Curvibasidium cygneicollum gen. nov., sp. nov. and Curvibasidium ...

International Journal of Systematic and Evolutionary Microbiology (2004), 54, 1401–1407 

DOI 10.1099/ijs.0.03037-0 

Curvibasidium cygneicollum gen. nov., sp. nov. 

and Curvibasidium pallidicorallinum sp. nov., 

novel taxa in the Microbotryomycetidae 

(Urediniomycetes), and their relationship with 

Rhodotorula fujisanensis and Rhodotorula 

nothofagi 

José Paulo Sampaio, 1 Wladyslav I. Golubev, 2 Jack W. Fell, 3 

Mário Gadanho 1 and Nikita W. Golubev 4 

Correspondence 

José Paulo Sampaio 

jss@fct.unl.pt 

1 

Centro de Recursos Microbiológicos, Secção Autónoma de Biotecnologia, Faculdade de 

Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal 

2 

Russia Collection of Microorganisms, Institute for Biochemistry and Physiology of 

Microorganisms, Russian Academy of Sciences, Pushchino 142290, Russia 

3 

Rosenstiel School of Marine and Atmospheric Science, University of Miami, 

4600 Rickenbacker Causeway, Key Biscayne, FL 33419, USA 

4 

Mendeleev Chemical–Technological University, Moscow 125820, Russia 

Strains of Rhodotorula fujisanensis (Basidiomycota, Urediniomycetes, Microbotryomycetidae), 

including the type strain, are sexually compatible and produce clamped mycelium with teliospores. 

However, as teliospore germination had not been documented, the complete sexual cycle was not 

known. During the course of this work, the basidial stage of R. fujisanensis was characterized. 

In addition, mating studies employing isolates that were identified preliminarily as Rhodotorula 

nothofagi, a species that is related closely to R. fujisanensis, yielded mycelium with teliospores, 

which formed basidia and basidiospores. The new data were evaluated by using several criteria, 

including the available molecular phylogenetic framework for the Microbotryomycetidae. 

Curvibasidium gen. nov. is described here, to accommodate two teleomorphs: Curvibasidium 

cygneicollum sp. nov. (CBS 4551 T ), which is described as the sexual stage of R. fujisanensis, and 

Curvibasidium pallidicorallinum sp. nov. (CBS 9091 T ), which is related closely to R. nothofagi, but 

does not represent its sexual stage. 

The dimorphic basidiomycetes are distributed among 

several lineages of the Basidiomycota (Swann & Taylor, 

1995; Sampaio & Fonseca, 2002; Scorzetti et al., 2002; 

Sampaio & Bauer, 2003). They constitute a remarkably 

diverse group of fungi, based on DNA sequence divergence 

studies, ultrastructural markers, ecological adaptations and 

Published online ahead of print on 5 March 2004 as DOI 10.1099/ 

ijs.0.03037-0. 

Abbreviation: ITS, internal transcribed spacer. 

The GenBank/EMBL/DDBJ accession numbers for the sequences 

described in this work are as follows: AY383746, AY383747 and 

AY383748 (complete ITS region sequences of Curvibasidium pallidicorallinum 

CBS 6231, VKM Y-2861 and VKM Y-1135, respectively); 

AY383749 (complete ITS region sequence of Rhodotorula nothofagi 

A45); and AY383750 and AY383751 (partial 26S rRNA gene 

sequences of Rhodotorula ingeniosa CBS 6728 and Rhodotorula sp. 

CBS 4858, respectively). 

metabolic properties. The yeast stage allows the colonization 

of a wide range of ecological niches and is also important for 

dispersion. The filamentous stage tends to be more resilient, 

particularly when specialized resting structures, such as 

teliospores, are formed. Hyphae are also important in the 

development of the sexual stage and in the establishment of 

mycoparasitism or phytoparasitism. 

Many species of basidiomycetous yeasts are known only in 

their asexual phase and are classified in genera such as 

Rhodotorula Harrison or Cryptococcus Vuillemin. However, 

mating studies have allowed the disclosure of the sexual 

stage of species that were previously classified in these 

genera. Typically, the teleomorphic stage is initiated with 

conjugation between two compatible yeast cells, followed by 

production of mycelium. When environmental conditions 

are adequate, basidia and basidiospores are produced. 

