Chapter 108

Cuniculitrema Sampaio & R. Kirschner (2001)

Jose Paulo Sampaio and Roland Kirschner

DIAGNOSIS OF THE GENUS

Asexual reproduction: Yeast cells are ovoid or have an irregular shape, and produce one or more stalk-like conidiophores, each giving rise toa single conidium. The conidium is freed without forceful ejection at the distal end of the stalk. Ballistoconidia are not formed. Cultures arecream colored.Sexual reproduction: Basidiocarps are not known. Hyphae have clamp connections and haustorial branches. The sexual structures are formedin the filamentous phase. The basidia are of the Tremella-type, globose, with four compartments separated by longitudinal septa. The basidio-spores are passively released and germinate by budding. The septal pore is a dolipore with cupulate parenthesomes.Physiology/biochemistry: Fermentative ability is absent. myo-Inositol and D-glucuronate are utilized, but nitrate is not. Starch-like com-pounds are formed. The diazonium blue B reaction and production of urease are positive.Phylogenetic placement: Subphylum Agaricomycotina, Class Tremellomycetes, Order Tremellales, Family Cuniculitremaceae (Fig. 108.1).

TYPE SPECIES

Cuniculitrema polymorpha R. Kirschner & Sampaio

SPECIES ACCEPTED

1. Cuniculitrema polymorpha R. Kirschner & Sampaio (2001)

Kockovaella litseae JCM 10838T / AB292850

Kockovaella schimae CBS 8610T / AF363656

Kockovaella machilophila CBS 8607T / AF363654Kockovaella sacchari CBS 8624T / AF363650

Kockovaella thailandica CBS 7522T / AF075516

Kockovaella phaffii CBS 8608T / AF363655

Papiliotrema bandonii CBS 9107T / AF416642 10 changesAuriculibuller fuscus PYCC 5690T / AF444762

Bulleromyces albus CBS 500 / AF416643

Filobasidiella neoformans CBS 132 / AF07548471

76

72

69

98

81

Tremella mesenterica CBS 6973 / AF075518

Bulleribasidium oberjochense CBS 9110 / AF416646

CU

NIC

UL

ITR

EM

AC

EA

E

Fellomyces distylii CBS 8545T / AF363652

Fellomyces mexicanus CBS 8279T / AJ627906

Fellomyces polyborus CBS 6072T / AF189859

Fellomyces fuzhouensis CBS 6133T / AF075506

Cuniculitrema polymorpha CBS 9644T/ AY032662

FIGURE 108.1 Phylogenetic placement of Cuniculitrema polymorpha within the Tremellales. Maximum parsimony analysis (consensus tree)of an alignment of the D1/D2 region of the LSU rRNA gene sequences. The topology was rooted with Auriculibuller fuscus and Papiliotremabandonii. Numbers on the branches are bootstrap values (1000 replicates; values below 50% are not shown; T5 type strain).

1409The Yeasts, a Taxonomic Study© 2011 Elsevier B.V. All rights reserved.

SYSTEMATIC DISCUSSION OF THE SPECIES

108.1. Cuniculitrema polymorphaR. Kirschner & Sampaio (Kirschner et al. 2001a)

Anamorph: Sterigmatosporidium polymorphum G. Kraepelin &U. Schulze (1982)

Growth on 5% malt extract agar: After 6 days at 20�C, the yeastcells are ovoid or have an irregular shape, 2�433�10 μm(Fig. 108.2A). Buds are formed at the end of stalk-like conidiophoresor spiny denticles. Stalk-like conidiophores are narrow (approxi-mately 1 μm), but vary in length from 3�11 μm. The new bud sepa-rates at the distal end of the condidiophore. The streak culture iscream colored, smooth or verrucose, glossy or with a powdery sur-face, butyrous, and with hyphae or pseudohyphae developing fromthe margin.Dalmau plate culture on corn meal agar: Pseudohyphae and truehyphae are formed.Sexual state: In culture, self-fertile or mating strains form hyphaewith complete clamp connections and haustoria (Fig. 108.2C).Conidiogenic cells that form on the mycelium produce, at the base ofa clamp connection, conidia that probably are dikaryotic(Fig. 108.2B). In old conidiogenic structures, clusters of clamp rem-nants form peculiar structures (Fig. 108.2B). Basidia have only been

observed in nature or in primary mixed cultures composed of bacte-ria, yeasts and hyphomycetes, but not in pure cultures. Basidia are ofthe Tremella type, globose or subglobose, 9�11 μm in diameter, withlongitudinal septa and four compartments (Fig. 108.2D, E). The basi-dial sterigmata can be long, 1�2312�88 μm, and in the apex formallantoid basidiospores measuring 4�738�13 μm (Fig. 108.2F). Thebasidiospores germinate by budding.

Fermentation: Absent.

Growth (in Liquid Media)1

Glucose 1

Inulin 2

Sucrose 1

Raffinose 1

Melibiose sGalactose 2

Lactose sTrehalose sMaltose 1

Melezitose 1

Methyl-α-D-glucoside 1

Soluble starch 1

Cellobiose 1

Salicin 1

L-Sorbose 1

L-Rhamnose 1

D-Xylose 1

L-Arabinose vD-Arabinose 2

D-Ribose 1

Methanol 2

Ethanol 1

Glycerol 2

Erythritol vRibitol sGalactitol sD-Mannitol 1

D-Glucitol 1

myo-Inositol 1

DL-Lactate 2

Succinate 1

Citrate 1

D-Gluconate 1

D-Glucosamine 1

N-Acetyl-D-glucosamine nHexadecane nNitrate 2

Vitamin-free 1

1Based on CBS 8088, CBS 9643, CBS 9644, CBS 9645 and CBS 9646.

