Foliicolous fungi of Silent Valley National Park, Kerala, India

The work is the result of the foliicolous fungal collections made in the Silent Valley National Park, Palghat, Kerala, since 1985, resulted in recording 139 fungal taxa belonging to 30 fungal genera: Acremoniula (1), Acrodictys (1), Amazonia (3), Aphanopeltis (1), Armatella (4), Asteridiella (12), Asterina (32), Asterostomella (2), Asterostomula (1), Balladyna (2), Didymopsorella (1), Diplococcium (1), Dysrhynchis (1), Echidnodella (1), Endophyllum (1), Eupelte (1), Irenopsis (1), Leptosphaerulina (1), Meliola (47), Meliolina (1), Oidium (1), Palawaniella (1), Phakopsora (1), Prataprajella (1), Prillieuxina (1), Puccinia (1), Sarcinella (3), Schiffnerula (4), Spiropes (2) and Teratosperma (1), infected 138 plants belonging to 55 host families. The description of all these taxa are provided with illustrations. This area is the type locality for several fungal taxa.


INTRoDuCTIoN
Tropical forests are rich in their biodiversity and play an important role in the socio-economic development of the country. Floristic work on flowering plants and ferns of some regions and revisionary work of some flowering plants in India have appeared and Western Ghats region of peninsular India harbour about 4000 flowering plants. However, study of lower groups like fungi are yet to be taken up systematically.
The leaf and other chlorophyll bearing plant parts are the vital and work as a 'mini industries' in the preparation of food materials and such parts are subjected to several fungal diseases. Leaves of all types form suitable substrates for many fungi. As and when leaf unfolds, it will be almost clean but provides a landing site for all microbes. Leaf surfaces are differential spore traps. Their efficiency of trapping depends upon their position and nature such as: vertical, wet or dry, hairy or glabrous, glossy or mat, waxy or non-waxy, etc. Though all spores of the obligate parasites will not germinate on all hosts, they never miss to infect the suitable or compatible host because of their host specificity. It is also evidenced in several instances that the plants are identified by using the microbes as tools.
Leaves are one of the most important, vital and precious parts of plants to indicate health of plants.
Healthy leaves indicate health of plants and their produce. They are the mini industry for the production of the food materials both for the plants and its dependent animals. However, these green parts of the plants are directly exposed to interact with environment and microbes like algae, fungi, bacteria, virus, etc. The knowledge about this interaction of the plants with other organisms is meager. There are certain instances that fungi erode certain plant community as is evidenced in several cultivated plants infected with rusts, smuts, etc. Hence, an understanding of the occurrence of different foliicolous fungi on the plants of this area is essential.
Silent Valley forest represents a unique patch of tropical evergreen rain forest very rich in its biodiversity with many new, rare and important species. It is located in Palghat District in Kerala state having high ridges and valleys. Though the floristic wealth of this area is well explored, study on the occurrence and distribution of foliicolous fungi is very much sporadic and fragmentary. Foliicolous fungi are leaf infecting fungi occur on almost all angiosperms with high host specificity. It reduces the photosynthetic efficiency and causes several diseases of the leaves. Hence, the study of leaf infecting microfungi in Silent Valley area has revealed novelties and discoveries.
Silent Valley National Park is important tropical virgin rain forests of India noted for its biodiversity and species richness. It is a much whispering place, located in Palghat District in Kerala State, believed to be more than fifty million years old (Swaminathan 1999), having an area of 8952ha, located at an altitude ranging from 750-2383 m, receives more than 5000mm rain fall annually, temperature ranges from 8-29 0 C. It harbours evergreen forests. Manilal (1988) has given an account of 966 species belonging to 559 genera distributed among 134 families of flowering plants. An account of microfungi from water and litter has been studied by Subramanian (1986). The systematic study of the foliicolous fungi of this virgin forest is scanty. The present work is the consolidated account of the foliicolous fungi known from this area.
origin of Silent Valley: The evolutionary age of the Silent Valley evergreen rain forest is believed to be more than 50 million years. This is a cliff of forest which suddenly descends from the Nilgiri plateau to the plains of Kerala with a sudden drop in altitude from 2500-150 m causes a distance to three to four km.
The name 'Silent Valley': Silent Valley forests locally known as Sairandhrivanam, one linked to the mythological character, Droupadi in Mahabharata. Also the river Kunthipuzha named after Kunthi Devi, mother of Pandavas of Mahabharata, runs through the Silent Valley in north-south direction. It is popularly believed that Pandavas lived here with their consort Droupadi. It is also believed that Silent Valley has been given the name due to the absence of cicada insects which usually produce a distinct sound in tropical forests. However, cicadas have started to inhabit in these forests.
Kunthipuzha, which originate at an altitude of about 2400m in the outer rim of Nilgiris, descends rapidly to 1150m of the northern edge of the plateau and flows in the north-south direction. The high peaks in the study area are: Anginda (2383m), Sispara (2206m) and Kozhipara (1904m). Part of the Silent Valley comprises Nilambur and Nilgiris. The southern boundary is with Palghat forest division, while on the east is with Attapadi reserve forests.
