Coprinopsis caesia Sch, 2023

Schünemann, Bárbara Letícia Botura, Westphalen, Mauro, Díazvalderrama, Jorge Ronny, Aguilar, Vilma & Silveira, Rosa Mara Borges Da, 2023, Coprinopsis (Psathyrellaceae, Agaricales) in the Neotropics: three new species and a new combination, Phytotaxa 585 (2), pp. 113-134 : 122-124

Coprinopsis caesia Sch ̧nemann & R.M.Silveira, sp. nov.

FIG. 2

Mycobank: 846926

Typification:— BRAZIL. Rio Grande do Sul: S „o Francisco de Paula , PRÓ MATA, growing on decayed leaves, 29°27’56.6”S, 50°09’28.2”W, 17 May 2018 , B. L. B. Schünemann 142 (holotype ICN 200439 ), Gen-Bank accession : MK843960 .

Diagnosis: —Pileus greyish blue; squamose yellowish brown universal veil, composed of yellowish, thick-walled and diverticulate elements; lentiform basidiospores; habitat on decayed leaf.

Etymology: —The name caesia refers to the greyish blue color of the pileus.

Description:—Pileus 5–8 × 1–3 mm, parabolic becoming applanate with lacerate and revolute edges, bluish grey (21C3) to greyish blue (21D6), slightly translucid when mature, plicate; veil squamose, radially splitting into patches, dense on umbo, yellowish brown (5D5) on umbo, and yellowish white (4A2) towards margin. Lamellae free, subdistant to crowded, dark brown (7F7) at maturity, edge concolor, deliquescent; pleurocystidia visible with hand magnifier. Stipe 13–30 × 0.5–1 mm, central, equal, fistulose, longitudinally striate, white (1A1), slightly translucid. Annulus absent.

Basidiospores 6–7.5 × 5.5–6.5 × 4.5–5.9 μm, Q= 1.13–1.20, Qav = 1.18; subtriangular to lentiform in frontal view, smooth, dark brown in KOH, thick-walled; apiculus visible; germ pore central, covered with a hyaline cap (0.6–1 μm). Basidia dimorphic, clavate 13–15 × 6.5–7 μm and long clavate 19–21 × 7–8 μm, 4-spored, hyaline; pseudoparaphyses 10–15 × 10–13 μm, hyaline, thin-walled, 4–5 surrounding the basidia. Cheilocystidia absent. Pleurocystidia clavate with lanceolate apex. Hymenophoral trama parallel to subparallel. Pileipellis a cutis of elongated hyphae, radially oriented, hyaline, thin-walled. Veil elements of two kinds: 1) elements 25–39 × 6–15 μm, branched, diverticulate, thick-walled (0.5–1 μm), yellowish and 2) elements 35–70 × 5–8 μm, elongated, slightly diverticulate, thin-walled, hyaline. Stipitipellis a cutis with diverticulate elements, hyaline, thin-walled. Clamp connections present.

Habitat and known distribution: —Growing solitary in decayed leaves of Araucaria Moist Forest ; recorded from Parque Estadual do Papagaio Char„o, Sarandi and PRÓ MATA, S„o Francisco de Paula (Rio Grande do Sul, Brazil).

Additional specimens examined: — BRAZIL. Rio Grande do Sul: Sarandi, Parque Estadual do Papagaio Char „o, growing on decayed leaves, 27°54’41.5”S, 52°49’11.1”W, 31 October 2017, B. L. B . Schünemann 117 ( ICN 200440 ), Gen Bank accessions: MK843959 , ON640621 , ON653380 .

Comments: —The main distinguishing features of Coprinopsis caesia is the small bluish grey to greyish pileus, the yellowish brown squamose veil, radially splitting into patches and composed of thick-walled and diverticulate elements, and the subtriangular to lentiform basidiospores (5.5–7 × 4.5–7 μm). In addition, it was found growing on decayed leaves ( FIG. 2 ).

Based on the diverticulate and thick-walled velar elements, Coprinopsis caesia belongs to section Alachuani ( Schafer 2010). In the phylogeny, C. caesia is nested in the clade / Coprinopsis ( Wächter & Melzer 2020) , characterized by strongly developed veil, consisting of chains of diverticulate, thin and thick-walled, hyaline or brownish pigmented cells, subtriangular basidiospores and clavate pleurocystidia.

Coprinopsis caesia is morphologically and phylogenetically related to the European species C. argentea (P.D. Orton) Redhead, Vilgalys & Moncalvo (2002: 226) in Redhead, Vilgalys, Moncalvo, Johnson & Hopple (2001), C. episcopalis (P.D. Orton) Redhead, Vilgalys & Moncalvo (2001: 228) in Redhead, Vilgalys, Moncalvo, Johnson & Hopple (2001) and C. gonophylla (Quél.) Redhead, Vilgalys & Moncalv (2001: 228) in Redhead, Vilgalys, Moncalvo, Johnson & Hopple (2001) included in the clade/ Coprinopsis . However, in C. argentea the pileus is greyish up to 15 mm and the veil is white with thin-walled diverticulate elements ( Orton 1972; Uljé 2005). Coprinopsis episcopalis differs in a convex pileus up to 30 mm wide, mitriform basidiospores (7.5–10 μm), cheilocystidia present and vesiculose pleurocystidia often narrowed at apex ( Orton 1972). Coprinopsis gonophylla can be distinguished by presenting a white pileus with up to 30 mm wide, cheilocystidia present, slightly incrusted thin-walled veil elements and terrestrial habitat ( Uljé 2005).

The two collections examined of C. caesia were variable in the size of stipe, but the molecular data confirmed they are conspecific. Therefore, we consider that variation as a morphological plasticity within the species, probably in response to the environment.

Figures

FIGURE 2. Macroscopic details of Coprinopsis caesia (ICN 200439) a, b. basidioma in situ c. details of the habitat. Microscopic features d. basidiospores e. basidia f. pseudoparaphyses g. veil elements on the pileipellis. Scale bars: a, c. 10 mm b. 5 mm d. 10 µm e, f, g. 20 µm. Photos: a, b, c. Oscar Adolfo Perdomo Báez d–g. Bárbara Scḩnemann.