Geastrum gorgonicum M.P. Martín, M. Dueñas & Telleria, sp. nov.

Index Fungorum number: IF 834616; MycoBank number: MB 834616; Facesoffungi number: FoF 09203; Fig. 1

Etymology – Named after Gorgades, an ancient name for the Cape Verde Islands, Atlantic Ocean.

Holotype – MA-Fungi 92118

Colour code follow – XXX Code Universal des couleurs (Séguy 1936).

Unexpanded basidiomata 11–12 mm high, 7–11 mm diam., rounded with an umbo, and attached to the ground by a basal mycelium tuft, with many rhizomorphs. Peridium smooth to felt-like, pale brown (702); when the surface is damaged the fibrous layer appears dirty white (680). Expanded basidiomata 10–11 mm high×11–23 mm diam. Exoperidium splitting in 8–10 more or less equal rays, not hygroscopic; the rays are often recurved under the exoperidial disk. Mycelial layer brownish (702) to dirty white (680), when peeling off. Fibrous layer dirty white (680), papery when dry. Pseudoparenchymatous layer pale brown (190), peeling off when dry. Endoperidium globose, 7–11 mm diam., sessile, brown (702), without crystals. Peristome finely fibrillose, well delimited, conical, colour similar to the mycelial layer (190). Mature gleba brown (697, 702). Mycelial layer with the outer part formed by 2–3 μm diam., brownish, unbranched, aseptate hyphae, with walls<0.2 μm wide; and inner part with 1.5–2 μm diam., hyaline, unbranched, aseptate hyphae, with some clamps, and with very thin walls (<0.1 μm wide). Fibrous layer 1.5–3 μm diam., hyaline, thick-walled hyphae with narrow lumen. Pseudoparenchymatous layer with thin-walled, hyaline cells, variable in shape and size, about 18–58 μm diam. Endoperidial layer with 2.5–4 μm diam., hyaline hyphae, some with thin walls (<0.2 μm wide) and others thick-walled with narrow lumen. Peristome with 2–3 μm diam., yellowish, aseptate hyphae, thick-walled with narrow lumen and without clamps. Capillitium formed by 1.5–3 μm diam., brown, aseptate hyphae with walls<0.2 μm wide. Basidia not seen. Basidiospores globose to subglobose, brownish to yellowish brown, with an oil drop; basidiospores 4.5–5 μm diam. including the baculate ornamentation (0.3–0.5 μm high).

Material examined – CAPE VERDE, Santiago, Parque Natural da Serra da Malagueta, Concejo de Sta. Catarina, 15°10′28″ N 28°40′37″ W, 914 msl, in a slope under Pinus sp., 20 November 2010, J. Cardoso, L.M. Caterino, L.M. Catarino, M. Dueñas, M.P. Martín, I. Melo, I. Salcedo and M.T. Telleria, 3242MPM (MA-Fungi 92118, holotype); idem, 3243MPM (MA-Fungi 92116); idem, 3244MPM (MA-Fungi 92114); idem, 13248MD (MA-Fungi 92112).

GenBank numbers – MA-Fungi 92118: ITS=MN754045, LSU = MN754083; MA-Fungi 92116: ITS= MN754046, LSU = MN754084; MA-Fungi 92114: ITS= MN754047, LSU=MN754085.

Notes – Based on ITS and LSU analyses (Fig. 2), Geastrum gorgonicum clustered in sect. Corollina J.C. Zamora in its own well-supported clade (100% MPBS, 95% MLBS, 1.00 BYPP) close to two collections under Geastrum aff. saccatum 1 in Zamora et al. (2014), one from Argentina (MA-Fungi 83775), and the other from Bolivia (MA-Fungi 47185-2). On the other hand, the G. gorgonicum clade grouped separately from other species of section Corollina: Geastrum corollinum, G. flexuosum, G. lageniforme, G. morganii and G. saccatum, as well as from Geastrum aff. saccatum 4, 5, 6 and 7 from Zamora et al. (2014). Geastrum gorgonicum can be separated from G. saccatum by a number of characters (Fig. 1). The expanded basidiomata of G. saccatum are larger (10–40 mm diam.) with an endoperidium of 10–20 mm diam., beige to greyish brown; whereas in G. gorgonicum the endoperidium is brown, and the two types of hyphae (thin and thick-walled) are not wider than 11 μm diam. The capillitium in G. saccatum is formed by hyphae up to 10 μm wide, but in G. gorgonicum these hyphae are not wider than 3 μm. In general, in G. gorgonicum all the hyphae are narrower than those mentioned by Sunhede (1989) for G. saccatum. Geastrum gorgonicum can be separated easily from G. lageniforme by the kind of rhizomorph crystals: acicular in G. gorgonicum (Fig. 1), and horn-like in G. lageniforme; as well as by the basidiospores that, according to Jeppson et al. (2013), are smaller (2.5–3.5 μm) in G. lageniforme. Geastrum morganii has larger fully expanded basidiomata (30–60 mm diam.) and an irregularly folded peristome; whereas in G. gorgonicum the basidiomata are not larger than 23 mm diam., and the peristome is fibrillose.

Figure 1 – Geastrum gorgonicum (MA-Fungi 92118, holotype). a, b Fresh basidiomata in field. c, d Rhizomorphs with acicular crystals. e, f Basidiospores. Scale bars: a=1 cm, b=5 mm, c=10 µm, d–f=2 µm

Figure 2 – Phylogram generated from Bayesian analysis based on ITS and LSU nrDNA sequence data representing Geastrum from Section Corollina, with G. pleosporum from Sect Micelistroma as outgroup. Related sequences are mainly taken from Zamora et al. (2014). Twenty-three sequences are included in the combined analyses, which comprise 1561 characters. Maximum parsimony (MP) and maximum likelihood (ML) analyses were undertaken; MP and ML tree topologies (not shown) were similar to the Bayesian one. Bootstrap values for MP and ML equal to or greater than 50%, and clade credibility values greater than 0.90 (the rounding of values to 2 decimal places) from Bayesian-inference analysis are labeled on the nodes. The newly generated sequences are in blue bold