Lyomyces pantropicus Yurchenko & Riebesehl, 2024

Yurchenko, Eugene, Langer, Ewald & Riebesehl, Janett, 2024, A high species diversity of Lyomyces (Basidiomycota, Hymenochaetales) in Central and South America, revealed after morphological and molecular analysis, MycoKeys 109, pp. 131-169 : 131-169

Lyomyces pantropicus Yurchenko & Riebesehl sp. nov.

Figs 8 C, D , 11 , 12 , 16 F

Type.

Panama • Chiriquí Province: W of Boquete town, Bajo Boquete community , 08 ° 46.45 ' N, 082 ° 28.03 ' W, about 1400 m a. s. l., evergreen montane tropical mixed forest (with Pinus ), on fallen decorticated bush stem, 27 Jul 2019, E. Yurchenko EYu 190727-23 b (holotype: BLS M-2679 ; isotype: CFMR). GenBank: ITS = PP 471808; 28 S = PP 471825 .

Etymology.

The epithet refers to the extended character of species’ distribution in the tropics: pan - (Lat.) = throughout.

Description.

Basidiomata effused, 0.1–5 and more cm in extent, adnate, membranaceous, cracking with age, continuous to discontinuous-porulose to the periphery, 35–85 μm thick. Hymenial surface from furfuraceous to usually smooth, rarely colliculose, white or greyish. Margin concolourous, thinning out or diffuse, 0.5–1.5 mm wide. Hyphal system monomitic, hyphae clamped at all septa, thin-walled, colourless, smooth or loosely encrusted by crystals or their aggregates 2–5 (– 10) μm in size. Subicular hyphae moderately branched, disordered or subhorizontal, (1.7 –) 2.3–3.2 μm wide. Subhymenium little differentiated from subiculum; subhymenial hyphae moderately to richly branched, with cylindrical or sometimes short swollen segments, 2–4 (– 5) μm wide. Hymenial elements smooth to moderately encrusted. Cystidia inconspicuous, thin-walled, immersed or slightly protruding over other hymenial elements, of four types: 1) irregularly cylindrical scattered, 20–35 × 4–5.5 μm; 2) subcapitate and capitate scattered, 13–23 × 3.5–5 μm, with the capitate end often slightly flattened from the top; 3) fusoid scarce, 16–23 × 5 μm; 4) hyphidia-like occasional, 13–27 × 2.5–3 μm. Basidioles subcylindrical, narrowly clavate, rarely clavate, subcapitate, utriform, (9 –) 11–25.5 × 3.3–4.5 (– 5) μm, often minutely guttulate or granulose inside. Basidia subcylindrical, subclavate, utriform, 16–17 (– 22) × 4–4.5 (– 5) μm; sterigmata four, 3–4.5 × 0.5–0.7 μm. Basidiospores ellipsoid to oblong, (5 –) 5.5–7 (– 7.5) × (3.2 –) 3.5–4.5 μm (in holotype L = 6.5 μm, W = 4.3 μm), Q = (1.3 –) 1.4–1.7, with thin or barely thickened wall, smooth, colourless, with granulose or heterogeneous contents and often with a large oildrop, Mz –, acyanophilous; apiculus minute or indistinct.

Distribution.

Our collections originate from the western part of Panama and from the northwest, northeast, and southern parts of Ecuador. Supposedly, it is a common species in Central and South America. The ITS alignment and phylogenetic inference results suggest that the distribution range of this new species also includes Southeast Asia ( China and Sri Lanka).

Ecology.

The fungus grows on dead branches and various wooden stems of angiosperms in humid and semi-arid, angiosperm and mixed tropical forests, from sea level to about 1900 m a. s. l.

