Amanita castanea Thongbai, Tulloss, Raspé & K.D. Hyde, 2016

Thongbai, Benjarong, Tulloss, Rodham E., Miller, Steven L., Hyde, Kevin D., Chen, Jie, Zhao, Ruilin & Raspé, Olivier, 2016, A new species and four new records of Amanita (Amanitaceae; Basidiomycota) from Northern Thailand, Phytotaxa 286 (4), pp. 211-231 : 216-219

Amanita castanea Thongbai, Tulloss, Raspé & K.D. Hyde , sp. nov. ( Figure 1 and 2 )

Index Fungorum number: IF552009; MycoBank: MB 818356; Facesoffungi number: FoF 02074

Etymology:—‘castanea’ refers to the chestnut color of the pileus.

Holotype: — THAILAND, Chiang Mai Province, Doi-saket District, Thep-sadet Subdistrict , elev. 1300 m, 30 June 2014, B. Thongbai ( MFLU15-1424 !).

Basidiomata [ Fig. 1 (a)] small to medium-sized. Pileus 50–75 mm wide, parabolic to hemispheric when young, convex to plane at maturity, sometimes depressed at center, dry, slightly viscid when moist, with shiny, sericeous or silky surface, chestnut to dark brown colored, darker at center, light brown to brownish orange (7D6–7C5) towards margin, with universal veil mostly towards margin, rarely over disc, as scattered gray to brownish gray, reddish brown to grayish brown warts or small floccose patches; margin incurved to flaring upward, non-striate, non-appendiculate; context 2–4 mm thick above stem, soft to slightly hard; pale yellowish or cream (4A2–3). Lamellae 4–6 mm broad, free to nearly free, subdistant when mature, yellowish white (3A2–3) to very pale greenish white (30A2–3); lamellulae of 3–6 lengths, attenuate to nearly truncate. Stipe 50–95 × 10–15 mm (length includes bulb), nearly cylindrical or slightly tapering upwards, bulbous, white to dull white ground becoming brown (6D 5, 6E 5) at maturity, often covered with light orange grayish orange (6B3–6C3) squamules or fine flocculae, often with brownish cirrate scales formed from the outer layer of stipe below the partial veil in mature material (note: this is a common environmental effect seen in many amanitas), turning slightly yellow brown when bruised; context stuffed to nearly hollow, thin, yellowish white (4A2). Bulb compressible, subglobose to hemispheric, marginate, up to 28 mm wide, white to dirty white (1A1–2). Universal veil on stipe base as very short volval limb on bulb margin, cottony, greenish gray (30A1–2). Partial veil subapical, membranous, robust, skirt-like, greenish gray or greenish yellow (3B2), darker grayish green at thickened edge. Odor potato-like.

