name | Amanita siamensis |
name status | nomen acceptum |
author | R. Sanmee, Zhu L. Yang, P. Lumyong & S. Lumyong |
english name | "Thailand Amanita" |
images | |
cap |
The cap of A. siamensis is 75 - 95 mm wide, greenish yellow to olivaceous buff, grayish brown in the center, convex to plano-convex, with a low broad umbo, with a nonappendiculate and slightly down turned, striate margin (20 - 40% of radius). Volval remnants are present as cinnamon buff powdery or as floccose patches. The flesh is white and unchanged. |
gills |
The gills are free, white, crowded, with a farinose edge. The short gills are truncate to subtruncate. |
stem |
The stem is 90 - 150 × 10 - 15 mm, subcylindric or slightly narrowing upward, slightly expanded at the top, greenish yellow to olivaceous, and densely covered with cinnamon buff, farinose, squamules. The bulb is subglobose and 15 - 25 mm wide. The ring is membranous but easily broken during expansion, upper surface is white with fine radial striation, lower surface is cinnamon buff. Cinnamon buff volval material can be seen on the edge of the ring when viewed from above. The flesh is white. |
odor/taste | not recorded. |
spores |
The spores measure (9.0-) 9.5 - 11.5 (-13.0) × (5.0-) 5.5 - 7.0 (-8.0) µm and are ellipsoid to elongate and inamyloid. Clamps are absent at base of basidia. |
discussion |
This species is known only from Thailand from which it was described. It occurs in groups on the ground in forest dominated by trees of the beech family (Fagaceae). The authors compared the present species to east Asian and North American taxa. Among these were A. roseitincta (Murrill) Murrill, however, the present species lack the unusual and complex veil of A. roseitincta and is unlikely to be closely related. Other taxa to which they compare the present species are A. rufoferruginea Hongo, A. xerocybe Bas, and A. levistriata Dav. T. Jenkins. In general this species appears to belong to the group in section Amanita in which the skin of the cap is delayed in its separation from the volva. Hyphae intergrowing between the two tissues is common even up to maturity. This is one of the reasons why the powder on the cap persists so long, even through rain. Moreover this taxon belongs in the subgroup which lacks clamps and the further subgroup which bears brightly colored pigments. From all other known taxa, this species is separated by the proportionately narrow shape of its spores, the size and habit of the fruiting body, its set of pigments, and the marginal striation of the cap which is present from the beginning of expansion of the fruiting body.—R. E. Tulloss and L. Possiel |
brief editors | RET |
name | Amanita siamensis | ||||||||
author | R. Sanmee, Zhu L. Yang, P. Lumyong and S. Lumyong. 2003. Mycotaxon 88: 225. | ||||||||
name status | nomen acceptum | ||||||||
english name | "Thailand Amanita" | ||||||||
MycoBank nos. | 489411 | ||||||||
GenBank nos. |
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holotypes | CMU; isotype in HKAS | ||||||||
intro |
The following text may make multiple use of each data field. The field may contain magenta text presenting data from a type study and/or revision of other original material cited in the protolog of the present taxon. Macroscopic descriptions in magenta are a combination of data from the protolog and additional observations made on the exiccata during revision of the cited original material. The same field may also contain black text, which is data from a revision of the present taxon (including non-type material and/or material not cited in the protolog). Paragraphs of black text will be labeled if further subdivision of this text is appropriate. Olive text indicates a specimen that has not been thoroughly examined (for example, for microscopic details) and marks other places in the text where data is missing or uncertain. The following material is derived from the protolog of the present species. NOTE: Sanmee et al. used the spore data notation of Z. L. Yang in their protologue. Spore measurements from papers by Z. L. Yang use his "Times New Roman" face for RET's "Q" and "Q'"—respectively, " from protolog: The basidiomes of A. siamensis are medium-sized. | ||||||||
pileus | from protolog: 75 - 95 mm wide, greenish yellow to olivaceous buff, with disc grayish brown, convex to plano-convex, with low broad umbo; context white, unchanging; margin striate (0.2 - 0.4R), nonappendiculate, slightly reflexed; universal veil farinose or as floccose patches, cinnamon buff. | ||||||||
lamellae | from protolog: free, crowded, white, with "farinose" edge; lamellulae truncate to subtruncate. | ||||||||
stipe |
from protolog: 90 - 150 × 10 - 15 mm, greenish yellow to
olivaceous, covered with cinnamon
