker stipe (2–3 mm), and smaller sized cheilocystidia (23–27 × 3–6 mm) (Deng et al. 2016).

Epithet “orientisubnuda” meaning the new species has originated from the East and is morphologically similar to Co. subnuda.

The Republic of Korea, Gyeongsangbuk-do: Ulleung-gun, 37°31'21"N, 130°53'14"E, alt. 757 m, 19 July 2016, Changmu Kim, Jinsung Lee, Jae Young Park, NIBRFG0000500990 (GenBank accession no. ITS: OL467262; nrLSU: OL546546).

It features a brownish, 15‒50 mm pileus, orangish cream-colored lamellae, greyish to brownish orange, tomentose, 20–80 × 2.5‒6 mm stipe, subcylindrical to fusoid, 6.7–8.6 × 1.8–3.2 μm basidiospores, and cylindrical, flexuose, sometimes irregular or curved, 26.3–52 (63) × 3.5–6.5 μm caulocystidia. This species is morphologically similar to Co. subnuda.

Pileus: 15‒50 mm, convex to plano-convex, sometimes subumbonate; Surface smooth, brownish orange (6C5 to 7C4), becoming paler to the margin (5A2). Lamellae: distant, L = 16–28, l = 3–7, adnexed, pale yellow (4A3) to orange white (5A2). Stipe: 20–80 (100) × 2.5‒6 mm, central to eccentric, cylindrical, tomentose, often twisted, greyish orange (6B4) to brownish orange(7C4), becoming paler and thinner to the base. Basidiospores: 6.7–8.6 × 1.8–3.2 μm (average 7.5 × 2.5 μm), Q = 2.5–3.2 (mean = 2.92), cylindrical to fusoid, smooth, hyaline, non-dextrinoid, with drops. Basidia: (17) 19.8–28.7 (29) × 3.7–7.3 μm, 4-spored, narrowly clavate, often constricted. Cheilocystidia: variable in shape and size, 21–33.3 × 4.7–8.2 μm, lobed, clavate, slightly sphaeropendunculate, sometimes constricted or with rostrate apex. Pleurocystidia: 24.7–52.3 × 5.1–9.1 μm, narrowly utriform, clavate, sometimes clavate with rostrate apex. Trama hyphae: cylindrical, often subinflated, smooth, branched, non-dextrinoid, 2.0–7.0 μm wide. Pileipellis: a cutis made up of cylindrical, 2‒8 μm wide hyphae; terminal elements adpressed, cylindrical, often subinflated, with weak annular ornamentation, 3‒6 μm wide. Stipitipellis: a cutis of cylindrical, smooth, 2.5–7 μm wide hyphae. Caulocystidia: 26.3–52 (63) × 3.5–6.5 μm, cylindrical, flexuose, sometimes irregular or curved. Clamp connections: present in all tissues.

The Republic of Korea, Chungcheongnam-do: Yesan-gun, Mt. Gaya, 35°48'14"N, 128°5'49”E, alt. 863 m, 23 August 2017, Hae Jin Cho, Ki Hyeong Park, SFC20170823–39. The Republic of Korea, Gangwon-do: Pyeongchang-gun, Mt. Odae, 37°43'54"N, 128°35'42"E, alt. 683 m, 8 July 2017, Nam Kyu Kim, SFC20170708–14. The Republic of Korea, Gyeongsangbuk-do: Ulleung-gun, 37°31'30"N, 130°52'21"E, alt. 718 m, 2 September 2015, Jae Young Park, SFC20150902-01.

Scattered to gregarious on the ground covered with dead and decaying leaves of broadleaf forest, from summer to autumn.

The Republic of Korea.

Collybiopsis orientisubnuda is morphologically similar to Co. peronata (Bolton) R.H. Petersen and Co. subnuda (Ellis ex Peck) R.H. Petersen. Collybiopsis peronata can be distinguished from Co. orientisubnuda by fewer and buff lamellulae (1–3), a thicker stipe (3–8 mm), smaller Q value (2.3), longer basidia (20–40 μm), and longer cheilocystidia (25–90 × 5–10 μm) (Noordeloos et al. 1999). Collybiopsis subnuda differs from Co. orientisubnuda with thinner stipe (~3 mm), larger basidiospores (8–11 × 3–4.5 μm) and the absence of pleurocystidia (Tekpınar and Acar 2020).

Epithet “subumbilicata” referring to having a small depressed center in pileus.

