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New species of Dictyochaetopsis and Paraceratocladium from Brazil

     Unitat de Microbiologia, Facultat de Medicina i Ciències de la Salut, 43201 Reus and Institut d'Estudis Avançats, Universitat Rovira i Virgili, Tarragona, Spain

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS TAXONOMY LITERATURE CITED

 

Two new conidial fungi, Dictyochaetopsis brasiliensis and Paraceratocladium bacilliformis, both isolated from plant debris collected in Brazil, are described and illustrated. Dictyochaetopsis brasiliensis differs from the previously described species of the genus mainly by small, fusiform conidia with a very thin apical setula, absence of setae, and lateral, discrete conidiogenous cells with usually numerous sympodial proliferations. Paraceratocladium bacilliformis is characterized by small, bacilliform and aseptate conidia.

Key words: conidial fungi, litter, systematics, tropical hyphomycetes

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS TAXONOMY LITERATURE CITED

 
In the course of a study of decaying plant material collected in different locations from Brazil, two hyphomycetes with morphologic features typical of Dictyochaetopsis Aramb. & Cabello (Arambarri and Cabello 1990) and Paraceratocladium R. F. Castañeda (Castañeda 1987) were found respectively on an unidentified decaying Papillonaceae fruit and on an unidentified decaying rotten twig. However, they do not fit into any of the currently accepted species of these genera and they are therefore described as new.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS TAXONOMY LITERATURE CITED

 
Samples were collected from different localities in Brazil, put into sterilized polyethylene bags and stored in the refrigerator at 4–7 C in the laboratory until they were processed. The plant material was placed into moist chambers that were incubated at room termperature (22–25 C) and examined under a stereomicroscope over a 3-wk period. In order to isolate the hyphomycetes in pure culture, conidia were transferred from the natural substrate to potato carrot agar (PCA: 20 g potatoes, 20 g carrots, 20 g agar, 1 L distilled water) and oat-meal agar (OA: 30 g flakes, 20 g agar, 1 L distilled water), and were incubated at room temperature. Dried and living cultures have been preserved in the collections indicated in the text. Micrographs were obtained with a Leitz Dialux 20 EB microscope and a Jeol JSM-6400 scanning electron microscope using the techniques described previously by Figueras and Guarro (1988).

	TAXONOMY

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS TAXONOMY LITERATURE CITED

 

Dictyochaetopsis brasiliensis Calduch, Gené, Stchigel et Guarro, anam. sp. nov. Figs. 1– 13

View larger version (29K): [in this window] [in a new window]    FIGS. 1–3. Dictyochaetopsis brasiliensis, IMI 386278. 1. Sketch habit. 2. Conidiophores and conidia. 3. a. Detail of a conidiophore with conidiogenous cells and conidia. b. Conidia with setula. Bars: 1 = 100 µm, 2 = 10 µm, 3a = 10 µm, 3b = 5 µm.

View larger version (139K): [in this window] [in a new window]    FIGS. 4–13. Dictyochaetopsis brasiliensis, IMI 386278. 4. Conidiophores and conidia. 5–7. Detail of conidiophore upper part showing integrated mono- and polyphialidic conidiogenous cells and conidia. 8–11. Detail of discrete, lateral conidiogenous cells. 12, 13. Conidia. Bars: 4 = 20 µm, 5–11 = 5 µm, 12 = 10 µm, 13 = 5 µm