The investigation of new sexual states allows a better 

03037 G 2004 IUMS Printed in Great Britain 1401

J. P. Sampaio and others 

understanding of the evolutionary processes that underlie 

the present diversity of dimorphic basidiomycetes, including 

the phylogenetic relationships between and within 

anamorphic genera. 

Sexual compatibility is known for certain strains of 

Rhodotorula fujisanensis (Soneda) Johnson & Phaff, and 

clamped mycelium with teliospores has been documented 

(Fell et al., 1984; Barnett et al., 1990; Boekhout & Fell, 1995). 

However, until now, teliospore germination had not been 

reported and, therefore, the complete sexual cycle was 

not known. In the present report, the basidial stage of 

R. fujisanensis is characterized. In addition, the study of 

another sexual stage, obtained by using isolates that were 

identified preliminarily as R. nothofagi Ramírez & González, 

a species related closely to R. fujisanensis, is also presented. 

The data were evaluated by using several criteria, including 

the molecular phylogenetic framework that is available 

for the Microbotryomycetidae. A new genus, Curvibasidium 

gen. nov., is described, to accommodate the two 

teleomorphs. The relationship of Curvibasidium with R. 

fujisanensis and R. nothofagi is discussed. 

For microscopy, cultures were grown on MYP agar (malt 

extract, 0?7 % w/v; yeast extract, 0?05 % w/v; soytone 

peptone, 0?25 % w/v; agar, 1?5 % w/v) at room temperature 

(20–23 uC) and studied with an Olympus BX50 microscope, 

using phase-contrast optics. For determination of sexual 

compatibility, pairs of 2–4-day-old cultures were crossed on 

MYP agar, potato dextrose agar (PDA) and corn-meal agar 

(CMA), incubated at room temperature and examined 

regularly for the production of mycelium and teliospores. 

Teliospore germination required a prolonged resting stage 

(9–12 months). After this period, agar blocks containing the 

teliospores were transferred to 2 % water agar and observed 

regularly under the microscope. 

Physiological and biochemical characterization was carried 

out according to techniques described by Yarrow (1998). 

Additional assimilation tests were performed by using 

aldaric acids and aromatic compounds as described by 

Fonseca (1992) and Sampaio (1999), respectively. 

For determination of the extent of DNA homology, total 

genomic DNA was extracted and purified by using 

procedures described previously (Sampaio et al., 2001). 

For DNA–DNA reassociation experiments, a Gilford 

Response UV-VIS spectrophotometer and its thermal 

programming software were used and the methods of 

Kurtzman et al. (1980) were followed. 

For rRNA gene sequence analysis, total DNA was extracted 

by using the protocol of Sampaio et al. (2001) and amplified 

by using primers ITS5 (59-GGAAGTAAAAGTCGTAAC- 

AAGG-39) and LR6 (59-CGCCAGTTCTGCTTACC-39). 

Cycle sequencing of the 600–650 bp region at the 59 end 

of the 26S rRNA gene D1/D2 domains employed forward 

primer NL1 (59-GCATATCAATAAGCGGAGGAAAAG-39) and 

reverse primer NL4 (59-GGTCCGTGTTTCAAGACGG-39). 

The internal transcribed spacer (ITS) region was sequenced 

by using the forward primer ITS1 (59-TCCGTAGGTGAA- 

CCTGCGG-39) and the reverse primer ITS4 (59-TCCTCC- 

GCTTATTGATATGC-39). Sequences were obtained with 

an Amersham Pharmacia ALF Express II automated 

sequencer by using standard protocols. Alignments were 

made with MegAlign (DNAStar) and corrected visually. 

Heuristic maximum-parsimony analysis was employed (100 

rounds of heuristic search with tree bisection–reconnection 

branch-swapping, starting from trees that were obtained by 

random addition of sequences, multrees option on, deepest 

descent option off) and was validated by using 1000 rounds 

of bootstrap analysis (Felsenstein, 1985). Maximumparsimony 

and bootstrap calculations used PAUP* software 

(Swofford, 2001). 

Latin diagnosis of Curvibasidium Sampaio et 

W. Golubev gen. nov. 

Fungi dimorphi Microbotryomycetidarum. Mycelium poris 

simplicibus fibulatis. Colacosomata nulla. Teliosporae globosae, 

holobasidiis germinant. Basidiosporae ovoideae ad 

bacilliformes, sessiles, gemmis germinant. Ballistoconidia 

nulla. Fermentatio nulla. D-Glucuronatum nitratumque non 

assimilantur. Productio compositorum amylo similium nulla. 

