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Department of Biology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSSYSTEMATIC CONSIDERATIONDISCUSSIONLITERATURE CITED |
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Recent studies in the Gomphidiaceae have clearly delimited two genera, Gomphidius and Chroogomphus, both of which are mycorrhizal associates only with the Pinaceae. Ecological studies show Chroogomphus as a mycorrhizal associate of Pinus (Pinoideae), while Gomphidius is associated with the other three gymnosperm subfamilies Piceoideae, Lariceideae, and Abietoideae. The genus Brauniellula, which is based upon the secotioid habit and the presence of orthotropic, statismosporic basidia, falls within Chroogomphus in a clade with ballistosporic species. Brauniellula is, therefore, placed in synonymy with Chroogomphus. Molecular and morphological studies of new material from Nepal, Russia, Korea, and the United States have delimited two new species in each genus. The morphologically identical Chroogomphus rutilus clades are separate, one European and one North American. The relationship of the two genera in the Gomphidiaceae, with their mycorrhizal associates, is related to similar host relationships within other genera in the Suilloid Clade.
Key words: Basidiomycetes, Gomphidiaceae, Gomphidius, Chroogomphus, Brauniellula
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSSYSTEMATIC CONSIDERATIONDISCUSSIONLITERATURE CITED |
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in the Corpus Flororum Provincialus Sueciae I Forum Scanicam Siripait. In this work only a diagnosis was given, but in 1836 when the name Gomphidius was used he referred back to Ag. Gomphi S.M. p. 314. In the Systema Mycologicum Vol. 1.1821, his first work, Fries recognized two species in the genus Gomphidius. However, the taxonomic position of the genus was that of a tribe, Gomphus, under the expansive genus Agaricus. The two recognized species were listed in the Systema Mycologicum as 1. A. Gomph glutinosus and 2. A. Gomph. rutilus (Fries 1821). Beneath these two species Fries listed two other species and cited the authors, but he had apparently not seen the specimens himself. These were A. maculatus Scop. and A. viscidus l.c. totus flavescens Schaeff. In 1838, when Elias Fries published the "Epicrisis Systematis Mycologici" he included three species (Gomphidius glutinosus Schaeff. : Fr., G. viscidus Linn. : Fr., and G. maculatus Scop. : Fr.) and listed G. roseus (F.) Karst. and G. testaceus, but did not accord them equal standing. The species incorporated in the works of Elias Fries (Gomphidius maculatus Scop. : Fr., and G. viscidus (Scop. : Linn.) Fries) were first described by Scopoli and Schaeffer in Scopoli's Prima Flora Carnolica, published in 1772, as species in the genus Agaricus. Jacob Christian Schaeffer, a contemporary of Scopoli, published his five volume work Fungorum qui in Bavaria et Palatinotu circa Ratisbonam nascuntur icones during the period 1762–1770. He also described Gomphidius rutilus Schaeff. : Fr., G. glutinosus Schaeff. : Fr. and G. roseus (Schaeff. : Fr.) Karst. under the genus Agaricus.
In 1860 Miles J. Berkeley published the first description of G. gracilus Berk. and Broome. He included a plate with a painting of the fungus but no microscopic details were included in the description. From this point on the description and naming of the new species switched predominantly to mycologists working in the United States.
In 1897 Peck described three new species in Gomphidius that were found only in North America. These were G. vinicolor Pk., G. nigricans Pk., and G. oregonensis Pk. (Peck 1897, 1898a, b). Gomphidius furcatus Pk. was subsequently placed in synonymy under G. maculatus (Scop. : Fr.) Fr. by Singer (1949), where it undoubtedly belongs. In 1912 William A. Murrill collected and described G. tomentosus Murr. Kauffman (1925), and added two more species to the growing list of North American taxa, namely G. subroseus Kauf. and G. ochraceus Kauf. ssp. typicus. Rolf Singer (1948) also made contributions to the genus with three species, G. leptocystis Sing. G. smithii Sing., and G. septentrionalis Sing. The latter is one of the few species of European origin described in recent years. Singer (1948) and Singer and Kuthan (1976) also described several other species and varieties which have either been placed in synonymy or are from Europe and are differentiated on the basis of their characters in the fresh condition. Miller (1963) revised the Gomphidiaceae and subsequently published a monograph of Chroogomphus in 1964 followed in 1971 by a monograph of the genus Gomphidius.
