Moniliophthora mayarum differs from M. aurantiaca and Crinipellis hygrocyboides by larger pileus (> 15–20 mm) and narrower basidiospores (3.2–4.2 vs > 4–6 µm). Differs from M. ticoi by smaller basidiospores (8.0 +/-1.3 × 3.8 +/-0.3 µm vs 12.1 +/-0.8 × 5.4 +/-0.4 µm).

Belize, Stann Creek District, Cockscomb Basin Wildlife Sanctuary, Jaguar Preserve, near Maya Center Community, Rubber Tree Trail, on dead tree roots, possibly Ceiba pentandra, 16°42'58.32"N, 88°39'38.88"W, 180 m a.s.l., 16. 11. 2001, D.J.Lodge, K.K.Nakasone, S.Schmeiding, E.Gaitlan BZ-43-Nov-2001, BZ-511 (Holotype: CFMR!)

Pileus 7–20 mm, convex with an inrolled margin when young, broadly convex with age, some slightly depressed at center, some with a papillate umbo, color Chrome Orange (Plate II, 11, -), with center Scarlet (Plate I, 5, -) to Flame Scarlet (Plate II, 9, -), surface moist or slightly viscid when wet but not gelatinized, smooth, rarely sparsely minutely pubescent on umbo when dry, margin translucent-striate to disc, some sulcate-striate with age. Lamellae subdistant, 2 per mm on margin and half-way to margin, adnate or slightly adnexed, 2–4 mm broad, regular, 1 or more lengths of lamellulae inserted, Spectrum Orange with a coral tint, margin even, concolorous. Stipe central, 12–27 × 0.8–1.2 mm, equal or slightly clavate, some flared at apex, pale Spectrum Orange, pale Orange-Yellow (Plate III,17, f) at apex, surface dry, densely minutely pubescent, dense Warm Buff (Plate XV, 17´, d) mycelial pad at base. Annulus absent. Spore-print not observed, presumably white. Context pale orange in pileus and stipe, odor none, taste sweet. KOH and NaOH reactions on pileus surface negative.

Figure 2. 

Photographs of sister species, Moniliophthora mayarum and M. ticoi: A basidiomes of M. mayarum on piece of tree root in Belize (BZ-511) (photo by S. Schmeiding) B–F Basidiomes of M. ticoi on trunks of Holocalix balansae (Fabaceae) and Pogonopus tubulosus (Rubiaceae) in Argentina. Scale bars: 10 mm.

Basidiospores on lamellae of two sizes, larger ones 6.5–8.5(–10.5) × 3.2–4.2 µm, x = 8.0 +/-1.3 × 3.8 +/-0.3 µm, Q= 1.60–2.65, Q_x= 2.02 +/-0.3, n=14; smaller spores 4–6 × 2.4–4.2 µm, x= 5.2 +/-0.8 × 3.3 +/-0.6 µ µm, Q= 1.25–1.89, Q_x= 1.60 +/-0.3, n=10. Basidia 4-sterigmate, 14.4–28 × 4–8 µm, sterigmata up to 6.4 µm long, with basal clamp connections. Pleurocystidia absent. Cheilocystidia 22–26.5 × 6–13 µm, of three types: 1) clavate or hyphoid, 2) with 2–3 lobes, 3) clavate with apical digitate appendages or irregular lumps overall. Hymenophoral trama regular, hyphae 2.6–5.2 µm diameter, smooth, thin-walled, not dextrinoid, with clamp-connections. Pileipellis a cutis of repent, more or less interwoven hyphae, 4–8 µm broad, thin-walled ones occasionally with incrusted rusty pigments, apical segments of some hairs thick-walled and dextrinoid. Hairs of the pileus surface setiform, dextrinoid thick-walled part (66–)86–240 × (4.8–) 5.1–8.2 µm, comprised of 1–3 segments dextrinoid, walls (1.4–)2–4 µm thick, hyphae sometimes almost occluded, septa usually with clamp connections but clamp connections absent on the few secondary septations, with obtuse or acute apex. Hypodermium of short, broad, thin-walled cells 21.6–24 × 16–17.5 µm, with basal clamp connections.

Know only for the type locality.

