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Centre for Research in Fungal Diversity, Department of Ecology and Biodiversity, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONTAXONOMYDISCUSSIONLITERATURE CITED |
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Spadicoides hodgkissa sp. nov. and Spadicoides arengae sp. nov., recorded from submerged decaying wood in Hong Kong and from decaying palm fronds in Brunei, are described and illustrated. Spadicoides hodgkissa is characterized by versicolored, obovoid conidia with up to 2 septa, including a distal distoseptum and a proximal euseptum, while Spadicoides arengae is characterized by unicellular, ellipsoidal conidia with verruculose walls that are relatively large. Eight genera, including Dendrographium, Helminthosporium, Luzfridiella, Paliphora, Polyschema, Polytretophora, Porosubramaniania, and Weufia, have the same conidiogenesis as Spadicoides. A key to these genera is provided.
Key words: freshwater fungi, palm fungi, polytretic conidiogenesis, taxonomy, tropical fungi
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONTAXONOMYDISCUSSIONLITERATURE CITED |
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, Hyde et al 1999
) and palm fungi (Yanna et al 2000
) in the tropics, an undescribed dematiaceous hyphomycete was found on wood baits of Pinus massoniana Lamb. submerged in a small stream in Hong Kong and another on decaying fronds of Arenga undulatifolia Becc. in Brunei. These fungi produce macronematous, mononematous conidiophores, polytretic, integrated conidiogenous cells, and acropleurogenous, solitary, obovoid to ellipsoidal conidia. Critical examination of the morphological characters suggested placement in the genus Spadicoides.
The genus Spadicoides was erected by Hughes (1958)
to accommodate a single species, S. bina (Corda) S. Hughes. Taxa producing conidia with solitary or catenate conidia on branched or unbranched conidiophores were included in Spadicoides or Diplococcium. The catenation of conidia is considered taxonomically more important than the branching of conidiophores, and thus the generic description of Spadicoides was emended to include taxa producing solitary conidia on branched or unbranched conidiophores, whereas Diplococcium includes taxa producing catenate conidia (Sinclair et al 1985
). The teleomorph of Spadicoides is unknown.
The species of Spadicoides collected in Hong Kong and Brunei differ from the described species and are therefore described as new.
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TAXONOMY |
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TOPABSTRACTINTRODUCTIONTAXONOMYDISCUSSIONLITERATURE CITED |
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Colonies on decaying wood effuse, dark brown, hairy (Figs. 1, 2, 9 ). Mycelium partly immersed in the substrata, composed of pale brown, septate, smooth-walled, branched hyphae, 3–4 µm wide. Conidiophores macronematous, mononematous, erect, solitary, unbranched, dark brown, paler towards the apex, straight or slightly flexuous, smooth, thick-walled, multiseptate, 60–120 x 3.5–4 µm (
= 82 x 3.8 µm, n = 25), occassionally swollen at the apex, slightly swollen, 4.5–6 µm at the base (Figs. 3–5, 10
). Conidiogenous cells polytretic, integrated, terminal and intercalary, with pale colored pores remaining at the conidiogenous loci (Figs. 3, 4, 11 ). Conidia acropleurogenous, solitary, versicolored, obovoid, smooth, guttulate, unicellular (5 x 3 µm), 1-euseptate or 2-septate (9–13 x 5–8 µm; = 11.8 x 7 µm, n = 25) comprising a proximal euseptum and a distal distoseptum (Figs. 6–8, 12
); distal distosepta possess a conspicuous central pore which is surrounded by a pigmented ring, appearing as dolipores in side view; distal cells thick-walled, olivaceous brown; basal cells thin-walled, very pale brown or hyaline, with a small hilum at the base.
Etymology. In honor of Prof. Sir I. John Hodgkiss who has promoted ecological and biodiversity studies in Hong Kong since 1968.
Material examined. CHINA. HONG KONG: Tai Po Kau Forest Stream, wood baits of Pinus massoniana, 28 Jun 1997, W. H. Ho WH307 [HKU(M) 6155, HOLOTYPE]; 29 Dec 1996, W. H. Ho & S. Y. Ho [HKU(M) 5965].
Spadicoides arengae W. H. Ho, Yanna et K. D. Hyde, sp. nov.
Coloniae effusae, atro-brunneae, pilosae. Mycelium partim in substrato immersum, ex hyphis pallide brunneis, septatis, laevibus, ramosis, 2–3.5 µm crassis compositum. Conidiophora macronemata, mononemata, erecta, solitaria, non ramosa, brunnea, apicem versus pallidiora, recta vel leniter flexuosa, laevia, tenuitunicata, multisepata, 210–400 x 3.5–4 µm, ad basim 5–6 µm lata. Cellulae conidiogenae polytreticae, in conidiophoris incorporatae, terminales et intercalares. Conidia acropleurogena, solitaria, unicellularia, ellipsoidea, 11–18 x 4–6 µm, pallide brunneae, aguttulatae, verruculosae, cum hilo.