Mycorrhizal affinities and ecology –
The Pinaceae are clearly separated from the Gymnosperm families Cupressaceae, Taxaceae, and Taxodiaceae by Tsumura et al (1995), Stephanovic et al (1998), and Liston et al (1999). There are four subfamilies according to Farjon (1990) and Labandeira et al (2001) within the Pinaceae, including the Pinoideae, Piceoideae, Laricoideae, and Abietoideae. Additional analyses by Tsumura et al (1995) clearly show the Pinoideae Clade with two clusters, namely the haploxylon and diploxylon pines; a second cluster with Pseudotsuga (Douglas fir) and Larix (larch); a third cluster including Picea (spruce) and Cedrus (cedar); and lastly Abies (fir), Tsuga (hemlock), and Keteleeria in one cluster. The results of Tsumura et al (1995) clearly indicate the four subfamilies accepted by Labandeira et al (2001). These four subfamilies include Pinoideae with Pinus (pine); Piceoideae with Picea; Lariceideae with Larix, Pseudotsuga, and Cathaya; and lastly the Abietoideae with Abies, Cedrus, Keteleeria, Nothotsuga, Pseudolarix, and Tsuga. The authors also point out that the larches occur in the most extreme environments, above northernmost altitudinal limits for normal conifer growth.
A variety of recent molecular studies suggest that Pinus and Picea within the Pinaceae form a basal portion which is supported by the Early Cretaceous fossil record (Cenozoic Era—65 my). Picea can only be traced and extended to the middle Eocene, but the ancestry of Picea may extend to the late Cretaceous (Mesozoic Era—160 my) with relationships to the extinct genera Pityostrobus Nathorst ex Dutt and Pseudoaraucaria Filche (Labandeira et al 2001). It is important to note that they also make the point that the Abietoideae is at least as old as the Pinoideae and probably basal, indicating that these subfamilies have been separated for a very long time (Harris 1979, LePage and Basinger 1995). This information is important in considering the co-evolution of the Pinaceae and the Suilloideae.
Genera such as Suillus, Rhizopogon, Truncocolumella, Chroogomphus, and Gomphidius are mycorrhizal associates of the Pinaceae either completely or with only a very few exceptions. It is even more interesting that we have many specific fungus-host mutually symbiotic pairs. For example, Suillus americanus (Pk.) Snell ex Slipp and Snell only associates with eastern white pine (Pinus strobus L.), Fuscoboletinus ochraceoroseus (Snell) Pomerleau and A.H. Sm. only with western larch (Larix occidentalis Nutt.), and Suillus lakei (Murr.) A. H. Sm. and Thiers only with Douglas fir (Pseudotsuga menziesii Mirib.). Rhizopogon species have a similar pattern and are, in turn, related to specific genera of hosts or sections within genera in the Pinaceae (Molina et al 1997). These patterns of specific host associations are clearly present in the Gomphidiaceae. Chroogomphus species are associated with a wide variety of species of pines worldwide. In over 400 collections that I have made in which the habitat has been noted and recorded, haploxylon and diploxylon pines served as hosts for the various species of Chroogomphus. There appear to be no exceptions in the association of Chroogomphus with Pinus. By the same token, over 350 collections of Gomphidius were almost totally associated with the subfamilies Piceoideae (Picea), Laricoideae (Larix and Pseudotsuga), and Abietoideae (Abies and Tsuga). There is also strong evidence of more specific associations such as Gomphidius maculatus with the larches (Larix), G. glutinosus with spruce (Picea) or Douglas fir (Pseudotsuga menziesii), and G. subroseus with Douglas fir (Pseudotsuga menziesii). An exception to this generic separation by host is Gomphidius nigricans, which is associated only with eastern white pine (Pinus strobus) where I have recorded it in pure stands. These observations give strength to the hypothesis that co-evolution of the Pinoideae (Pinus) with Chroogomphus species was accompanied by co-evolution of Gomphidius species with the Piceoideae (Picea) and the Laricoideae (Larix and Pseudotsuga). There are few specific observations in pure stands of fir (Abies) or hemlock (Tsuga), both in the Abietoideae. There may be specific associations with grand fir (Abies grandis (Dougl.) Lind.) in mixed stands where G. glutinosus, G. subroseus, G. smithii, and G. oregonensis are found, but Douglas fir and Engelmann spruce (Picea engelmanni Parry ex Engelm.) are usually present as well.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSSYSTEMATIC CONSIDERATIONDISCUSSIONLITERATURE CITED |