The Republic of Korea, Seoul, Gwanak-gu, Mt. Gwanak, 37°12'39"N, 128°19"E, alt. 877 m, 01 July 2014, Young Woon Lim, SFC20140701–03 (GenBank accession no. ITS: OL467232; nrLSU: OL462787).

The distinctive features include a brownish, 10–35 mm pileus, white colored lamellae, a brownish, 25–60 × 1‒3 mm stipe covered with pubescence, ellipsoid to oblong basidiospores, narrowly clavate and cylindrical, 17–24.3 × 3.5–5.1 μm basidia, and cylindrical, flexuose, sometimes curved, 12.6–38.2 × 2.4–6.6 μm caulocystidia.

Pileus: 10–35 mm, plano-convex to plano-concave, subumbilicate, becoming undulate and uplifted in age; Surface smooth, greyish orange (5B3) to brown (6E5). Lamellae: subdistant, L = 22–38, l = 3–7, free to adnexed, white. Stipe: 25–60 × 1‒3 mm, cylindrical, tomentose, hollow, light brown (7D4) to dark brown (9F8), becoming paler to the apex, covered with pubescence. Basidiospores: 5.5‒7.5 × 2.5‒3.6 μm (average 6.47 × 3.0 μm), Q = 1.8–2.2 (mean = 2), oblong to fusiform, smooth, hyaline, non-dextrinoid, with drops. Basidia: (15.6) 17–24.3 (27.6) × 3.5–5.1 (5.9) μm, 4-spored, narrowly clavate, cylindrical. Cheilocystidia: 17.6–38.4 × 5–7.8 μm, various in shape, lobed. Pleurocystidia: 20.3‒30.7 × 6.8‒9.5 μm, clavate, fusiform, slightly sphaeropedunculate. Trama hyphae: cylindrical, subinflated, branched, smooth, non-dextrinoid, 1.5‒8 μm wide. Pileipellis: a cutis made up of cylindrical, often incrusted, with heavy annular ornamentation, 5.0‒15 μm wide hyphae; terminal elements adpressed to suberect, fusoid, clavate, 6.0‒16 μm wide. Stipitipellis: a cutis of cylindrical, smooth, thin-walled, 2.0‒6.0 μm wide hyphae. Caulocystidia: 12.6–38.2 × 2.4–6.6 μm, cylindrical, flexuose, sometimes irregular or curved. Clamp connections: present in all tissues.

The Republic of Korea, Gangwon-do: Goseong-gun, Hwajinpo, Hwajinpo Condominium, 38°28'24"N, 128°26'30"E, alt. 7 m, 2 August 2012, Young Woon Lim, SFC20120802–03. The Republic of Korea, Gyeongsangbuk-do: Ulleung-gun, Ulleung island, 37°30'38"N, 130°51'44"E, alt. 429 m, 22 August 2017, Jae Young Park, Nam Kyu Kim, SFC20170822–14.

Scattered to gregarious on the ground covered with dead leaves in temperate mixed forests, from summer to autumn.

The Republic of Korea.

Collybiopsis subumbilicata appears similar to Co. villosipes (Cleland) R.H. Petersen. Collybiopsis villosipes is distinguished from Co. subumbilicata by fewer and brownish lamellae (also lamellulae), a noninsititious, light-colored stipe, larger basidiospores (6.5‒10.5 × 3.5‒4.5 μm) and basidia (25‒34 × 6.5‒7.5 μm) (Desjardin et al. 1997). Furthermore, Co. subumbilicata is phylogenetically close to Co. biformis and Co. disjuncta (R.H. Petersen & K.W. Hughes) R.H. Petersen & K.W. Hughes. Collybiopsis biformis is morphologically similar to Co. subumbilicata but can be distinguished by elongated basidiospores (6.4‒9.2 × 2.4‒4.8 μm), thicker basidia (6‒7 μm thick) and cheilocystidia (6‒12 μm thick) (Morgan 1905; Mata 2002). Collybiopsis disjuncta can be distinguished from Co. subumbilicata by a smaller pileus (7–12 mm) with olivaceous tint, pinkish lamellae, slender stipe (0.5–1 mm thick), bigger basidiospores (6–7.5 × 3–3.5 μm), bigger basidia (22–34 × 5–7 μm), and a seldom incrusted pileipellis (Petersen and Hughes 2014).

Epithet “undulata” referring to having an undulate margin of pileus.

