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Instituto de Ecologia y Sistematica, Carretera de Varona Km 3.5, Capdevila, Boyeros, A.P. 8029, 10800 C. Habana, Cuba
Cony Decock 1
Mycothèque de l'Université catholique de Louvain (MBLA, MUCL,2), Faculté des Sciences Agronomiques, Place Croix du Sud 3, 1348 Louvain-la-Neuve, Belgium
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ABSTRACT |
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Phialomyces fusiformis sp. nov., isolated from soil in Singapore, is described and illustrated. The species is similar to P. macrosporus-type species of the genus but differs in that it has longer, more ellipsoid-limoniform, fusiform and more coarsely ornamented conidia.
Key words: Hyphomycetes, Penicillifer, soil fungi, Stachybotrys, tropical Asia
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIAL AND METHODSDESCRIPTIONLITERATURE CITED |
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for a peculiar phialidic hyphomycete, P. macrosporus Misra & Talbot. The genus was characterized by large, sub-globose to broadly ellipsoid-fusoid, bi-apiculated, darkly pigmented and coarsely roughened conidia born in basipetal chains from ampulliform phialides arranged in a whorl of two or three at the apex of a long (up to 1 mm), hyaline conidiophore. Furthermore, the conidia in the chains are separated by a connective.
Two other species later were described in the genus: Phialomyces taiwanensis Matsush (Matsushima 1985) and P. striatus Castañeda & W. Gams (Castañeda and Gams 1991). Their placement in Phialomyces was justified by the verticillate disposition of the phialides and the pigmented, catenate conidia. However, they both differ from P. macrosporus in that they have much smaller conidia, striated in P. striatus, smooth and furthermore lacking connective in P. taiwanensis, a feature emphasized by Mercado et al (1998), who then excluded the latter species from Phialomyces and transferred it to Thysanophora W.B. Kendr. (T. taiwainensis [Matsush.] Mercado et al).
During a study of leaf litter and soil mycobiota from Singapore, a typical Phialomyces species was isolated. It appeared to be similar to P. macrosporus in that it has identical phialides and the characteristic darkly pigmented, warted conidia forming long chains. However, after a closer comparison with the type of P. macrosporus (MUCL 9776), it was found to differ from the latter in conidial size, shape and ornamentation, and the roughness of the conidiophores. It therefore is described here as Phialomyces fusiformis.
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MATERIAL AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIAL AND METHODSDESCRIPTIONLITERATURE CITED |
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. Microscopic measurements were made in lacto-phenol cotton blue. In microscopic measurements, 5% of the ranges were excluded from each extreme and, when relevant, are given in parentheses. In the text, these abbreviations are used: 
= arithmetic mean; R = ratio of length/width of the conidia; R = arithmetic mean of the ratio R. In preparation for scanning electron microscopy (SEM Phillips XL20), specimens were flash frozen (-212 C) in liquid nitrogen under vacuum for cryo-SEM (Oxford CT1500 cryo-system), transferred to the preparation chamber and then to the SEM chamber, where the frozen samples were sublimated (-80 C) to remove ice particles. Samples were sputter coated with gold in the preparation chamber for 75 s under 1.2 KV at -150 to -170 C. Specimens were viewed under 2–5 KV at -170 to -190 C. |
DESCRIPTION |
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TOPABSTRACTINTRODUCTIONMATERIAL AND METHODSDESCRIPTIONLITERATURE CITED |
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[Typo generis Phialomyces macrosporus Misra & Talbot affinis, sed conidiis ellipsoideis-limoniformibus, fusiformibus, magnis, ornamentioribus, (31–)33–44(–49) x (16–)17–21(–25) µm, = 37.5 x 19.0 µm, R = 1.6–2.2(–2.4), R = 2.0, et conidiophoris verrucosis satis differt.]
Colonies on cornmeal agar reaching 30 mm diam in 7 d. Mycelium mainly immersed or superficial, hyaline. Sporulation starting from center after 3–4 d, then extending over colony, with abundant, erect conidiophores giving the colony a loose velutinous aspect, white at first changing progressively to grayish brown, then blackish (6(D–F)3) when conidia mature. Conidiophores macronematous, mononematous, erect, unbranched or rarely branched at the apex, thick-walled, septate, hyaline or faintly yellowish, smooth to verruculose, especially in upper third, up to 1.2 mm long, 4.0–6.0 µm wide, bearing commonly a single apical cluster of 2–3(–5) verticillate conidiogenous cells, and occasionally a subapical cluster of 2–3 verticillate conidiogenous cells. Conidiogenesis enteroblastic. Conidiogenous cells monophialidic. Phialides discrete, determinate, lageniform-ampulliform, smooth to slightly verruculose at the basis, with a short collar, thin- to slightly thick-walled, with a periclinal thickening at aperture resulting from successive conidial formation, hyaline to pale yellowish, (28–)30–40(–42) x 8.00–10(–11.0) µm, = 35.4 x 9.0 µm, 2.5–4.0(–5.0) µm at the apex. Conidia ellipsoid to fusiform-limoniform, bi-apiculate, with a hyaline, truncate basis and a pointed apex, the latter often with a short, cylindrical remnant of connective, covered with remnant of cell wall, the wall smooth or faintly striated (under SEM) at first, covered with a thin (mucilaginous) membrane, then becoming progressively coarsely and densely verrucose when maturing, pale to dark olive brown to golden brown, nonseptate, (31–)33–44(–49) x (16–)17–21(–25) µm, = 37.5 x 19.0 µm, R = 1.6–2.2(–2.4), R = 2.0, in long (up to 40 conidia), dry chains, each conidia separated by a connective, as a short straight, narrow, short, cylindrical "rod" of unknown constitution, covered with remnant of cell wall.