Colonies on decaying palm frond effuse, dark brown, hairy (Fig. 13 ). Mycelium partly immersed in the substrata, composed of pale brown, septate, smooth-walled, branched hyphae, 2–3.5 µm wide. Conidiophores macronematous, mononematous, erect, solitary, unbranched, brown, paler towards the apex, straight or slightly flexuous, smooth, thin-walled, multiseptate, 210–400 x 3.5–4 µm ( = 312 x 3.7 µm, n = 25), slightly swollen, 5–6 µm at the base (Figs. 14 , 17
). Conidiogenous cells polytretic, integrated, terminal and intercalary, with pale colored pores remaining at the conidiogenous loci after conidial secession (Figs. 15, 18
). Conidia acropleurogenous, solitary, unicellular, ellipsoidal, 11–18 x 4–6 µm ( = 15.2 x 5.6 µm, n = 25), very pale brown, non-guttulate, wall verruculose, with a small hilum at the base (Figs. 16, 19
).
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Material examined. BRUNEI DARUSSALAM. TEMBURONG: Batu Apoi Forest Reserve, The University of Brunei Darussalam Kuala Belalong Field Studies Centre (KBFSC), Baki Tributary, on decaying rachis of Arenga undulatifolia, 13 Dec 1998, Yanna (Yan75Ar, HOLOTYPE).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONTAXONOMYDISCUSSIONLITERATURE CITED |
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), where 31 species were discussed, of which 21 were accepted, 1 was transferred to Hemicorynespora, 6 were transferred to Diplococium, 1 retained in its previous genus Polytretophora, and 2 remain doubtful. One new species and 1 variety were described thereafter, including S. palmicola Goh & K. D. Hyde and S. obclavata var. heterocolorata R. F. Castañeda, Guarro & Cano (Castaneda et al 1997
, Goh and Hyde 1998
). The later was elevated to species rank as S. heterocolorata (R. F. Castañeda, Guarro & Cano) Goh & K. D. Hyde (Goh and Hyde 1998
).
Spadicoides hodgkissa is similar to S. macroobovata and S. obovata in producing 2-septate, obovoid conidia, and similar to S. cordanoides, S. cubensis, S. curvularioides, S. heterocolorata, S. klotzschii, S. macroobovata, S. obclavata, S. obovata, and S. subramanianii in producing versicolored conidia (Goh and Hyde 1996
). Spadicoides hodgkissa is distinct in producing conidia, each with a proximal euseptum and a distal distoseptum. Other species of Spadicoides do not produce distoseptate conidia.
In Spadicoides hodgkissa, the distal distoseptum of conidia has a conspicuous central pore, surrounded by a pigmented ring (Figs. 7, 8
). Ho (1998)
listed 46 mitosporic fungi producing conidia with pigmented ring at the central septal pore, including 30 producing distoseptate conidia and 16 producing euseptate conidia. Janetia curviapicis Goh & K. D. Hyde is similar to Spadicoides hodgkissa in producing conidia with both types of septa, and the pigmented rings are restrictively found on the distosepta (Goh and Hyde 1996
). This pigmented ring can be a generic feature [e.g., all species of Canalisporium possess this structure (Goh et al 1998
)], or a specific feature [e.g., only some species of Digitodesmium possess this structure (Ho et al 1999b
)].
Spadicoides arengae resembles S. verrucosa in producing unicellular conidia with verruculose wall, but differs in conidial size (11–18 x 4–6 µm vs 4–5.5 x 2–3 µm). Spadicoides afzeliae, S. aggregata, S. carpatica, S. cordanoides, S. curvularioides, and S. palmicola also produce conidia with verruculose wall, but all have septate conidia. Spadicoides arengae resembles S. atra in producing unicellular ellipsoidal conidia, but differs in conidial size and wall ornamentation (Goh and Hyde 1996, 1998
).
Eight other genera also produce solitary conidia from polytretic conidiogenous cells with several conidiogenous loci in each of the conidiogenous cells (Hawksworth et al 1995
). A key to these genera and Spadicoides is presented.
Isolation of Spadicoides hodgkissa and S. arengae on water agar was attempted using single spore isolation technique (Choi et al 1999
). The conidia of both species did not germinate after one month. Their teleomorphs are not known.
