Mycologia, 94(3), 2002, pp. 554-558.
© 2002 by The Mycological Society of America
A new species of Podospora from soil in Chile
Alberto M. Stchigel 1
Misericordia Calduch
Josep Guarro
Unitat de Microbiologia, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, and Institut d'Estudis Avançats, C/Sant Llorenç, 21, 43201 Reus, Spain
Luís Zaror
Instituto de Microbiología Clínica, Universidad Austral de Chile. Casilla 567, Valdivia, Chile
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ABSTRACT
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Podospora selenospora sp. nov. isolated from soil in Chile is described and illustrated. It belongs to the group of Podospora species with cylindrical asci, and inequilateral or curved ascospores, with a small, quickly evanescent primary appendage and absence of secondary appendages.
Key words: Lasiosphaeriaceae, soil fungi, Sordariales
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INTRODUCTION
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During the course of a study of soil ascomycetes from Chile, an interesting species of Podospora Ces. was isolated from Colbún, Linares Province, VII Region, Chile. The vegetation in the Chilean xerophylic forest is composed mainly of Boldea boldus (Molina) Looser, Chusquea quila Kunth, Cryptocarya alba (Molina) Looser, Quillaja saponaria Molina, Maytenus boaria Molina and Nothofagus spp. The soil is dark and calcareous. The area is dominated by a temperate Mediterranean climate, with 5–6 arid and 1–2 semi-arid months. The land rises to 1000 m. The average temperature is 19 C, with a minimum of 7 C and a maximum of 30 C. The average annual rainfall is 330–700 mm. Morphological characteristics differentiate this taxon from all previously described species in the genus, and it is thus described here as new.
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MATERIALS AND METHODS
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Soil samples were collected from the Ao horizon using sterilised polyethylene bags. These were closed with a rubber band and labelled. On returning to the laboratory, soil was stored for approx 5 yr at 4–7 C. Members of the Ascomycota and mitosporic fungi were isolated using a soil bait technique. Sterile Petri dishes were half-filled with the soil samples which were moistened thoroughly with sterile distilled water. Small pieces (approx 1 x 2 cm) of sterile wood were then placed on the soil surface and incubated at 22–25 C under 12 h of darkness alternating with 12 h of cool white fluorescent light. Ascomata developing on wood pieces were transferred to 5-cm-diam Petri dishes containing oatmeal agar (OA; Difco) and potato carrot agar (PCA, potatoes, 20 g; carrot, 20 g; agar, 20 g; tap water, 1 L), using a sterile dissection needle. The morphological characteristics of the colonies were studied on malt extract agar (MEA; Difco), OA and PCA, at 5, 15, 25, and 35 C, under 12 h of darkness alternating with 12 h of cool white fluorescent light. Color notations in parentheses are from Kornerup and Wanscher (1984)
. Measurements of the fungal structures were taken in water or lactophenol. Photomicrographs were obtained with a Leitz Dialux 20 EB microscope.
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RESULTS
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Podospora selenospora Stchigel, Guarro & M. Calduch, sp. nov. Figs 1–
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FIGS. 1–6. Podospora selenospora. 1. Upper part of ascomatal peridium. 2. Detail of the ostiole (cross section). 3, 4. Asci with ascospores. 5, 6. Ascospores. Scale bars: 1 = 40 µm, 2 = 30 µm, 3 = 50 µm, 4 = 35 µm, 5–6 = 10 µm
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FIGS. 7–10. Podospora selenospora. 7. Ascoma. 8. Agglutinated hairs. 9. Ascospores. 10. Ascus with ascospores. Scale bars: 7 = 25 µm, 8–10 = 10 µm
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Mycelium ex hyphis subhyalinis vel pallide brunneis, ramosis, septatis, 1–3 µm diam composito. Coloniae in agaro cum decocto tuberorum et carotarum "PCA" atroviride, planae, tenues, cum ascomata copiosa; reversum atrovirens. Ascomata superficialia, ostiolata, translucida, pallide brunnea vel brunnea, lageniformis vel piriformis, 250–350 x 100–150 µm; apex cum collum papillatum, 50–90 x 70–110 µm. Peridium 4–6 stratiorum compositum, 10–15 µm crassitunicatum, pallide brunneum vel brunneum, tenue, ex textura globulosa vel angularis. Asci octospori, cylindrici, brevistipitati, cum muris tenuibus, deliquescenti, 90–110 x 13–16 µm. Paraphysis nullae. Ascosporae atro-brunneae, levae, uniseriatae, 10–12 x 8–9 x 9–10 µm, cordisformae vel lunatae, appendicis principalis hyalinis vel subhyalinis, clavatis, labilis, 4–6 x 1–1.5 µm, appendicis secundaris nullis. Status conidialis nullis.
Hyphae subhyaline to pale brown, branched, septate, smooth, 1–3 µm diam. Colonies on PCA growing slowly, attaining 18–22 mm diam in 14 d at room temperature, dark green (M. 29F8), flat, thin, felty, consisting of submerged mycelium and sparse aerial hyphae, producing abundant ascomata; reverse dark green (M. 29F8). Ascomata superficial, scattered, ostiolate, flask-shaped to piriform, translucent, light brown to brown, 250–350 x 100–150 µm, with a papillate neck measuring 50–90 x 70–110 µm, covered on the upper part with brown to dark brown, short, 1–2-celled agglutinated hairs. Peridium 4–6-layered, 10–15 µm thick, light brown to brown, with textura globulosa to textura angularis in surface view, composed of globose to polygonal cells measuring 5–25 µm diam. Asci 8-spored, cylindrical, short-stipitate, thin-walled, evanescent, fasciculate, without apical structures, 90–110 x 13–16 µm. Paraphyses not observed. Periphyses present. Ascospores dark brown to blackish-brown, smooth-walled, uniseriate, strongly curved and strongly concave on one side, 10–12 x 8–9 x 9–10 µm, heart-shaped to lunate, with both ends acute and a lateral germ pore on the convex side; germ pore 1–2 µm diam; primary appendage hyaline or subhyaline, clavate, slender, fugaceous, 4–6 x 1–1.5 µm; secondary appendages absent. Anamorph not observed.