HOLOTYPE. SINGAPORE: Mac Ritchie Reservoir, forest soil, collected by O. Laurence, isolated by G. Delgado Rodriguez, Feb 2002, MUCL 43747 (ISOTYPE SING).
Commentary. Two species so far are accepted in Phialomyces, P. macrosporus and P. striatus. Phialomyces fusiformis morphologically is close to P. macrosporus, from which it differs in having longer, ellipsoid-fusiform to limoniform, more coarsely ornamented conidia. Furthermore, the conidiophores and the bases of the phialides occasionally are slightly verrucose (Figs. 9–11). In P. macrosporus, conidiophores and phialides are completely smooth.
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= 22.5 x 16.0 µm), with a ratio length/width (R) of 1.0–1.6 (R = 1.4). Misra and Talbot (1964) and Ellis (1971) gave the measurements 20–26 x 16–20 µm and 22–27 x 16–20 µm, respectively. The conidia in P. fusiformis are longer, mostly 33–44 µm, averaging 37.5 µm long, with R = 1.6–2.2(–2.4) (R = 2.0).
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reported the species from soil in Japan. From his descriptions and illustrations, it appeared that his culture differs from P. macrosporus in that it has larger (24–37 x 18–22 µm), more ellipsoid-limoniform, fusiform conidia and roughened conidiophores, which better would agree with P. fusiformis. Phialomyces striatus differs from the two latter species in that it has more numerous and compacted phialides and smaller and striated conidia.
Within the other genera of Hyphomycetes, Stachybotrys theobromae Hansf. has somewhat similar, large (16–28 x 12–16 µm) and pigmented (dark green) conidia, occasionally verrucose, born from large phialides in a whorl of 3–5 (Jong and Davis 1976). Penicillifer van Emden, especially P. japonicus Matsush., also has large phialides with a conspicuous collarette born in clusters of 3–6, which resemble Phialomyces (Matsushima 1985). However, S. theobromae and P. japonicus differ in their conidial shape and the conidia mostly aggregating in a slimy drop. In the case of P. japonicus, conidia also may form chains but without connective (Matsushima 1985).
Key to the Phialomyces Species:
1a Conidia striated . . . . . P. striatus
1b Conidia verruculose . . . . . 2
2a Conidia mainly 20–26 µm long, always smaller than 30 µm, subglobose to slightly ellipsoid limoniform, bi-apiculated . . . . . P. macrosporus
2b Conidia mainly longer or equal to 30 µm, up to 40 µm, ellipsoid-limoniform, fusiform, bi-apiculated . . . . . P. fusiformis
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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2 Part of the Belgian Coordinated Collections of Micro-organisms (BCCM).
Accepted for publication November 20, 2002.
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LITERATURE CITED |
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TOPABSTRACTINTRODUCTIONMATERIAL AND METHODSDESCRIPTIONLITERATURE CITED |
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Ellis MB., 1971 Dematiaceous hyphomycetes. Kew, Surrey, UK: Commonwealth Mycological Institute. 608 p
Jong SC, Davis EE., 1976 Contribution to the knowledge of Stachybotrys and Memnoniella in culture. Mycotaxon 3:409-485
Kornerup A, Wanscher JH., 1981 Methuen handbook of color. 3rd ed. London: Methuen. 282 p
Matsushima T., 1975 Icones Microfungorum a Matsushima lectorum, Kobe, Japan:1– 209, Plates 1–405
Matsushima T., 1985 Matsushima Mycological Memoirs No. 4. Matsushima Fungus Collect., Kobe, Japan: 1–68
Mercado-Sierra A, Gené J, Figueras MJ, Rodriguez K, Guarro J., 1998 New or rare Hyphomycetes from Cuba. IX. Some species from Pinar del Rio. Mycotaxon 68:417-426
Misra PC, Talbot PHB., 1964 Phialomyces, a new genus of the Hyphomycetes. Can J Bot 42:1287-1290
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