Systema CoQ 9 dominans. Polysaccharida extracellularia 

fucosum rhamnosumque continent. 

Description of Curvibasidium Sampaio & 

W. Golubev gen. nov. 

Curvibasidium (Cur.vi.ba.si9di.um. N.L. neut. n. Curvibasidium 

referring to the curved shape of the basidium). 

Dimorphic. Belongs to the subclass Microbotryomycetidae. 

Mycelium with clamp connections. Simple septal pore. 

Colacosomes are not produced. Spherical teliospores 

germinate, producing a holobasidium. Sessile, ovoid-tobacilliform 

basidiospores are released passively and germinate 

by budding. Ballistoconidia are not formed. Fermentative 

ability is absent. No assimilation of D-glucuronate or 

nitrate occurs. Starch-like compounds are not formed. 

Dominant CoQ system is 9. Extracellular polysaccharides 

contain fucose and rhamnose. Phylogenetic placement, as 

deduced by analysis of the D1/D2 domains of 26S rRNA 

gene, is shown in Fig. 1. The type species is Curvibasidium 

cygneicollum Sampaio. 

Latin diagnosis of Curvibasidium cygneicollum 

Sampaio sp. nov. 

Fungus dimorphus. Hyphae 1?5–2?5 mm diametro, conjugatione 

culturarum compatibilium procreantur. Septa fibulata, 

colacosomata nulla. Teliosporae plerumque globosae, 12–18 

(22) mm diametro, terminales vel intercalares. Basidia 

stipitata, curvata, matura retroflexa, 6–8 (10)615–22 

(26) mm, aseptata, basidiosporas sessiles, ovoideas ad bacilliformes 

in appendicibus basidialibus brevibus procreant. 

Basidiosporae gemmis germinant. Cellulae zymosae longe 

ovoideae ad cylindraceae, (1?5) 2–36(5) 7–12 (15) mm. 

1402 International Journal of Systematic and Evolutionary Microbiology 54

Curvibasidium gen. nov. 

Fig. 1. Phylogenetic tree of Curvibasidium and related taxa of the Microbotryomycetidae. Maximum-parsimony analysis of an 

alignment of the D1/D2 region of the 26S rRNA gene. The topology was rooted with Naohidea sebacea, Occultifur externus, 

Rhodotorula minuta and Sakaguchia dacryoidea. Numbers on branches are bootstrap values (1000 replicates; values below 

50 % are not shown). GenBank accession numbers of the sequences are indicated after strain numbers. 

Cultura in striis cremea ad aurantiaca. Characteres biochemici 

physiologicique Curvibasidii cygneicolli in http://www.crem. 

fct.unl.pt/dimorphic_basidiomycetes/Databases/databases.htm 

describuntur. 

Description of Curvibasidium cygneicollum 

Sampaio sp. nov. 

Curvibasidium cygneicollum (cyg.nei.col9lum. L. n. cygnus 

swan; L. n. collum neck; N.L. n. cygneicollum swan-neck, 

referring to the typical shape of the stalked basidium, which 

resembles the neck of a swan). 

Dimorphic. Hyphae (1?5–2?5 mm in diameter) are formed 

after mating of sexually compatible strains. Two mating 

types are known (see Table 1). Clamp connections are 

present, but colacosomes are lacking. Teliospores are usually 

spherical [12–18 (22) mm in diameter], terminal or intercalary 

(Fig. 2a). Basidia are produced after a prolonged 

resting stage of the teliospores. Basidia are stalked, curved 

and bent over the stalk when matured (Fig. 2b). Stalks 

http://ijs.sgmjournals.org 1403


Table 1. Strain numbers, isolation source and sexuality of the two novel species of Curvibasidium described in this study and 

