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New hyphomycete genera on Qualea species from the Brazilian cerrado

     Departamento de Fitopatologia, Universidade de Brasília, 70910-900 Brasília, D.F., Brasil

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS TAXONOMY LITERATURE CITED

 

As part of studies on cerrado fungi three new hyphomycetes are described in association with trichomes on leaves of native species of Qualea (Vochysiaceae). These are: Trichomatomyces gen. nov. (type species: T. byrsonimae comb. nov.), Trichosporodochium gen. nov. (type species: T. cerradensis sp. nov.), and Phaeoidiomyces gen. nov. (type species: P. qualeae).

Key words: systematics, taxonomy, trichome-associated fungi, tropical fungi

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS TAXONOMY LITERATURE CITED

 
Approximately one-forth of Brazil (2 million km²) is covered by a type of savanna known as cerrado (Eiten 1972). The cerrado is the second largest South American biome, surpassed in area only by the Amazon rainforest. The cerrado, with more than 6000 plant species (Mendonça et al 1998), also has a diverse and large population of plant-associated fungi (Dianese et al 1997, Dianese 2000, Dianese et al 2001). Batista and co-workers described more than 200 species collected by botanist H.P. Heringer (Silva and Minter 1995), Paul Hennings contributed with 69 taxa and Viégas with 47, among others (Dianese et al 1997). Several papers on cerrado hyphomycetes recently have been published (Dianese and Câmara 1994, Medeiros and Dianese 1994, Inácio et al 1996, Furlanetto and Dianese 1998, Inácio and Dianese 1999, Furlanetto and Dianese 1999, Dianese et al 1999, Dornelo-Silva and Dianese 2003).

The present work is a continuation of studies on hyphomycetes associated with cerrado hosts present in the Mycological Collection of the Herbarium UB, at University of Brasília. New fungal taxa detected on Qualea Mart. species are described.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS TAXONOMY LITERATURE CITED

 
Exsiccates of Qualea grandiflora Mart. and Q. multiflora Mart., collected in cerrado natural reserves, and held in Herbarium UB initially were studied under a stereomicroscope. Fungal samples were mounted in squash preparations or sectioned in a freezing microtome for morphological studies and microphotography. In most cases the samples were stained with lacto-glycerol-cotton blue or glycerol-KOH-phloxine B and the slides sealed with nail polish.

Pieces of leaves with one or more lesions showing representative samples of fruiting bodies were used for scanning electron microscopy (SEM) after being fixed in sodium cacodylate buffer, pH 7.4, 0.1M; containing glutaraldehyde 2%, for at least 24 h. The samples were dehydrated in an aqueous series with increasing acetone concentrations from 15, 30, 50, 75, 90 up to 100% acetone for 15 min in each concentration. Leaf pieces were dried at the critical point before being covered by a thin layer of gold in a sputter coater for 2 min (Souza 1998) before being observed under a scanning electron microscope (Jeol, model JSM 840-A E).

	TAXONOMY

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS TAXONOMY LITERATURE CITED

 
1. Trichomatomyces Dornelo-Silva & Dianese, nom. nov.

Type species: Trichomatomyces byrsonimae (Bat. & Peres) Dornelo-Silva & Dianese comb. nov. FIGS. 1–6

View larger version (142K): [in this window] [in a new window]   FIGS. 1–6. Trichomatomyces byrsonimae. 1, 2. Colonies on trichomes (bar = 10 µm). 3. Superficial mycelium on a trichome (bar = 10 µm). 4. Conidia (bar = 10 µm). 5. Polyblastic conidiogenous cells bearing conidia. 6. Conidia with rough surface, connected to a conidiogenous cell (bar = 10 µm).

Coloniae hypophyllae, brunneae, sparsae, prope costas, in trichomate insidentes. Mycelium superficiale, sparsum, pallido brunneum, in trichomate insidentes. Conidiophora 12–23 x 5–6 µm, micronematica, brunnea, laevia, 0–2-septata, simplicia, erecta vel curvata, plures cellulae conidiogenae ferentes. Cellulae conidiogenae 10–17 x 5–6 µm, integratae, polyblasticae, sympodiales, 0–2 septatae. Conidia 19–35 x 7–15 µm, brunnea, elliptico-fusiformia, apicibus acutis, cum basibus truncatis, 1–5-septata, aliquando muriformia, acropleurogena, leviter unilateraliter curvata; paries curvatus crassus cum constrictionibus septalibus; paries rectus tenuis.

Colonies hypophyllous, brown, sparse, near ribs, on trichomes (FIGS. 1, 2). Mycelium superficial, sparse, light brown, on trichomes (FIG. 3). Conidiophores 12–23 x 5–6 µm, micronematous, brown, smooth, 0–2-septate, single, straight to curved, giving rise to conidiogenous cells. Conidiogenous cells 10–17 x 5–6 µm, integrated, polyblastic, sympodial, 0–2-septate (FIGS. 4–6). Conidia 19–35 x 7–15 µm, brown, ellipticofusiforme, with acute apex and truncate base, 1–5 septate, seldom muriform, acropleurogenous, slightly unilaterally curved, wall with curved sector thicker than the straight portion; constricted at the septum but only towards the thinner lateral wall (FIGS. 4–6).