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. Primers ITS1 and ITS4 were used to both amplify and sequence the entire ITS region. In some instances, primers ITS1 and 5.8S as well as the ITS4 and 5.8SR (Vilgalys and Hester 1990) were used to separately amplify the ITS-1 and ITS-2 regions. All analyses were conducted in PAUP 40b2. The collections sampled for ITS sequencing are listed in TABLE 1 of Miller and Aime (2001). |
SYSTEMATIC CONSIDERATION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSSYSTEMATIC CONSIDERATIONDISCUSSIONLITERATURE CITED |
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with strong bootstrap support. The Gomphidiaceae is nested in the Suilloid Clade according to Bruns et al (1998) and distinctly apart from Suillus, Truncocolumella, and Rhizopogon (Miller and Aime 2001). The genus Chroogomphus is clearly separated from the genus Gomphidius (Fig. 1).
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Clade II.
Clade II, subclade A also has strong bootstrap support (Fig. 1). Brauniellula was described by Smith and Singer (1958) to accommodate secotioid species that would otherwise be included in either Chroogomphus or Gomphidius. Later, Miller (1973) erected the genus Gomphogaster to accommodate the nonamyloid taxon Brauniellula leucosartz A.H. Sm. and Singer (1958) (Gomphogaster leucosartz), leaving B. albipes (Zeller) A.H. Sm. and Singer and B. nancyae A. H. Sm. with amyloid trama in Brauniellula. Passione and Fogel (1990) described B. crassitunicata from New Mexico from Harrison's collections with thick-walled cystidia. An extensive study that I carried out revealed that some collections had thick- and thin-walled cystidia, some only thin-walled and some only thick-walled. rDNA sequence data that included the holotype of B. crassitunicata placed B. albipes, B. nancyae, and B. crassitunicata with both thick and thin-walled cystidia in the same subclade with very high bootstrap support. Close study reveals that B. nancyi is a synonym of B. albipes and the sequence data support the conclusion that the thickness of the cystidia is not a sufficient character to use to erect a new taxon. I requested and received the holotype of Secotium albipes Zeller based upon material collected by Thelma Norman in California in 1932 and identified by Elizabeth Morse as Secotium erythrocephalum Tul. Anatomical study revealed that there are very thick-walled cystidia in the hymenium and amyloid tramal hyphae. Therefore, B. crassitunicata is also a synonym of B. albipes. Since Fogel will not allow the holotype of Gomphogaster leucosartz to be taken on loan because of the single fruiting body that makes up the holotype, I have not been able to restudy it to determine its placement. However, this well supported clade is in the middle of Chroogomphus, and the secotioid habit combined with the statismosporic habit are the only characters on which the genus is based. Steven Miller has shown that both ballistosporic and statismosporic basidia may occur in the same hymenium (S. L. Miller and Miller 1988). The genetic change may not be more than one gene and describing a genus on this basis should be accompanied by other relevant genetic changes. It is the conclusion in this study that Brauniellula is not a good genus and the species, therefore, is transferred to Chroogomphus, C. albipes (Zeller) O.K. Mill. comb. nov. Once restudy is possible there is little doubt that Gomphogaster leucosartz will be transferred to Gomphidius taxa.