of R. nothofagi 

Species/strain* Isolation source SexualityD 

C. cygneicollum 

CBS 4551 T d Hare faeces, Mount Fuji, Japan MT A1 

CBS 7950 Wood of Quercus suber, Arrábida, Portugal MT A1 

CBS 8056 Berry of Vitis coignetiae (wild grape), Japan MT A1 

PYCC 4187 Flower of Acacia sp., Portugal MT A1 

CBS 6371 Leaf, France MT A2 

PYCC 4694 Rotten wood, Arrábida, Portugal MT A2 

CBS 8163§ Rotten trunk of Laurelia sempervirens, Futrono, Chile ANA 

CBS 7949 Dry leaf, Arrábida, Portugal SF|| 

CBS 7951 Tree root, Gerês, Portugal ANA 

CBS 8264 Leaf of Acacia sp., New Zealand ANA 

PYCC 4705 Caterpillar nest, Sintra, Portugal ANA 

PYCC 4445 Woodland soil, Lisbon, Portugal ND 

PYCC 4968 Tree trunk, Arrábida, Portugal ANA 

PYCC 4947 Rotten tree trunk, Lisbon, Portugal ANA 

VKM Y-2859 Herbaceous plants, Prioksko-terrasny Biosphere Reserve, Moscow region, Russia MT A2 

JI 06 Fruiting body of Exidiopsis sp., Caramulo, Portugal ND 

JI 21 Fruiting body of Exidiopsis sp., Caramulo, Portugal ND 

C. pallidicorallinum 

VKM Y-2284 T (=CBS 9091 T ) Gramineous plant, Moscow region, Russia MT A1 

CBS 6231 Frass of Ruguloscolytus rugulosus MT A1 


VKM Y-1135 Air, Kishinev, Moldavia MT A2 


PTZ 185 Herbaceous plants, Prioksko-terrasny Biosphere Reserve, Moscow region, Russia MT A1 

R. nothofagi 

CBS 8166 T Rotten trunk of Nothofagus obliqua, Futrono, Chile ANA 

A45 Sea water off Faro, south of Portugal ANA 

*CBS, Centraalbureau voor Schimmelcultures, Yeast Division, Utrecht, The Netherlands; PYCC, Portuguese Yeast Culture Collection, FCT-UNL, 

Portugal; VKM, All-Russian Collection of Microorganisms, Pushchino, Russia; JI, PTZ personal collections of J. Inácio and W. I. Golubev, 

respectively; A, collection of yeasts isolated from aquatic environments by M. Gadanho and J. P. Sampaio. 

DANA, Anamorphic; MT, mating type; ND, not determined. 

dType strain of R. fujisanensis (Soneda) Johnson & Phaff. 

§Type strain of Rhodotorula futronensis (Ramírez & González) Roeijmans et al. 

||Originally this strain was self-fertile, but currently it lacks the ability to produce mycelium with teliospores. 

measure 1?5–2?5615–35 (50) mm. Basidia [6–8 (10)615– 

22 (26) mm] are devoid of septa and produce sessile, ovoidto-bacilliform 

basidiospores [1?5–266–12 (20) mm] on 

short basidial appendages (Fig. 2b). Each basidium has two 

to four sites of basidiospore formation and multiple 

basidiospores are formed at each site. Basidiospores 

germinate by budding. Yeast cells are long and ovoid to 

cylindrical [(1?5) 2–36(5) 7–12 (15) mm] (Fig. 2a). Streak 

cultures are cream-coloured or pale orange, butyrous 

and semi-dull. Colony margins are entire, and fringed 

with pseudomycelium in some cases. Physiological 

and biochemical features of C. cygneicollum are available 

at http://www.crem.fct.unl.pt/dimorphic_basidiomycetes/ 

Databases/databases.htm and tests that allow its differentiation 

from Curvibasidium pallidicorallinum are depicted in 

Table 2. The phylogenetic placement of C. cygneicollum is 

shown in Fig. 1. C. cygneicollum is sensitive to the mycocins 

produced by Rhodotorula glutinis and Rhodotorula mucilaginosa, 

but insensitive to mycocins secreted by Rhodotorula 

pallida and by species of the genera Cryptococcus, 

Cystofilobasidium, Filobasidium and Sporidiobolus. 

Microscopic slides from the crossing of CBS 4551 T and CBS 

6371, showing mycelium, teliospores, basidia and basidiospores, 

were deposited in the Portuguese Yeast Culture 

Collection under number ZP-01-03 (holotype). As the 

physiological and molecular characterization of a mixed 

culture presents obvious difficulties, we propose that 

strain CBS 4551 T , isolated from hare droppings collected 

at Mount Fuji, Japan, should be designated as the type 

strain of C. cygneicollum. This strain is deposited in the 

Centraalbureau voor Schimmelcultures, Yeast Division, 



Fig. 2. Line drawings of different developmental 

stages of Curvibasidium cygneicollum 

(a, b), Curvibasidium pallidicorallinum 

(c, d) and Leucosporidium fasciculatum 

(e, f). Yeast cells (after 4–6 days on MYP 

agar), mycelium and teliospores (after 

1–2 weeks on PDA) (a, c, e) are shown; for 

Curvibasidium pallidicorallinum, the detail of 

the clamp connections is presented. 