KEY TO SPADICOIDES-LIKE GENERA
1. Conidiophores synnematous, conidia pigmented and distoseptate . . . . . Dendrographium (Ellis 1971
)
1. Conidiophores mononematous, conidia hyaline or pigmented, euseptate or distoseptate . . . . . 2
2. Conidiophores in fascicles, conidia pigmented and euseptate . . . . . Luzfridiella (Castañeda and Kendrick 1991
)
2. Conidiophores solitary, conidia hyaline or pigmented, euseptate or distoseptate . . . . . 3
3. Conidiophores micronematous, conidia pigmented and euseptate . . . . . Polyschema (Upadhyay 1966
)
3. Conidiophores macronematous, conidia hyaline or pigmented, euseptate or distoseptate . . . . . 4
4. Conidia with curved, pigmented basal cells and cylindro-truncate, hyaline apical cells . . . . . Polytretophora (= Parahelminthosporium)(Mercado Sierra 1983
)
4. Conidia not as mentioned . . . . . 5
5. Conidia hyaline, eusepate . . . . . Paliphora (Sivanesan and Sutton 1985
)
5. Conidia pigmented, euseptate or distoseptate . . . . . 6
6. Conidia distosepate . . . . . 7
6. Conidia euseptate and with or without distosepta . . . . . 8
7. Conidiophores unbranched, conidia obclavate or rostrate . . . . . Helminthosporium(= Helmisporium, Mydonotrichum, Oxysporium)(Ellis 1961
)
7. Conidiophores branched at the apex, conidia V-shaped . . . . . Weufia (= Granmamyces)(Bhat and Sutton 1985
)
8. Conidia euseptate, conidiogenous loci cicatrized . . . . . Porosubramaniania (Holubová-Jechová 1985
)
8. Conidia euseptate or with both eusepta and distosepta, conidiogenous loci not cicatrized . . . . . Spadicoides (Hughes 1958
)
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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Accepted for publication July 27, 2001.
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LITERATURE CITED |
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TOPABSTRACTINTRODUCTIONTAXONOMYDISCUSSIONLITERATURE CITED |
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Castañeda RF, Guarro J, Cano J., 1997 Notes on conidial fungi. XII. New or interesting hyphomycetes from Cuba Mycotaxon 63:169-181
———, Kendrick BW., 1991 Ninety-nine conidial fungi from Cuba and three from Canada Univ Waterloo Biol Ser 35:1-132
Choi YW, Hyde KD, Ho WH., 1999 Single spore isolation of fungi Fungal Divers 3:29-38
Ellis MB., 1961 Dematiaceous hyphomycetes III Mycol Pap 82:2-21
———. 1971 Dematiaceous hyphomycetes Kew, England: CAB International. 608 p
Goh TK, Ho WH, Hyde KD, Whitton SR, Umali TE., 1998 New records and species of Canalisporium (Hyphomycetes), with a revision of the genus Can J Bot 76:142-152
———, Hyde KD., 1996 Spadicoides cordanoides sp. nov., a new dematiaceous hyphomycete from submerged wood in Australia, with a taxonomic review of the genus Mycologia 88:1022-1031
———, ———. 1998 Spadicoides palmicola sp. nov. on Licuala sp. from Brunei, and a note on Spadicoides heterocolorata comb. nov Can J Bot 76:1698-1702
Hawksworth DL, Kirk PM, Sutton BC, Pegler DN., 1995 Ainsworth and Bisby's dictionary of the fungi. 8th ed CAB International, U.K. 616 p
Ho WH., 1998 Biodiversity, ecological and ultrastructural observations of fungi on wood submerged in tropical streams [PhD Dissertation]. Hong Kong: The University of Hong Kong. 229 p
———, Hyde KD, Hodgkiss IJ., 1999a Ultrastructure of Annulatascus aquaticus sp. nov., a freshwater ascomycete on submerged wood from Hong Kong Fungal Divers 2:119-128
———, ———, ———. 1999b Digitodesmium recurvum, a new species of chirosporous hyphomycete from Hong Kong Mycologia 91:900-904
Holubová-Jechová V., 1985 Porosubramaniana, new genus of lignicolous Hyphomycetes Proc Indian Acad Sci Pl Sci 94:253-258
Hughes SJ., 1958 Revisiones hyphomycetum aliquot cum appendice de nominibus rejiciendis Can J Bot 36:727-836
Hyde KD, Ho WH, Tsui KM., 1999 The genera Aniptodera, Halosarpheia, Nais and Phaeonectriella from freshwater Mycoscience 40:165-183
Mercado Sierra A., 1983 Nuevos e interesantes hifomicetes enteroblasticos de Cuba Acta Botanica Cubana 16:1-8
Sinclair RC, Eicker A, Bhat DJ., 1985 Branching in Spadicoides Trans Br Mycol Soc 85:736-738
Sivanesan A, Sutton BC., 1985 Microfungi on Xanthorrhoea Trans Br Mycol Soc 85:239-255
Upadhyay HP., 1966 Soil fungi from North-East Brazil. II Mycopathol Mycol Appl 30:276-286
Yanna, Ho WH, Goh TK, Hyde KD., 2000 A new species of Everhartia, associated with leaf spots of Phoenix hanceana from Hong Kong Bot J Linnean Soc 134:465-470
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