Clade II, subclade B (Fig. 1) only includes a small, non secotioid, Asian species collected by Dr. Van Cotter during his predoctoral Fulbright study in Nepal. This taxon, described as Chroogomphus asiaticus O.K. Mill. and Aime, has very high bootstrap support. It is clearly a new taxon that is associated with Pinus roxburghii Sar. (Miller and Aime 2001).
Clade III.
Chroogomphus rutilus (Schaeff. : Fr.) O.K. Mill. appears to be a European species and ITS sequences of all collections from Europe are in a clade distinctly separated from a clade of American taxa previously assigned to C. rutilus (Fig. 1). They are at best both morphologically very closely related but as Fig. 1 shows a separate Clade V contains the North American taxa. However, C. rutilus was described in Europe leaving C. ochraceus (Kauf.) O.K. Mill. from North America the next available name upon which to base the North American material. This is an acceptable name for the North American taxa. In both Europe and North America the pileus may be either light ochraceous or dark reddish brown, however, in both clades they are together. There is no evidence from our analysis that the pileus coloration is an important character at the species level (Miller and Aime 2001). A light-colored variant C. corallinus O.K. Mill and Watling (Fig. 1) described by Miller and Watling (1970) is included in Clade III, and is a synonym of C. rutilus. Chroogomphus britannicus Nowehere, Kahn, and Hora is a member of this complex and a synonym of C. rutilus (Nowehere et al 1978).
Clade IV.
Several species in this complex with darkly amyloid trama and thick-walled cystidia have been described from North America (Fig. 1). Chroogomphus vinicolor (Pk.) O.K. Mill. was described over 100 yr ago in 1898 and was followed by C. jamicansis by Murrill in 1918 from the Dominican Republic and C. pseudovinicolor O.K. Mill. from the Rocky Mountains (Miller 1966). They all form a very close clade as illustrated in Fig. 1. The sequences for C. jamaicensis from the Dominican Republic and Jamaica in the Greater Antilles are found in the general mix of taxa within this clade. This seems to indicate that the isolation of this taxon under Pinus occidentalis Swartz in the Dominican Republic and Jamaica has not created enough genetic drift to separate them from the main populations of the C. vinicolor complex. Chroogomphus pseudovinicolor, a very large, robust taxon from the Rocky Mountains, has the anatomical characters of C. vinicolor. It is also found within this clade but is somewhat separated from the other species. More molecular and morphological analyses are needed. Specimens referred to as C. jamaicensis in Florida and the Southeastern U.S. form sympatric distributions with C. vinicolor; moreover, the anatomical characters previously used do not seem to be valid. As of now I regard C. jamaicensis as a synonym of C. vinicolor but will continue to recognize C. pseudovinicolor as a separate taxon with a need for additional rDNA sequence analysis and descriptions of fresh material.
Clade V. All the taxa in the C. ochraceus/C. rutilus complex in North America, as described in Clade III, sequence closely together in one clade (Fig. 1) even though they are from Colorado, Idaho, and Virginia. Since the name C. rutilus now refers only to a European taxon, its use should be discontinued in North America. The phenotypic dark mahogany pileus with variants to light ochraceous are apparently variation within one species. Both forms are found in Europe and North America. This character does not warrant the erection of a species as we believed in the past. It should be noted that these species all have thin-walled cystidia and spores of similar size.
Clade VI.