Germinated teliospores, basidia and sessile 

basidiospores (b, d, f) are shown. Note the 

holobasidia of Curvibasidium cygneicollum 

and Curvibasidium pallidicorallinum and the 

phragmobasidia of L. fasciculatum. Bar, 

10 mm. 

Utrecht, The Netherlands, and in the Portuguese Yeast 

Culture Collection, FCT-UNL, Portugal, as PYCC 3116 T . 

Table 2. Physiological characteristics that allow differentiation 

between C. cygneicollum, C. pallidicorallinum, R. 

nothofagi and L. fasciculatum 

Species: 1, C. cygneicollum; 2,C. pallidicorallinum; 3,R. nothofagi; 

4, L. fasciculatum. D, Delayed results. The complete dataset of physiological 

and biochemical features is available at http://www.crem. 

fct.unl.pt/dimorphic_basidiomycetes/Databases/databases.htm. 

Characteristic 1 2 3 4 

Sucrose 2 2 2 + 

Maltose 2 2 2 + 

a,a-Trehalose 2 2 2 + 

m-Hydroxybenzoic acid 2 2 2 + 

Gallic acid + + + 2 

Catechol 2 2 2 + 

DL-Lactic acid 2 D + 2 

Cadaverine + 2 2 + 

Growth at 30 uC 2 2 + 2 

Latin diagnosis of Curvibasidium 

pallidicorallinum W. Golubev, Fell et 

N. Golubev sp. nov. 

Fungus dimorphum. Hyphae 1?5–2?5 mm diametro, conjugatione 

culturarum compatibilium procreantur, fibulatae. 

Colacosomata nulla. Teliosporae plerumque globosae (10– 

19 mm diametro) interdum ovoideae, pyriformes (9–16610– 

21 mm), terminales vel intercalares. Basidia unicellulata, 

3?5–5 (6?5)630–50 (70) mm, curvata. Basidiosporae 

sessiles, bacilliformes, 2?5–3?566–15 (19) mm, in appendicibus 

brevibus lateris convexi basidii procreantur, gemmis 

germinantes. Cellulae zymosae longe ovoideae ad cylindraceae, 

2–565–11 mm. Cultura in striis pallide corallina ad roseocremea. 

Characteres biochemici physiologicique Curvibasidii 

palleocorallini in http://www.crem.fct.unl.pt/dimorphic_ 

basidiomycetes/Databases/databases.htm describuntur. 

Description of Curvibasidium pallidicorallinum 

W. Golubev, Fell & N. Golubev sp. nov. 

Curvibasidium pallidicorallinum (pal.lid.i.cor.al9li.num. L. 

adj. pallidus pale; L. n. corallium coral; L. adj. pallidicorallinum 

pale coral, referring to the pinkish-cream colour of 

cultures of this species). 



Dimorphic. Hyphae (1?5–2?5 mm in diameter) are formed 

after mating of sexually compatible strains. Two mating 

types are known (see Table 1). Clamp connections are 

present and medallion-shaped (Fig. 2c). Colacosomes are 

absent. Teliospores are usually spherical (10–19 mm in 

diameter), sometimes ovoid or pear-shaped (9–166 

10–21 mm), terminal or intercalary (Fig. 2d). Basidia are 

one-celled [3?5–5 (6?5)630–50 (70) mm], curved and 

produced after a prolonged resting stage of the teliospores 

(Fig. 2d). Sessile, bacilliform basidiospores [2?5–3?566–15 

(19) mm] are produced on short basidial appendages that 

originate on the convex side of the basidium (Fig. 2d). Each 

basidium has one to four sites of basidiospore formation 

and multiple basidiospores are formed at each site. 

Basidiospores germinate by budding. Yeast cells are long 

and ovoid to cylindrical (2–565–11 mm) (Fig. 2c). Streak 

cultures are pale orange to pinkish-cream, flat, smooth, 

butyrous, semi-dull or glistening. Colony margins are entire. 

