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Systematic Botany and Mycology Laboratory, USDA, Beltsville, Maryland
H.-J. Schroers
Plant Protection Department, Agricultural Institute of Slovenia, Ljubljana, Slovenia
W. Gams
J. Dijksterhuis
R.C. Summerbell 1
Centraalbureau voor Schimmelcultures, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
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ABSTRACT |
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A hyphomycetous fungus isolated from montane fen soil in the Caucasus Mountains, Russia, had obscurely sympodial conidiogenous cells that suggested a link to the heterogeneous genus Leptodontidium. Sequence analysis of the nuclear ribosomal small subunit and internal transcribed spacer region, however, disclosed that the fungus was an anamorphic member of a clade containing the cleistothecial ascomycetous genus Pseudeurotium. Teberdinia, gen. nov., is proposed for the blastic, generally sympodially proliferating anamorphs in this group, and Teberdinia hygrophila, sp. nov., is proposed for the species from upland fens. Binomials are not proposed for the remaining Teberdinia anamorphs of Pseudeurotium species. Purely anamorphic isolates in this clade are difficult to recognize using current morphological keys and might be more widely distributed and ecologically significant than is currently evident.
Key words: fen habitat, internal transcribed spacer regions, Leptodontidium, Pseudeurotiaceae, phylogeny, small subunit ribosomal DNA
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSTAXONOMYRESULTSDISCUSSIONLITERATURE CITED |
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. Thirteen additional species subsequently were placed in the genus. They were P. ovale Stolk, P. multisporum (Saito & Minura) Stolk (Stolk 1955), P. indicum (Chattop. & Das Gupta) Chattop. (Chattopadhyay 1957), P. bakeri C. Booth, P. rilstonii C. Booth (Booth 1961), P. globosum J.N. Rai & Tewari (Rai and Tewari 1961), P. punctatum Panasenko (Panasenko 1964), P. irregulare Lodha, P. jaipurense Lodha (Lodha 1971), P. desertorum Mouchacca (Mouchacca 1971), P. luteolum Matsushima (Matsushima 1975) and P. macroglobosum Matsushima (Matsushima 1996). In addition two varieties were described, namely P. indicum var. oryzetorum A.M. Corte (Montemartini Corte 1968) and P. ovale var. milkoi Belyakova (Belyakova 1969). P. multisporum, P. indicum, P. globosum and P. rilstonii later were transferred to other genera (Cain 1961, Rai and Tewari 1963, Malloch 1974). Nothing has been published on the redisposition of P. indicum var. oryzetorum, but authentic culture CBS 309.72 later was found to be an isolate of Westerdykella multispora (Saito & Minoura) Cejp & Milko and it now is listed under this name in the CBS list of cultures (2001). Among the remaining Pseudeurotium taxa only P. zonatum, P. ovale, P. ovale var. milkoi, P. bakeri and P. desertorum are still available as living cultures. P. irregulare, P. jaipurense, P. luteolum and P. macroglobosum were preserved only as herbarium specimens. There is no indication of a type in the description of P. punctatum.
The position of the genus Pseudeurotium in the system of Ascomycetes was altered by Malloch and Cain (1970), who established the family Pseudeurotiaceae including four existing genera, Pseudeurotium, Emericellopsis, Fragosphaeria and Testudina, and five newly described genera, Cryptendoxyla, Hapsidospora, Leuconeurospora, Mycoarachis and Nigrosabulum. Phylogenetic research by Suh and Blackwell (1999) changed the concept of the family Pseudeurotiaceae so that among Malloch’s and Cain’s genera only Pseudeurotium and Leuconeurospora remained there while Connersia (with only one species initially placed in Pseudeurotium) and Pleuroascus were added. The data showed a strong distinction between Pseudeurotiaceae and Eurotiaceae. The partial 18S ribosomal subunit study of Gernandt et al (2001) grouped the Pseudeurotiaceae loosely as "incertae sedis," situated "near the base of Helotiales" and at considerable distance from the Eurotiales.