Chroogomphus tomentosus (Murr.) O.K. Miller was described in 1912 by W.A. Murrill from the Rocky Mountains (Fig. 1). It has a distinctive orange-brown cap and stipe, a fibrillose pileipellis, and a deeply amyloid pileitrama. A similar taxon was identified by Imai from Japan in 1938 as Gomphidius tomentosus. Chroogomphus loculatus O.K. Mill. and Trappe is a similar taxon which has very contorted lamellae but still is ballistosporic (Miller and Trappe 1970). Very recently, Dr. Thom Odell has collected this taxon from the same area in Oregon as the holotype and obtained material for sequencing. The sequence data were obtained by Dr. Aime and are in the clade with C. tomentosus with high bootstrap support. The abnormal hymenial structure described for C. loculatus does not appear to be a species-level distinguishing character. Since an established population is present in Oregon the designation of a variety seems more appropriate. In addition, specimens collected by both O.K. Miller and Van Cotter in Japan and Nepal were also sequenced from herbarium material by Dr. Aime. The results fit perfectly with anatomical data. A cluster of two subclades is indicated with 99% bootstrap support (Fig. 1). One cluster includes both C. loculatus and C. tomentosus; the second supports a new taxon from Asia, C. pseudotomentosus O.K. Mill. & Aime (Miller and Aime 2001). This Asian taxon has consistently smaller spores, a different aspect, and very different host associations.
Gomphidius clade. The genus Gomphidius has at least 10 taxa based upon the phylogenetic evidence that is available to date. There are several additional taxa that have not been collected fresh nor can sequences be obtained from herbarium materials, and therefore are not treated here.
Gomphidius maculatus clade (Fig. 1) has spores 14–22 x 6–8 µm, is not caespitose, and lacks a partial veil. The purplish black stains which occur on the lower stipe in age or when handled is a very distinctive character as is the lack of a yellow stipe base. It is only found associated with species of Larix throughout the Northern Hemisphere. It is a tight clade and collections from different continents, including the two examples given here, have strong bootstrap support.
Next is a clade which includes Gomphidius flavipes Pk. and G. pseudoflavipes O.K. Mill. and Camacho (Miller et al 2002). Gomphidius flavipes has spores that are the second largest in the genus, 18–29 x 6–8.5 µm. It is a very small mushroom with a thin fibrillose veil, and the lower two-thirds of the stipe is bright yellow. It is found in the Northeastern boreal forest, often in old glacial potholes under Picea, Tsuga, and Larix, and in high elevation bogs in the southeastern US under Picea. It sequences in a clade (Fig. 1) with a new species from California, G. pseudoflavipes O.K. Mill. & Camacho (Miller et al 2002). The two taxa are very similar and sequence together with very high bootstrap value in the same clade. It is interesting to note that Gomphidius flavipes was placed in Chroogomphus by Miller in 1964 since it has scattered amyloid tramal cells. However, unlike species of Chroogomphus, it has the yellow stipe base and white pileus trama of a typical species in Gomphidius. Our sequence data leave little doubt that this transitional species between the two genera really belongs in Gomphidius, where we have now placed it (Miller and Aime 2001). Gomphidius pseudoflavipes has spores that are the largest in the genus, 18–40 x 6–9.5 µm. The pileus is brown to orange-brown with a densely fibrous partial veil, which is soon gone. The stipe is yellow just at the base. It is found under Abies and Pinus and to date known only from Fresno County, California (Miller et al 2002).
A collection from Korea is referred to Gomphidius roseus Fr., but no material from the European population where the species was named by Fries has been successfully sequenced. The Korean collection forms a subclade by itself with G. flavipes and G. pseudoflavipes as shown in Fig. 1. The pileus is 4–8.5 cm broad, distinctively deep red, viscid, and larger than both G. flavipes and G. pseudoflavipes. The spores are smaller, 15.5–26 x 5–6.5 µm, with a viscid to glutinous veil, and the stipe base is pink to yellow. It is associated with Pinus and Picea in the higher elevations of the Republic of Korea. It may, in fact, be a new taxon.