The Republic of Korea, Chungcheongnam-do, Boryeong-si, recreation forest of Mt Sungju, 36°20'4"N, 126°39'50"E, alt. 241 m, 21 August 2012, Jae Young Park, SFC20120821–04 (GenBank accession no. ITS: OL467239; nrLSU: OL462813).

It is characterized by having 10‒23 mm sized pileus that is particularly brown in the middle with a wavy margin, subdistant and creamy lamellae, a dark brown, 35–55 × 0.8‒2 mm stipe that becomes lighter to the apex, subcylindrical, broadly clavate or irregular, sometimes lobed, 16.7–28 × 4.8–8 μm cheilocystidia, and 27–60 × 3.5–6 μm sized caulocysitida which has a morphology similar to cheilocystidia and sometimes grows in bundles.

Pileus: 10‒23 mm, convex to concave, margin becoming undulate with age; Surface smooth, hygrophanous, brown (7D2 to 7E6) in the center, becoming paler to the margin (5A2–5B3 to 7B2). Lamellae: subdistant, L = 15–30, l = 3–9, adnexed, cream. Stipe: 35–55 × 0.8‒2 mm, cylindrical, tomentose, dark brown (7F5 to 8F8), gradually becoming paler to apex (7B2 to 7C2). Basidiospores: 5.6–9.5 × 2–3.4 μm (average 7.3 × 2.8 μm), Q = 2–3.1 (mean = 2.58), cylindrical, smooth, hyaline, non-dextrinoid, with drops. Basidia: 15–22.3 × 3.6–6.8 μm, 4-spored, cylindrical, narrowly clavate to utriform, often curved. Cheilocystidia: 16.7–28 × 4.8–8 μm, subcylindrical, broadly clavate or irregular, sometimes lobed. Pleurocystidia: absent. Trama hyphae: cylindrical, sometimes subinflated, smooth, branched, non-dextrinoid, 2–8 μm wide. Pileipellis: a cutis made up of cylindrical, often incrusted, slightly brownish, with heavy annular ornamentation, 2.4–7 μm wide hyphae; terminal elements adpressed to suberect, cylindrical to clavate, 3–6 μm wide. Stipitipellis: a cutis of cylindrical, smooth, 2.0‒3.5 μm wide hyphae. Caulocystidia: 27–60 × 3.5–6 μm, irregularly cylindrical, narrowly utriform, seldom apically lobed, sometimes gathered in a bunch. Clamp connections: present in all tissues.

The Republic of Korea, Gyeonggi-do: Goyang-si, Deogyang-gu, Seooreung, 37°37'26"N, 126°54'4"E, alt. 35 m, 13 August 2015, Jae Young Park, SFC20150813–04. The Republic of Korea, Gyeongsangbuk-do, Sangju-si, Mt Noheum, 36°26'20"N, 128°5'48"E, alt. 695 m, 8 August 2013, Jae Young Park, SFC20130808–08.

Scattered to gregarious on leaf litter in mixed forest dominated with broadleaf trees, in summer.

The Republic of Korea.

Collybiopsis undulata is morphologically similar to Co. subpruinosa (Murrill) R.H. Petersen. Collybiopsis subpruinosa has differences in having small central papilla on pileus, fewer lamellulae (3–4 series), vivid colored lamellae, thicker basidiospores (4.5–5.2 μm wide), larger basidia (30–36 × 7.5–8.5 μm) and cheilocystidia (25–80 × 5–16 μm), thick-walled trama hyphae (0.5–1 μm), caulocystidia with a wider size range, and a habit of growing solitary on rotten twigs or logs (Desjardin et al. 1999). Collybiopsis undulata is phylogenetically close to Co. villosipes but Co. villosipes can be differentiated by having fewer lamelluale (2–3 series), vivid colored lamellae, thicker stipe (1.5–4.0 mm), slightly thicker basidiospores (3.5–4.5 μm wide), and basidia (25–34 × 6.5–7.5 μm) (Desjardin et al. 1997).

Epithet “vellerea” refers to having a velvety stipe.

The Republic of Korea, Seoul: Gwanak-gu, Mt. Gwanak, 37°27'32"N, 126°56'49"E, alt. 90 m, 21 August 2014, Young Woon Lim, SFC20140821–29 (GenBank accession no. ITS: OL467267; nrLSU: OL462810).

It has a dull, greyish orange, 18‒45 mm pileus with darker center, a tomentose (like velvet), insititious, orangish, 15–55 × 3‒5 mm stipe, sphaeropendunculate, subovoid, 23.4–49 × 7.5–13.4 μm pleurocystidia, oblong to subcylindrical basidiospores, narrowly clavate with rostrate apex, sometimes lobed, 7.7–49.7 × 3.8–14.6 μm cheilocystidia.