The conidial states of Pseudeurotium species have been described as Sporothrix-, Beauveria- or Acremonium-like. No generic name has been assigned to them.
During a synecological study on soil fungi of alpine ecosystems in Teberda State Reserve (Karachai-Cherkess Republic, Northwestern Caucasus, Russia), a number of anamorphic strains characterized by producing a sympodial succession of blastoconidia in obscurely rosette-like clusters was obtained from the soils of two alpine fens (Sogonov and Velikanov 2005). The strains were identified provisionally as Leptodontidium sp. Their morphology initially appeared suggestive of this genus, although the isolates clearly were not identifiable as any described member of the genus. Subsequent 18S ribosomal DNA sequence comparisons of two representative isolates showed that the alpine strains were not congeneric with the type species of Leptodontidium, L. elatius, but instead were close to P. zonatum.
The object of the current study was to investigate these isolates in terms of their phylogenetic relationships as well as their anamorph morphological similarities to the Pseudeurotium species available in culture.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSTAXONOMYRESULTSDISCUSSIONLITERATURE CITED |
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). For morphological observation and description, strains were grown on potato-carrot agar (PCA), oatmeal agar (OA) and malt-extract agar (MEA) (Gams et al 1998) at 18 C in the dark for 20 d. Colors of the colony obverse and reverse were determined according to Kornerup and Wanscher (1978). Microscopic observations, line drawings and photographs were made using the Olympus BX 50 microscope (Olympus Optical Co., Hamburg, Germany) with conventional bright-field or Nomarski interference contrast microscopy from preparations in lactic acid solutions with or without cotton blue (0.5 µg/mL). Drawings and light microscopy photographs were made with a U-DA camera lucida (Olympus) and DP 10 digital camera (Olympus). Photos were taken with bright-field illumination unless stated otherwise. Microscopic measurements were made with an ocular micrometer at 1000x and are given as the size range of perceived typical structures, flanked in parentheses by the extreme sizes seen in relatively rare variant structures.
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For scanning electron microscopy (SEM) strains were grown on synthetic nutrient agar (SNA) (Gams et al 1998) and OA at 18 C in the dark for 8 d. Blocks (ca. 3 x 7 mm) were cut from colonies growing on agar. They were fixed either in glutaraldehyde and chemically dehydrated before critical point drying as described by Samson et al (1979) or prepared for the low temperature SEM procedure described by Dijksterhuis et al (1991). SEM photographs were made with a JSM-840A scanning electron microscope ( Jeol Ltd., Tokyo, Japan).
For molecular study the fungi were grown on liquid complete yeast medium (CYM, Raper and Raper 1972). DNA was extracted with the cetyltrimethylammonium bromide (CTAB) procedure adopted from Gerrits van den Ende and de Hoog (1999) or with the FastDNA®Kit (Qbiogene, Irvine, California) according to the manufacturer’s instructions.
The 50 µL PCR mixtures contained 1–2 µL DNA extract, 0.25 mM of each dNTP (Amersham Pharmacia Biotech, Amersham Place, Little Chalfont, Buckinghamshire, UK), 0.25–3.0 pM of each of primers, 2 U DNA polymerase (Super Taq®, HT Biotechnology Ltd., Cambridge, UK), 5 µL of the standard PCR buffer provided together with the DNA polymerase and deionized water. PCR was performed in a GenAmp® PCR System 9700 (Applied Biosystems, Foster City, California) with this regime: 35 cycles consisting of denaturation for 30–35 s at 94 C, annealing for 50 s at 52–55 C and extension for 120 s at 72 C; a final extension period of 5–6 min at 72 C followed by chill to 4 C. The region of nuclear ribosomal DNA (rDNA) spanning the internal transcribed spacer 1, 5.8S RNA gene, and internal transcribed spacer 2 regions (ITS1-5.8S-ITS2, further abbreviated to ITS) was amplified with primer pairs ITS1/NL4 (White et al 1990, O’Donnell 1993) for strains CBS 102670, CBS 102671 and CBS 326.81, and V9D/ITS4 (de Hoog and Gerrits van den Ende 1998, White et al 1990) for CBS 878.71, CBS 986.72 and CBS 443.78. The 18S region was amplified with primers NS1 and NS24 (White et al 1990, Gargas and Taylor 1992). After cleanup of the PCR products with the GFXTM PCR DNA and Gel Band Purification Kit (Amersham Pharmacia) and a check on final concentration, the DNA amplified with primers ITS1 and ITS4 (White et al 1990) for the ITS region, and with NS1, OLI1, OLI2 and OLI9 for the 18S region, was sequenced with an ABI Prism® 3700 DNA sequencer (Applied Biosystems).
