Calostoma is a genus of 29 species of gasteroid fungi in the suborder Sclerodermatineae. Like other gasteroid fungi, Calostoma do not have the spore discharge mechanism associated with typical gilled fungi (ballistospory), and instead have enclosed spore-bearing structures. Resembling round puffballs with raised, brightly colored spore openings (ostioles), elevated on a thick, gelatinous stalks, species have been collected in regions of deciduous, temperate, tropical or subtropical forests. Their distribution includes eastern North America, Central America, Asia, and Australasia. The common name given to some species, "prettymouth", alludes to the brightly colored raised openings (ostioles) that may somewhat resemble lips. Other common names include "hotlips" and "puffball in aspic".
The unusual fruit body structure has historically led mycologists to suggest various classification schemes based on presumed relationships to other puffball or "stomach mushrooms". Phylogenetic analyses performed in the 2000s show the genus to be evolutionarily related to the Bolete mushrooms. Calostoma species are ectomycorrhizal, forming symbiotic associations with trees from various families. The type species, Calostoma cinnabarinum, is ectomycorrhizal with oak.
Taxonomy
The original genus description, based on the type speciesCalostoma cinnabarinum (synonymous with cinnabarina),[2] was published by French botanist Nicaise Auguste Desvaux in 1809.[3] Before the advent of modern genetic analysis, the Calostoma was considered to be part of the Gasteromycetes, a grouping of fungi with enclosed spore-bearing structures. Specifically, it was classified in the order of stalked puffballs,[4] although some mycologists have suggested that the genus Calostoma should be merged with Tulostoma[5] (xerophilic stalked puffballs), Scleroderma[6] (hard puffballs), Geastrum[7] (earthstars), or Pseudocolus[8] (stinkhorns). Some authors have placed Calostoma in its own family, the Calostomataceae.[9][10][11]
In the 2000s, a phylogenetic analyses using nuclear and mitochondrialribosomal gene sequences helped to clarify the phylogeny of Calostoma. Using the species C. cinnabarinum and C. ravenelli as representative examples, the research showed the genus to be evolutionarily part of the monophyletic Boletales clade, and separate from clades containing most of the gilled mushrooms, puffballs, stalked puffballs, earthstars, stinkhorns and non-bolete Gasteromycetes.[12]Calostoma belongs to the suborder Sclerodermatineae within the Boletales. The suborder comprises the following genera: Boletinellus, Calostoma, Gyroporus, Phlebopus, Pisolithus, Scleroderma, and Veligaster.[13]Calostoma is thought to have diverged evolutionarily from other Boletales taxa between 52 and 115 million years ago.[12] The most recent age estimates suggest Calostoma diverged from the most recent common ancestor in the "Core Sclerodermatineae" at a median age of 66.02 million years ago (highest posterior density range 49.27-90.28 million years ago). The median age of the most recent common ancestor for extant Calostoma is 42.73 million years ago (highest posterior density range 28.76-57.15 million years ago).[14]
The genus name Calostoma is derived from the Greekkallos or "beauty", and stoma (στóμα) or "mouth"; similarly, several species are referred to in the vernacular as "prettymouths". In Korea, it is called Yongi, or "red cheeks".[15]
Description
Fruit bodies, technically known as gasterocarps, form spherical spore-bearing heads with a peridium (outer tissue layer) made of two to four clearly defined layers of tissue. The outermost peridial layer is a thick gelatinous or shiny cuticle, which during maturity peels away to reveal the brightly colored peristome that has a star-shaped pore through which spores may escape. The innermost layer of the peridium is papery and membranous, and remains attached to the outer layers only at the apex of the star-shaped apical pore or slit. The fruit bodies may either have no stalk (sessile), or be atop a stalk. The stalk, made of thick, intertwined and fused cords of hyphae, is hygroscopic, and will expand upon absorbing moisture.[12] The spore mass in the head, the gleba, is pale, and initially has thick-walled skeletal hyphae called capillitia. Clamp connections are present in the fungal hyphae.[4]
Spores
The spores are spherical to elliptical in shape, and typically have surfaces that are reticulate (with interconnected grooves resembling a net) or pitted.[9] The variations in the elaborate pitted-spore reticulations have inspired investigation with techniques such as scanning electron microscopy and atomic force microscopy. The latter technique was used to distinguish subtle details (at the nanometer scale) and differences in the fine structure of the spores of various Calostoma species.[15] The spore reticulations have purpose: they become entangled and interwoven with nurse cells and scaly hyphae, the net effect of which is to prevent the spores from being blown away simultaneously.[16]
Development
When grown in humid conditions, such as might typically be found in a temperatedeciduous forest, Calostoma species develop a thicker, more gelatinous exoperidium (the outermost peridial layer). As the stalk expands, the exoperidium becomes sloughed off, exposing the endoperidium and a raised peristome—the ridge of tissue around the opening suggestive of the common name, "prettymouth".[17] The exoperidium may help to protect the maturing gleba of late-fruiting species from harmful variations in temperature or humidity, or from insect predation.[9]
In general, Calostoma species are not considered edible; because they typically begin their development underground, by the time fruit bodies appear they are too tough for consumption.[21] However, a 2009 study reported that in the community of Tenango de Doria (Hidalgo state, Mexico), Calostoma cinnabarinum used to be collected by children and consumed "like a tidbit", although the tradition seems to have been abandoned in recent years. Locals called the young fruit bodies "yemitas"or “little yolks”.[22]
Biochemistry
Calostoma cinnabarinum contains a pigment named calostomal that is responsible for its red color. The IUPAC name of this molecule is all-trans-16-oxohexadeca-2,4,6,8,10,12,14-heptaenoic acid.[23]
Species list
The following species list is compiled from Index Fungorum[24] as well as species published in the literature, but missing in Fungorum, specifically C. formosanum, C. junghuhnii, and C. sarasinii. The name listed under the species binomial is the authority—the author of the original description of that species, followed by the year of publication.
