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Unitat de Microbiologia, Facultat de Medicina i Ciències de la Salut, C/ Sant Llorenç 21, 43201 Reus, Tarragona, Universitat Rovira i Virgili, Tarragona, Spain
Walter Mac Cormack
Instituto Antártico Argentino, Departamento de Biología, C/ Cerrito 1248 (1010), Buenos Aires, Argentina
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ABSTRACT |
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Two new species of ascomycetes, Apiosordaria antarctica, isolated from soil, and Thielavia antarctica, isolated from a sample of the lichen Usnea cf. aurantio-atra, both collected on King George Island (Antarctica), are described and illustrated. Apiosordaria antarctica is characterized by ostiolate ascomata with agglutinated hairs, eight-spored, uniseriate and cylindrical asci, and two-celled, irregularly navicular ascospores, with an upper cell ornamented with very small warts and with an apical germ pore. Thielavia antarctica is characterized by nonostiolate ascomata, with a thick peridium, eight-spored, cylindrical asci, uniseriate, oblate, ovoid ascospores, a slightly protruding apical germ pore, and a phialidic anamorph.
Key words: Chaetomiaceae, Lasiosphaeriaceae, lichenicolous fungi, soil-borne fungi, Sordariales, systematics
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSTAXONOMYLITERATURE CITED |
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSTAXONOMYLITERATURE CITED |
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, Lindsay 1971, Möller and Dreyfuss 1996). The area is dominated by a cold climate. The climatological data include: average temperature, -2.1 C (min -20.0 C, max +10.0 C); total annual precipitation, 800 mm (mostly in the form of snow); minimum, average and maximum atmospheric pressure, 946 mb, 989.9 mb and 1025 mb, respectively; average humidity, 89%. Soil samples were collected from the A horizon and lichen samples directly from the rock surface, placed in sterilized polyethylene bags, closed by rubber band and stored in a refrigerator at -20 C. Approximately 1 g of each soil sample was suspended in 5 mL of 5% v/v acetic acid, shaken vigorously for 5 min and left for an additional 5 min. The layer of acetic acid was removed by decantation, the residual soil was resuspended in 9 mL of sterilized water and plated in a Petri dish. Potato-carrot agar with chloramphenicol (PCA; grated potatoes, 20 g; grated carrot, 20 g; agar-agar, 20 g; chloramphenicol, 50 mg; tap water, 1 L) was placed on top of the soil suspension and mixed. All cultures were incubated at 10 ± 1 C for 12 h in the dark, alternating with 12 h under a cool white fluorescent light.
Lichen samples were cut into small pieces (approx. 5 mm long) with sterile surgical steel blades and dissection clamps. The pieces were placed on the surface of Petri dishes with tap-water agar (TWA; agar-agar, 20 g; tap water, 1 L), and incubated at 10 ± 1 C for 12 h in the dark, alternating with 12 h under cool white fluorescent light.
The strains were grown on oatmeal agar (OMA; oatmeal 30 g; agar-agar, 20 g; tap water, 1 L) and PCA (without chloramphenicol) at 35 C, at room temperature (approx. 25 C), at 15 C and at 5 C for 12 h in the dark, alternating with 12 h under a cool white fluorescent light. Color notations in parentheses are from Kornerup and Wanscher (1984). The structures were measured in lactophenol.
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TAXONOMY |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSTAXONOMYLITERATURE CITED |
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[Mycelium ex hyphis olivaceo-brunneis, septatis, ramosis, levis, 1–3 µm diametro composita. Coloniae in PCA expansae, planae, ex mycelio vegetativo submerso et aereo, olivaceo-brunnea; reversum olivaceo-brunneum. Ascomata superficialia, ostiolata, atrobrunnea, pyriformia, 530–700 x 320–350 µm, cum collum papillatum, 260–400 x 240–260 µm; pilis conglutinatis, septatis, fasciculatis, ex cellulis dilute brunneis vel brunneis, 7–10 x 3–7 µm composita. Peridium 6–9 stratiorum compositum, ex textura angularis, brunneum. Asci 8-spori, cylindrici, 165–180 x 8–10 µm. Paraphysis nullis. Ascosporae uniseriatae, primum unicellulares, hyalinae et verrucosae, deinde brunneae, transverse septatae ad bicellularis; cellula superiore irregulariter naviculare, atrobrunnea vel nigra, 19–24 x 8–10 µm, verruculosae, cum foramine germinali singulari apicali praedita, 1 µm diam; cellula inferiore subhyalinae vel subbrunnea, conica, 3.5–4.5 x 3.5–4 µm, levae. Status conidialis nullis.]