Physiological and biochemical features of C. pallidicorallinum 

are available at http://www.crem.fct.unl.pt/dimorphic_ 

basidiomycetes/Databases/databases.htm and tests that allow 

its differentiation from C. cygneicollum and R. nothofagi 

are depicted in Table 2. The phylogenetic placement of 

C. pallidicorallinum is shown in Fig. 1. C. pallidicorallinum 

is sensitive to the mycocins produced by R. glutinis and 

R. mucilaginosa, but insensitive to mycocins secreted by 

R. pallida and by species of the genera Cryptococcus, 

Cystofilobasidium, Filobasidium and Sporidiobolus. 

Microscopic slides from the crossing of VKM Y-2284 T and 

VKM Y-2861, including mycelium, teliospores, basidia and 

basidiospores, were deposited in the Portuguese Yeast 

Culture Collection under number ZP-02-03 (holotype). As 

the physiological and molecular characterization of a mixed 

culture presents obvious difficulties, we propose that strain 

VKM Y-2284 T , isolated from a gramineous plant collected 

in the Moscow region, Russia, should be designated the 

type strain of C. pallidicorallinum. This strain is deposited 

in the Russia Collection of Microorganisms (VKM), 

Institute for Biochemistry and Physiology of Microorganisms, 

Russian Academy of Sciences, Pushchino, Russia. Two 

strains have also been deposited in the Centraalbureau voor 

Schimmelcultures (CBS), Yeast Division, Utrecht, The 

Netherlands: CBS 9091 T (=VKM Y-2284 T ) and CBS 9642 

(=VKM Y-2861). 

The life cycles of C. cygneicollum and C. pallidicorallinum 

were investigated on MYP agar, CMA and PDA. 

Conjugation of opposite mating types resulted in the 

formation of true mycelium with clamp connections. In 

C. pallidicorallinum, clamp connections have a peculiar 

medallion shape (Fig. 2c). For both species, teliospores are 

abundant 1 week after inoculation, but their germination 

requires a prolonged resting stage. For C. cygneicollum, 

crossings made on PDA plates and incubated for 2 weeks at 

room temperature were sealed and maintained at 15 uC 

for 9 months. After that period, small agar blocks containing 

teliospores were transferred to 2 % water agar and 

incubated at room temperature. Teliospores germinated 

approximately 1 week after transfer to water agar. Although 

the same procedures were also successful for C. pallidicorallinum, 

the original observation of the complete life cycle of 

this species employed CMA. Agar pieces containing 1- 

month-old teliospores were soaked in distilled water and 

maintained at 5 uC for 1 year. Teliospore germination 

occurred on transfer of the agar blocks to 2 % water agar and 

incubation for 1 week at room temperature. The type strain 

of C. pallidicorallinum has mycocinogenic activity (Golubev, 

1992). Its killing patterns are unique, as they include not 

only urediniomycetous yeasts (Rhodosporidium, Rhodotorula 

and Sporidiobolus), but also hymenomycetous yeasts 

(Cryptococcus, Cystofilobasidium, Filobasidium and Itersonilia). 

This is the first report of mycocins that are active against 

yeasts of two different classes. 

Phylogenetic placement 

The phylogenetic position of Curvibasidium was inferred 

by comparing the D1/D2 domains of the 26S rRNA gene 

sequences of the two species with representative members 

of the Microbotryomycetidae (Fig. 1). C. cygneicollum 

differed from C. pallidicorallinum by three substitutions. 

The sequences of the two species showed no intraspecific 

variability. The closest relative of Curvibasidium was 

Leucosporidium fasciculatum Bab’eva & Lisichkina, with 

19 mismatches with respect to C. cygneicollum and 22 

mismatches with respect to C. pallidicorallinum. The 

association of L. fasciculatum with Curvibasidium received 

strong statistical support (Fig. 1). As L. fasciculatum is not 

related to Leucosporidium scottii Fell, Statzell, Hunter & 

Phaff, this species was excluded from the circumscription of 

the order Leucosporidiales (Sampaio et al., 2003). We reexamined 

the micromorphological features of L. fasciculatum 

(Fig. 2e, f) and confirmed the observations made by 

Bab’eva & Lisichkina (2000). The mycelium of L. fasciculatum, 

in contrast to that of Curvibasidium, lacks clamp 

connections (Fig. 2e) and the basidia are septate (phragmobasidia) 

(Fig. 2f). As the holobasidium of Curvibasidium 

is a unique trait in the Microbotryomycetidae, this feature 

is an important diagnostic property for the new genus 

and is probably a derived characteristic. The absence of 

this characteristic in L. fasciculatum prevented us from 

transferring this species to Curvibasidium. Moreover, 

Curvibasidium has CoQ 9 (Goto & Oguri, 1983), which is 

an uncommon feature in the Microbotryomycetidae. 

