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A new species of Syspastospora from tropical soils

     Instituto de Investigaciones Fundamentales en Agricultura Tropical "Alejandro de Humbolt", calle 1 esq.2, Santiago de las Vegas, Boyeros, C. de La Habana, Cuba

A. M. Stchigel
J. Guarro ¹

     Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, C/ Sant Llorenç 21, 43201, Reus, Tarragona, Spain

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS LITERATURE CITED

 

Syspastospora tropicalis sp. nov. isolated from soil samples from different tropical regions is described and illustrated. The fungus can be easily separated from the other species of the genus by its setose perithecial ascomata with a short papillate neck.

Key words: Ascomycota, Ceratostomataceae, soil borne fungi

	INTRODUCTION

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The genus Syspastospora was erected by Cannon and Hawksworth (1982) to accommodate S. parasitica (Tul.) P. F. Cannon & D. Hawksw. (1982), which was removed from Melanospora Corda mainly on the basis of the neck structure. In Syspastospora the neck is long and formed by more or less parallel hyphae with remote septa, and in Melanospora it is short and composed of pseudoparenchymatous cells. The ring of hyaline setae around the ostiole, which is universally present in Melanospora, is lacking in Syspastospora. Another distinctive feature is the shape of the ascospores, which in Syspastospora are cylindrical to doliiform, with truncate ends and with large terminal crateriform germ pores, while in Melanospora they are usually ellipsoidal to citriform, and with small, slightly sunken germ pores (Cannon and Hawksworth 1982). The second species of the genus, S. boninensis Horie, Udagawa & P. F. Cannon (1986), is characterized by non-ostiolate ascomata and wider ascospores.

During a survey of soil-borne ascomycetes in tropical forests of different countries numerous strains of an interesting species of Syspastospora were isolated. This species proved to be sufficiently different from those previously described to warrant the proposal of a new taxon.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS LITERATURE CITED

 
The soil samples were collected in Argentina, Cuba, Nepal, and Nigeria in different forays (1995–2000). In Argentina, soil samples were collected in areas of the Las Yungas rainforest with average monthly temperatures between 11 and 30 C and an annual precipitation of 2500 mm. Samples from Cuba were collected from four localities with average monthly temperatures ranging from 24 to 26 C and an annual precipitation of approximately 1400 mm. Soil samples from Nepal were collected at a site 1440 m above sea level and with a subtropical climate (average monthly temperature 2–32 C, annual precipitation 1570 mm). Soils from Nigeria were collected at a site 300 m below sea level with a tropical hinterland climate (temperatures usually higher than 27 C, annual precipitation 2000–3000 mm).

Soil samples were collected from the A₀ horizon using sterile polyethylene bags. These were then sealed with a rubber band and labeled. Material was stored in a refrigerator at 4–7 C. A soil bait technique was used for recovering the fungi. Petri dishes were half-filled with the soil samples and moistened with sterile distilled water. Several pieces of sterile wood (approx 1 x 2 cm) were placed on the soil surface or partially buried in it. Petri dishes were incubated at room temperature, in darkness, and checked weekly. Axenic cultures of the growing fungi were obtained from masses of mature ascospores ejected from the ascomata. Isolates were grown on oatmeal agar (OA; Difco, Detroit, Michigan, USA), potato carrot agar (potatoes 20 g, carrot 20 g, agar 20 g, tap water 1000 mL) and malt extract agar (MEA, Difco, Detroit, Michigan, USA) and incubated at 15, 25, and 35 C. Color notations in parentheses are from Kornerup and Wanscher (1984). Measurements were made from slide preparations mounted in water and lactophenol. Photomicrographs were obtained with a Leitz Dialux 20EB microscope. Scanning electron microscopy techniques were described previously by Figueras and Guarro (1988).

Syspastospora tropicalis D. García, Stchigel & Guarro, sp. nov. Figs. 1–10

View larger version (48K): [in this window] [in a new window]    FIGS. 1–3. Syspastospora tropicalis FMR-7301. 1. Ascoma. 2. Ascus with ascospores. 3. Ascospores. Scale bars: 1 = 20 µm, 2, 3 = 5 µm

Mycelium composed of hyaline to pale yellowish-brown, branched, septate, smooth hyphae, 2–5 µm diam. Colonies on MEA attaining 80 mm diam in 14 d at 25 C, cottony, grayish-yellow (4B4); reverse similarly colored. Colonies on OA spreading, attaining 70–80 mm diam in 14 d at 25 C, consisting of abundant aerial mycelium, floccose, white to pale yellow (4A3); reverse brownish orange (5C5). Colonies on PCA spreading broadly, attaining a diam of 70–86 mm in 14 d at 25 C, consisting of a thin basal felt with abundant aerial growth, white to yellowish-white (4A2), granulose due to the production of abundant ascomata; reverse pale yellow (4A3) to yellowish-brown (5D5). Ascomata produced only on PCA.