Specimens examined. – BRAZIL. DISTRITO FEDERAL: Brasília, Parque Nacional de Brasília. On living leaves of Qualea grandiflora, 21 Aug 1995, M.F. Almeida 13 (NEOTY PUS: UB col. mycol. 9851). BRAZIL. MINAS GERAIS: Divinópolis, Fazenda Sebastião Filgueiras. On living leaves of Q. grandiflora, 28 June 1995, J.C. Dianese 2378 (UB col. micol. 9110). BRAZIL. DISTRITO FEDERAL: Planaltina, Estação Ecológica das Águas Emendadas. On living leaves of Q. grandiflora, 13 June 1995, Z.M. Chaves 100 (UB col. micol. 8787). BRAZIL. DISTRITO FEDERAL: Planaltina, Estação Ecológica das Águas Emendadas. On living leaves of Q. grandiflora, 17 Sep 1995, M. Sanchez 1248 (UB col. micol. 10041). BRAZIL. DISTRITO FEDERAL: Planaltina, Estação Ecológica das Águas Emendadas. On living leaves of Q. grandiflora, 17 Sep 1995, A.L. Barbará 5 (UB col. micol. 10487). DISTRITO FEDERAL: Planaltina, Estação Ecológica das Águas Emendadas. On living leaves of Q. grandiflora, 23 June 1997, M. Sanchez 2866 (UB col. micol. 10487).

Trichomatomyces has some characteristics in common with Monodictys Hughes. However, Monodictys species have monoblastic conidiogenous cells and muriform conidia with rhexolitic secession. In addition, Trichomatomyces is foliicolous, associated with foliar trichomes while Monodictys is a saprobe on wood and bark of trees (Ellis 1971, 1976, Carmichael et al 1980).

Batista et al (1962) described this Trichomatomyces species as Piricauda byrsonimae Bat. & Peres on leaves of Byrsonima basiloba A. Juss (Malpighiaceae). However, species of Piricauda Bubak have polytretic, markedly cicatrized, curved conidiogenous cells (Ellis 1976), but in Trichomatomyces the conidiogenous cells are integrated, sympodial, and polyblastic. Thus the name applied was not appropriate leading now to the establishment of the new genus, Trichomatomyces (type-species T. byrsonimae). As the type material of P. byrsonimae was not preserved a neotype is designated.

2. Trichosporodochium Dornelo-Silva & Dianese, gen. nov.

Type species: Trichosporodochium cerradensis Dornelo-Silva & Dianese, sp. nov. FIGS. 7–13

View larger version (140K): [in this window] [in a new window]   FIGS. 7–13. Trichosporodochium cerradensis. 7. Superficial mycelium and sporodochia (arrow) mostly on the apex of a trichome (bar = 25 µm). 8, 9. Detail of a sporodochium at a trichome apex (bars = 25 µm and 20 µm). 10. Polyblastic conidiogenous cells and conidia (bar = 10 µm). 11. Conidia showing a protruding hilum (arrow) (bar = 10 µm). 12. Detail of the conidiogenous cells with scars (arrow) in SEM (bar = 10 µm). 13. Conidia seen in SEM (bar = 10 µm).

Colonies hypophyllous, brown, along ribs and in leaf areas rich in trichomes (FIGS. 7–9). Mycelium superficial, on trichomes (FIGS. 7–9). Hyphae 3–4 µm diam., brown, septate, branched, and flexuous. Sporodochia located at the tip of trichomes, with variable sizes and shapes but always formed by a compact aggregation of conidiogenous cells (FIGS. 7–10). Conidiophores are reduced to conidiogenous cells. Conidiogenous cells 7–12(10) x 5–6(5) µm, light brown, geniculate polyblastic, discrete, aseptate, cicatrized; scars thick and conspicuous (FIGS. 9, 10, 12). Conidia 40–70(55) x 5–7(6) µm, light brown to brown, fusiform, obconic or obclavate, 3–6-septate, with obtuse apices and truncate bases, (FIGS. 11, 13).

Specimens examined. – BRAZIL. DISTRITO FEDERAL: Planaltina, Estação Ecológica das Águas Emendadas. On living leaves of Qualea grandiflora, 17 Sep 1995, M. Sanchez 1248 (HOLOTY PUS: UB col. micol. 10042). BRAZIL. DISTRITO FEDERAL: Brasília, Parque Nacional de Brasília. On living leaves of Q. grandiflora, 14 Aug 1995, A.S. Alves 247 (UB col. micol. 9782). BRAZIL. DISTRITO FEDERAL: Brasília, Parque Nacional de Brasília. On living leaves of Q. grandiflora, 21 Sep 1995, C.M. Leadebal 33 (UB col. micol. 10072).

