New and hitherto unrecorded black mildew causing fungus on the Syzygium mundagam an endemic plant in Southern Western Ghats, India

New and hitherto unrecorded black mildew causing fungus on the Syzygium mundagam an endemic plant in Southern Western Ghats, India | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article New and hitherto unrecorded black mildew causing fungus on the Syzygium mundagam an endemic plant in Southern Western Ghats, India Lini K. Mathew This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6789413/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The foliicolous black mildew fungus infected the leaves of an endemic plant Syzygium mundagam. The fungus was similar to the genus Asterina but differs from it in having septation at the extreme end of the ascospores making the extreme difference in the size and shape of both cells. Hence, this fungus has been accommodated in the genus, Vishnumyces , which is described and illustrated in detail. Biological sciences/Biological techniques/Microbiology techniques Biological sciences/Microbiology Earth and environmental sciences/Ecology Earth and environmental sciences/Environmental sciences Biological sciences/Plant sciences/Plant stress responses Foliicolous Fungi Black mildew new species Figures Figure 1 Introduction During a survey of the foliicolous fungi in the Western Ghats region of Kerala state, author came across an endemic plant, Syzygium mundagam endemic to southern Western Ghats- South Sahyadri and between Palakkad hills to Coorg Region in Central Sahyadris (Henry et al., 1987 , Gamble, 1997 ; Sasidharan, 2004 ), infected with a black mildew fungus. The microscopic analysis indicated that the fungus has a superficial mycelium, laterally situated appressoria, and thyriothecia that open stellately at the center, with the upper layer of the thyriothecia containing cells arranged radially. These characters confirms that the present fungus belongs to the family Asterinaceae (Arx and Muller, 1975 ). Notably, the septation at the terminal end of the ascospores distinguishes the size and shape of the two cells. This particular feature is exclusively associated with the recognized genus Vishnumyces within the family Asterinaceae. The genus Vishnumyces accommodates only a single species, all from the tropics, found on Otonephelium stipulaceum (Sapindaceae) (Hosagoudar and Harish, 2010 ). V. otonephelii , the type species of Vishnumyces , was collected by Jacob Thomas and Harish M from the Vazhachal forest, Trissur, Kerala, India in 2007 (Hosagoudar and Harish, 2010 ). Vishnumyces species are characterized by superficial hyphae with bicellular appressoria, orbicular ascomata, opening by a stellate fissure and 2-celled ascospores. The specimens studied here were collected from different areas of the Malabar Wildlife Sanctuary, Kerala State, India and yielded what is here recognised as novel taxa and host associations for Vishnumyces . This paper describes a new Vishnumyces species, V. malabarensis in association with a new host Syzygium mundagam of Myrtaceae. There were no previous reports on infection by Vishnumyces on the host family Myrtaceae. Methodology In the field, infected plants collected, and observations were documented about the nature of the colonies, the type of infection, and the collection site. A distinct field number was allocated for each collection. In the field, each infected plant was collected separately in polythene bags along with the host twig (preferably with the reproductive parts to facilitate the identity of the corresponding host). Infected plant tissues were systematically pressed and dried using blotting papers. Following the drying process, they were utilized for microscopic analysis. Scrapings were taken directly from the infected host and immersed in a 10% KOH solution. After 30 minutes, the KOH was replaced with Lactophenol. Both mountants functioned effectively as clearing agents, allowing for the visibility of septa for measurement. In order to examine the entire colony in its natural state, a drop of high-quality natural colored or clear nail polish was applied to the chosen colonies and carefully thinned with a delicate brush, guaranteeing that the colonies were not disturbed.. Colonies exhibiting hyper parasites with a woolly appearance were excluded from this process. The treated colonies, along with their host plants, were placed in a dust-free chamber for a duration of thirty minutes. After the nail polish on the colonies had fully