However, this chemotaxonomic marker has not yet been 

determined for L. fasciculatum. From nutritional and 

physiological perspectives, L. fasciculatum is also wellseparated 

from Curvibasidium (Table 2). We consider 

that a study of additional teleomorphic species related to 

Curvibasidium and L. fasciculatum is needed before a change 

in the scope of Curvibasidium, or the creation of a new genus 

for L. fasciculatum, is made. 

Another important feature of Curvibasidium is the absence 

of colacosomes (also referred to as lenticular bodies). 

Among members of the Microbotryomycetidae that are 



depicted in Fig. 1, the plant parasites of the Microbotryales 

and Kriegeria eriophori Bresadola lack colacosomes, as do the 

non-plant parasites Camptobasidium hydrophilum Marvanová 

& Suberkropp, Leucosporidium antarcticum Fell, Statzell, 

Hunter & Phaff and L. fasciculatum. The presence of colacosomes 

has been related to a mycoparasitic life strategy 

(Bauer & Oberwinkler, 1991). These subcellular structures 

have only been reported for certain dimorphic basidiomycetes 

classified in the Microbotryomycetidae, such as 

Colacogloea Oberwinkler & Bandoni, the Sporidiobolales 

(Rhodosporidium Banno and Sporidiobolus Nyland), the 

Leucosporidiales (L. scottii, Leucosporidium fellii Giménez- 

Jurado & van Uden and Mastigobasidium Golubev) and 

Heterogastridium Oberwinkler & Bauer, which lacks a yeast 

stage (Kreger-van Rij & Veenhuis, 1971; Sampaio et al., 2003). 

Anamorph–teleomorph connections 

As the type strain of R. fujisanensis is a mating strain of 

C. cygneicollum, it is evident that C. cygneicollum is the 

sexual stage of R. fujisanensis. A similar connection was 

suggested for C. pallidicorallinum and R. nothofagi on the 

basis of phylogenetic analysis of the D1/D2 domains 

(Fig. 1). However, several attempts to mate the type strain 

of R. nothofagi with the available sexually compatible strains 

of C. pallidicorallinum invariably gave negative results. The 

relationships of R. nothofagi, C. pallidicorallinum and 

C. cygneicollum were investigated further by analysing the 

complete ITS region (ITS1+5?8S rRNA gene+ITS2). No 

variability was detected for C. cygneicollum in the ITS 

region, whereas for C. pallidicorallinum–R. nothofagi, four 

sites were variable (a phylogenetic tree is available at http:// 

www.crem.fct.unl.pt/dimorphic_basidiomycetes/Databases/ 

databases.htm). In the analysis of the ITS data, the four 

sexually compatible strains of C. pallidicorallinum were 

separated from the two asexual strains (the type strain of 

R. nothofagi and strain A45). Nuclear DNA–DNA reassociation 

experiments also supported this separation, as 

homology between the type strains of C. pallidicorallinum 

and R. nothofagi was not high and ranged from 40 to 46 % in 

three independent essays. Therefore, on the the basis of 

the lack of sexual compatibility and the ITS and DNA 

reassociation data, we consider that R. nothofagi is not the 

asexual state of C. pallidicorallinum. R. nothofagi can be 

distinguished from C. pallidicorallinum on the basis of the 

ITS sequences, the absence of mating and the ability to grow 

at 30 uC. In both C. cygneicollum and C. pallidicorallinum, 

sexual compatibility seems to be biallelic, as crossing 

experiments suggested the presence of only two mating 

types. Six strains of C. cygneicollum (Table 1) are regarded as 

anamorphic, as they did not react sexually with the two 

mating types of this species. 

Acknowledgements 

We thank M. Weiß (University of Tübingen, Germany) for preparing 

the Latin diagnoses. M. G. was supported by grant SFRH/BD/1170/ 

2000. J. W. F. was supported by the USA National Science Foundation, 

Division of Environmental Biology (DEB 0206521). 

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