Mycelium composed of olivaceous-brown, septate, branched, smooth, 1–3 µm diam hyphae. Colonies on PCA 67–71 mm diam within 7 d at room temperature (ca 25 C), flat, felty, consisting of submerged mycelium and sparse aerial hyphae, olive brown (4F8), producing abundant ascomata; reverse olive brown (4F8); ascomatal initials originating as coiled hyphae of vegetative mycelium soon interwoven by neighboring hyphae. Ascomata superficial, scattered, ostiolate, dark brown, pyriform, 530–700 x 320–350 µm, setose, with a distinctive neck; neck papillate, conical, 260–400 x 240–260 µm; ascomatal hairs agglutinated, spread along the neck, consisting of septate, fasciculate, pale brown to brown cells measuring 7–10 x 3–7 µm. Peridium 6–9 layered, 14–17 µm thick, textura angularis, brown; external cells polygonal, measuring 6–25 µm diam. Asci 8-spored, fasciculate, cylindrical, 165–180 x 8–10 µm, apex flattened, with a conspicuous apical ring. Paraphyses absent. Ascospores uniseriate, one-celled, hyaline and verrucose when young, becoming dark brown, two-celled by the formation of a transverse septum when mature; upper cell irregularly navicular, truncate and darkened at the base, dark brown to black, 19–24 x 8–10 µm, ornamented with small warts, with conspicuous apical, 1 µm diam germ pore; lower cell subhyaline to light brown, conical, 3.5–4.5 x 3–4 µm, smooth. The apical ascospore sometimes appearing inverted with respect to the others. Anamorph unknown.
Colonies on OMA attaining more than 70 mm diam within 7 d at room temperature, similar to those on PCA; ascomata abundant. Colonies on OMA 41–45 mm diam within 7 d at 15 C, flat, olive brown (4D6); reverse the same color. Colonies on PCA and OMA <10 mm diam within 7 d at 5 C; ascomata not produced. No growth at 35 C.
[Specimens examined. ANTARCTICA. King George Island: Jubany Argentinian base, from soil, 11-XI-1996, col. W. Mac Cormack, isol. A. M. Stchigel (holotype: IMI 381338, isotype: FMR 6675. Living cultures: CBS 101.966, FMR 6675, IMI 381338).]
Apiosordaria (Lasiosphaeriaceae, Sordariales) was proposed by von Arx and Gams (1967). It is characterized by pale or dark, operculate ascomata, nonamyloid asci lacking distinct apical structures, and two-celled ascospores, with a dark and ornamented upper cell and a lower hyaline or paler cell. Later, Krug et al (1983) considered the two morphologically similar genera Echinopodospora Robinson and Lacunospora Cailleux as synonyms of Apiosordaria. The genus currently comprises 20 species (Krug et al 1983, Guarro and Cano 1988, Udagawa 1990, Mukerji et al 1995, Stchigel et al 2000), most of them reported from soil.
Apiosordaria antarctica resembles A. otanii Udagawa (1990) by the presence of agglutinated hairs and ascospores with a warted wall. However, the ascomata of A. otanii have an inconspicuous to short neck, with long hypha-like hairs, and its ascospores are broader (15–18 µm). The anamorph of A. otanii is chrysosporium-like.
Thielavia antarctica Stchigel et Guarro, sp. nov. Figs. 11–22
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[Mycelium ex hyphis hyalinis vel dilute brunneis, septatis, ramosis, levis, 1–20 µm diam composita. Coloniae in PCA expansae, floccosae, hyalinae; reversum hyalinum. Ascomata superficialia, non-ostiolata, glabra, atrobrunnea, globosa, 250–450 µm diam. Peridium 5–8 stratiorum compositum, ex textura epidermoidea et textura intrincata, dilute brunneum. Asci 8-spori, cylindrici, 40–65 x 7–11 µm. Paraphysis nullis. Ascosporae uniseriatae, unicellulares, brunneae, crassae ovoideae et complanatae, 9–11 x 8–10 x 6.5–7 µm, levae, cum foramine germinali singulari apicali praedita. Anamorphosis Paecilomyces similis.]