dried, a delicate, transparent or subtly apple rose-tinted layer was created, contingent upon the color of the nail polish, with the colonies firmly encased within it. For softer host materials, the film could be gently lifted off by applying slight pressure on the opposite side of the leaves, just beneath the colonies. In contrast, for harder host materials, the film was carefully detached using a razor or scalpel. A drop of DPX was applied to a clean slide, onto which the film was properly spread. Additional drops of DPX were added on top of the film, followed by the placement of a clean cover glass. By applying gentle pressure to the cover glass, any excess DPX was removed after drying, ensuring that air bubbles were avoided. The slides were then labeled and stored in a dust-free environment for one to two days to allow for drying. These permanent slides were subsequently utilized for further research. For intrinsic fungi, sections were prepared and stained with cotton blue. After analyzing each collection, a portion of the material was preserved in the regional herbarium, Mar Thoma College Herbarium, Thiruvalla (MTCHT). Taxonomy THE GENUS VISHNUMYCES Hosag. Fungal parasites on leaves. The mycelium is ectophytic with lateral appressoria. The thyriothecia are orbicular, featuring radiating cells, are astomatous, and dehisce stellately at the center; the asci are ellipsoidal, containing eight spores, and are bitunicate; the ascospores are brown, conglobate, uniseptate, with septa positioned at the extreme end creating a single pinch-off cell. Type sp.: V. otonepheli Hosag. & Harish The genus is characterized by having orbicular thyriothecia, dehisce stellately at the center, ascospores conglobate, uniseptate, septa laid at the extreme end forming one pinch-off cell. Vishnumyces malabarensis sp. nov. Lini K. Mathew (Fig. – 1) (Plate – 1) Colonies hypophyllous, subdense to dense, crustose, up to 2 mm in diameter, confluent. Hyphae substraight to crooked, branching opposite to irregular at acute to wide angles, loosely to rarely closely reticulate, cells 18-33 x 3-4 µm. Appressoria alternate to unilateral, antrorse to retrorse, ovate to clavate, curved to hook shaped, slightly truncate at the tip, 12-20 x 4-6 µm. Thyriothecia scattered, orbicular, stellately dehisced at the centre, up to 200 µm in diam., margin fimbriate, fringed hyphae straight to flexuous; asci oblong to cylindrical, slightly stipitate, bitunicate, octosporous, 40-60 x 30-40 µm; ascospores pale brown, uniseptate, septum at the distal end makes the spore proper “budding-off or pinching off” appearance, constricted at the septum to form one larger and one very smaller cell, 12-16 x 3-10 µm; larger cell ovate to oblong, 10-14 x 3-10 µm, smaller cell ovate to globose, often mammiform, 5-7 x 4-7 µm, wall smooth. Material examined: On leaves of Syzygium mundagam (Bourd.) Chitra (Myrtaceae), Urakuzhy, Malabar Wildlife Sanctuary, Calicut, Kerala, India, Jan. 27, 2013, Lini K. Mathew, MTCHT 102 (Type), TBGT 6981 (isotype) Etmology: The specific epithet is based Type locality. Discussion The genus Vishnumyces is reported here for the first time on the members of the family Myratceae (Hosagoudar and Harish, 2010). It is significant to that the ascospores germinate from the apical tip of the smaller cell by dissolving the cell wall and producing the mycelium from the inner content. Microscopic study revealed that the fungus possesses superficial mycelium and laterally located appressoria. The upper layer of the thyriothecia possessing radially arranged cells and dehiscing stellately at the centre. These are the characters of the family Asterinaceae and of the genus Asterina (Arx and Muller, 1975). Nonetheless, the septation at the terminal end of the ascospores results in variations in the size and shape of both cells. Hence, it has been accommodated in the genus Vishnumyces. The members of Asterinaceae showing host specificity and earlier, Vishnumyces was reported only on the host Otonephelium stipulaceum of Sapindaceae from Vazhachal forest, Trissur, Kerala (Hosagoudar et al, 2011; Hosagoudar, 2012). Hence based on the host specificity the present species may accommodated as a new species of the Genus Vishnumyces. Based on the host specificity, colony morphology, measurement of mycelium and ascospores, shape, the present species can be included under the category of new species. Declarations Funding Declaration There was no funding for the above research work. Author Contribution Writing – review & editing, Writing – original draft, Validation, Methodology, Investigation, Formal analysis, Conceptualization. Acknowledgement Writing – review & editing, Writing – original draft, Validation, Software, Methodology, Investigation, Formal analysis, Conceptualization. References Arx, J.A. V. and Muller, E.M., A re-evaluation of the bitunicate Ascomycetes with keys to families and genera. Stud. Mycol., 9 :1-159 (1975). Gamble, J. S. 1915-1936, The flora of the Presidency of Madras. Adlard & Son Ltd., London, (re ed, 1997) Henry, A. N., G. R. Kumari and V. Chithra, Flora of Tamil Nadu, India. ser. 1, vol. 2. Botanical Survey of India, Coimbatore, (1987). Hosagoudar VB, Thomas J, Agarwal DK., Four new asterinaceous members from Kerala, India. Taprobanica 3 : 15– 17, (2011). Hosagoudar VB., Asterinales of India, Mycosphere, 2 : 617– 852 (2012). Hosagoudar, V. B., Chandra Prabha, A. and Agarwal, D.K. Asterinales of Kerala . Associated Publishing Company, pp. 270 +pl.23, (2011). Hosagoudar, V.B. and Harish, M.. Vishnumyces , a new genus of the family Asterinaceae from India. Indian Phytopath . 63 : 85-86, (2010). Sasidharan, Biodiversity documentation for Kerala- Flowering Plants, part 6 : 178, (2004). Plate Plate 1 is available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files plate1.png Plate-1: Vishnumyces malabarensis sp. nov. 1. Infected leaves of Syzygium mundagam (Bourd.) Chitra (Myrtaceae, 2. Colony with thyriothecia, 3. Branched appressoriate mycelium with thyriothecia, 4. Mycelium showing appressoria plugged around the stomata, 5. Developing thyriothecium, 6, Mature thyriothecium, 7. Ascospore Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6789413","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":465321424,"identity":"4ba137a5-658c-4ec9-82d6-807c20c9fab1","order_by":0,"name":"Lini K. Mathew","email":"data:image/png;base64,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","orcid":"","institution":"St. Thomas College","correspondingAuthor":true,"prefix":"","firstName":"Lini","middleName":"K.","lastName":"Mathew","suffix":""}],"badges":[],"createdAt":"2025-05-31 07:38:17","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6789413/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6789413/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":83810385,"identity":"fd4e9d44-e007-4880-8932-401b0b47dd44","added_by":"auto","created_at":"2025-06-03 06:52:06","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":507684,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003e\u003cstrong\u003eVishnumyces malabarensis\u003c/strong\u003e\u003c/em\u003esp. nov.\u003c/p\u003e\n\u003cp\u003ea. Appressoriate mycelium, b. Thyriothecium, c. Ascus, d. Ascospores\u003c/p\u003e","description":"","filename":"fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-6789413/v1/bbad103a6f968e8a625d43f6.png"},{"id":84479147,"identity":"c56858c8-a275-4352-8fbc-ce71dd69e32a","added_by":"auto","created_at":"2025-06-12 12:17:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":954629,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6789413/v1/039bcb8f-7597-4416-a95e-652b43686638.pdf"},{"id":83810387,"identity":"942e48e5-990d-41d7-8af6-1075142e003b","added_by":"auto","created_at":"2025-06-03 06:52:06","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":3169660,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePlate-1:\u003c/strong\u003e \u003cem\u003e\u003cstrong\u003eVishnumyces malabarensis\u003c/strong\u003e\u003c/em\u003e sp. nov. 1. Infected leaves of \u003cem\u003eSyzygium mundagam\u003c/em\u003e (Bourd.) Chitra (Myrtaceae, 2. Colony with thyriothecia, 3. Branched appressoriate\u003cem\u003e \u003c/em\u003emycelium with thyriothecia, 4. Mycelium showing appressoria plugged around the stomata, 5. Developing thyriothecium, 6, Mature thyriothecium, 7. Ascospore\u003c/p\u003e","description":"","filename":"plate1.png","url":"https://assets-eu.researchsquare.com/files/rs-6789413/v1/b333572190e26e8f2e9bca59.png"}],"financialInterests":"No competing interests reported.","formattedTitle":"New and hitherto unrecorded black mildew causing fungus on the Syzygium mundagam an endemic plant in Southern Western Ghats, India","fulltext":[{"header":"Introduction","content":"\u003cp\u003eDuring a survey of the foliicolous fungi in the Western Ghats region of Kerala state, author came across an endemic plant, \u003cem\u003eSyzygium mundagam\u003c/em\u003e endemic to southern Western Ghats- South Sahyadri and between Palakkad hills to Coorg Region in Central