Ascomata superficial or immersed, sparse or aggregated in small groups, pyriform to globose, ostiolate, (71–) 90–109 (–220) x 45–85 (–156) µm, pale yellow to yellowish-brown, usually appearing darker when full of mature ascospores, setose; setae stiff to slightly curved or sinuous, 30–80 µm long, 1.5–4 µm wide at the base, pale yellow to yellowish-brown, non-septate, thick-walled; beak short or absent, conical, up to 30 µm long, 20–30 µm wide at the base, made up of relatively short cells, similar to those of the body wall, but longer and with a rounded tip. Peridium membranaceous, 2–3 layered, translucent, composed of thin-walled cells measuring 4–15 µm in diam that form a textura angularis in surface view. Paraphyses absent. Asci 8–spored, obovate to broadly clavate, fasciculate, 12–19 x 6–12 µm, with a rounded apex and without apical structures, short stipitate, evanescent. Ascospores irregularly arranged, at first hyaline and guttulate, becoming light brown to olive-brown, doliiform to cylindrical, 4–5.5(–6) x (3–) 3.5–4.5 µm, one-celled, smooth and thick-walled, with truncate ends and a large, slightly sunken germ pore at each end, behind which the ascospore wall is slightly constricted; germ pores 1–1.5 (–2.5) µm in diam, surrounded by a flange formed from the ascospore wall that sometimes extends as a conspicuous crest along one side of the ascospore. Chlamydospores globose to ovoid, 7–10 µm in diam, brown, thick-walled, terminal or intercalate. Conidial anamorph absent.

Material examined. ARGENTINA. SALTA PROVINCE: Rosario de la Frontera, from soil, 18-V-2000, col. A.M. Stchigel, J. Guarro and J. Cano, isol. D. García (HOLOTYPE: IMI 385315, ISOTYPE: FMR 7301).

Other specimens examined. ARGENTINA.TUCUMAN PROVINCE: Cerro San Javier, 15-V-2000, col. A.M. Stchigel, J. Guarro and J. Cano (FMR-7403); SALTA PROVINCE: Rosario de la Frontera, 8-V-2000, col. A.M. Stchigel, J. Guarro and J. Cano (FMR-7444); CUBA. HOLGUIN PROVINCE: Loma La Gloria, 6-XII-1995, col. J. Guarro and E. Mayayo (FMR-7260, FMR-7261, FMR-7438), CAMAGÜEY PROVINCE: Camagüey City, col. J. Guarro and E. Mayayo, 7-XII-1995 (FMR-7440), MATANZAS PROVINCE: Zapata, 8-XII-1995, col. J. Guarro and E. Mayayo (FMR-7404, FMR-7441), LA HABANA PROVINCE: San Antonio de Los Baños, "Las Yagrumas", 9-XII-1995, col. J. Guarro and E. Mayayo (FMR-7439); NEPAL, Dhulikhel, 3-VI-1996, col. J. Gené (FMR-7399, FMR-7402); NIGERIA. ANAMBRA STATE: Campus Nsukka University, 2-VII-1997, col. A.M. Stchigel, M. Calduch and J. Guarro (FMR-7442, FMR-7443).

Syspastospora tropicalis can be easily differentiated from S. parasitica, a species that possesses a long neck (400–3000 µm in length) composed of parallel adhering hyphae, and narrower ascospores (2–2.5 µm) (Doguet 1955, Cannon and Hawksworth 1982). Syspastospora boninensis is distinguished from S. tropicalis by its non-ostiolate ascomata and longer ascospores (6–9 µm) (Horie et al 1986). Some strains of the new species exhibit a peculiar characteristic never seen before in this genus in that a conspicuous crest extends along one side of the ascospore (FMR-7301, FMR-7399, FMR-7402, FMR-7404, and FMR-7441). However, because the other important morphological characteristics of these strains are identical to those of the other isolate studied, we do not think that this feature alone justifies the erection of a different species.

View larger version (145K): [in this window] [in a new window]    FIGS. 4–10. Syspastospora tropicalis. 4–10. Syspastospora tropicalis FMR-7301. Ascoma. 5. Detail of the neck. 6, 7. Asci. 8. Ascospore. 9. Ascospores (SEM). 10. S. tropicalis FMR-7399. Ascospores (SEM). Scale bars = 5 µm. Scale bars: 4 = 20 µm, 5–7 = 10 µm, 8–10 = 5 µm

	ACKNOWLEDGMENTS

	FOOTNOTES

 
¹ Corresponding author, Email: umb{at}fmcs.urv.es

Accepted for publication February 8, 2002.

	LITERATURE CITED

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS LITERATURE CITED

 
Cannon PF, Hawksworth DL., 1982 A re-evaluation of Melanospora Corda and similar Pyrenomycetes, with a revision of the British species. Bot J Linn Soc 84:115-160

Doguet G., 1955 Le genre Melanospora. Le Botaniste 39:1-313

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

Horie Y, Udagawa SH, Cannon PF., 1986 Four new Japanese species of the Cerastostomataceae (Ascomycetes). Mycotaxon 25:229-245

Kornerup A, Wanscher JH., 1984 Methuen handbook of color. 3rd ed. Erye Methuen, London. 252 p

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