In damp depressions on sand ridges in Victoria, Australia
It has dark grey to brown fruit bodies made of a short gelatinous stalk, up to 2 cm (0.8 in) long, and a spherical head up to 0.8 cm (0.3 in) wide. The outer layer of the peridium does not fall off in one piece (as in C. fuscum) but persists as small black granules. The spores are elliptical, white, and smooth-walled, with dimensions of 22–25 by 10–11.5 μm.[34]
Originally described as Mitremyces junghuhnii by Schlechtendal and Müller in 1844, this species was discovered in 1842 on an expedition to collect biota in the forest of Batta-Lauder, near Tapoilang, Java.[42] It has bright orange to red fruit bodies made of a stalk 1.5 to 2.5 cm (0.6 to 1.0 in) long and 1.5 to 2.0 cm (0.6 to 0.8 in) thick. The spores are spherical, covered with rounded to pyramid-shaped warts 1–2 μm long, with diameters of 12.5–15 μm; the spore surface ornamentation appears to be unique in the genus.[43]
C. ravenelii var. microsporum (G.F. Atk.) Castro-Mend. & O.K. Mill. (1983)
This variant was first described by George Atkinson in 1903, who noticed a close resemblance to C. ravenelii, but believed that an often longer stalk and smaller, oblong spores (measuring 6–9 by 3.5–4.5 μm) were sufficient to warrant naming it a new species.[48]
First studied by Brazilian mycologist Johann Rick, the species was published posthumously, 15 years after his death in 1946.[54] Initially named Myremyces zanchianus, only a single specimen is known.[55] The species has an egg-shaped head, 1.3 cm (0.5 in) long by 1 cm (0.4 in) wide, atop a stalk. The "mouth" is star-shaped and made of 4 long slits that open at maturity. The spores are 30–35 by 15–20 μm, spindle-shaped to elliptical, smooth, and have a prominent longitudinal groove.[55]
^de Bary A. (1887). Fungi, mycetozoa and bacteria, English edition. Oxford, UK: Clarendon Press.
^ abcdMiller HR, Miller OK (1988). Gasteromycetes: Morphological and Developmental Features, with Keys to the Orders, Families, and Genera. Eureka, California: Mad River Press. ISBN0-916422-74-7.
^Li F, Bo L, Hua LY (1994). The gasteromycetes of China: A supplement to Beihefte zur Nova Hedwigia. Berlin, Germany: J. Cramer. ISBN3443510302.
^ abcHughey BD, Adams GC, Bruns TD, Hibbett DS (2000). "Phylogeny of Calostoma, the gelatinous-stalked puffball, based on nuclear and mitochondrial ribosomal DNA sequences". Mycologia. 92 (1): 94–104. doi:10.2307/3761453. JSTOR3761453.
^Binder M, Bresinsky A (2002). "Derivation of a polymorphic lineage of Gasteromycetes from boletoid ancestors". Mycologia. 94 (1): 85–98. doi:10.2307/3761848. JSTOR3761848. PMID21156480.
^ abcCastro-Mendoza E, Miller OK Jr, Stetler DA (1983). "Basidiospore wall ultrastructure and tissue system morphology in the genus Calostoma in North America". Mycologia. 75 (1): 36–45. doi:10.2307/3792921. JSTOR3792921.
^Wilson AW, Hobbie EA, Hibbett DS (2007). "The ectomycorrhizal status of Calostoma cinnabarinum determined using isotopic, molecular, and morphological methods". Canadian Journal of Botany. 85 (4): 385–93. doi:10.1139/B07-026.
^Liu B. (1984). "The Gasteromycetes of China". Beihefte zur Nova Hedwigia. 74. Vaduz: J. Cramer: 1–235. ISBN3768254763.
^Dumont KP, Umana MI (1978). "Fungi of Colombia part 5 Laternea triscapa new record and Calostoma cinnabarina new record in Colombia". Caldasia (in Spanish). 12 (58): 349–52.
^ abOtani Y. (1976). "On the genus Calostoma in Japan". Transactions of the Mycological Society of Japan (Nippon Kingakukai Kaiho). 17 (3–4): 358–62.
^Balfour-Browne FL. (1955). "Some Himalayan fungi". Bulletin of the British Museum (Natural History), Botany. 1 (7): 189–218.
^Berkeley MJ. (1854). "Decades XLIV—XLVI. Indian fungi". Hooker's Journal of Botany. 6: 161–74.
^Kobayasi Y. (1965). "Himalayan Calostoma and Isaria". Journal of Japanese Botany. 40: 228–29.
^Singh SC, Nisha. (1976). "Some fleshy fungi of Nepal". Journal of Science (Kathmandu, Nepal). 6: 73–88.
^Schlechtendal V, Müller K (1844). "Mitremyces junghuhnii eine neue Art, beschreiben und abgebildet". Botanische Zeitung. 2 (23): 401–4.
^Miller OK, Van Cotter H (1988). "Observations on tissue morphology and spore ultrastructure of Calostoma junghuhnii (Gasteromycetes)". Canadian Journal of Botany. 66 (12): 2470–73. doi:10.1139/b88-335.