Sahyadris (Henry et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e1987\u003c/span\u003e, Gamble, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e1997\u003c/span\u003e; Sasidharan, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2004\u003c/span\u003e), infected with a black mildew fungus. The microscopic analysis indicated that the fungus has a superficial mycelium, laterally situated appressoria, and thyriothecia that open stellately at the center, with the upper layer of the thyriothecia containing cells arranged radially. These characters confirms that the present fungus belongs to the family Asterinaceae (Arx and Muller, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1975\u003c/span\u003e). Notably, the septation at the terminal end of the ascospores distinguishes the size and shape of the two cells. This particular feature is exclusively associated with the recognized genus \u003cem\u003eVishnumyces\u003c/em\u003e within the family Asterinaceae.\u003c/p\u003e \u003cp\u003eThe genus \u003cem\u003eVishnumyces\u003c/em\u003e accommodates only a single species, all from the tropics, found on \u003cem\u003eOtonephelium stipulaceum\u003c/em\u003e (Sapindaceae) (Hosagoudar and Harish, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). \u003cem\u003eV. otonephelii\u003c/em\u003e, the type species of \u003cem\u003eVishnumyces\u003c/em\u003e, was collected by Jacob Thomas and Harish M from the Vazhachal forest, Trissur, Kerala, India in 2007 (Hosagoudar and Harish, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). \u003cem\u003eVishnumyces\u003c/em\u003e species are characterized by superficial hyphae with bicellular appressoria, orbicular ascomata, opening by a stellate fissure and 2-celled ascospores. The specimens studied here were collected from different areas of the Malabar Wildlife Sanctuary, Kerala State, India and yielded what is here recognised as novel taxa and host associations for \u003cem\u003eVishnumyces\u003c/em\u003e. This paper describes a new \u003cem\u003eVishnumyces\u003c/em\u003e species, \u003cem\u003eV. malabarensis\u003c/em\u003e in association with a new host \u003cem\u003eSyzygium mundagam\u003c/em\u003e of Myrtaceae. There were no previous reports on infection by \u003cem\u003eVishnumyces\u003c/em\u003e on the host family Myrtaceae.\u003c/p\u003e"},{"header":"Methodology","content":"\u003cp\u003eIn the field, infected plants collected, and observations were documented about the nature of the colonies, the type of infection, and the collection site. A distinct field number was allocated for each collection. In the field, each infected plant was collected separately in polythene bags along with the host twig (preferably with the reproductive parts to facilitate the identity of the corresponding host). Infected plant tissues were systematically pressed and dried using blotting papers. Following the drying process, they were utilized for microscopic analysis. Scrapings were taken directly from the infected host and immersed in a 10% KOH solution. After 30 minutes, the KOH was replaced with Lactophenol. Both mountants functioned effectively as clearing agents, allowing for the visibility of septa for measurement. In order to examine the entire colony in its natural state, a drop of high-quality natural colored or clear nail polish was applied to the chosen colonies and carefully thinned with a delicate brush, guaranteeing that the colonies were not disturbed.. Colonies exhibiting hyper parasites with a woolly appearance were excluded from this process. The treated colonies, along with their host plants, were placed in a dust-free chamber for a duration of thirty minutes. After the nail polish on the colonies had fully dried, a delicate, transparent or subtly apple rose-tinted layer was created, contingent upon the color of the nail polish, with the colonies firmly encased within it. For softer host materials, the film could be gently lifted off by applying slight pressure on the opposite side of the leaves, just beneath the colonies. In contrast, for harder host materials, the film was carefully detached using a razor or scalpel. A drop of DPX was applied to a clean slide, onto which the film\u0026nbsp;was properly spread. Additional drops of DPX were added on top of the film, followed by the placement of a clean cover glass. By applying gentle pressure to the cover glass, any excess DPX was removed after drying, ensuring that air bubbles were avoided. The slides were then labeled and stored in a dust-free environment for one to two days to allow for drying. These permanent slides were subsequently utilized for further research. For intrinsic fungi, sections were prepared and stained with cotton blue. After analyzing each collection, a portion of the material was preserved in the regional herbarium, Mar Thoma College Herbarium, Thiruvalla (MTCHT).