Data analysis.— –
BLAST searching in GenBank was used to obtain relevant comparison sequences (TABLE II). Sequences were aligned manually in BioEdit 4.8.9 (Hall, http://www.mbio.ncsu.edu/BioEdit/bioedit.html). Phylogenetic analysis was performed by heuristic tree searches using the maximum parsimony criterion in PAUP 4.0b4a (Swofford 2000). Branch robustness was tested based on 1000 bootstrap replicates (randomly sampled datasets with replacements). Heuristic tree searches were performed with starting trees obtained via stepwise sequence addition, tree bisection-reconnection (TBR) as swapping algorithm, multrees on, and using all optimal trees for the next round of swapping. For the analysis of 18S and ITS sequences, the maximal tree number was set respectively at 10 000 (1000 in bootstrap analyses) and at 1000 (10 in bootstrap analyses). Parsimony uninformative characters were excluded from the analyses. Characters were unordered and equally weighted. Sequence addition was random and was done in 100 (10 in bootstrap analyses) replications on the 18S rDNA dataset and 1000 (10 in bootstrap analyses) on the ITS dataset. A large intron in the 18S region of Leptodontidium boreale was not found in any other sequence and hence was excluded from parsimony analysis. Uninformative and constant characters were excluded from the bootstrap analysis. Trees were rooted with basal polytomy.
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TAXONOMY |
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Coloniae albidae vel griseo-virides. Cellulae conidiogenae hyalinae, seu solitariae seu in conidiophoris plus minusve ramosis, terminales, intercalares vel laterales, cylindricae vel ad basim inflatae; conidia apicalia in successione sympodiali e cicatricibus inconspicuis producta. Conidia levia, hyalina, ellipsoidea ad globosa.
Colonies pale, white or gray-green, moderately fast growing. Conidiogenous cells hyaline, arising on aerial or submerged mycelium, smooth walled; in disposition highly variable (FIGS. 1–6), found as integrated hyphal elements giving rise to short, lateral conidiogenous outgrowths (FIGS. 1E; 2F, H, K–M; 5D–F; 6A–D), or as unicellular lateral branches or terminal cells (FIGS. 1C, D; 2A, E, G; 3B; 4B, D; 5A, C, G–I), or as intercalary or terminal elements on discrete, unbranched or irregularly branched, minimally differentiated conidiophores (FIG. 1B, F, G; 2B, C; 3A, E, F; 4E); in shape generally lageniform to broadly aculeate to undulate, often with a distinctly inflated region near the base and with an initially narrow apex; conidiophore apex giving rise successively to blastoconidia in an irregular (in electron microscopy seen to be sympodial manner [FIG. 1G, H]) from a foreshortened terminal region that appears progressively more inflated after several conidia have been produced. Conidia hyaline, glabrous, formed singly or closely aggregated in pairs or rosette-like clusters, borne initially on inconspicuous, short denticles but tending to be detached by the expansion of later-formed conidia and then aggregating in a loose clump simulating a mucoid head, ellipsoidal, obpyriform, subglobose or globose, with a blunt, slightly protuberant attachment scar. Chlamydospores not observed. Often associated with Pseudeurotium teleomorphic structures.
