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Mycologia, 95(5), 2003, pp. 896–901.q 2003 by The Mycological Society of America, Lawrence, KS 66044-8897

Phialomyces fusiformis sp. nov. from soil in Singapore isidentified and described

G. Delgado RodriguezInstituto de Ecologia y Sistematica, Carretera deVarona Km 3.5, Capdevila, Boyeros, A.P. 8029,10800 C. Habana, Cuba

Cony Decock1

Mycotheque de l’Universite catholique de Louvain(MBLA, MUCL2), Faculte des SciencesAgronomiques, Place Croix du Sud 3, 1348 Louvain-la-Neuve, Belgium

Abstract: Phialomyces fusiformis sp. nov., isolatedfrom soil in Singapore, is described and illustrated.The species is similar to P. macrosporus-type speciesof the genus but differs in that it has longer, moreellipsoid-limoniform, fusiform and more coarsely or-namented conidia.

Key words: Hyphomycetes, Penicillifer, soil fungi,Stachybotrys, tropical Asia

INTRODUCTION

The genus Phialomyces was established by Misra andTalbot (1964) for a peculiar phialidic hyphomycete,P. macrosporus Misra & Talbot. The genus was char-acterized by large, sub-globose to broadly ellipsoid-fusoid, bi-apiculated, darkly pigmented and coarselyroughened conidia born in basipetal chains from am-pulliform phialides arranged in a whorl of two orthree at the apex of a long (up to 1 mm), hyalineconidiophore. Furthermore, the conidia in thechains are separated by a connective.

Two other species later were described in the ge-nus: Phialomyces taiwanensis Matsush (Matsushima1985) and P. striatus Castaneda & W. Gams (Casta-neda and Gams 1991). Their placement in Phialo-myces was justified by the verticillate disposition of thephialides and the pigmented, catenate conidia. How-ever, they both differ from P. macrosporus in that theyhave much smaller conidia, striated in P. striatus,smooth and furthermore lacking connective in P. tai-wanensis, a feature emphasized by Mercado et al(1998), who then excluded the latter species from

Accepted for publication November 20, 2002.1 Corresponding author. E-mail: decock@mbla.ucl.ac.be2 Part of the Belgian Coordinated Collections of Micro-organisms(BCCM).

Phialomyces and transferred it to Thysanophora W.B.Kendr. (T. taiwainensis [Matsush.] Mercado et al).

During a study of leaf litter and soil mycobiotafrom Singapore, a typical Phialomyces species was iso-lated. It appeared to be similar to P. macrosporus inthat it has identical phialides and the characteristicdarkly pigmented, warted conidia forming longchains. However, after a closer comparison with thetype of P. macrosporus (MUCL 9776), it was found todiffer from the latter in conidial size, shape and or-namentation, and the roughness of the conidio-phores. It therefore is described here as Phialomycesfusiformis.

MATERIAL AND METHODS

Cultures were grown on cornmeal agar (CMA) at 25 C, witha 12/12 h incident near ultra-violet light periodicity. Colorsare described according to Kornerup & Wanscher (1981).Microscopic measurements were made in lacto-phenol cot-ton blue. In microscopic measurements, 5% of the rangeswere excluded from each extreme and, when relevant, aregiven in parentheses. In the text, these abbreviations areused: x 5 arithmetic mean; R 5 ratio of length/width ofthe conidia; xR 5 arithmetic mean of the ratio R. In prep-aration for scanning electron microscopy (SEM PhillipsXL20), specimens were flash frozen (2212 C) in liquid ni-trogen under vacuum for cryo-SEM (Oxford CT1500 cryo-system), transferred to the preparation chamber and thento the SEM chamber, where the frozen samples were sub-limated (280 C) to remove ice particles. Samples were sput-ter coated with gold in the preparation chamber for 75 sunder 1.2 KV at 2150 to 2170 C. Specimens were viewedunder 2–5 KV at 2170 to 2190 C.

DESCRIPTION

Phialomyces fusiformis Delgado et Decock, sp. nov.FIGS. 1–15

[Typo generis Phialomyces macrosporus Misra & Talbot af-finis, sed conidiis ellipsoideis-limoniformibus, fusiformibus,magnis, ornamentioribus, (31–)33–44(–49) 3 (16–)17–21(–25) mm, x 5 37.5 3 19.0 mm, R 5 1.6–2.2(–2.4), xR 52.0, et conidiophoris verrucosis satis differt.]