Conidial fungi, hyphomycetes. Colonies on the natural substrate effuse, hairy, pale brown to brown. Mycelium partly immersed in the substrate. Hyphae septate, branched, smooth-walled, pale brown to brown, 1.5–2 µm diam. Setae absent. Conidiophores macronematous, mononematous, arising single or in small groups, erect, straight or somewhat flexuous, unbranched, 4–8-septate, smooth, thick-walled, brown, paler and thin-walled towards the apex, up to 135 µm long, with a swollen base, 6–10 µm wide, 3–5 µm wide in the middle and 1.5–2.5 µm wide towards the apex, which is always fertile. Conidiogenous cells monophialidic or polyphialidic, with a funnel-shaped collarette at each conidiogenous aperture, integrated at the apex, subhyaline, up to 6.5 µm long, or discrete, lateral, ampulliform or lageniform, sometimes slightly curved, orthotropic and usually arranged in 3–5 whorls along the conidiophore stipe, olive, smooth-walled, 4.5–12 µm long, 3–4.5 µm wide at the broadest part. Conidia in colorless slimy masses, fusiform, straight to slightly curved, aseptate, hyaline, thin- and smooth-walled, 5–6.5 x 1–2 µm, bearing a very thin (almost inconspicuous), undulate, single setula of up to 14 x 0.5 µm at the apex. Secession schizolytic. Teleomorph unknown.

Specimen examined. BRAZIL. RIO DE JANEIRO: Corcovado Mountain Forest, on an unidentified decaying Papillonaceae fruit, 11 May 1999, J. Guarro and M. Calduch, (HOLOTYPE: IMI 386278; ISOTYPE: FMR 7058).

Etymology. From the Latin brasiliensis, referred to the country where the fungus was collected.

Known distribution. Brazil.

Habitat. Saprobic on plant debris.

Colonies on OA at 25 C growing slowly, attaining 14–16 mm diam in 21 d, velvety, pale gray to dark brown, with a regular margin; reverse dark brown. Colonies on PCA at 25 C, attaining 8–10 mm diam in 21 d, velvety, pale gray at the center, pale brown to dark brown at the periphery, with submerged mycelium at the margin; reverse pale brown to dark brown. On both media the sporulation was very poor and the conidiophores never developed lateral conidiogenous cells.

The genus Dictyochaetopsis, with D. apicalis (Berk. & M. A. Curtis) Aramb. & Cabello as the type species, was characterized by macronematous, brown and setiform conidiophores with fertile or sterile apex, which bear phialidic, mostly discrete conidiogenous cells with distinct flared collarettes, and by hyaline, fusoid to cylindrical slimy conidia with or without setulae. The genus was established by Arambarri and Cabello (1990) to redispose those species of Codinaea Maire and Dictyochaeta Speg. that produced discrete and lateral phialides. According to this criteria, more recently, Whitton et al (2000) transferred other four Dictyochaeta species, i.e., D. antillana R. F. Castañeda, D. gonytrichoides (Shearer & J. L. Crane) Kuthub. & Nawawi, D. hamata Kuthub. & Nawawi and D. pahangensis Kuthub. & Nawawi to Dictyochaetopsis. Therefore, a total of 12 species, all of them reported from litter or submerged plant debris, are presently accepted in the genus (Whitton et al 2000).

Our specimen is clearly a species of Dictyochaetopsis because its conidiophore and conidial morphology. It is morphologically close to D. antillana (R. F. Castañeda) Whitton, McKenzie & K. D. Hyde, D. pahangensis (Kuthub. & Nawawi) Whitton, McKenzie & K. D. Hyde and D. gonytrichoides (Shearer & J. L. Crane) Whitton, McKenzie & K. D. Hyde (Kuthubutheen and Nawawi 1990, Whitton et al 2000). However, D. antillana differs mainly by the presence of setae and longer conidia (11–15 µm), and D. pahangensis and D. gonytrichoides by their longer conidia (8.5–13 µm and 12–16 µm, respectively) with a simple setula at both ends. Furthermore, the conidiogenous cells of D. pahangensis grow out from bulbous hyphae and those of D. gonytrichoides are borne on nodose hyphae which encircle the stipe of the conidiophore.

Dictyochaeta unisetula (Morgan-Jones & E. G. Ingram) Whitton, McKenzie & K. D. Hyde (Morgan-Jones and Ingram 1976, Whitton et al 2000) has similar conidia to Dictyochaetopsis brasiliensis, but the former differs by the conidiophore morphology, which are shorter (28–76 µm) and without discrete, lateral conidiogenous cells.

