Moniliophthora mayarum Lodge, Aime & Niveiro, 2020

Niveiro, Nicolas, Ramirez, Natalia A., Michlig, Andrea, Lodge, D. Jean & Aime, M. Catherine, 2020, Studies of Neotropical tree pathogens in Moniliophthora: a new species, M. mayarum, and new combinations for Crinipellis ticoi and C. brasiliensis, MycoKeys 66, pp. 39-54 : 39

Moniliophthora mayarum Lodge, Aime & Niveiro sp. nov. Figs 2A , 3A-F

Diagnosis.

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).

Type.

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!)

Description.

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.

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.

Distribution.

Know only for the type locality.

Ecology.

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

Etymology.

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

Specimens studied.

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!).

Observations.

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.

Figures

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.

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).