Additional Growth Tests and Other Characteristics1

Nitrite 2

D-Glucuronate 1

Xylitol 2

L-Tartaric acid 2

Saccharic acid 2

Protocatechuic acid 2

p-Hydroxybenzoic acid 2

m-Hydroxybenzoic acid 2

Gallic acid 2

Gentisic acid 2

Vanillic acid 2

Ethylamine 1

L-Lysine 1

Cadaverine 2

Creatine 2

Creatinine 2

Cycloheximide 0.1% 1/sGrowth at 25�C 1

Growth at 30�C 1

Growth at 35�C 2

Starch formation 1

DBB 1

1Based on CBS 8088, CBS 9643, CBS 9644, CBS 9645 and CBS 9646.

CoQ: 10, determined from the anamorph (S. polymorphum) byYamada and Banno (1984).Mol% G1C: 51.3, PYCC 5647 (Tm: Kirschner et al. 2001a).Gene sequence accession number, type strain: CBS 9644: D1/D2LSU rRNA5AY032662.Cell carbohydrates: Not determined.Origin of the strains studied: All strains representing the sexualstate were isolated from bark pieces of Norway spruce (Picea abies)or Scotch pine (Pinus silvestris) infested with bark beetles and col-lected in Germany as follows: CBS 9643, CBS 9645 and CBS 9646,from six-toothed spruce bark beetle (Pityogenes chalcographus)infesting Scots Pine (Picea abies); CBS 9644 (PYCC 5647), from weevil(Gnathotrichus materiarius) infesting Norway spruce (Pinus sylvestris)(Kirschner et al. 2001a). CBS 8088, type strain of Sterigmatosporidiumpolymorphum, from water-logged plank in old ore mine, Germany(Kraepelin and Schulze 1982).

(A)

(B) (C)

(D)(E) (F)

FIGURE 108.2 Cuniculitrema polymorpha CBS 9644. (A) Buddingcells on 5% malt extract agar after 6 days at 20�C. (B) Conidiophores,conidiogenic cells and conidia (note the numerous clamp remnantsin old conidiogenic structures). (C) Haustoria (one attached to ahypha of Hormonema dematioides). (D) Cluster of matured basidia.(E) Two basidia with basidiospores. (F) Basidiospores. Bars510 μm.Bar in (B) is the same for (C�F).

1410 PART | VB Descriptions of Teleomorphic Basidiomycetous Genera and Species

Type strain: No living culture was derived from the type material.CBS 9644 was designated a representative strain of C. polymorpha(Kirschner et al. 2001a).Systematics: Within the Tremellales, Cuniculitrema polymorpha isplaced in a clade of stalk-forming yeasts of the genera Fellomyces andKockovaella (Fig. 108.1). According to the phylogenetic tree depictedin Fig. 108.1, C. polymorpha occupies a basal position in relation toboth Fellomyces and Kockovaella.

Kirschner et al. (2001a) proposed that Sterigmatosporidium polymor-phum should be considered as the asexual stage of C. polymorpha. Usingthe HCl-Giemsa staining method, Kraepelin and Schulze (1982)observed that in S. polymorphum, the spores arising from clamp connec-tions contained one or two nuclei after liberation from the conidiogen-ous cells and more than four nuclei prior to germination. Uninucleateand binucleate yeast cells were also found. The authors concluded thatkaryogamy and meiosis took place in those propagules, and conse-quently that S. polymorphum should be regarded as a teleomorphictaxon. This view was followed in subsequent editions of monographsdealing with yeast systematics (Barnett et al. 1990; Statzell-Tallman1998). In a contrasting view, Bandoni (1986a) described the heterobasi-diomycetous anamorph genus Tremellina, in which propagules arisefrom clamps developing on inflated cells. In the description ofTremellina pyrenophila, Bandoni illustrated spores apparently containingone or two nuclei and reported that they contained four nuclei prior toproduction of the germ tube. He also found uninucleate and binucleateyeast cells. In contrast with Kraepelin and Schulze (1982), Bandoniregarded those propagules as conidia. The close phylogenetic resem-blance between Sterigmatosporidium and Cuniculitrema (namely, twosubstitutions in the D1/D2 region of the LSU rRNA gene), the high

nuclear DNA�DNA reassociation values, the identical nutritional pro-files, and the fact that other asexual species possess structures with themorphological and cytological features of Sterigmatosporidium, ledKirschner et al. (2001a) to consider Sterigmatosporidium as the asexualstate of Cuniculitrema.Ecology: Cuniculitrema polymorpha was found to be carried by barkbeetles infesting Picea abies, Pinus sylvestris and Larix decidua in sev-eral localities in Germany and Switzerland (Kirschner et al. 2001a).The fungus was found in slimy microbial masses in the galleries ofbark beetles. The anamorph S. polymorphum was reported from asimilar micro-habitat on wood in an old mine by Kraepelin andSchulze (1982). Since the fungus develops haustorial cells that can beattached to other fungal cells, it is probably a mycoparasite. Barkbeetles might act as vectors of C. polymorpha.Biotechnology: Unknown.Agriculture and food: Unknown.Clinical importance: Unknown.Additional comments: Besides the basidial and the yeast states dis-cussed above, C. polymorpha forms a type of conidiogenous cells inwhich conidia secede from a basal clamp connection (Fig. 108.2B).

COMMENTS ON THE GENUS

The salient features of Cuniculitrema are the production of Tremella-typebasidia, combined with the formation of stalked conidiophores, and anintermediate, probably dikaryotic, conidial stage. A Cuniculitrema-likelife cycle might be hypothesized for its asexual relatives presentlyclassified in Fellomyces and Kockovaella.

1411Chapter | 108 Cuniculitrema Sampaio & R. Kirschner (2001)