Gregarious, putatively parasitic on roots of a tree, possibly Ceiba pentandra (L.) Gaertn.

mayarum – of the Maya people in the region where the fungus was found.

Belize • Stann Creek District, Cockscomb Basin Wildlife Sanctuary, Jaguar Preserve, near Maya Center Community, Rubber Tree Trail, on dead tree roots, possibly Ceiba pentandra; 16°42'58.32"N, 88°39'38.88"W, 180 m a.s.l.; 16.XI.2001; D.J.Lodge, K.K.Nakasone, S.Schmeiding, E.Gaitlan BZ-43-Nov-2001, BZ-511 (Holotype: CFMR!; Isotype BRH!).

Few previously described Crinipellis and Moniliophthora species share the striking bright orange coloration of M. mayarum. This taxon most closely resembles M. aurantiaca Kropp & Albee-Scott described from the South Pacific island of Samoa, Crinipellis hygrocyboides (Henn.) Singer (= Marasmius hygrocyboides Henn.) described by Hennings from Africa, and M. ticoi (Halling) Niveiro, Ramírez, Lodge & Aime described from South America. Our phylogenetic analysis places M. mayarum as a sister species to M. ticoi-the other Neotropical species in this complex.

The two Neotropical species are more robust, reaching 20 mm in diameter (or more in M. ticoi), compared to the two Paleotropical species, 6–11 mm in C. hygrocyboides and 3–15 mm in M. aurantiaca. Antonín (2007) published a type revision of C. hygrocyboides based on study of an isotype that included microscopic measurements and observations of spores and cheilocystidia as neither Hennings (1902) nor Singer (1989) included these details and Halling (1993) reported he could not find spores or cystidia in the type. The spores of M. mayarum are distinctly narrower (3.2–4.2 µm) than those of C. hygrocyboides [4.5–6(–7) µm]. While Antonín’s description of the cheilocystidia in C. hygrocyboides notes they are ornamented with apically branched obtuse projections, cheilocystidia shape seems to be highly variable and therefore unreliable for distinguishing species in this group. The basidiospores are longer and broader in both M. aurantiaca 7.5–11 × 4–6, and M. ticoi (9.5–)10.5–13.7 × (3.8–) 4.5–6.3 µm, than in M. mayarum 6.5–8.5(–10.5) × 3.2–4.2 µm. Only the larger spores of M. mayarum are used in the preceding comparison, and it is not clear why there is a cohort of smaller basidiospores also present. Although, different spore sizes are often observed in the presence of bisporic basidia, lacking clamp-connection and bearing larger spores that are mixed with tetrasporic basidia bearing smaller spores, in repeated examination of the material specifically looking for 2-sterigmate basidia and absence of basal clamps, we observed only 4-sterigmate basidia, and all hymenial elements with clamp-connections. Furthermore, one of the illustrated 4-spored basidia (Fig. 3C), shows a large spore attached to a 4-sterigmate basidium with a basal clamp connection, which negates the hypothesis of a bisterigmate origin for the large spore cohort in M. mayarum. Although small spores observed on the hymenium could have been immature and thus smaller, basidiospores of similar size and shape were observed on the pileipellis surface that must have been released from basidia, which indicates they were mature. A similar case occurs in Crinipellis trinitatis Dennis. Dennis (1951) in the original description reported smaller basidiospores (5–7 × 2–4 µm) than the revised description of the type by Pegler (1983) (7–9 × 4.1–5.1 µm), so there may be something unusual in the phenology of spore production in this group that leads to two size classes of spores depending on when they are formed and released.

Figure 3. 

Moniliophthora mayarum: A basidiomes B basidiospores C basidium D cheilocystidia E hypodermium cells F pileipellis elements. Scale bars: 10 mm (A); 10 µm (B–F).

This species is known from Minas Gerais, Brazil (Arruda et al. 2005).

Moniliophthora brasiliensis is characterized by the light pink to crimson red pileus surface, ellipsoidal basidiospores, 10–14 × 5–7 µm, and lageniform cheilocystidia, with a thin apex, 28–37 × 10–16 µm in size (Arruda et al. 2005). Moniliophthora brasiliensis is a parasite of Heteropterys acutifolia (Malpighiaceae). Only ITS sequence data are available for this taxon, which was derived from a dikaryotic basidiome collected from a necrotic broom on H. acutifolia (Arruda et al. 2005). Moniliophthora brasiliensis is extremely similar to M. perniciosa and diagnosis between the two species at present is based soley on differences in ITS sequence data (Arruda et al. 2005).