Additional specimens examined

(paratypes). Panama • Chiriquí Province: W of Boquete town, Bajo Boquete community , 08 ° 46.53 ' N, 082 ° 27.87 ' W, 1450 m a. s. l., mixed (with Pinus ) evergreen montane tropical forest, on a dead corticated woody stem, 27 Jul 2019, E. Yurchenko EYu 190727-5 c ( BLS M-9943 ) ; Ecuador • Zamora Chinchipe Province: 17 km NW of Zamora, in the vicinity of Estación Científica San Francisco, Permanent sample plot No. 5 , 03 ° 58.38 ' S, 079 ° 04.65 ' W, 1860 m a. s. l., on dead bamboo stem, 8 Mar 2002, E. Langer 1 / 727 ( KAS-Ec 727-2002 ) ; • Orellana Province: near Puerto Francisco de Orellana ( El Coca ), S of Flor de Oriente village, 00 ° 30.25 ' S, 076 ° 58.92 ' W, 295 m a. s. l., equatorial rainforest on hilly relief, on a fallen decorticated branch, 21 Jul 2019, E. Yurchenko EYu 190721-12 ( BLS M-3484 ) ; • Esmeraldas Province: NW of Esmeraldas town, Pacific Ocean shore , 00 ° 59.13 ' N, 079 ° 40.15 ' W, 5–10 m a. s. l., semi-xerophytic bush vegetation on a coastal hill, on a dead corticated still-attached branch, 24 Jul 2019, E. Yurchenko EYu 190724-12 ( BLS M-3447 ; GenBank: ITS = PP 471807; 28 S = PP 471824) ; • ibid., on a mostly corticated fallen twig, 24 Jul 2019, E. Yurchenko EYu 190724-16 ( BLS M-3406 ) ; • ibid., on fallen corticated branches, 24 Jul 2019, E. Yurchenko EYu 190724-17 ( BLS M-3545 ) .

Notes.

The main diagnostic features of this species are membranaceous basidiomata with slightly furfuraceous to usually smooth hymenial surface, thin-walled hyphae, presence of inconspicuous, scattered, irregularly cylindrical and subcapitate cystidia, large crystalline aggregates in basidioma, and relatively large basidiospores with a thin or barely thickened wall. This species is phylogenetically very close to L. microfasciculatus , but in contrast to the latter, the hymenial surface of L. pantropicus lacks any projections like warts or aculei. Further L. pantropicus has morphologically much more diverse cystidia, and larger spores. In morphology, L. pantropicus is most similar to L. gatesiae due to the presence of slightly constricted, subcylindrical cystidia, large crystals on the hyphae, and spores with one large drop inside. From the latter species, it differs by ellipsoid spores and the lack of pigmentation of the hymenial surface. The new species is differentiated from L. sambuci and L. densiusculus by slightly apically flattened capitate ends of cystidia.

This fungus can develop fairly large basidiomata and their groups, e. g., in KAS-Ec 727-2002 there is a notation that fruiting bodies cover 90 cm of stem length and provoke the features of white rot. Besides, KAS-Ec 727-2002 can be noted as a variation of L. pantropicus , which almost entirely lacks crystalline deposits and has spindle-shaped cystidia.

Figures

Figure 8. Macromorphology of Lyomyces species A L. oleifer, holotype (KAS-Ec 47-2001) B L. orarius, holotype (BLS M- 2995) C L. pantropicus, holotype (BLS M- 2679) D L. pantropicus, BLS M- 3545 E L. parvus, holotype (KAS-GEL 1599) F L. parvus, BLS M- 2990 G L. sceptrifer, holotype (KAS-Ec 661-2002) H L. subcylindricus, holotype (BLS M- 2668). Scale bars: 1 mm.

Figure 11. Micromorphology of Lyomyces pantropicus (holotype, BLS M- 2679) A vertical section through basidioma B subicular hyphae C portion of hymenium and subhymenium D cystidia E basidioles F basidia G basidiospores. Scale bars: 20 μm (A); 10 μm (B – G).

Figure 12. Micromorphology of Lyomyces pantropicus (BLS M- 3447) A vertical section through basidioma B portion of hymenium and subhymenium C cystidia D basidioles E basidiospores. Scale bars: 10 μm.

Figure 16. SEM of crystalline deposits on hymenial elements and hyphae in holotypes of Lyomyces species A, B L. boquetensis C L. granulosus D L. napoensis E L. neocrustosus F L. pantropicus G L. parvus H L. subcylindricus. Scale bars: 5 μm.