A heavily supported clade includes G. glutinosus, G. smithii, G. oregonensis, and G. subroseus. Gomphidius glutinosus was described from Europe by Fries (1821) and is commonly found associated with Picea, Abies, Pseudotsuga, and perhaps Tsuga. The pileus is glutinous and ranges in color from dark brown to ochraceous or purple. The spores are 15–21 x 4–6(–7.5) µm, with a glutinous partial veil, and a stipe with the lower two-thirds yellow to bright yellow. The basal mycelium has clamps, and in the Rocky Mountains it is associated with Picea and Abies and has been found at Nordman, Idaho, under a Norway spruce plantation (Picea abies (L.) Karst.). I have examined this species from both Europe and Asia where it is common. Gomphidius oregonensis has the smallest spores in the genus, 10–14 x 4–5 µm. It is a large, robust, routinely caespitose, glutinous species distributed in the Pacific Northwest and the Rocky Mountains. Fruiting bodies come from massive tissue just below surface of soil and are mycorrhizal associates of Picea, Abies, and Pseudotsuga. A very recent sequence from Oregon is the first known sequence of this species and is in a subclade (Fig. 1) in the G. glutinosus clade. Gomphidius smithii is very closely related to G. glutinosus as stated by Miller (1971), and ITS data from a Utah collection (Fig. 1) bears this out. The spores are 14–18.5 x 5.4–6 µm, not caespitose, veil present (glutinous), and a stipe base that is not yellow nor with a trace of yellow. It was recorded by Singer under Pinus flexilis James but there are no good characters to separate it from G. glutinosus. Since it is in the same clade with G. glutinosus, I regard it as a synonym of that species. Gomphidius largus O.K. Mill. is a very robust taxon, up to 21 cm diam, not caespitose, with a glutinous veil and a bright yellow stipe base, spores 14–18 x 5.5–6.5 µm diam and a pileus trama with inflated cells up to 30 µm diam. Gomphidius largus is associated with Picea engelmanni Parry & Engelm. from New Mexico to Idaho, and is very similar to G. glutinosus with only the size of the fruiting body and very large tramal cells differing from it. No DNA could be recovered from herbarium material, so there is no molecular evidence. Nevertheless, it is likely a synonym of G. glutinosus. Gomphidius subroseus is distinguished from G. glutinosus by its uniformly cherry red, glutinous pileus and routinely smaller size (3–5.5 cm diam). The spores are (11–)15–20.5 x 4.5–7 µm, it is never caespitose, and the stipe has a yellow base. It is associated with Picea, Pseudotsuga, and Abies in North America (Miller 1971). It is close to but distinctly separated from the G. glutinosus clade with strong bootstrap support.
Gomphidius nigricans was described in 1897 by Peck (Miller 1971). The pileus is 2–10 cm broad, glutinous, never caespitose with a very thin fibrillose veil and spores 13–22 x 4.5–7 µm diam. A very distinctive character is the lower stipe that blackens when handled and is purplish black at first. Its constant association with eastern white pine (Pinus strobus L.) is an exception in the genus Gomphidius, which is uniformly associated with other genera in the Pinaceae. It is found in the general range of eastern white pine. Two sequences form a clade in Gomphidius with 100% bootstrap support (Fig. 1).
Gomphidius borealis O.K. Mill., Aime, & Peintner (Miller et al 2002) has a pileus 1.5–3 cm broad, red to orange–red, viscid, with a superior, thin, white fibrillose veil leaving a thin white annulus on the upper stipe. The lower stipe is light orange at the base inside and out and the lower surface blackens in age when handled. This very unusual fungus is most likely associated with Asian larch (Larix gmelini Turczaninow) in eastern Russia. ITS sequences derived from two of the three collections (Peintner 1999/0532 and Peintner 1999/0726) are in a separate, strongly supported clade (Fig. 1). There is a third collection for which there was no molecular data, but which has the morphological characteristics of the other two, and was found under the same host (Miller et al 2002). This taxon is in a clade on the very fringe of the genus Gomphidius and may form a distinct section. A revision of the genus based on our current studies is underway and it is our objective to obtain multilocus molecular analysis of the taxa under study.