Pileus: 18‒45 mm, hemispherical, appendiculate to convex, subumbonate with an uplifted margin when old; Surface smooth, dull, hygrophanous, orange white (5A2) to greyish orange (6E8 to 7F8) on the center, gradually becoming paler to the edge (5A1 to 5B2). Lamellae: crowded to close, L = 38‒52, l = 3‒7, furcate, white. Stipe: 15–55 × 3‒5 mm, cylindrical, finely tomentose, insititious, pale orange (5A3) to reddish grey (7B2), becoming darker to the base (6A2 to 7C2). Basidiospores: 5.2‒7 × 2.5‒3.8 μm (average 6.17 × 3.06 μm), Q = 1.8–2.4 (mean = 2.03), oblong to subcylindrical, smooth, hyaline, non-dextrinoid, with drops. Basidia: 16.2–24.8 × 3.3–5.3 μm, 4-spored, (narrowly) clavate, often curved or constricted. Cheilocystidia: 7.7–49.7 × 3.8–14.6 μm, narrowly clavate with rostrate apex, sometimes lobed. Pleurocystidia: 23.4–49 × 7.5–13.4 μm, sphaeropendunculate, subovoid. Trama hyphae: cylindrical, often subinflated, thin-walled, smooth, branched, non-dextrinoid, 2‒5 μm wide. Pileipellis: a cutis made up of cylindrical, thin-walled, with weak annular ornamentation, 3‒10 μm wide hyphae; terminal elements adpressed to suberect, cylindrical, fusoid, clavate, 5‒11 μm wide. Stipitipellis: a cutis of cylindrical, thin-walled, smooth, 2.0‒6.0 μm wide hyphae. Caulocystidia: 12–38 × 2.4–6.6 μm, cylindrical, narrowly utriform, sometimes irregular, or curved. Clamp connections: present in all tissues.

The Republic of Korea, Chungcheongnam-do: Seosan-si, Mt. Gaya, 36°41'0"N, 126°35'19"E, alt. 260 m, 20 August 2012, Jae Young Park, SFC20120820–02. The Republic of Korea, Incheon: Ongjin-gun, 37°13'10"N, 126°10'4"E, alt. 6 m, 4 September 2018, Changmu Kim, Jin Sung Lee, NIBRFG0000502858. The Republic of Korea, Jeollanam-do: Jindo-gun, Seogeocha island, 34°15'22"N, 125°55'11"E, alt. 38 m, 5 July 2018, Jae Young Park, Tae Heon Kim, SFC20180705–90.

Scattered to gregarious on the ground covered with dead and decaying conifer needles, from summer to autumn.

The Republic of Korea.

Collybiopsis vellerea is morphologically similar to Co. menehune and G. spongiosus Halling. Collybiopsis menehune has a paler stipe, a smaller pileus (8–30 mm), and fewer lamellulae (4–6 series) (Desjardin et al. 1999). Gymnopus spongiosus has a smaller pileus (8–20 mm) and longer stipe (20–55 mm). Micromorphologically, Co. menehune has larger basidiospores, basidia, and caulocystidia (Desjardin et al. 1999). Gymnopus spongiosus differs from Co. vellerea in that its pileipellis is a Dryophila-type cutis and its color changes in alkalies. Furthermore, its basidia (18–25 × 6–9 μm) and trama hyphae (3.5–17 μm) are thicker and its caulocystidia (3.5–10.5 μm broad) are smaller (Halling 1996). Collybiopsis vellerea is phylogenetically close to Co. omphalodes. Collybiopsis omphalodes differs in having smaller basidiomata (20–30 mm) and its habit on logs (Dennis 1951).

Marasmiellus istanbulensis E. Sesli, Antonín & E.Aytaç. Pl. Biosystems 152(4): 669. 2018.

Marasmiellus koreanus Antonín, Ryoo and H.D.Shin. Mycotaxon 112: 190. 2010.

Marasmius omphalodes Berk., Hooker’s J. Bot. Kew Gard. Misc. 8: 138. 1856.

Collybia pseudomphalodes Dennis, Kew Bull. 15(1): 74 (1961).

Gymnopus ramulicola T.H. Li & S.F. Deng, in Deng, Li, Jiang and Song, Mycotaxon 131(3): 665. 2016.