buff farinose particles, subcylindric or slightly narrowing upward, with apex slightly expanded; bulb 15 - 25 mm wide; context white; partial veil superior, membranous, sometimes torn during cap expansion, above white with fine radial striation and cinnamon buff edge, below cinnamon buff; universal veil not specifically described. [Note: Sanmee et al. (2003: 226, fig. 1) illustrate the pulverulence of the stipe surface extending from the partial veil to about mid-height of the stipe's basal bulb. This pulverulence probably represents remnants of the universal veil and its limbus internus.—ed.] | ||||||||
odor/taste | not recorded. | ||||||||
macrochemical tests |
none recorded. | ||||||||
pileipellis |
from protolog: 60 - 80 μm thick, barely gelatinized, filamentous, undifferentiated hyphae 3 - 6 μm wide, subradially arranged, with brownish vacuolar pigments. [ZLY observed that, even in mature basidiomes, hyphal connections persist between elements of the universal veil and the pileipellis.—ed.] | ||||||||
pileus context | not described. | ||||||||
lamella trama | from protolog: bilateral[, divergent]; wcs = 25 - 40 μm; with subhymenial base (lateral stratum) comprising long ellipsoid and fusiform cells (intercalary, in chains of 2 or 3, 10 - 15 μm wide). | ||||||||
subhymenium | from protolog: 30 - 40 μm thick, with 2 - 3 layers of pyriform to broadly clavate cells (10 - 20 × 7 - 13 μm) | ||||||||
basidia | from protolog: 36 - 48 × 9.5 - 14.5 μm, 4-sterigmate, with sterigmata 4 - 7.5 (-9.5) μm long; clamps lacking. | ||||||||
universal veil | from protolog: On pileus: elements irregularly disposed; undifferentiated filamentous hyphae not described [see "pileipellis" data field, above—ed.]; inflated cells fairly abundant to abundant, globose to subglobose to ovoid (with major diameter 9 - 18 μm long) or spheropedunculate (20 - 25 × 12 - 18 μm), sometimes doliform to sublangeniform (20 - 22 × 6 - 8 μm) or pyriform to broadly clavate (16 - 24 × 10 -12 μm), terminal, singly or in chains of 2 - 3, thin-walled, with yellowish to brownish vacuolar pigment. On stipe: filamentous undifferentiated hyphae 2 - 5 μm wide, more abundant than on pileus, mostly colorless, some brownish; inflated cells globose to subglobose (18 - 24 × 17 - 23 μm) or ovoid (20 - 26 × 15 - 20 μm) or spheropedunculate (25 - 34 × 18 - 20 μm), rarely pyriform (29 - 34 × 15 - 18 μm). | ||||||||
stipe context | from protolog: longitudinally acrophysalidic; filamentous undifferentiated hyphae 2 - 8 μm wide, scattered in interior, more plentiful near surface; acrophysalides 100 - 360 × 20 - 35 μm, dominant in interior. | ||||||||
partial veil | from protolog: absent in exsiccatum. | ||||||||
lamella edge tissue | from protolog: sterile; inflated cells abundant, globose to subglobose (15 - 30 μm wide) to spheropedunculate (25 - 30 × 20 - 25 μm) to pyriform (20 - 35 × 15 - 30 μm), rarely broadly clavate (20 - 40 × 15 - 30 μm), terminal singly or in chains of 2 - 5, thin-walled, colorless, hyaline. | ||||||||
basidiospores |
from protolog: [60/2/1] (9.0-) 9.5 - 11.5 (-13.0) × (5..0-) 5.5 - 7.0 (-8.0) μm, ( | ||||||||
ecology | from protolog: Gregarious. In forest dominated by Fagaceae. | ||||||||
material examined | from protolog: THAILAND: CHIANG MAI PROV.—Doi Suthep-Pui Nat. Pk., Chang-Kian, 11.vi.2002 R. Sanmee, P. Lumyong, S. Lumyong, R. Kodsueb & W Chittrong s.n. (holotype, CMU 4528; lectotype, HKAS 41153). | ||||||||
discussion |
ZLY found the universal veil of this species to be persistently connected to the pileipellis, which the protolog indicates is not seen to gelatinize very much in mature material. Hence, for the moment it seems that the species could be grouped with other species with pulverulent volva having that characteristic—in the provisional Amanita subsect. Amanitella on this site. Within this group, the present species can be easily separated from the one taxon with a membranous limbus internus (A. crenulata) and the white or gray to brown, mostly exannulate species of the proposed stirpes Farinosa, Friabilis, and Nehuta. Likewise, those species with pink, orange, and rusty tones and very thick universal veils producing detersile, pyramidal warts set loosely on a residual pulverulent layer (found in the taxa in stirps Roseitincta) are easily distinguished from A. siamensis. As was pointed out in the protolog, the present species is quite distinct from A. xerocybe. Amanita rufoferruginea is not placed in subsection Amanitella for the present because of its "more or less gelatinized" pileipellis as noted by Yang (1997). This would appear to segregate it from the present species. As was pointed out by Sanmee et al. (2003), the pigmentation and spore size and shape of A. rufoferruginea further differentiate it from A. siamensis. Readers may wish to compare the present species with two somewhat similar North American taxa: Amanita levistriata (rather common in U.S. states north of the Gulf of Mexico) and Amanita sp-N50 (known from a single collection made in eastern Connecticut). The following figure compares the sporographs of the three, somewhat similarly pigmented taxa: | ||||||||
citations | —R. E. Tulloss | ||||||||
editors | RET | ||||||||
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