Diversity of Passalora on Ficus
Raghvendra Singh, Shambhu Kumar,
Dinesh Chandra Saini, Parmatma Prasad
Upadhyaya, Kamal & Uwe Braun
Mycological Progress
ISSN 1617-416X
Mycol Progress
DOI 10.1007/s11557-012-0870-6
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DOI 10.1007/s11557-012-0870-6
ORIGINAL ARTICLE
Diversity of Passalora on Ficus
Raghvendra Singh & Shambhu Kumar &
Dinesh Chandra Saini & Parmatma Prasad Upadhyaya &
Kamal & Uwe Braun
Received: 28 August 2012 / Revised: 13 October 2012 / Accepted: 23 October 2012
# German Mycological Society and Springer-Verlag Berlin Heidelberg 2012
Abstract During a survey of hyphomycetes, Passalora trichophila sp. nov. was discovered on living leaves of Ficus mysorensis (Moraceae) in a subtropical forest of eastern Uttar Pradesh,
India. This species is described, illustrated and compared with
morphologically similar species. A key to species of Passalora
found on Ficus is provided. Descriptions and nomenclatural
details were deposited in MycoBank (www.MycoBank.org).
Keywords Biodiversity . Foliar diseases . Hyphomycetes .
Anamorphic fungi . Taxonomy
Introduction
The Indian subcontinent is well known as an area with enormous biodiversity, including a very wide range of vascular
plants which are the base for a huge variety of foliicolous fungi.
Cercosporoid hyphomycetes are among the most important
components of the latter fungal group. They have a worldwide
distribution, with special focus in tropical and subtropical areas.
Cercospora Fresen. and allied genera of India are relatively
well documented, and data on host range and distribution of
Indian cercosporoid hyphomycetes have recently been summarized by Kamal (2010). Nevertheless, the inventory of species
of this fungal group in India is far from being complete. During
R. Singh (*) : P. P. Upadhyaya : Kamal
Department of Botany, D.D.U. Gorakhpur University,
Gorakhpur, UP, India 273009
e-mail: drsinghtaxon@gmail.com
S. Kumar : D. C. Saini
Birbal Sahni Institute of Palaeobotany,
53, University Road,
Lucknow, UP, India 226007
U. Braun
Martin-Luther-Universitat, FB Biologie,
Institut fUr Geobotanik und Botanischer Garten,
Neuwerk 21,
0-06099, Halle, Germany
the course of explorations of foliicolous micromycetes in a
subtropical forest of eastern Uttar Pradesh (Sohagi Barwa
Wildlife Sanctuary, Mahrajganj) in India, a hitherto unknown
cercosporoid hyphomycete was found on living leaves of Ficus
mysorensis. Detailed morphological examinations showed that
this fungus represents an undescribed new species. Because of
the formation of superficial hyphae with pigmented conidiophores formed single, thickened and darkened conidiogenous
loci and pigmented conidia, the new species proved to be a
member of the former genus Mycovellosiella (Muntañola 1960,
Deighton 1974), which is nowadays considered a synonym of
Passalora emened. Detailed discussions on nomenclature, phylogeny, synonymy and taxonomy of Passalora have been
published by Braun (1995), Crous et al. (2000, 2001a, b),
Crous and Braun (2003), Kamal (2010) and in various other
books and papers. An updated key to cercosporoid genera has
recently been published by Braun in Seifert et al. (2011). With
regard to the generic concept applied in the case of the new
species on Ficus, we follow the new circumscriptions outlined
in the cited works and assign it to Passalora.
Materials and methods
Specimens with disease symptoms of cercosporoid fungi on
living leaves were collected during the course of field trips.
Photographs of infection spots on leaves were taken with a
Sony DSC-5730 camera. Specimens for microscopic observation were prepared by hand sectioning. Morphological descriptions are based on slide preparations mounted in clear glycerin
from infected areas of leaves. Observations were made with an
Olympus BX-51 light microscope using a Syntek USB camera
and LEO-430 scanning electron microscope. SEM micrographs
were prepared at Birbal Sahni Institute of Palaeobotany,
Lucknow, India. The specimens were coated with a thin layer
of gold-paladium using a POLARON Sputter coater (180 s in
nitrogen atmosphere of 20 mA, 30 mm distant from the electrode) and examined with a LEO-430 scanning electron
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microscope. Detailed observations of morphological characters
and line drawings were carried out at different magnifications
through light microscopy (300× and 1,000×) and scanning
electron microscopy (500×, 2,000×, 4,000× and 5,000×).