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTaxonomy\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTHE GENUS\u003cstrong\u003e\u003cem\u003e\u0026nbsp;VISHNUMYCES\u0026nbsp;\u003c/em\u003e\u003c/strong\u003eHosag.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFungal parasites on leaves. The mycelium is ectophytic with lateral appressoria. The thyriothecia are orbicular, featuring radiating cells, are astomatous, and dehisce stellately at the center; the asci are ellipsoidal, containing eight spores, and are bitunicate; the ascospores are brown, conglobate, uniseptate, with septa positioned at the extreme end creating a single pinch-off cell.\u003c/p\u003e\n\u003cp\u003eType sp.: \u003cem\u003eV. \u0026nbsp; otonepheli\u0026nbsp;\u003c/em\u003eHosag. \u0026amp; Harish\u003c/p\u003e\n\u003cp\u003eThe genus is characterized by having orbicular thyriothecia, dehisce stellately at the center, ascospores conglobate, uniseptate, septa laid at the extreme end forming one pinch-off cell.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eVishnumyces malabarensis\u003c/em\u003e sp. nov. Lini K. Mathew (Fig. \u0026ndash; 1) (Plate \u0026ndash; 1)\u003c/p\u003e\n\u003cp\u003eColonies hypophyllous, subdense to dense, crustose, up to 2 mm in diameter, confluent. Hyphae substraight to crooked, branching opposite to irregular at acute to wide angles, loosely to rarely closely reticulate, cells 18-33 x 3-4 \u0026micro;m. Appressoria alternate to unilateral, antrorse to retrorse, ovate to clavate, curved to hook shaped, slightly truncate at the tip, 12-20 x 4-6 \u0026micro;m. Thyriothecia scattered, orbicular, stellately dehisced at the centre, up to 200 \u0026micro;m in diam., margin fimbriate, fringed hyphae straight to flexuous; asci oblong to cylindrical, slightly stipitate, bitunicate, octosporous, 40-60 x 30-40 \u0026micro;m; ascospores pale brown, uniseptate, septum at the distal end makes the spore proper \u0026ldquo;budding-off or pinching off\u0026rdquo; appearance, constricted at the septum to form one larger and one very smaller cell, 12-16 x 3-10 \u0026micro;m; \u0026nbsp; larger cell ovate to oblong, 10-14 x 3-10 \u0026micro;m, smaller cell ovate to globose, often mammiform, 5-7 x 4-7 \u0026micro;m, wall smooth.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMaterial examined:\u003c/strong\u003e On leaves of \u003cem\u003eSyzygium mundagam\u003c/em\u003e (Bourd.) Chitra (Myrtaceae), Urakuzhy, Malabar Wildlife Sanctuary, Calicut, Kerala, India, Jan. 27, 2013, Lini K. Mathew, MTCHT 102 (Type), TBGT 6981 (isotype)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEtmology:\u0026nbsp;\u003c/strong\u003eThe specific epithet is based Type locality.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe genus\u003cstrong\u003e\u003cem\u003e\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003cem\u003eVishnumyces\u003c/em\u003e is reported here for the first time on the members of the family Myratceae (Hosagoudar and Harish, 2010). It is significant to that the ascospores germinate from the apical tip of the smaller cell by dissolving the cell wall and producing the mycelium from the inner content. Microscopic study revealed that the fungus possesses superficial mycelium and laterally located appressoria. The upper layer of the thyriothecia possessing radially arranged cells and dehiscing stellately at the centre. These are the characters of the family Asterinaceae and of the genus \u003cem\u003eAsterina\u0026nbsp;\u003c/em\u003e(Arx and Muller, 1975). Nonetheless, the septation at the terminal end of the ascospores results in variations in the size and shape of both cells. Hence, it has been accommodated in the genus \u003cem\u003eVishnumyces.\u0026nbsp;\u003c/em\u003eThe members of Asterinaceae showing host specificity and earlier, \u003cem\u003eVishnumyces\u0026nbsp;\u003c/em\u003ewas reported only on the host \u003cem\u003eOtonephelium stipulaceum\u003c/em\u003e of Sapindaceae from Vazhachal forest, Trissur, Kerala (Hosagoudar et al, 2011; Hosagoudar, 2012). Hence based on the host specificity the present species may accommodated as a new species of the Genus \u003cem\u003eVishnumyces.