Lamellar trama bilateral, divergent; mediostratum 30–40 μm wide; filamentous hyphae 1.8–6 μm wide, branching, hyaline, with slightly inflated elements; vascular hyphae not observed. Subhymenium [ Fig. 1 (l)] 22–35 μm thick; inflated cells dominating, in 3–4 layers, subglobose, ovoid, 10–20 × 8–12 μm, subtended by concatenated partially inflated hyphal segments. Basidia [ Fig. 1 (l–o)] 32–39(–44) × 11–13(–14) μm, narrowly clavate to clavate, mostly 4-, occasionally 2-spored, with sterigmata up to 5 μm long; clamps absent. Basidiospores [ Fig. 1 (b–k)] [53/1/1] (7.2–) 7.3–9.4 (–9.7) × (6.3–) 6.5–8.7 (–9.4) μm, (L’ = 8.2 μm; W’ = 7.6 μm; Q = 1.0–1.19 (–1.25); Q’ = 1.09 ± 0.06), smooth, hyaline, colorless, thin-walled, amyloid, globose to subglobose, infrequently broadly ellipsoid, occassionally adaxially flattened; apiculus rather variable, sublateral, very prominent to rather small, cylindric to truncate-conic; contents monoguttulate or occasionally granular; white in deposit. Lamellar edge sterile; filamentous hyphae 3– 7 μm wide, hyaline, colorless or pale yellow, thin-walled; inflated cells dominating, mostly globose to subglobose and sometimes ovoid, 9–22 × 9–18(–22) μm, colorless, thin-walled. Pileipellis [ Fig. 2 (c)] up to 200 μm thick, 1- layered; loose, sometime branching, filamentous hyphae with slightly swollen tips, 4–10(–20) μm wide, minimal gelatinization limited to the pileipellis surface, thin-walled, with intracellular pale yellow pigment. Universal veil on pileus [ Fig. 2 (b)] filamentous hyphae, 2.5–6.2 μm wide, branching, with slightly inflated elements, with terminal subfusiform to narrowly clavate cells, 30–53 × 15–21 μm, hyaline, thin-walled; inflated cells, globose to subglobose to ovoid to elongate, dominating, 9–22 × 9–18(–22) μm; vascular hyphae occasional. Universal veil on stipe base filamentous hyphae 3–8.5 μm wide, more abundant than on pileus, branching, hyaline, or with intracellular pale brown pigment; inflated cells similar in form to but less frequent than those on pileus; vascular hyphae occasional, 7–8.5 μm wide. Stipe trama [ Fig. 2 (d)] longitudinally acrophysalidic; filamentous hyphae 2.2–8.8 μm wide; acrophysalides subfusiform to clavate, 120–310 × 25–45 μm; vascular hyphae rare. Partial veil [ Fig. 2 (a)] filamentous hyphae 2–5 μm wide, gelatinized, branching, hyaline, inflated cells terminal, thin-walled, subclavate to clavate, 114–120 × 25–36 μm, occasionally with intracellular pale brown pigment; vascular hyphae rare.

Habitat: scattered on the ground in forest of Fagaceae .

Specimen examined: THAILAND, Chiang Mai Province, Doi-saket District, Thep-sadet Subdistrict, elev. 1,300 m, 30 June 2014, B. Thongbai BZ201405 (holotype MFLU15-1424!, isotype BBH 40844!).

Known distribution: Only reported from northern Thailand.

Remarks: Amanita castanea belongs to subgenus Lepidella , section Validae , which is characterized by amyloid spores, non-appendiculate pileus margin and non-membranous universal veil ( Corner & Bas 1962, Bas 1969). Within sect. Validae , A. castanea fits in the stirps Citrina ( Singer 1975) of series Mappae ( Drehmel et al. 1999) , which is characterized by a compressible, marginate to submarginate bulb at the stipe base with universal veil remnants as a low and irregular marginal rim or limb ( Tulloss & Yang 2016d). The species of series Mappae frequently have a potato- or radish-like odor ( Tulloss et al. 2001). Molecular phylogenetic analyses also support our view that A. castanea is a novel species belonging to series Mappae because Amanita castanea is included in a well-supported clade comprised only of taxa from series Mappae . Amanita castanea is easily recognized by its chestnut colored pileus, small to medium-sized basidiomata, easily detachable universal veil in the form of scattered gray to brownish-gray, reddishbrown to grayish brown warts or small patches; a subglobose to hemispheric bulb with pale green tinge on top of the volval limb; and greenish gray or greenish yellow skirt-like partial veil that is darker grayish green at the thicker free edge. Morphologically, A. castanea is most closely related to A. citrina var. grisea and A. porphyria . Amanita citrina var. grisea , originally described from Japan, and later reported from southwestern China, has larger gray to dark gray basidiomata, and yellowish felty universal veil on the pileus ( Tulloss & Yang 2016b). Amanita porphyria , originally described from Germany, has a virgate pileus that is dull red to grayish dull red, grayish purple, or pale brownish gray to violaceous brown, and is darkest in the center, and has a gray, thin, skirt-like partial veil. Amanita porphyria differs from A. castanea by having violaceous gray longitudinal fibers below the partial veil ( Albertini & Schweinitz 1805, Neville & Poumarat 2004). Another brown-capped species in stirps Citrina , A. solaniolens ( Stewart & Grund 1974) , was originally described from eastern Canada and is now understood to occur at least as far south as Costa Rica (Tulloss et al. 2016a) and probably Andean Colombia. It is distinguished by a virgate cap that is dull-yellow to light blond at the margin and abruptly darkening to olive-brown at the center or largely brown, reminiscent of the cap of a tiny A. brunnescens . Amanita solaniolens also differs from A. castanea by having a creamy white to yellowish white universal veil comprised of flat patches on the pileus and a white to cream stipe with a partial veil that is white to pale yellow.