Colonies on cornmeal agar reaching 30 mm diamin 7 d. Mycelium mainly immersed or superficial, hy-aline. Sporulation starting from center after 3–4 d,then extending over colony, with abundant, erect co-nidiophores giving the colony a loose velutinous as-pect, white at first changing progressively to grayish

897RODRIGUEZ AND DECOCK: PHIALOMYCES FUSIFORMIS SP. NOV.

FIGS. 1–2. Phialomyces fusiformis. 1. Conidiophores and phialides. 2. Conidia (scale bar 5 10 mm).

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FIGS. 3–4. Phialomyces macrosporus, type (MUCL 9776). 3. Conidiophores and phialides. 4. Conidia (scale bar 5 10 mm).

brown, then blackish (6(D–F)3) when conidia ma-ture. 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, upto 1.2 mm long, 4.0–6.0 mm wide, bearing commonly

a single apical cluster of 2–3(–5) verticillate conidi-ogenous cells, and occasionally a subapical cluster of2–3 verticillate conidiogenous cells. Conidiogenesis en-teroblastic. Conidiogenous cells monophialidic. Phial-ides discrete, determinate, lageniform-ampulliform,smooth to slightly verruculose at the basis, with a

899RODRIGUEZ AND DECOCK: PHIALOMYCES FUSIFORMIS SP. NOV.

FIGS. 5–8. 5. Phialomyces macrosporus, type (MUCL 9776) Conidia. 6–8. Phialomyces fusiformis. 6. Phialides and conidia.7–8. Conidia. (scale bar 5 25 mm).

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FIGS. 9–15. Phialomyces fusiformis. 9–11. Conidia and phialides. Scale bar on image. 12–15. Conidia at different stage ofmaturity. Scale bar on image. On FIG. 11, the white material at the top of the phialides represents remnants of cell wallmixed with ice that was not removed from sublimation.

short collar, thin- to slightly thick-walled, with a per-iclinal thickening at aperture resulting from succes-sive conidial formation, hyaline to pale yellowish,(28–)30–40(–42) 3 8.00–10(–11.0) mm, x 5 35.4 39.0 mm, 2.5–4.0(–5.0) mm at the apex. Conidia ellip-soid to fusiform-limoniform, bi-apiculate, with a hy-aline, truncate basis and a pointed apex, the latteroften with a short, cylindrical remnant of connective,covered with remnant of cell wall, the wall smooth orfaintly striated (under SEM) at first, covered with athin (mucilaginous) membrane, then becoming pro-gressively coarsely and densely verrucose when ma-turing, pale to dark olive brown to golden brown,nonseptate, (31–)33–44(–49) 3 (16–)17–21(–25)mm, x 5 37.5 3 19.0 mm, R 5 1.6–2.2(–2.4), xR 52.0, in long (up to 40 conidia), dry chains, each co-nidia separated by a connective, as a short straight,narrow, short, cylindrical ‘‘rod’’ of unknown consti-tution, covered with remnant of cell wall.

HOLOTY PE. SINGAPORE: Mac Ritchie Reservoir,forest soil, collected by O. Laurence, isolated by G.Delgado Rodriguez, Feb 2002, MUCL 43747 (ISO-TY PE SING).

Commentary. Two species so far are accepted inPhialomyces, P. macrosporus and P. striatus. Phialomy-ces fusiformis morphologically is close to P. macrospo-rus, from which it differs in having longer, ellipsoid-

fusiform to limoniform, more coarsely ornamentedconidia. Furthermore, the conidiophores and the ba-ses of the phialides occasionally are slightly verrucose(FIGS. 9–11). In P. macrosporus, conidiophores andphialides are completely smooth.

