Coprinopsis myceniformis Schunemann & R. M. Silveira 2023, comb. nov.

Coprinopsis myceniformis (Dennis) Schünemann & R.M.Silveira, comb. nov.

= Psathyrella myceniformis Dennis 1961, Kew Bull. 15(1): 128 (1961).

FIG. 5

Mycobank: 846929

Description:—Pileus 7–10 × 3–5 mm, campanulate to cuspidate, white (1A1) to greenish grey (1D2) in maturity; slightly squarrose universal veil on umbo, adhered, becoming floccose towards margins and sparse, soon disappearing, white (1A1) at first, then light orange (5A5). Lamellae adnexed, subdistant, white (1A1) to dark brown (6F8); edges fimbriate with remains of the veil. Stipe 13–30 × 0.5–1 mm, central, equal, hollow, squamulose, white (1A1), with annulus flocculose on apex. Not deliquescent.

Basidiospores 13–14.5 × 5.5–7 × 6–7 μm, Q= 1.94–2.25, Qav = 2.1, cylindric to amygdaliform in frontal view, smooth, dark grey in KOH, guttulate, thick-walled; apiculus visible; germ pore eccentric, covered with a hyaline cap. Basidia monomorphic, 18.5–30 × 10.5–14.5 μm, clavate, hyaline, guttulate, 4-spored, surrounded by 4–5 pseudoparaphyses. Cheilocystidia 29.5–37 × 10–16 μm, pyriform to lageniform, hyaline, abundant. Pleurocystidia absent. Hymenophoral trama parallel to subparallel. Pileipellis a cutis with elongated hyphae, radially oriented, hyaline, thin-walled. Veil composed of elongated elements, slightly thick-walled, yellowish in KOH. Stipitipellis is a trichoderm with elongated hyphae, hyaline; terminal cells similar to cystidia. Clamp connections present.

Habitat and known distribution: —Gregarious on woody litter in Araucaria Moist Forest; recorded from Parque Estadual do Papagaio Char„o, Sarandi (Rio Grande do Sul, Brazil).

Specimens examined: — BRAZIL. Rio Grande do Sul: Sarandi, Parque Estadual Papagaio Char „o, gregarious on woody litter, 27°54’41.5”S, 52°49’11.1”W, 31 October 2017, B. L. B. Schünemann 118 (neotype ICN 200438), Gen Bank accessions: MK843967, ON640623, ON653384, ON707701. S „o Paulo: Cruzeiro, Pico dos Marins, solitary on woody litter, 22°30’33.0”S, 45°08’52.3”W, 10 December 2019, B. L. B. Schünemann 250.

Comments: —This species can be recognized by the campanulate to cuspidate non deliquescent pileus with white to greyish color, covered by a slightly squarrose veil on the umbo. The stipe is squamulose with annulus flocculose on apex. Microscopically, it is distinguished by the pyriform to lageniform cheilocystidia and the slightly thick-walled and yellowish elongate veil elements (FIG. 5).

Based on the white squarrose veil on umbo becoming floccose to the margin, Coprinopsis myceniformis belongs in section Nivei (Schafer 2010). Based on phylogenetic data, C. myceniformis belongs to the clade/Canocipes (Wächter & Melzer 2020), which can be corroborated by not deliquescent basidioma, elongate veil elements, pyriform to lageniform cheilocystidia and lack of pleurocystidia.

Coprinopsis myceniformis was originally described as Psathyrella myceniformis (Dennis 1961), but the morphological and molecular data obtained support that it belongs to Coprinopsis. Dennis (1961) description and illustration match with the specimens collected in Brazil, and the type locality is Venezuela, so we consider it as the same Neotropical region. Compared with others Coprinopsis species, C. myceniformis has pilleipelis as a cutis of radially arranged elements, veil composed of inflated elements, hymenium with pseudoparaphyses and dark basidiospores with germ pore, but have a psathyrelloid habit (non-deliquescent and non-striate pileus). As the others psathyrelloids species included in Coprinopsis, as C. canoceps (Kauffman) Örstadius & E. Larss. (2015: 37) in Örstadius, Ryberg & Larsson (2015), C. melanthina (Fr.) Örstadius & E. Larss. (2015: 37) in Örstadius, Ryberg & Larsson (2015), C. submicrospora (Heykoop & G. Moreno) Örstadius & E. Larss. (2015: 37) in Örstadius, Ryberg & Larsson (2015) and C. uliginicola (McKnight & A.H. Sm.) Örstadius & E. Larss. (2015: 37) in Örstadius, Ryberg & Larsson (2015), as C. myceniformis is not deliquescent and the basidia are monomorphic.

Coprinopsis myceniformis is phylogenetically related to C. aesontiensis A. Melzer, Ferisin & Dovana (2017: 124) and C. udicola Örstadius,A. Melzer & E. Larss. (2015: 16) in Örstadius, Ryberg & Larsson (2015), and morphologically similar to C. canoceps, and C. submicrospora. C. aesontiensis has relatively robust, non-striate pileus, light grey cap and absence of pseudoparaphyses (Melzer et al. 2016). C. udicola has larger pileus (20–25 mm broad), sparsely fibrillose stipe and pleurocystidia present (Örstadius et al. 2015). C. canoceps has cinnamon-drab pileus, pilleipelis as a cutis with transition to a paraderm, pleurocystidia present and cheilocystidia absent (Kauffman 1918). C. submicrospora has convex to applanate convex pileus, ochraceous-beige, fugacious veil, smooth with pruinose apex stipe, smaller basidiospores (6.5-9.0 × 4.5-6.0 um) and yellowish himenophoral trama (Örstadius et al. 2015).

Another similar species is Coprinopsis lotinae (Picón) Picón (2011: 45), described from Spain. Morphologically, C. lotinae has the most similarities to C. myceniformis, the fibrillose-setose stipe and presence of caulocystidia are the only distinguishable differences (Picón 2002). Based on the distribution and the lack of phylogenetic data to confirm if they could be conspecific, we prefer to keep them as separate species. More information is need to determinate if they could be synonymous.