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Department of Chemical Engineering, Southern Taiwan University of Technology, Young-Kang, 710 Taiwan
Franz Oberwinkler 3
Institute of Botany and Mycology, University of Tübingen, 72076 Tübingen, Germany
Zuei-Ching Chen
Department of Botany, Taiwan National University, Taipei, 106 Taiwan
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ABSTRACT |
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A new genus, Heterorepetobasidium, is proposed to accommodate two new species, H. subglobosum and H. ellipsoideum, recently collected in Taiwan. These species have apically, partially septate basidia, strongly swollen sterigmata, and repetobasidia. The systematics of the new taxa and related ones, inclusive of Ceratobasidium and the Ceratobasidiaceae, are reinterpreted.
Key words: Auriculariales, Ceratobasidium, Ceratobasidiaceae, Ceratobasidiales, continuous parenthesomes, Heterorepetobasidium ellipsoideum, Heterorepetobasidium subglobosum, partially septate basidia, repetobasidia
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSTAXONOMYDISCUSSIONLITERATURE CITED |
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and considered as a unique character for the genus Repetobasidium J. Erikss. & Hjortst. Later, repetobasidia were found to occur occasionally in different taxa of the Homobasidiomycetes. The genus Repetobasidiellum J. Erikss. & Hjortst. (Eriksson et al 1981
) deviates from Repetobasidium by suburniform basidia, also developing repetitively.
In a comparative study, Oberwinkler (1972)
found striking micromorphological similarities between Repetobasidium and Oliveonia Donk. The latter genus was originally described as Heteromyces L. S. Olive (non Müll. 1889) by Olive (1957)
, and was nomenclaturally formalized by Donk (1958)
as Oliveonia.
Rogers (1935)
described Ceratobasidium D. P. Rogers designating C. calosporum D. P. Rogers as the type species. In his description of C. calosorum partially septate basidia were not mentioned (Rogers 1935
). Based on a restudy of the type material, Oberwinkler (1982)
reported and illustrated partially septate basidia in C. calosporum. Apically partially septate basidia occur in several heterobasidiomycetous taxa, e.g., in some species of Tremellodendropsis (Corner) D. A. Crawford (Crawford 1954
, Corner 1970
, Oberwinkler 1972
), Pseudotulasnella Lowy (Lowy 1964
, Oberwinkler 1982
), and Sebacina pulverulenta Hauerslev (1976)
. Some species are without septation and some are completely septate. Partially septate meiosporangia may represent intermediate stages in the evolution of holobasidia.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSTAXONOMYDISCUSSIONLITERATURE CITED |
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). Series of sections were cut on a Reichert ultramicrotome using a diamond knife and, after mounting on Formvar coated single slot copper grids, stained with lead citrate at room temperature for 3–5 min, and washed again with water. The thin sections were examined with a LEO EM 109 transmission electron microscope at 80 kV. |
TAXONOMY |
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Carposoma effusum, adnatum, albidum vel cremeum. Hyphae basales hyalinae, tenuituicatae, nodulosi-septatae. Septa hypharum doliporis parenthesomatibus continuis vel minutissime apicaliter perforatis constructis. Gloeocystidia breve cylindrica, partim pleuraliter exorta. In hymenio hyphis angustis dendrohyphidiis simplicibus simillimis. Basidia subglobosa vel breve cylindracea, basaliter attenuata an stipitata, apicaliter partim septata, frequenter per repetitionem formata. Sterigmata 4, basaliter incrassata, demum incurvata. Basidiosporae hyalinae, tenuitunicatae, tunicis levibus, non amyloideis, per repetitionem germinantes. In ligno putrido crescunt. Typus generis: Heterorepetobasidium subglobosum C.-J. Chen & Oberw.
Basidiomata thin, effused, waxy when fresh, horny when dry, whitish, creamy or translucent. Basal hyphae thin, mostly tortuous, clamped. Dolipores with continuous parenthesomes (Fig. 5 ), each perforated only centrally by one micropore (not illustrated). Branched hyphidia are usually present but rarely abundant (Figs. 1, 7, 8 , 9 ), protruding into the hymenium, rarely above it. Gloeocystidia (Figs. 1 , 2 , 8 , 9 ) arising terminally or laterally from basal or subhymenial hyphae, mature with oily contents, and in some cases thick-walled in older stages. Pleurogloeocystidia with lateral hyphal appendages. Basidia (Figs. 1 , 3 , 9 ) developing terminally from small, clamped generative hyphae, subglobose to clavate or pyriform, at maturity becoming distally partially, longitudinally septate (Figs. 1, 3, 6, 9 ). Sterigmata basally strongly swollen, often abruptly tapering into spiculae. New basidia growing through the mature (repetobasidial development, Figs. 1, 3, 7, 9 ), the old basidia remaining as sheaths around new ones. Young fruiting bodies without repetobasidia. Basidiospores, hyaline, thin-walled, smooth, and non amyloid, mostly germinating by secondary spores or by germination tubes (Figs. 4, 9 ). On decaying wood.
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Type of genus: Heterorepetobasidium subglobosum C.-J. Chen & Oberw.
