Stephanospora xibalba de la Fuente & Pinzón, 2020

Fuente, Javier Isaac De La, Pinzón, Juan P., Guzmán-Dávalos, Laura, Uitzil-Colli, Michael Oswaldo, Bahram, Mohammad & Lebel, Teresa, 2020, A new Stephanospora (Agaricales, Basidiomycota) from the Yucatan peninsula, Mexico, Phytotaxa 436 (1), pp. 63-71 : 67

Stephanospora xibalba de la Fuente & Pinzón , sp. nov. ( Fig. 2 ).

Mycobank no. MB 834633

Diagnosis: — Stephanospora xibalba is distinguished by the reddish orange peridermium, the reddish hymenophore with small, irregular locules, broadly ellipsoid to ellipsoid, 6.8–11.6 × 6.3–9.5 µm spinose basidiospores, with a small (3.2–4.5 × 1–1.5 µm) partial corona, and the hypogeous to semi hypogeous habit under Gymnopodium floribundum .

Type: — MEXICO. Yucatán: Tekax municipality, 2 km south of Alfonso Caso village, 20°03’36.6” N, 89°08’30.6”W, 120 m a.s.l., 22 September 2018, de la Fuente 405 (holotype UADY [04864], isotype ITCV [JF-405- ITCV]).

Description: — Basidiomata 6–9 × 4–5 mm, globose to subglobose, without rhizomorph s, reddish orange (6A8, 6B8), not bruising when touched, dry, translucent, revealing the locules beneath. Hymenophore friable, reddish orange (6A8, 6B8), with empty, irregular locules; trama reddish orange (6A8–6B8); odor absent; taste fungoid. Peridermium 50–80 µm thick, composed of loosely interwoven, hyaline to pale yellowish, thin-walled, narrow to inflated hyphae, 4–7 µm in diameter. Hymenophoral trama irregular, 40–60 µm wide, composed of irregular, globose or isodiametric elements, 4–24 µm in diameter, hyaline, thin-walled. Basidia 11–15.4 × 6–7 µm, clavate, thin-walled, hyaline, guttulate, 2-spored with up to 4 µm long sterigmata. Basidiospores 6.8–11.6 × 6.3–9.5 µm (L= 9.1±1.06 µm, W= 7.9±0.88 µm, N= 50), Q= 1.25–1.5, broadly ellipsoid to ellipsoid, slightly smooth when immature, in age ornamented with small truncate spines reaching 1.5 µm long, sometimes coalescing, with a small (3.2–4.5 × 1–1.5 µm) partial corona composed of coalescing truncate spines, hyaline to yellowish in KOH and yellowish in Melzer reagent; spore walls 0.5–1 µm thick; hilar appendage reaching 2 µm long. Clamp connections absent in all tissues.

Etymology: —Named xibalba in reference to the name of the underworld in the cosmogony of the ancient Mayan culture because of its hypogeous habit in Mayan lands, where this species was found.

Distribution: —Known from the Mexican state of Yucatán, Mexico, growing hypogeous or semi hypogeous under small monodominant Gymnopodium floribundum patches in a tropical dry forest, which probably means an ectomycorrhizal association. Members of the Polygonaceae , such as Coccoloba uvifera and Gymnopodium floribundum , have been reported as ectomycorrhizal hosts in neotropical ecosystems ( Oberwinkler et al. 2013; Bandala & Montoya 2015; Sené et al. 2015; Polmë et al. 2017).

Comments: — Stephanospora xibalba can be identified by its small, semi hypogeous basidiomata, reddish to orangish peridermium, irregular locules, and ellipsoid basidiospores with a small partial corona. Stephanospora mayana differs by the yellowish basidiome, greyish hymenophore, angular locules, and bigger basidiospores (up to 16 µm long) ( de la Fuente et al. 2019), and S. michoacanensis differs by the light brown peridermium, large corona (4–9 × 1.3–3 µm) of the basidiospores, and the habit in temperate forest with Pinus and Quercus species ( Guevara-Guerrero et al. 2015). The reddish peridermium resembles the European S. caroticolor , but that species differs by the angular to rounded locules, the large corona (5–9 × 1.5–2.5 µm) of the basidiospores, and the habit under Abies , Fagus , Pinus , and Quercus species ( Vidal 2005). Stephanospora chilensis ( Horak 1964: 311) Vidal (2005: 102) , described from Chile, and reported from Europe, also has a reddish-orange peridermium, with irregular locules, and basidiospores with a small corona; however, it differs in the slightly smaller basidiospores (7.9–9 µm diam.), a basidiospore ornamentation of more acute and longer spines (reaching 2.5 µm), and the distribution in Europe under Abies , Fagus , Picea , and in Chile under trees in the Aextoxicaceae , Proteaceae , Myrtaceae , and Lauraceae ( Vidal 2005; Fraiture & Novelo 2013). Mayamontana coccolobae has a reddish to orangish peridermium and can also be found in dry forest under Coccoloba and Gymnopodium ( Castellano et al. 2007; de la Fuente et al. 2018); it lacks the characteristic spore ornamentation of Stephanospora . According to the molecular analysis, S. xibalba is closely related to an undescribed Stephanospora species from Belize and Puerto Rico. However, those specimens have larger basidiomata, more acute spines on the basidiospores, a well-defined corona, as well as different peridermium and hymenophore color, strikingly different from the Mexican material (Lebel unpublished data).

Figures

FIGURE 2. Stephanospora xibalba (JF–405–UADY, HOLOTYPE). A Peridermium, B Hymenophore, C Basidiospores showing the corona (arrows), D Details of the corona (arrow).Scale bars: 10 mm (A–B); 20 µm (C–D). Photographs by Javier I. de la Fuente.