The conidia in the type culture of P. macrosporus(MUCL 9776) are mainly subglobose to slightly ellip-soid, bi-apiculated (FIG. 4), (18–)20–25.3(–27) 3(14–)15–19(–22) mm (x 5 22.5 3 16.0 mm), with aratio length/width (R) of 1.0–1.6 (xR 5 1.4). Misraand Talbot (1964) and Ellis (1971) gave the mea-surements 20–26 3 16–20 mm and 22–27 3 16–20mm, respectively. The conidia in P. fusiformis are lon-ger, mostly 33–44 mm, averaging 37.5 mm long, withR 5 1.6–2.2(–2.4) (xR 5 2.0).

Searching the literature for other reports of P. ma-crosporus, we found that Matsushima (1975) reportedthe species from soil in Japan. From his descriptionsand illustrations, it appeared that his culture differsfrom P. macrosporus in that it has larger (24–37 318–22 mm), more ellipsoid-limoniform, fusiform co-nidia and roughened conidiophores, which betterwould agree with P. fusiformis.

Phialomyces striatus differs from the two latter spe-cies in that it has more numerous and compactedphialides and smaller and striated conidia.

Within the other genera of Hyphomycetes, Stachy-

901RODRIGUEZ AND DECOCK: PHIALOMYCES FUSIFORMIS SP. NOV.

FIGS. 9–15. Continued

botrys theobromae Hansf. has somewhat similar, large(16–28 3 12–16 mm) and pigmented (dark green)conidia, occasionally verrucose, born from largephialides in a whorl of 3–5 ( Jong and Davis 1976).Penicillifer van Emden, especially P. japonicus Mat-sush., also has large phialides with a conspicuous col-larette born in clusters of 3–6, which resemble Phi-alomyces (Matsushima 1985). However, S. theobromaeand P. japonicus differ in their conidial shape andthe conidia mostly aggregating in a slimy drop. In thecase of P. japonicus, conidia also may form chains butwithout connective (Matsushima 1985).

Key to the Phialomyces Species:

1a Conidia striated . . . . . . . . . . . . . . . . . . . . . . . . . P. striatus1b Conidia verruculose . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2a Conidia mainly 20–26 mm long, always smaller than 30mm, subglobose to slightly ellipsoid limoniform, bi-api-culated . . . . . . . . . . . . . . . . . . . . . . . . . P. macrosporus

2b Conidia mainly longer or equal to 30 mm, up to 40 mm,ellipsoid-limoniform, fusiform, bi-apiculated . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . P. fusiformis

ACKNOWLEDGMENTS

We wish to express our thanks to the National Parks Boardof Singapore for having granted Mycosphere Ltd. researchand collection permits for investigations of Singapore fun-gal diversity. Part of this work was done during a stay of G.Delgado Rodriguez at MUCL, financed by a grant fromUNESCO-IUMS-MIRCEN-SGM. This work was partly fi-nanced by a sponsorship from Mycosphere Ltd., Singapore.

Prof. C. Evrard (BOTA, UCL) is sincerely thanked for hishelp with the Latin diagnosis. Cony Decock gratefully ac-knowledges the financial support received from the BelgianFederal Office for Scientific, Technical and Cultural Affairs(OSTC, Contract BCCM/MUCL C2/10/007) and thanksthe directors of MUCL for the provision of facilities andcontinual encouragement. Gregorio Delgado Rodriguezalso acknowledges the Cuban Ministry of Science, Technol-ogy and Environment for providing facilities and financialsupport.

LITERATURE CITED

Castaneda Ruiz RF, Gams W. 1991. A new species of Phialo-myces. Mycotaxon 42:239–243.

Ellis MB. 1971. Dematiaceous hyphomycetes. Kew, Surrey,UK: Commonwealth Mycological Institute. 608 p.

Jong SC, Davis EE. 1976. Contribution to the knowledge ofStachybotrys and Memnoniella in culture. Mycotaxon 3:409–485.

Kornerup A, Wanscher JH. 1981. Methuen handbook ofcolor. 3rd ed. London: Methuen. 282 p.

Matsushima T. 1975. Icones Microfungorum a Matsushimalectorum, Kobe, Japan:1– 209, Plates 1–405.

———. 1985. Matsushima Mycological Memoirs No. 4. Mat-sushima Fungus Collect., Kobe, Japan: 1–68.

Mercado-Sierra A, Gene J, Figueras MJ, Rodriguez K, Guar-ro 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 ofthe Hyphomycetes. Can J Bot 42:1287–1290.