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Etymology. – Teberda refers to the place of isolation of the ex-type strain.
Teberdinia hygrophila Sogonov, W. Gams, Summerbell et Schroers anam. sp. nov. FIG. 1
Coloniae post 20 dies 18 C 20–40 mm diam, albidae vel griseo-virides. Cellulae conidiogenae seu solitariae seu in conidiophoris plus minusve ramosis, terminales, intercalares vel laterales; terminales 6–14 µm longae, cylindricae vel ad basim inflatae. Conidia late ellipsoidea vel ovoidea, 4.5–5.5 x 2.8–3.0 µm.
Description from pure culture. PCA: Colony diameter after 20 d at 18 C in the dark 19–42 mm. Colony surface smooth or slightly powdery at center (FIG. 1L), colorless, pale green (28A3), or greyish green (29E5), semitransparent. Reverse concolorous with the surface. OA: Colony diameter 19–45 mm. Surface smooth, powdery, or loosely cottony (FIG. 1M), white, or greyish green (29B4–29E5). Margins whitish. Reverse colorless or greyish green to dark green (29E4–29F4). MEA: Colony diameter 25–45 mm. Surface powdery, velvety or cottony (FIG. 1N), whitish, light green (27B5), greyish green (26C3–28B4), or dull green (25D3). Reverse pale to olive brown (4E4–4F4).
Hyphae hyaline, 1.8–2.5 µm wide; conspicuous hyphal strands not observed. Conidiophores arising from prostrate aerial or substrate hyphae, consisting of single conidiogenous cells or side branches (up to 100–200 µm long) that often display one or more successive orders of subordinate branches disposed singly or in whorls (FIGS. 1A–G; 2A, B). Conidiogenous cells terminal or intercalary; terminal conidiogenous cells 6–14 µm long, 2.0–2.8 µm wide at the base, usually cylindrical or inflated in the lower part, tapering and often bent or sinuous near the tips; intercalary conidiogenous cells are ordinary looking, cylindrical hyphal cells bearing a single, often pro-clinally curved, laterally disposed, cytoplasmically contiguous conidiogenous projection near the apical end or less commonly near the midregion (FIGS. 1E; 2A, B). These conidiogenous projections are usually small, cylindrical 1.5–2.5 x 0.5–0.9 µm but are variable and occasionally are similar to terminal conidiogenous cells in size and shape. Conidia seen singly or closely aggregated in pairs or rosette-like clusters at the apices of conidiogenous cells and lateral projections, borne initially on inconspicuous, short denticles but tending to become detached by the expansion of later-formed conidia and then aggregating in a loose clump simulating a mucoid head. Conidia glabrous, normally hyaline but becoming dark brown after prolonged storage (1 y), globose to ellipsoidal, (2.4–)2.7–3.4(–4.1) x (2.1–)2.3–2.8(–3.1) µm. Basal scars are scarcely visible in light microscopy but are clear in SEM. Chlamydospores not observed.
Infertile cleistothecial structures (FIG. 1I–K; compare homologous structures for P. zonatum in FIG. 3G, H) seen in a mating cross of CBS 102670 and CBS 326.81 superficial or immersed, dark brown, globose, (90–)130–200 µm diam. Peridium consisting of inner membranaceous layer of dark-brown, thick-walled, polygonal cells (FIG. 1J, cf. P. zonatum structure in FIG. 3H) measuring 4.6–8.0 µm in face view and 3.5–4.0 µm thick in cross section as well as an outer layer composed of loose network of dark-brown, thick-walled hyphae (FIG. 1K) 2.3–4.1 µm wide.