Two Chaetopsis Grev. species sensu DiCosmo, S. M. Berch & W. B. Kendr. (DiCosmo et al 1983), C. cubensis R. F. Castañeda (Castañeda 1985) and C. intermedia R. F. Castañeda & W. B. Kendr. (Castañeda and Kendrick 1991), both described from plant debris in Cuba, have some morphological features similar to Dictyochaetopsis brasiliensis, especially those of the conidiogenous cells. However, C. cubensis has conidiogenous cells with percurrent proliferations and its conidia are 1-septate, lunate and longer (8.5–12.5 µm), and C. intermedia has setiform conidiophores and the conidia are mostly 1-septate, falcate and larger (21–23 x 1–2 µm). In our opinion, C. cubensis and C. intermedia should be transferred to Dictyochaetopsis on the basis of conidiogenesis and the arrangement of the conidiogenous cells on the conidiophores. However, a more extensive study of the type material including more strains, if available, should be done.

Paraceratocladium bacilliformis Calduch, Stchigel, Gené et Guarro, anam. sp. nov. Figs. 14– 24

View larger version (46K): [in this window] [in a new window]    FIGS. 14–17. Paraceratocladium bacilliformis, IMI 386071. 14. Sketch habit. 15. Basal and distal part of setae bearing conidiogenous cells and conidia. 16. Detail of conidiogenous cells and conidia. 17. Conidia. Bars: 14 = 100 µm, 15, 16 = 10 µm, 17 = 5 µm

View larger version (150K): [in this window] [in a new window]    FIGS. 18–24. Paraceratocladium bacilliformis, IMI 386071. 18, 19. Colony from natural substrate. 20, 21. Conidia. 22, 23. Part of conidiophores with phialidic conidiogenous cells and conidia. 24. Detail of the conidiophores twining and ascending the basal portion of a setae. Bars: 18 = 50 µm, 19 = 100 µm, 20, 21 = 5 µm, 22 = 10 µm, 23 = 5 µm, 24 = 10 µm

Conidial fungi, hyphomycetes. Colonies on the natural substrate hairy, hyaline to grayish due to abundance of conidial sporulation. Mycelium partly immersed in the substrate. Hyphae septate, branched, pale brown to brown, smooth-walled, 1.5–2.5 µm diam. Setae unbranched, subulate, up to 9 septate, erect, straight, brown to dark brown, paling distally, smooth- and thick-walled, 220–335 x 4–6.5 µm, base swollen, 10–18 µm wide. Conidiophores micronematous to semimacronematous, mononematous, irregularly branched, septate, flexuous, ascendent, adhering and twining around the setae, smooth-walled, pale brown. Conidiogenous cells monophialidic, discrete, mostly intercalary, lageniform to ampulliform, collarette conspicuous, pale brown, 4.5–6.5 µm long, 2.5–4 µm wide at the broadest part, mostly orthotropic. Conidia in slimy heads, aseptate, bacilliform, slightly curved, with an eccentric inflated scar at the base (under SEM), hyaline, smooth-walled, 3–4.5 x 0.5–1 µm. Secession schizolytic. Teleomorph unknown.

Specimen examined. BRAZIL. RIO DE JANEIRO: Corcovado Mountain Forest, on unidentified decaying rotten twig, 11 May 1999, J. Guarro, A. M. Stchigel and M. Calduch, (HOLOTYPE: IMI 386071; ISOTYPE: FMR 7289; ex-type culture: CBS 1095243).

Etymology. From the Latin bacilliformis, referring to the conidial shape.

Known distribution. Brazil.

Habitat. Saprobic on plant debris.

Colonies on OA at 25 C, attaining 29–31 mm diam in 21 d, flat, velvety and pale grey colored at the center, white at the periphery, with a regular margin, mycelium mainly submerged; reverse white. Colonies on PCA at 25 C growing slowly, attaining 13–16 mm diam in 21 d, with similar macroscopic characteristics to those on OA. On both media the microscopic features were very similar to those observed on the natural substrate.