Initial BLAST searches on the ITS data in both GenBank and Tulloss’ personal database, indicated the most similar sequences were from the following (author citations, source collections, and countries of collection in Table 1): A. citrina var. grisea —GB AB015680 with 94.1% similarity and 97% query cover ( Oda et al. 1999); material possibly misidentified as A. citrina —GB JF273504 with 94.1% similarity and 100% query cover.

1) A. porphyria —GB KP866181 with 91.7% similarity and 99% query cover.

The BLAST search on the LSU sequence from A. castanea was also performed against both GenBank and Tulloss’ personal database. The most similar sequences were from:

1) material probably misidentified as A. citrina —GB AF097378 with 98.3% similarity and 100% query cover ( Drehmel et al. 1999).

2) A. lavendula —GB KR865979 with 98.3% similarity and 99% query cover ( Tulloss et al. 2015).

Amanita series Mappae was proposed by Drehmel et al. (1999) on genetic and morphological grounds. Drehmel’s clade is reproduced in general form at the top of Figure 7 , although some names associated with GenBank sequences appear to be misapplied, A. mappa (Batsch) Fr. (= A. citrina ), A. porphyria , A. citrina var. grisea , and A. lavendula are all classic taxa of stirps Citrina and are presented as a group sister to A. brunnescens as in the tree of Drehmel et al. (1999). In a study of long branch attraction in LSU trees involving 230 species of the Amanitaceae (Tulloss unpub. data, briefly discussed in Tulloss et al. 2016), a topology of the Validae similar to that in Figure 7 was achieved. In both cases, a small group of taxa including species such as A. congolensis and A. media Dav. T. Jenkins ( Jenkins1983; Tulloss 2016g) (not treated in the present study) are shown as sister to Series Mappae or appear as earlier divergent than the Mappae . This seems improbable to us, Series Mappae includes all the soft, globose to subglobose-bulbed taxa of the Validae that are known. This characteristic type of bulb is shared with a large number of the taxa of section Phalloideae , which is commonly shown as a sister group to the Validae as in Figure 7 . Amanita congolensis and A. media have firm, fusiform bulbs in contrast with the Mappae and have evolved longer and proportionately narrower (elongate to cylindric) spores than are to be found in most of the Phalloideae and Validae . Hence, it is desirable to have more information before concluding that such taxa could be among the earliest diverging in the Validae . Insufficient sampling, particularly in subsaharan Africa, southern Asia, and Australia may be contributing to error.

Figures

FIGURE 1. Basidiomata of Amanita castanea. a young and mature basidiomata. b–d basidiospores in 5% KOH. f–h basidiospores in congo red. i–k basidiospores in Melzer’s reagent. l–o basidia and subhymenium at different stages of development. (a–o: BZ201405, holotype) (scale bar: a = 2 cm, b–k = 6 μm, l–o = 10 μm).

FIGURE 2. Microcharacters of Amanita castanea. a section of outer layer from partial veil. b section of velar remnants from pileus. c section of outer layer from pileus. d longitudinally acrophysalidic stipe trama. (a–d: BZ201405, holotype) (scale bars: a–d = 5 μm).

FIGURE 7. Phylogenetic relationships of Amanita species inferred from combine gene tree (LSU and ITS) sequences using Maximum Likelihood (ML). Posterior Probabilities (PP) from Bayesian Inference ≥0.95 are indicated as thick branches and bootstrap value ≥70 % are shown above the branches at nodes. Amanita species collected from Thailand are highlighted in bold. Voucher collection identifiers are provided after each species name.