Mycelium composed of hyaline to pale brown, septate, branched, anastomosing, smooth-walled, 1–20 µm wide hyphae. Colonies on PCA, attaining 63–65 mm diam within 14 d at 15 C, cottony, white, producing abundant ascomata after 2 mo; reverse uncolored; ascomatal initials originating as coiled hyphae of vegetative mycelium. Ascomata superficial (rarely immersed), scattered, nonostiolate, glabrous, dark brown, globose, 250–450 µm, covered with abundant hyaline hyphae. Peridium 5–8 layered, 12–30 µm thick, textura epidermoidea to intrincata, light brown, with irregularly polygonal dark brown zones up to 60 µm diam; external cells measuring 5–25 µm diam. Asci eight-spored, nonfasciculate, cylindrical, 40–65 x 7–11 µm, inconspicuously stipitate, without apical structures. Paraphyses absent. Ascospores uniseriate, one-celled, brown, broadly ovoid and bilaterally flattened, 9–11 x 8–10 x 6.5–7 µm, smooth-walled, with a slightly protruding apical germ pore, to 1 µm diam. Anamorph Paecilomyces-like. Conidia one-celled, hyaline, produced in dry chains, obovoid with a truncate base, 3.5–5 x 1.5–2.5 µm, smooth-walled. Phialides borne terminally or laterally on the vegetative hyphae, usually solitary, rarely forming verticils of 2–3 phialides hyaline, flask-shaped to needle-shaped, 15–45 x 1.5–3 µm, tapering toward the tips; collarette inconspicuous.
Colonies on OMA at 15 C, similar to those on PCA; ascomata and anamorph abundant. Colonies on OMA and PCA at 25 C, similar to those on PCA at 15 C; ascomata not produced. Colonies on PCA and OMA at 5 C, with a very slow growth (<10 mm); ascomata not produced. No growth at 35 C.
[Specimens examined. ANTARCTICA. King George Island: Three Brothers Hill, from Usnea cf. aurantio-atra, 22-XI-1996, col. W. Mac Cormack, isol. A. M. Stchigel (holotype: IMI 389346, isotype: FMR 7920. Living cultures: FMR 7920, IMI 389346).]
Species of Thielavia Zopf (Chaetomiaceae, Sordariales) have a humicolous or fungicolous habit. The genus is characterized by spherical, glabrous or setose, nonostiolate ascomata, having a thin peridium with textura epidermoidea; asci eight-spored, fasciculate or clustered, ellipsoidal, saccate or rarely more or less cylindrical; and ascospores one-celled, fusiform, ellipsoidal, slightly clavate or ovoid, brown, with a conspicuous, terminal or lateral germ pore; and occasionally with aleurioconidia. This genus was monographed by Mouchacca (1973), Malloch and Cain (1973) and von Arx et al (1988). It currently contains 18 species (von Arx et al 1988, Chen and Chen 1996, Ito et al 1998, Stchigel et al 2002). Other genera that are related morphologically are compared in Table II.
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). Moreover, T. antarctica has cylindrical asci, which are present in Thielavia tortuosa Udagawa & Sugiyama, and phialoconidia similar to those seen in Thielavia terrestris (Apinis) Malloch & Cain. Both characters, although exceptional in Thielavia, in which ellipsoidal or saccate asci and aleurioconidia typically are formed, are absent in Melanocarpus, in which cylindrical-saccate asci and arthroconidia are typical. However, Thielavia tortuosa and T. terrestris differ from T. antarctica in having sinuous asci and large and fusiform ascospores, with a subterminal to lateral germ pore and clavate asci and small and pyriform ascospores, respectively. On the basis of the shape of the ascospores, the species closest to Melanocarpus are M. albomyces (Cooney & Emerson) Arx and M. oblatus Guarro & Aa. However, M. albomyces has bigger ascospores (13–16 x 11–14 x 9–11 µm) and ascospores of M. oblatus are circular in face view (ovate in T. antarctica).
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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Accepted for publication August 5, 2003.
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LITERATURE CITED |
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