\u003c/em\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eBased on the host specificity, colony morphology, measurement of mycelium and ascospores, shape, the present species can be included under the category of new species.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eFunding Declaration\u003c/h2\u003e\n\u003cp\u003eThere was no funding for the above research work.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eWriting \u0026ndash; review \u0026amp; editing, Writing \u0026ndash; original draft, Validation, Methodology, Investigation, Formal analysis, Conceptualization.\u003c/p\u003e\n\u003ch2\u003eAcknowledgement\u003c/h2\u003e\n\u003cp\u003eWriting \u0026ndash; review \u0026amp; editing, Writing \u0026ndash; original draft, Validation, Software, Methodology, Investigation, Formal analysis, Conceptualization.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eArx, J.A. V. and Muller, E.M., A re-evaluation of the bitunicate Ascomycetes with keys to families and genera. \u003cem\u003eStud. Mycol.,\u0026nbsp;\u003c/em\u003e\u003cstrong\u003e9\u003c/strong\u003e:1-159 (1975).\u003c/li\u003e\n \u003cli\u003eGamble, J. S. 1915-1936, The flora of the Presidency of Madras. Adlard \u0026amp; Son Ltd., London, (re ed, 1997)\u003c/li\u003e\n \u003cli\u003eHenry, A. N., G. R. Kumari and V. Chithra, Flora of Tamil Nadu, India. ser. 1, vol. 2. Botanical Survey of India, Coimbatore, (1987).\u003c/li\u003e\n \u003cli\u003eHosagoudar VB, Thomas J, Agarwal DK., Four new asterinaceous members from Kerala, India. \u003cem\u003eTaprobanica\u003c/em\u003e \u003cstrong\u003e3\u003c/strong\u003e: 15\u0026ndash; 17, (2011).\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eHosagoudar VB., Asterinales of India, Mycosphere, \u003cstrong\u003e2\u003c/strong\u003e: 617\u0026ndash; 852 (2012).\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eHosagoudar, V. B., Chandra Prabha, A. \u0026nbsp;and Agarwal, D.K. \u003cem\u003eAsterinales of Kerala\u003c/em\u003e. Associated Publishing Company, pp. 270 +pl.23, (2011).\u003c/li\u003e\n \u003cli\u003eHosagoudar, V.B. and \u0026nbsp;Harish, \u0026nbsp;M.. \u003cem\u003eVishnumyces\u003c/em\u003e, a new genus of the family Asterinaceae from India. \u003cem\u003eIndian Phytopath\u003c/em\u003e.\u0026nbsp;\u003cstrong\u003e63\u003c/strong\u003e: 85-86, (2010).\u003c/li\u003e\n \u003cli\u003eSasidharan, Biodiversity documentation for Kerala- Flowering Plants, part \u003cstrong\u003e6\u003c/strong\u003e: 178, (2004).\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Plate","content":"\u003cp\u003ePlate 1 is available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Foliicolous Fungi, Black mildew, new species","lastPublishedDoi":"10.21203/rs.3.rs-6789413/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6789413/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe foliicolous black mildew fungus infected the leaves of an endemic plant \u003cem\u003eSyzygium mundagam.\u003c/em\u003e The fungus was similar to the genus \u003cem\u003eAsterina\u003c/em\u003e but differs from it in having septation at the extreme end of the ascospores making the extreme difference in the size and shape of both cells. Hence, this fungus has been accommodated in the genus, \u003cem\u003eVishnumyces\u003c/em\u003e, which is described and illustrated in detail.\u003c/p\u003e","manuscriptTitle":"New and hitherto unrecorded black mildew causing fungus on the Syzygium mundagam an endemic plant in Southern Western Ghats, India","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-03 06:51:59","doi":"10.21203/rs.3.rs-6789413/v1","editorialEvents":[{"type":"communityComments","content":1}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"8537591f-6467-4be7-982a-de61ab60fa6b","owner":[],"postedDate":"June 3rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":49397038,"name":"Biological sciences/Biological techniques/Microbiology techniques"},{"id":49397039,"name":"Biological sciences/Microbiology"},{"id":49397040,"name":"Earth and environmental sciences/Ecology"},{"id":49397041,"name":"Earth and environmental sciences/Environmental sciences"},{"id":49397042,"name":"Biological sciences/Plant sciences/Plant stress responses"}],"tags":[],"updatedAt":"2025-08-23T15:23:15+00:00","versionOfRecord":[],"versionCreatedAt":"2025-06-03 06:51:59","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6789413","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6789413","identity":"rs-6789413","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}