Specimens examined. – RUSSIA. KARACHAI-CHERKESS REPUBLIC: Teberda, Teberda State Reserve (43°27'N, 41°41'E) from peaty soil in an alpine fen. Feb 2000. M.V. Sogonov. HOLOTY PE: Herb. CBS 7947, ex-type culture: CBS 102670. Additional specimen from same site: CBS 102671. THE NETHERLANDS: Overijsselse Vecht, polluted water from potato-meal factory: CBS 326.81.
Etymology. – From the Latin hygrophila, refers to the apparent affinity for moist or aqueous habitats.
Habitats. – Soil, industrial wastewater.
Known distribution. – Karachai-Cherkess Republic (Russian Federation), the Netherlands.
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RESULTS |
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) and SNA. There was no such production of infertile ascomata on potato-carrot agar (PCA), hay-decoction agar (HAY), potato-dextrose agar (PDA) or Leonian’s agar (Gams et al 1998) under either daylight or combined UV/daylight. Ascospores were not formed in any subculture.
Comparative morphological studies of additional Teberdinia anamorphic states.— –
The colonial macromorphology of Pseudeurotium species generally is included in descriptions of the species known in pure culture. The anamorphic structures present in these cultures, however, generally are described incompletely. More detailed descriptions of these micromorphological features are given below to aid morphological comparison among members of this group. For quick reference a summary is provided (TABLE III). Because the anamorphs are not sharply morphologically distinct, those wishing to identify these species morphologically are strongly advised to allow sufficient time for formation of any teleomorphs that may develop.
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, 2C Conidiophores arising from aerial or substrate mycelium, consisting of single conidiogenous cells (terminal or intercalary) or short side branches (up to 50–100 µm). The pattern of conidiophore branching is simpler than that of T. hygrophila. Most conidiophore side branches are single; whorls of more than two branches are rare. Terminal conidiogenous cells 9–22 µm long, lageniform or cylindrical tapering near their tips, usually bent or sinuous. Conidiogenous projections from intercalary cells usually small, cylindrical 1.0–2.0 x 0.7–1.0 µm but variable, occasionally similar to terminal conidiogenous cells in size and shape. Conidiogenesis similar to that of T. hygrophila. Conidia glabrous, broadly ellipsoid, ellipsoid or obovoid (4.0–)4.5–5.5(–6.1) x (2.4–)2.8–3.1(–3.6) µm.
Teberdinia state of Pseudeurotium bakeri..
FIGS. 4; 2D, E
Conidiophores arising from aerial or substrate mycelium, mostly consisting of single conidiogenous cells (terminal or intercalary). Short side branches (up to 25–60 µm) occasionally are found. Terminal conidiogenous cells lageniform, often bent or sinuous 10–22 µm; intercalary conidiogenous cells giving rise to lateral conidiogenous processes similar to terminal cells or reduced to small denticles on intercalary cells. Conidiogenesis similar to that of T. hygrophila. Conidia glabrous, subglobose, ellipsoid or obovoid (4.6–)5.0–5.7(–7.4) x (2.8–)3.2–3.5(–4.4) µm.
Teberdinia state of Pseudeurotium ovale.
FIGS. 5, 2F–J
Conidiophores arising from aerial or substrate mycelium, prostrate, loosely branched. Most conidiogenous cells are intercalary and bear minute or distinct (up to 12 µm long, 1.5 µm diam) conidiferous processes. Terminal conidiogenous cells arise on side branches and on the main branch of conidiophore. Terminal conidiogenous cells mostly 7–12(–40) µm long, cylindrical slightly tapering at the tips, bent or sinuous, sometimes slightly inflated in their midregion. Sometimes conidiogenous cells have a second, laterally situated conidiogenous locus. Conidiogenesis similar to that of T. hygrophila. Conidia glabrous, globose, subglobose or obovoid (3.8–)4.5–5.5(–6.5) x (2.9–)3.5–4.0(–4.4) µm. Basal scars are clearly seen in light microscopy. Conidiogenous structures of the Teberdinia state of CBS 443.78 (FIGS. 2J, 5F–I), the strain of P. ovale var. milkoi studied, did not show any significant difference from those of the Teberdinia state of P. ovale var. ovale.