On OMA at 25 C, colonies attaining 48–50 mm diam in 14 d, flat, dark green (M. 29F8); reverse deep green to dark green (M. 29E8 to 29F8). Ascomata abundant. On MEA at 25 C, colonies attaining 43–47 mm diam in 14 d, flat, olive brown (M. 4E3 to 4F3); reverse dark green(M. 29F8). Ascomata rare. On PCA, at 15 C, attaining 19–21 mm diam in 14 d, flat, felty, dark green (M. 30F4 to 30F6); reverse dark green (M. 29F5). Ascomata very abundant. On OMA, at 15 C, attaining 27–29 mm diam in 14 d, flat, felty, with concentric areas, dark green (M. 30F8); reverse same colored. Ascomata less abundant. On MEA, at 15 C, attaining 23–25 mm diam in 14 d, flat, felty, greenish gray to dark green (M. 30D2 to 30F3) ; reverse same colored. Ascomata absent. No growth was observed at 5 C or 35 C.
Specimen examined. CHILE. LINARES: Colbún. From forest soil, 30-IV-1997, L. Zaror (IMI 386068–HOLOTYPE, FMR 7394–ISOTYPE). Living cultures ex type: CBS 109403, FMR 7394, IMI 386068.
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DISCUSSION
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Podospora is a large and polymorphic genus with numerous species. There is considerable variation in the structure of the ascomatal wall and the morphology of ascospore appendages. The most recent full revision of the genus was by Mirza and Cain (1969)
who listed 64 species, and Lundqvist (1972)
who reviewed the Nordic coprophilous species, re-introducing the genus Schizothecium Corda and transferring 31 species of Podospora to it. This author re-established Schizothecium for relatives of Podospora which have swollen peridial cells, ascospores becoming septate at an early stage of development, and a persistent hyaline basal cell (in Podospora this cell, referred as primary appendage, appears to lose its contents soon after maturity and frequently collapses). Other authors (e.g., Mirza and Cain 1969
, Bell and Mahoney 1995
) have not accepted the separation of Schizothecium from Podospora. Other genera of Lasiospheriaceae (notably Cercophora Fuckel and Lasiosphaeria Ces. & De Not.) have a wide variety of peridial forms within the genus, and we are not convinced that either of the distinguished features of the ascospores stated by Lundqvist are significant at generic level. Podospora species are mostly coprophilic in habit. The non-coprophilic species constitute a group which includes Podospora selenospora and whose most distinctive features are the presence of cylindrical asci with uniseriate, inequilateral ascospores without secondary (gelatinous) appendages (Guarro et al 1991
). These fungi are found generally on decaying plant material or soil. The adaptation of such species to these substrates would explain the loss of the secondary appendages of their ascospores otherwise useful for their dispersion from dung through insects or mites. The other species of the group are Podospora austro-americana (Speg.) Mirza & Cain from Pircunia dioica, P. carpinicola Mouchacca, from dead leaves of Carpinus betula, P. curvispora (Cain) Cain, from seeds of Daucus carota, P. fimbriata (Bayer) Cain, from goose dung, P. horridula (Sacc.) Dennis & S. Francis, from Opuntia ficus-indica, P. inaequalis (Cain) Cain, from seeds of Daucus carota, P. inquinata Udagawa & Ueda, from marine sediments, P. lautaurea Guiraud, Sage, Seigle-Murandi & Steinman, from soil, P. minor Ell. & Everh., from old stalks of Zea mays and P. unicaudata (C. Moreau & M. Moreau ex Smith) Cain from felt lining of an ammunition box stacked in a gold mine. Although, it is not proved that the non-coprophilous species constitute a natural group within Podospora, it can be considered a transitional group between Podospora and Zopfiella Winter (Guarro et al 1991
). Podospora may be distinguished from Zopfiella by having relatively large ascospores with an elongated primary appendage and often elaborate secondary appendages. In contrast, Zopfiella usually has rather small ascospores, with a short primary appendage and always without secondary appendages (Guarro et al 1991
). Podospora selenospora can be differentiated from the group of non-coprophilic species, with exception of P. curvispora (Cain) Cain, by its lunate to heart-shaped ascospores. Podospora curvispora is the closest species. However, P. selenospora has more strongly curved and shorter and broader ascospores than P. curvispora [11–13 (–17) x 6–8 µm] but the most important distinguishing feature is the presence of a lateral germ pore on the convex surface of the ascospores in P. selenospora, while in P. curvispora the germ pore is apical.
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FOOTNOTES
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1 Corresponding author, umb{at}astor.urv.es 
Accepted for publication October 15, 2001.
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LITERATURE CITED
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Bell A, Mahoney DP., 1995 Coprophilous fungi in New Zealand. I. Podospora species with swollen agglutinated perithecial hairs Mycologia 87:375-396
Guarro J, Cannon PF, Aa HA van der., 1991 A synopsis of the genus Zopfiella (Ascomycetes, Lasiosphaeriaceae) Sys Ascom 10:79-112
Kornerup A, Wanscher JH., 1984 Methuen handbook of colour. 3rd ed London: Erye Methuen. 252 p
Lundqvist N., 1972 Nordic Sordariaceae s. lat Symb Bot Upsal 20:1-374
Mirza JH, Cain RF., 1969 Revision of the genus Podospora Can J Bot 47:1999-2048
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ABSTRACT
INTRODUCTION