Measurements were made of 25 conidia, hila, and conidiophores and of 10 external stromata, with the extremes given in
parentheses. Drawings of three other Passalora species reported
by different authors on Ficus are provided which is based on
original publications (Braun 1995, Crous and Braun 2003,
Crous et al. 1998) for direct comparison with novel species.
The holotype is deposited in Ajrekar Mycological Herbarium
(AMH), Agharkar Research Institute, Pune, India, and an isotype is retained in the herbarium of the Department of Botany,
D.D.U. Gorakhpur University (GPU) for further reference.
Results
Taxonomic description
Passalora trichophila R. Singh, S. Kumar, D. Saini, P.
Upadhyaya, Kamal & U. Braun, sp. nov. (Figs. 1, 2, 3, and 4)
Mycobank No: MB 800961
Differt ab omnibus speciebus Passalorae ad species Fici
(P. bolleana, P. ficina, P. urostigmatis) stromatibus et hyphis
superficialibus cum conidiophoris solitariis.
Infection spots hypogenous, dark brown to black, discrete and at first limited to midribs and lateral veins, latter
spreading over the lamina and coalescing, finally irregular
and more or less necrotic (Fig. 1b, c). Colonies hypophyllous, effuse, brown to black, velvety, mostly along the
midrib and veins. Mycelium superficial, hyphae branched,
septate, thick-walled, dark brown, forming rope-like structures ascending leaf hairs, 1.5–3.5 μm wide. Stromata external, only on trichomes (Figs. 2e–h and 4b), compact
stroma on top of trichomes (Figs. 2b–d and 3a), pseudoparenchymatous, initially small, 3–13(25)×(3)3.5–10(14) μm,
later 32–80(130)×30–60(127) μm. Conidiophores macronematous, born terminally and as lateral branches from
superficial hyphae (Figs. 2i and 4e) or in loose fascicles of
2–14 arising from poorly developed external stromata on
trichomes (Figs. 2f–h and 4b), later forming crown-like
aggregations at the top of trichomes arising from welldeveloped external stromata (Figs. 2b–d, 3a and 4a, c, d),
Fig. 1 Passalora trichophila (AMH 9476, holotype) causing symptoms on leaf. a Ficus mysorensis. b Early symptoms on the lower side of the
leaf. c Late symptoms on the lower side of the leaf. Scale bar b, c 15 mm
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Fig. 2 Passalora trichophila, microscopic characteristics (AMH
9476, holotype). a Heavy infection on leaf trichomes. b–d Crown of
conidiophores on compact stromata at the top of trichomes in late
stage. e–h Loose stromata with conidiophores on trichomes in early
stage. i Superficial hyphae. j Conidiogenous cells with thickened and
darkened–refractive scars (black arrows for polyblastic nature). k
Intertwining conidiophores. l–n Conidia. Scale bars a 100 μm, b–
h 50 μm, i 20 μm, j 10 μm, k–n 20 μm
unbranched to branched, very variable in length, 4–20(60)×
(1.5)2–3.5(5) μm, simple, erect to procumbent, straight to
flexuous, geniculate, wall smooth, thick, 0–5-septate, intertwining, light to mid brown. Conidiogenous cells integrated,
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Fig. 3 Passalora trichophila,
SEM characteristics (AMH
9476, holotype). a Heavy
infection on leaf trichomes
showing crowns of
conidiophores (white arrows).