The genus Paraceratocladium was erected by Castañeda (1987) with P. silvestre, as type species, and P. polysetosum. Both species were found colonizing plant debris from Cuba. The genus was characterized by conidiophores which arise from the substrate and entwine on dematiaceous, erect setae, by monophialidic conidiogenous cells with a conspicuous collarette, and by 1-septate, hyaline conidia. Paraceratocladium triseptata Dulym., W. Wu & Peerally (Dulymamode et al 1998) occurring on leaves of Pandanus palustris Thou. in Mauritius, P. malaysianum Goh & K. D. Hyde (Goh and Hyde 2000) found on submerged wood in Malaysia, and P. seychellarum Whitton, McKenzie & K. D. Hyde (Whitton et al 2001) found on decaying leaves of Pandanus seychellarum Balf.f. in Seychelles have been recently included in the genus. The former differs from the rest of the species by its polyphialidic conidiogenous cells and 3-septate conidia, P. malaysianum by its conidia, which are the largest in the genus, and P. seychellarum by its branched setae, and by the small and aseptate conidia. The present species has similar conidial morphology to that of P. seychellarum, but conidia of P. bacilliformis are narrower and its setae are unbranched.

	ACKNOWLEDGMENTS

 
The authors are grateful to R. F. Castañeda (INIFAT, Ciudad de La Habana, Cuba) for his helpful comments and to E. Descals (IMEDEA, CSIC-UIB, Esporles, Mallorca, Spain) for reviewing the manuscript.

	FOOTNOTES

 
¹ Corresponding author, jgd{at}fmcs.urv.es

Accepted for publication March 31, 2001.

	LITERATURE CITED

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS TAXONOMY LITERATURE CITED

 
Arambarri AM, Cabello MN., 1990 Considerations about Dictyochaeta, Codinaeopsis and a new genus Dictyochaetopsis. Mycotaxon 38:11-14

Castañeda RF., 1985 Deuteromycotina de Cuba. Hyphomycetes III. C. Habana, Cuba: Instituto de Investigaciones Fundamentales en Agricultura Tropical "Alejandro de Humboldt". 42 p

———. 1987 Fungi cubenses II. C. Habana, Cuba: Instituto de Investigaciones Fundamentales en Agricultura Tropical "Alejandro de Humboldt". 22 p

———, Kendrick WB., 1991 Ninety-nine Conidial Fungi from Cuba and three from Canada. Waterloo, Canada: University of Waterloo. Biology Series 35. 132 p

Dicosmo F, Berch S, Kendrick WB., 1983 Cylindrotrichum, Chaetopsis, and two new genera of Hyphomycetes, Kylindria and Xenokylindria. Mycologia 75:949-973

Dulymamode R, Wu W, Peerally A., 1998 Three new hyphomycetes on Pandanus leaves from Mauritius. Mycoscience 39:285-291

Figueras MJ, Guarro J., 1988 A scanning electron microscopic study of ascoma development in Chaetomium malaysiense. Mycologia 80:298-306

Goh TK, Hyde KD., 2000 Paraceratocladium malaysianum sp. nov. (mitosporic fungi) from submerged wood in Malaysia. Nova Hedwigia 71:95-100

Kuthubutheen AJ, Nawawi A., 1990 Dictyochaeta hamata and D. pahangensis, two new species with lateral phialides. Mycol Res 94:840-846

Morgan-Jones G, Ingram EG., 1976 Notes on Hyphomycetes. XV. Two new species of Codinaea. Mycotaxon 4:504-509

Whitton SR, McKenzie EHC, Hyde KD., 2000 Dictyochaeta and Dictyochaetopsis species from the Pandanaceae. Fungal Diversity 4:133-158

———, ———, ———. 2001 Microfungi on the Pandanaceae: Paraceratocladium seychellarum sp. nov. and a review of the genus. Fungal Diversity 7:175-180

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