Pileus 7–40(–62) mm, parabolic to convex when young, convex to plane with age, with a shallow umbilicus, surface bright orange (7A8–8A8) with reddish to dark brown center (7C7–7C8), with a narrow light yellowish margin (6A7–6B7 to near 5A6–5A7), dry or moist but not hygrophanous, tomentose or subtomentose in disc, pubescent margin in young specimens, striate disc in young specimens, more marked at the margin, in mature or driest basidiomes with reddish to dark brown sulcate margin (7C8–8C8). Lamellae subdistant, 1 per mm, adnexed to narrowly adnate, thick and broad, not intervenose, concolorous with the pileus surface (7A8–6A8); edge entire, concolorous with sides, with 2 tiers lamellulae inserted. Stipe 18–68 × 1–3.5 mm, central, cylindrical, equal or slightly thinner towards the middle, sometimes with a small basal bulb, solid, surface orange to reddish (7A7–7A8) in young specimens, light orange, yellowish orange to creamy yellow (5A6–5A7 to 4A8) and brown (6D8–6D7) toward base in older specimens, densely pubescent at apex when young, then fibrillose-pruinose, dry, insititious. Annulus absent, but forming a strongly pubescent zone where the veil is inserted in young specimens. Spore-print not observed, presumably white. Context pale orange (5A5) in pileus, thin, fleshy in the center and membranous towards the margins, orange white (5A2) in stipe. Odor and taste not tested. KOH and NaOH reactions on pileus surface negative.

Figure 4. 

Moniliophthora ticoi: A spores B basidia C cheilocystidia D pileipellis elements. Scale bars: 10 µm.

Basidiospores (9.5–)10.5–13.7 × (3.8–)4.5–6.3 µm, x= 12.1 +/-0.8 × 5.4 +/-0.4 µm; Q= 2.11–2.67; Q_x= 2.38 +/-0.1; n= 60; N=2; oblong to subcylindrical, phaseoliform in side view, thin-walled, smooth, hyaline, inamyloid, without germ-pore. Basidia 34.3–58 × 7.7–8.6 µm, subcylindrical to narrowly clavate, 4-spored. Pleurocystidia absent. Cheilocystidia 32–43 × 7–10 µm, subcylindrical to narrowly clavate, inconspicuous, thin-walled, smooth, hyaline. Hymenophoral trama subregular, hyphae 40–150 × 5–12 µm, smooth, thin-walled, with clamp-connections. Pileipellis a cutis of repent, more or less interwoven hyphae, 4–15 µm broad, occasionally with incrusted pigments, covered by clusters of dextrinoid hairs and chains of thin-walled monilioid, inamyloid hyphae. Hairs of the pileus surface setiform, scattered on the surface, distributed mainly towards the margin, arising from a pileipellis, 90–560 × 4.5–9 µm, dextrinoid, thick-walled, hyphal walls 1.5–3 µm diam, with basal clamp-connection, occasionally 1 or 2 septate, with obtuse apex. Stipitipellis a cutis of repent hyphae, 6–10 µm broad, with abundant dextrinoid hairs, 40–370 × 5–10 µm, setiform, thick-walled, with obtuse apex, basal clamp-connections.

This species is known from Bolivia (Halling 1993) and northern Argentina (Yungas and Chaco region).

Gregarious. Parasitic on living roots and trunks of Myrcianthes pungens (O.Berg) D.Legrand, (Myrtaceae) Holocalix balansae Micheli (Fabaceae) and Pogonopus tubulosus (A.Rich.) K-Schum (Rubiaceae), in tropical and subtropical forest.