b–d Superficial hyphae with
fallen conidia at different
magnification. Scale bars a
60 μm, b 20 μm, c, d 6 μm
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Fig. 4 Drawings of Passalora trichophila (AMH 9476, holotype). a
Heavy infection on leaf trichomes. b Loose stromata with conidiophores at trichomes in early stage. c–d Crown of conidiophores on
compact stromata at the top of trichomes in late stage. e Hyphae with
branched conidiophores. f Conidia. Scale bars a 100 μm, b 20 μm, c
100 μm, d 50 μm, e, f 20 μm
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Fig. 5 Drawings of conidiophores and conidia of Passalora species on Ficus spp. other than P. trichophila a Passalora bolleana (Braun 1995). b
Passalora ficina (Crous and Braun 2003). c Passalora urostigmatis (Crous et al. 1998). Scale bars 10 μm
terminal and lateral, monoblastic to polyblastic (Figs. 2h, j),
cylindrical to clavate, cicatrized, scars somewhat thickened
and darkened-refractive. Conidia acropleurogenous, solitary, straight to slightly curved, cylindrical, narrowly ellipsoidal, fusiform or obclavate to oval, unbranched, light to
mid brown, wall smooth and thick, septa very thick, in some
conidia constricted at septa, dry, apex rounded to subacute,
base rounded to obconicotruncate, usually 0–5-septate,
(5)8–20(29)×2–4(5) μm, hila 0.5–1.5 μm wide, thickened
(Figs. 2l–m, 3b–d and 4f).
Type On living leaves of Ficus mysorensis B. Heyne ex
Roth (Moraceae), Sohagi Barwa Wildlife Sanctuary,
Mahrajganj, eastern Uttar Pradesh, India, 22 March 2012, coll.
Raghvendra Singh, AMH 9476 (holotype), GPU-KSR 600
(isotype).
Etymology Latin, trichophila refers to trichomes of
leaves, the ecological niche where the fructification of the
fungus is formed.
Discussion
Passalora trichophila are easily distinguishable from all
other Passalora spp. [P. bolleana (Thüm.) U. Braun (≡
Septosporium bolleanum Thüm.) on Ficus carica, P.
ficina (S.K. Singh & R.K. Chaudhary) U. Braun &
Crous (≡ Phaeoramularia ficina S.K. Singh & R.K.
Chaudhary) on Ficus hererophyllae and P. urostigmatis
(Henn.) U. Braun & Crous (≡ Cercospora urostigmatis
Henn.) on Ficus citrifolia and Urostigma sp.] reported on
the hosts of the same genus (Braun 1995, Crous and
Braun 2003, Crous et al. 1998) (Fig. 5) by being a
member of the former genus Mycovellosiella, i.e. by the
formation of superficial hyphae giving rise to solitary
conidiophores. The formation of superficial stromata is
an additional striking character unknown in all other
Passalora species on Ficus spp. Moreover, the conidia
in P. ficina are formed in chains.
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Some other cercosporoid species have been described on
Ficus mysorensis, viz, Scolecostigmina fici-elasticae (J.N.
Kapoor) U. Braun (Braun 1999), Scolecostigmina fici-mysorensis (Muthappa) U. Braun (Braun 1999), Scolecostigmina
maculata (Cooke) U. Braun (Braun 1999), but all these species are different from P. trichophila due to strictly immersed
mycelium, formation of sporodochia which are immersed to
erumpent, subglobose to somewhat aplanate stromata, densely
arranged and conidiophores, subcylindrical or somewhat attenuated towards the apex, usually verruculose, arising from
stroma cells, reduced to a single conidiogenous cell, percurrently proliferating, conspicuously annellate, with unthickened conidiogenous loci.
Key to Passalora species on Ficus spp
1. External stroma and mycelium formed, conidiophores
arising from superficial hyphae
P. trichophila
1* Stroma and mycelium only internal, solitary conidiophores lacking
2 Conidia solitary to catenate, catenation simple to
branched
P. ficina
2* Conidia solitary
3 Conidiophores mostly reduced to conidiogenous
cells, conidia (11)17–25(35)×(3)4–5(5.5) μm
P. urostigmatis
3* Conidiophores at least partly septate, i.e. conidiogenous cells integrated, terminal, conidia 10–
40(70)×4.5–6 μm
P. bolleana
Acknowledgments We are grateful to an anonymous reviewer for
helpful remarks on the manuscript. We are much obliged to the Head of
the Department of Botany, DDU Gorakhpur University, Gorakhpur and
the Director, Birbal Sahni Institute of Palaeobotany, Lucknow, for
providing library and laboratory facilities. We thank the technical staff,
Subodh Kumar for scanning electron microscopy. Authors’ thanks are
also due to the Curator, HCIO, New Delhi, for accepting the holotype
specimens and providing an accession number thereof.
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