Heterorepetobasidium subglobosum C.-J. Chen et Oberw., sp. nov.
Hyphae basales 1–2 µm in diam. Gloeocystidia conspicua (17)–21–34–(36) x 7–10–(12) µm, mature partim crasse tunicata. Basidia clavata an pyriformia, (15)–18–25–(29) x 8–10–(11) µm. Basidiosporae subglobosae vel brevissime cylindraceae, 7–8.5 x 5.5–6.5 µm. Habitatio: In ramis emortuis.
Basidiomata thin-resupinate, 40 to 80 µm thick (Fig. 1 ), fresh white, drying grayish and glittering film-like on the surface. Hyphae thin-walled, 0.5–2 µm in diameter, hyaline, strongly tortuous, embedded in a gelatinous matrix. Hyphidia (Fig. 1 ) arising from subhymenial hyphae, clamped, tortuous and apically branched, growing into the hymenium and interspersed with basidia and gloeocystidia. Gloeocystidia (Figs. 1, 2 ) originating from subhymenial hyphae, often with short pleural hyphal appendages, at maturity thick-walled, (17)–21–34–(36) x 7–10–(12) µm. Basidia (Fig. 3 ) obovoid, pyriform, clavate to suburniform, (15)–18–25 x 8–10–(11) µm, with or without stalks, stalks up to 9 µm long, apically partially longitudinally cruciate-septate; sterigmata thick, basally swollen, 3.5–4.5 µm in diam., up to 12 µm long; young basidia develop through the bases of old ones which remain as sheaths (basidial repetition; repetobasidia). Basidiospores (Fig. 4 ) subglobose to broadly ellipsoid, 7–8.5 x 5.5–6.5 µm, smooth, hyaline, nonamyloid, germinating by repetition or by germ tubes.
HOLOTYPE. TAIWAN. TAICHUNG: Tashueshan, 2000–2200 m; leg. Chee-Jen Chen CCJ1410, 24-VI-1996, in TNM.
Heterorepetobasidium subglobosum is characterized by its subglobose spores, and mature thick-walled gloeocystidia. So far there is only one collection from a mountain forest site in central Taiwan. The unique morphological characters of the well developed material justify the erection of a new species and a new genus.
Heterorepetobasidium ellipsoideum F. Oberw. et C.-J. Chen, sp. nov.
Hyphae basales 1–2 µm in diam. Gloeocystidia rara et inconspicua 15–30 x 8–12 µm, tenuitunicata. Basidia clavata an pyriformia, 15–25 x 8–12 µm. Basidiosporae cylindraceae, 10–11 x 5 µm. Habitatio: In ramis emortuis.
Basidiomata thin-resupinate, 30 to 50 µm thick (Fig. 8 ), fresh whitish to pale cream, dry transparent, very inconspicuous. Hyphae thin-walled, 0.5–1.5 µm in diameter, hyaline, slightly tortuous, embedded in a gelatinous matrix. Hyphidia scattered, developing from subhymenial hyphae, clamped, tortuous and apically branched, growing into the hymenium and interspersed with basidia and gloeocystidia. Gloeocystidia inconspicuous, developing laterally from basal hyphae, thin-walled at maturity, short-cylindrical, 15–30 x 8–12 µm. Basidia obovoid, pyriform or stout clavate 15–25 x 8–12 µm, stalked, stalks up to 10 µm long, mature apically shortly longitudinally cruciate-septate; sterigmata thick, basally swollen, 2–3.5 µm in diam., up to 12 µm long; occasionally basidial development of the Repetobasidium-type. Basidiospores short-cylindrical, 10–11 x 5 µm, smooth, hyaline, nonamyloid, only germination by repetition observed.
HOLOTYPE. TAIWAN. TAIPEI: Yangminshan, 300–400 m; leg. Franz Oberwinkler, FO 46996, 8-V-1998, in TNM.
Heterorepetobasidium ellipsoideum is characterized by its elliptical spores and inconspicuous, mature thin-walled gloeocystidia, thus clearly distinguishable from H. ellipsoideum.
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DISCUSSION |
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A comparison with other similar genera follows. Well developed and old specimens of species of the genus Repetobasidium are easily recognized by columns of generative hyphae, surrounded by old basidial sheaths, and globose, subglobose or short-cylindrical holobasidia with 4 slender sterigmata. Repetobasidium species have no partially septate basidia, no secondary spores and no gloeocystidia. However, their close relationship to heterobasidiomycetous taxa is suggested by the possession of dolipores with continuous parenthesomes (Oberwinkler and Tschen 1990
). Heterorepetobasidium species share some unique features of Repetobasidium, i.e., septal pore apparatus and repetitive basidial ontogeny.
The genus Repetobasidiellum (Eriksson et al 1981
) is characterized by subuniform repetobasidia, the presence of hyphidia, and the lack of cystidia. Basidia are not septate, secondary spores and gloeocystidia are lacking. The ultrastructure of the septal pores is unknown.