Argentina • Chaco, 1° de Mayo, Colonia Benitez Educational Reserve, interpretative trail; 27°19'04.12"S, 058°56'59.58"W, 64 m a.s.l.; on Guabiyú (Myrcianthes pungens – Myrtaceae) trunk and roots; 21.III.2014; N.Ramírez & N.Niveiro CB 23-65 (CTES). • Ibid., on trunk and roots of Alecrín (Holocalix balansae – Fabaceae); 22.III.2016; N.Ramírez & N.Niveiro 103, 105 (CTES). • Jujuy, Ledesma, Calilegua National Park, Guarani trail; 23°45'66.1"S, 064°51'15.0"W, 627 m a.s.l.; on montane forest, on Pogonopus tubulosus (Rubiaceae); 24.III.2011; N.Niveiro, E.Albertó, B.Lechner & T.Baroni 2249 (CTES). Bolivia • Beni, Iturralde, S of Rurrenabaque, Rio Tuichi near junction with Rio Beni, “Laguna del Tigre”; 14°25'S, 067°30'W; 14.IV.1990; R.Halling 6433 (Isotype: NY00511157!).

This species was described by Halling (1993) from Bolivian specimens. It is characterized by its relatively large, bright orange basidiomes, covered with scattered dextrinoid setiform hairs. The most similar species is M. mayarum, which shares morphological characters such as the large basidiomes with bright orange coloration. These two species, however, differ clearly by the smaller spores and by the presence of ornamented cheilocystidia in M. mayarum. Another similar species is M. aurantiaca from American Samoa (Kropp and Albee-Scott 2012). Both share the orange colored pileus surface with a narrow light yellowish margin. However, they differ in that M. aurantiaca has the smaller pileus (3–15 mm broad), smaller basidiospores (7.5–11 × 5–8 µm) and numerous cheilocystidia with several irregular apical appendages resembling fingers (Kroop and Albee-Scott 2012). Another similar species is C. hygrocybioides (Henn.) Singer from Africa (Singer 1989), however this is a smaller fungus (pileus 6–11 mm broad) with an umbilicate to papilate pileus that is pilose at the margin (Halling 1993). Based on its morphological characters such as the bright orange pileus surface, C. hygrociboides could be included in the genus Moniliphthora, but new collections are needed to elucidate its habitat and to obtain sequences and corroborate this hypothesis (currently there are not sequences available for C. hygrocybioides).

Other known parasitic Neotropical species are M. perniciosa, C. trinitatis Dennis and C. siparunae Singer. Moniliophthora perniciosa, a destructive parasite of Theobroma cacao, differs in having smaller basidiomes (pileus up to 25 mm diam) with a red pileus surface and white stipe (Singer 1976; Aime and Phillips-Mora 2005). Crinipellis trinitatis has a smaller, red pileus and smaller spores [5–7 × 2–4 µm ss. Dennis (1951) and 7–9 × 4–5 µm ss. Pegler (1983)].

Crinipellis siparunae is a widely distributed species that is microscopically similar to M. ticoi, especially regarding the range of spore size. However, C. siparunae is distinguished by its lilac to brownish lilac pileus surface and by its appendiculate cheilocystidia (Singer 1942, 1976). A taxon thought to be closely related to C. siparunae, C. eggersii Pat. var. lilaciceps Singer and described from Amazonian Ecuador shares unornamented cheilocystidia with C. ticoi, but it differs from the latter in having a violet to lilac vs orange pileus, and broader basidiospores 6–6.5 × (3.8–)4.5–6.3 µm (Singer 1976; Kerekes and Desjardin 2009). Crinipellis eggersii var. eggersii, which includes the facultative synonym Marasmius vinosus Speg. described from Argentina, has similar spore dimensions (mostly 11–13 × 5.5–6.3 μm) but differs in having a purple to violet purple pileus and a variety of cheilocystidia shapes (ampullaceous, fusiform, cylindrical or clavate and mostly forked, obtuse or mucronate, sometimes with a subcapitate or capitate apex).

Of the three recent collections in northern Argentina, the specimens of the Yungas forest (Niveiro et al. 2249) closely resemble the original description of M. ticoi, with specimens not exceeding 40 mm broad and having a bright red pileus surface (Halling 1993). However, the specimens of the Chaco region differ in having larger basidiomes up to 60 mm broad, and a paler coloration (orange with a yellowish margin), differences that may be due to the drier weather conditions in the Chaco region. Another important difference observed in the Argentinean specimens is the habitat. Halling (1993) found this species growing on rotten wood, however, the new specimens examined were growing on tree trunks and roots of living trees, confirming a biotrophic habit for this species during at least part of its life history.