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DISCUSSION |
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or suilloid radiation as described by Grubisha et al (2001). Evidence for this is presented by Molina and Trappe (1994) and Molina et al (1997). The Section Villosuli has six species that strongly colonized Pseudotsuga menziesii Mirb. and five of the six species very lightly colonized Tsuga heterophylla (Rafn.) Sarg. (less than 5%), but no colonization of Pinus contorta Dougl. took place (Molina and Trappe 1994, TABLE 5). Conversely, all seven species in Section Rhizopogon colonized Pinus contorta while three did not colonize and three colonized Pseudotsuga menziesii. One species in Section Rhizopogon strongly colonized both Pinus contorta and Tsuga heterophylla, but no colonization of Pseudotsuga menziesii was recorded. Species in Section Amylopogon exhibited a wide host range and formed mycorrhizae with all three hosts.
Species in two other genera in the Suilloid Clade are also host specific in their mycorrhizal associations. These include Truncocolumella citrina associated with Pseudotsuga menziesii, and Alpova diplophloeus Zeller & Dodge with Alnus rubra Bong., according to Massicotte et al (1994). I have observed these same relationships under field conditions in the Rocky Mountains and Alaska. Suillus, a major genus in the Suilloid Group, also exhibits strong preferences for host specific associations. Suillus americanus, S. pictus (Pk.) A.H Sm. and Thiers and S. sibericus (Sing.) Sing. form mycorrhizae with five needle haploxylon pines. However, S. lakei (Murr.) A.H. Sm. and Thiers is associated with Pseudotsuga menziesii. Suillus grevillei (Klotz.) Sing. and Fuscoboletinus ochraceoroseus (Snell) Pomerl. are only associated with species of larch (Larix). In contrast, S. granulatus (L : Fr.) Kuntz and S. tomentosus (Kauff.) Sing. have a broad host range. The co-evolution of hosts and their ectomycorrhizal partners may well be one of the important factors in the ability of the ancient members of the Pinaceae to extend their distribution. This includes vast climatic differences, from Larix in Arctic Siberia, to Pinus on the Island of Hispaniola near the equator There are vast areas of ectomycorrhizal conifers in the Northern Boreal Forest to the Sierra Madre Orientalis and Occidentalis in Mexico (Perry et al 1999) and extending south through Nicaragua and Belize in Central America usually at high elevations. Throughout the entire range of the Pinaceae in the native range in the Northern Hemisphere, species of Rhizopogon, Suillus, Truncocolumella, Chroogomphus, and Gomphidius are found in association with the host species in various genera of the Pinaceae.
Summary –
Phylogenetic analyses strongly support the ecological and morphological data in the Gomphidiaceae and the delimitation of two clearly distinctive genera, Chroogomphus and Gomphidius. The further delineation of two secotioid partially hypogeous genera with Brauniellula related to Chroogomphus and Gomphogaster (Miller 1973) related to Gomphidius, is not supported by the molecular data. In contrast, Brauniellula albipes in the genus Chroogomphus is strongly supported (Fig. 1). Chroogomphus albipes is proposed. It is also proposed but, without molecular evidence, to transfer Gomphogaster leucosarx to Gomphidius leucosarx (A.H. Sm. and Singer) O.K. Mill. comb. nov. Previously Miller (1988) and Miller and Miller (1988) have provided strong evidence that the loss of forcible spore discharge does not constitute a major genetic event. Macowanites Kalchbr. may have both statismosporic and ballistosporic basidia within a single hymenium and in these cases a scanty spore discharge has been observed according to Miller and Miller (1988). Geographical distribution and ecological evidence indicate that the secotioid habit has evolved many times in various genera in montane habitats in response to harsh climatic conditions. In the current study it does not seem that the genetic changes that took place to produce orthotropic, statismosporic basidia, and a secotioid basidiome are important enough to warrant generic level status.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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Accepted for publication July 11, 2002.
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LITERATURE CITED |
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Fries E., 1821 Systema mycologicum. Vol. 1. 521 p
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