Renatobasidium notabile Hauerslev (Hauerslev 1993
) is characterized by thin basidiomes with longitudinally one-septate, two-sterigmate basidia, developing repetitively, and partly pleural gloeocystidia. Thus, Renatobasidium is a genus of the Auriculariales, related to taxa with tremelloid basidia.
Heterobasidiomycetous species with short cylindrical to globose holobasidia and small, short sterigmata, secondary spores and gloeocystidia-like sterile cells in the hymenium fit the generic concept of Oliveonia Donk (Donk 1958
). Oberwinkler (1972)
has shown that basidial ontogeny in older specimens of Oliveonia may occur repetitively. Heterorepetobasidium deviates from Oliveonia in having partly septate basidia and stout sterigmata.
The genus Pseudotulasnella was proposed by Lowy (1964)
to accommodate a tulasnelloid species with apically partly cruciately septate basidia. Otherwise, basidial ontogeny follows typical Tulasnella patterns, i.e., there are strongly swollen sterigmata (epibasidia) which, at maturity, are basally abstricted from the basidial body. Basidia are formed in clusters and repetobasidia are lacking (Oberwinkler 1982
, Roberts 1999
).
The genus Metabourdotia Olive (1957)
was described with apically partially septate basidia. It was proposed as the ancestor of Ceratobasidium Rogers. Repetobasidia were not described and examination of the type specimen for M. tahitiensis Olive, the type specimen (T 358 in New York Botanical Garden) confirms their absence. Evidentially Metabourdotia and Heterorepetobasidium are found to be two different genera.
Ceratobasidium is typified by C. calosporum D. P. Rogers (1935)
, a resupinate species, with hyphae without clamps and often branching at right angles, typically stalked and swollen basidia with stout sterigmata, and basidiospores germinating by repetition. A restudy of the type material showed that the basidia are apically partially cruciately septate (Oberwinkler 1982
). In addition, the septal pore apparatus was found to be a dolipore with continuous parenthesomes (Oberwinkler 1982
). There is no basidial repetition and cystidia, inclusive of gloeocystidia and hyphidia, are lacking. Both the genus Ceratobasidium and the family Ceratobasidiaceae have to be based on these major features of the type species. It is therefore clear that species with holobasidia do not fit the generic concept of Ceratobasidium in a strict sense, and most of the species currently assigned to this genus are systematically misinterpreted. Thus those taxa that do not share the Ceratobasidium dolipore type should not be assigned to this genus. Furthermore it is evident that Ceratobasidium belongs in the Auriculariales, and it is unclear whether the Ceratobasidiaceae can be maintained as a separate family. Consequently, the Ceratobasidiales are suggested as a synonym of the Auriculariales.
We have shown that the unique character set of Heterorepetobasidium does not fit in any of the basidiomycetous genera described to date. Therefore, we suggest that a new genus for two new species is justified. Our systematic evaluation indicates that Heterorepetobasidium belongs in the Auriculariales. This order needs detailed systematic reinterpretation before we can suggest family placement for Heterorepetobasidium.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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2 Corresponding author, c5200999{at}ms23.hinet.net
3 franz.Oberwinkler{at}uni-tuebingen.de
Accepted for publication September 25, 2001.
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LITERATURE CITED |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSTAXONOMYDISCUSSIONLITERATURE CITED |
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Crawford DA., 1954 Studies on New Zealand Clavariaceae I Trans Roy Soc New Zealand 82:617-631
Donk MA., 1958 Notes on resupinate Hymenomycetes—V Fungus 28: (1–4) 16-36
Eriksson J., 1958 Studies in the Heterobasidiomycetes and Homobasidiomycetes-Aphyllophorales of Muddus National Park Symb Bot Ups 16:1-172
Eriksson J., Hjortstam K, Ryvarden L., 1981 The Corticiaceae of North Europe 6:1051-1276
Hauerslev K., 1976 New and rare Tremellaceae on record from Denmark Friesia 11:94-115
Hauerslev K., 1993 New tremellaceous fungi from Denmark Mycotaxon 49:217-233
Lowy B., 1964 A new genus of the Tulasnellaceae Mycologia 56:696-700
Oberwinkler F., 1972 The relationships between the Tremellales and the Aphyllophorales Persoonia 7:1-16
Oberwinkler F., 1982 The significance of the morphology of the basidium in the phylogeny of Basidiomycetes In: Wells K, Wells EK, eds. Basidium and basidiocarp. Evolution, cytology, function, and development. New York: Springer Verlag. p. 9–35
Oberwinkler F., Tschen J., 1990 A new Repetobasidium species from Taiwan Trans Mycol Soc Japan 30:343-347
Olive LS., 1957 Two new genera of the Ceratobasidiaceae and their phylogenetic significance Am J Bot 44:429-435
Roberts P., 1999 Rhizoctonia-forming fungi. A taxonomic guide The Herbarium, Royal Botanic Gardens, Kew
Rogers DP., 1935 Notes on the lower Basidiomycetes Univ Iowa Stud Nat Hist 17:3-43
Spurr AR., 1969 A low viscosity epoxid embedding medium for electron microscopy J Ultrastr Res 26:31-43[Medline]
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