Teberdinia state of Pseudeurotium desertorum.
FIGS. 6, 2K–M
The anamorph of P. desertorum is the most highly morphologically reduced anamorph referable to the genus Teberdinia. It never produces conidia in dense clusters on inflated tips of conidiogenous cells or processes. Most conidia are single, sessile or disposed on short (2–3.5 x 1.5–1.6 µm) denticles on mycelial cells. Two conidia occasionally are produced closely together on separate short branches at the terminus of denticles (as shown in FIG. 5A and as depicted by Mouchacca [1971]). Conidia are glabrous, broadly ellipsoidal to subglobose, occasionally pyriform, 6.7–10.3 x 5.2–7.6(–7.9) µm.
Phylogenetic analysis.— –
Maximum parsimony analysis of 18S rDNA sequences (FIG. 7) yielded 524 equally parsimonious trees based on 118 parsimony informative characters, 303 steps in length with a consistency index (CI) of 0.518 and a retention index (RI) of 0.664. The trees showed that T. hygrophila strain CBS 102670 is related more closely to P. zonatum, including both the ex-type isolate and the rather disparate ATCC 62440 (= CBS 480.86), than it is to the type species of Leptodontidium, L. elatius. Some other taxa possessing conidiogenesis similar to that seen in CBS 102670 (e.g. L. boreale, Sporothrix inflata) also were shown to be unrelated. Two relatively closely related fungi on a well supported branch, Connersia rilstonii (originally Pseudeurotium rilstonii) and Pleuroascus nicholsonii, do not have distinct conidial anamorphs. Resolution of the phylogenetic position of these anomalous fungi, which appeared to make Pseudeurotium paraphyletic in parsimony analysis but not in neighbor-joining analysis (not shown), was considered beyond the scope of the present study.
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Maximum parsimony analysis of ITS sequences (FIG. 8) yielded two equally parsimonious trees based on 71 parsimony informative characters, 139 steps in length with a CI of 0.748 and a RI of 0.767. In these trees Teberdinia clustered into a well supported Pseudeurotium clade (bootstrap: 94%). The number of base pairs distinguishing members of that clade in the complete ITS region are provided (TABLE IV). A weakly supported clade (bootstrap = 59%) was formed by the Pseudeurotium taxa and some species classified in the Myxotrichaceae, including Pseudogymnoascus roseus, Gymnostellatospora japonica and the anamorphic species Geomyces pannorum, all of which are morphologically distinct from Pseudeurotium/Teberdinia. Leptodontidium elatius, the type species of Leptodontidium, and L. boreale, both forming a strongly supported (bootstrap = 99%) clade, were related more distantly to Pseudeurotium than were the Myxotrichaceous taxa despite their morphological similarity to Teberdinia anamorphs. The affinity of the pseudeurotiaceous taxa to Pseudogymnoascus also was reflected in 18S rDNA analysis.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSTAXONOMYRESULTSDISCUSSIONLITERATURE CITED |
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), but the invariable appearance of the teleomorph in cultures of these species precluded any need to coin a generic name for these anamorphs. The appearance of T. hygrophila alters this situation. Without a teleomorph it cannot be classified as a Pseudeurotium species and an anamorph genus is needed. In proposing the genus Teberdinia, we have designated T. hygrophila as type species in preference to the anamorph of one of the relatively widely distributed Pseudeurotium species. This was partly because T. hygrophila bore the only binomial in the genus but also because of the classical nomenclatural consideration that it is the most extensively developed, morphologically distinctive Teberdinia species. Another factor was that T. hygrophila was clearly situated in the core group of the relevant clade.