The sporodochial trichome-associated fungi are small and poorly studied. The sporodochial dematiaceous hyphomycetes in general (Ellis 1971, 1976, Carmichael et al 1980) are not related to Trichosporodochium because the known genera have macronematous conidiophores and mostly muriform conidia but never multiseptate, dark phragmoconidia. Thus, the specimen studied with conidiophores reduced to polyblastic, geniculate conidiogenous cells, is placed in the new genus, Trichosporodochium.

3. Phaeoidiomyces Dornelo-Silva & Dianese gen. nov.

Type species: Phaeoidiomyces qualeae Dornelo-Silva & Dianese sp. nov. FIGS. 14–20

View larger version (71K): [in this window] [in a new window]   FIGS. 14–20. Phaeoidiomyces qualeae. 14, 15. Erect conidiophores with a basipetal series of conidiogenous cells on superficial mycelium growing on a trichome (bar = 25 µm). 16. Early phase of conidiophore development and formation of conidiogenous cells (bar = 10 µm). 17. Conidiophores with catenate conidiogenous cells laterally forming conidia (bar = 10 µm). 18. Two conidiophores with percurrent proliferation (arrow) topped by a chain of conidiogenous cells (bar = 10 µm). 19, 20. Catenate conidia (bar = 8 µm).

Colonies hypophyllous, effuse, light brown. Mycelium superficial, located on the trichomes (FIGS. 14, 15). Conidiophores 18–185(49) x 5–9(5) µm, macronematous, mononematous, straight, solitary, brown to reddish brown, proliferating percurrently, successively forming a basipetal chain of conidiogenus cells from an ellongating apical cell (FIGS. 16–18). Conidiogenous cells 13–25(19) x 4–6(5) µm, cylindrical to doliiform, polytretic, dark brown, with walls thick and striate, proliferating meristemarthrosporically (sensu Hughes 1953) (FIGS. 17–18). Conidia 13–25(19) x 4–6(5) µm, fusiform, 0–3-euseptate, with septal constrictions, brown to reddish brown, with thick striate walls at maturity, solitary or short catenate; chains single or sympodially branched (FIGS. 19–20).

Specimens examined. – BRAZIL. DISTRITO FEDERAL: Brasília, Parque Nacional de Brasília. On living leaves of Qualea grandiflora, 21 Aug 1995, M.F. Almeida 13 (HOLOTY PUS: UB col. micol. 9851). BRAZIL. DISTRITO FEDERAL: Brasília, Parque Nacional de Brasília. On living leaves of Qualea grandiflora, 21 Aug 1995, K.B.D. Pereira 15 (UB col. micol. 9820). BRAZIL. DISTRITO FEDERAL: Brasília, Parque Nacional de Brasília. On living leaves of Q. multiflora, 13 Sep 1995, Z.M. Chaves 157 (UB col. micol. 9983).

Phaeoidiomyces is closely related to the genera Spadicoides S. Hughes (Hughes 1958) and Diploccocium Grove (Grove 1912, Ellis 1963, 1971, 1976). All three genera are dematiaceous hyphomycetes with polytretic terminal or intercalary conidigenous cells and unthickened conidiogenous loci (pores). Following Sinclair et al (1985), Kuthutheen and Nawawi (1991), Goh and Hyde (1996) and Ho et al (2002) it here is accepted that conidial catenation is taxonomically more relevant to segregate hyphomycete genera than conidiophore branching. Thus, Spadicoides was separated from Diplococcium mainly on the basis of this sole diagnostic character (Goh and Hyde 1996). The new genus is closer to Diplococcium because both have catenate conidia. However, in Phaeoidiomyces the conidiophore always is unbranched, it proliferates percurrently, giving rise to a basipetal chain of conidiogenous cells through successive elongations of the apical cell before a septum is formed to separate the newly developed conidiogenous cell. These thick walled striate cells will develop one or more conidiogenous sites where conidial short chains are formed. In Diplococcium, conidial chains are formed in apical and intercalary conidiogenous cells at the tips of branched conidiophores that are unable to proliferate percurrently. Conidiogenous cells in Diplococcium are not formed as a basipetal chain integrated in the conidiophore axis as in Phaeoidiomyces.

	ACKNOWLEDGMENTS

 
The authors thank CAPES-Brazilian Ministry of Education for a master’s fellowship granted to the first author, Fundação Banco do Brasil for a grant supporting the Cerrado Fungi Project at Universidade de Brasília, CNPq 1A-Fellowship granted to the second author and Prof. Mariza Sanchez for herbarium support.

	FOOTNOTES

 
Accepted for publication December 19, 2004.

Corresponding author. E-mail: jcarmine{at}unb.br

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