The recognition of Teberdinia does not, to our knowledge, conflict with any existing generic concept. The anamorph genera heretofore described as producing single-celled blastoconidia grouped at the apices of unswollen or minimally swollen conidiogenous cells arising from nonmelanized conidiophores are Sporothrix Hektoen & C.F. Perkins, Cerinosterus R.T. Moore, Beauveriphora Matsushima, Microhilum Yip & Rath, and Leptodontidium de Hoog. The first four genera are distinguished readily in that they produce conidia on denticles that remain distinct long after conidial secession (de Hoog 1974, 1993, Benade et al 1997, Matsushima 1975, Yip and Rath 1988). The denticles of Teberdinia often are indistinct from the beginning; moreover, in species other than the Teberdinia anamorph of P. desertorum, they soon are effaced through swelling of the fertile apex after several conidia have been produced. Cerinosterus has been shown to be a basidiomycetous anamorph with typical dolipore septa (Smith and Batenburg-van der Vegte 1985, Moore 1987). Two species of Sporothrix, including the type, S. schenckii, can be seen in phylogenetic analysis of 18S rDNA to be unrelated to Teberdinia (FIG. 7). S. schenckii has long been known to be ophiostomatalean in phylogenetic affinity (Summerbell et al 1993). Leptodontidium, although a highly heterogeneous group, is overall the genus most similar to Teberdinia based on morphological comparison. Our observations on L. elatius, the type species, show that it produces two types of conidiophores; one of them is indeed similar to typical Teberdinia conidiophores while the other features a Rhinocladiella-like long, rigid, dark-walled stalk bearing a sympodially elongating conidiogenous rachis. Teberdinia lacks the latter type. The core group of Leptodontidium species including L. elatius appear in 18S rDNA analysis to be related to the discomycete Bulgaria inquinans; this affinity also is reflected in the description and photograph of the anamorph of B. inquinans published by Fenwick (1992). Most of the other anamorph species placed in Leptodontidium produce some conspicuously melanized structures; colonies generally appear black in age (de Hoog 1977). Teberdinia colonies as such generally lack melanized structures, although the peridia of subsequently developing Pseudeurotium ascomata are black. In mating trials with T. hygrophila, in which plates were held for up to 1 y under ultraviolet light, it was noted that conidia eventually became melanized (and thus were deceptively suggestive of liberated ascospores) but some months were needed for this development. Certainly no possible confusion with Leptodontidium species arises as a result. No described Leptodontidium species represented in CBS has been found to have rDNA sequences compatible with those of Teberdinia (unpubl data).
It is possible that T. hygrophila, although failing to form mature ascomata in culture, might do so in nature. We cannot exclude the possibility that T. hygrophila corresponds to one of the described Pseudeurotium species that is unavailable in living culture. Further efforts are needed to obtain new collections and isolates of these species.
T. hygrophila was relatively common within the north temperate montane habitat (alpine fens, Teberda Reserve) from which it was isolated. It might be found to be a relatively common fungus in similar habitats worldwide. Certainly none of the related Pseudeurotium species to date has been shown to have any plant host specificity or other specific relationships limiting its distribution within the climate zone in which it is typically found in soils. The difficulty of interpreting T. hygrophila’s conidiogenesis under the light microscope makes it a singularly difficult organism for users of morphological keys to deal with, and this might have hindered its recognition in the past. It must be cautioned that relatively morphologically complex Teberdinia anamorphs obtained from natural substrata cannot be assumed to be T. hygrophila whenever they fail to form Pseudeurotium cleistothecia in culture. Purely conidial strains suggestive of Pseudeurotium anamorphs have been isolated repeatedly from soil (Gams unpubl) and it is not clear whether some of these isolates correspond to undescribed species or to asexual variants of common Pseudeurotium species. We hope that the description of T. hygrophila as well as the extended descriptions of other Pseudeurotium anamorphs will aid recognition of these species in biodiversity studies and therefore promote further understanding of the diversity of anamorphs and teleomorphs in this group.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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1 Corresponding author. E-mail: summerbell{at}cbs.knaw.nl
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LITERATURE CITED |
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