Climate: Silent Valley is an example for distinct microclimate. The Attapadi and other areas of Palghat district experience dry climate with high temperature. In contrast to this, just 20km away from Attappadi, Silent Valley receives maximum rain, enjoys mist and low temperature. Both south west and north east monsoons are active in Silent Valley with a precipitation of 3180 mm per annum and the highest rain fall is recorded during the month of July (885.8mm). Average minimum temperature ranges from 8-14 0 C and average maximum from 23-29 0 C. The highest temperature is experienced during May (30 0 C) and the lowest during January (7 0 C). Maximum precipitation during south-west monsoon brings over 500mm annually. Highest rain fall recorded during the month of July.
Biotic features: Silent Valley is an undisturbed maiden forest, is a habitat of many common, vulnerable, rare, threatened, endangered and critically endangered animals and plants. The forests of Silent Valley mainly consist of tropical evergreen, grass land and shola vegetation, with tremendous complexity as well as floral and faunal diversity. Several new species of flora and fauna including amphibian, fish, insects, mosses, ferns, flowering plants and fungi have been described from the valley. The animals comprise 315 species of mammals including monkey, civet, dear, leopard, Nilgiri Thar, Wild Dog, Slender Loris, elephant, tiger; 19 species of amphibians, 35 species of reptiles, 12 species of fishes, six species of bats, 100 species of butterflies, 400 species of moths and 220 species of insects. Among these animals, 14 species of amphibians and 11 species of reptiles are endemic to Silent Valley. It is famous for the highly attractive: Lion-tailed Macaque Macaca silenus. Western Ghats are the only natural habitat for the Lion-tailed Macaque. Tropical evergreen forests are necessary for the life of these monkeys. They eat flowers, fruits and tender leaves of some selected trees of about 92 species of trees. Of these, the fruits of Cullenia exarillata, commonly known as 'Vedichakka' or 'Vediplavu', form the most delicious food.
Reserve forest notification: The Silent Valley forests with an area of 89.52km 2 were notified as reserve Review of research work in Silent Valley: Silent Valley is originated approximately 5 crore years ago. There was no detailed study till the first two decades of 19 th century. Since 1840, Robert White, Beddome, Gamble and several others have studied the plant wealth of this area. In 1860, T.C. Jerdon discovered an orchid, Malabar Daffodil Ipsea malabarica, which remained unknown for 120 years. During the period of 1981-1985, Manilal (1988 and Vajravelu (1990) (1996,2009,2010,2011) have contributed towards the foliicolous fungi of this region. Mohanan (2003Mohanan ( , 2011 has studied several macrofungi including mycorrhizal fungi of commercially timber yielding plants in Kerala State but as such there is no study in the compact forest like Silent valley. Hence, the present study has got much importance. Forest types of Silent Valley: Forests are the complex natural ecosystems, form the factory of water recycling and climatic variation. On the basis of ecological characteristics, the forests are classified into four types: Upland region, Riparian region, Slopes and Submersible area. Based on the vegetation, we come across four types of forests, namely, moist evergreen forests, dry evergreen forests, high land grass land, low land grassland and high altitude sholas (Images 2-5).
Forest Divisions: Silent Valley National Park has four forest divisions, namely, Sairandhri, Neelikallu, Poochipara and Wallakad. Each forest division has evergreen forests, grass lands and shola forests.
Sairandhri forest division: This is a tourist zone, located 23km away from Mukkali in Palghat District, dominated with evergreen forests.
Poochipara forest division: It is 8km away from Sairandhri, having evergreen forests and grass land. Important places of this forest division are Poochipara Peak, Thondakulam, Thoppimala, Chempatty, etc. Wallakad forest division: It is situated 24km away from Sairandhri, having more grasslands and shola forests than the evergreen forests. Sispara, Anginda, Cheriya Anginda, Wallakad, Cheriya Walakad are the high altitudinal places in this section.
In such an interesting forest, persistent efforts have been put along with a team of researchers and the consolidated account of the present work on the foliicolous fungi is the maiden venture (Image 6).

MeTHoDS
Infected plant parts were noticed and collected carefully in the field and notes were made regarding their pathogenicity, nature of colonies, nature of infection, locality, altitude, etc. For each collection, a separate field number was given. Each infected plant parts was collected separately in polythene bags along with a host twig (preferably with the reproductive parts) to facilitate the identity of the corresponding host. These collections were pressed neatly and dried between blotting papers. The host plants were identified by matching them with the authentic herbarium materials and also by consulting the experts. However, the knowledge of identification of flowering plants is the pre-requisite for this study.
In the laboratory, nail polish technique (Hosagoudar & Kapoor 1984) was used to study the structural and morphological characters of the fungi. Since the desired quality and quantity of nail polish is difficult to procure from the market, this problem eased by preparing a xylene-thermocol solution. 5ml or desired quantity of xyline poured in a container, very bright and clean thermocol cut into minute pieces, added to xyline, mixed thoroughly till getting it to a particular consistency and poured it into air tight bottle for use. A drop of xylinethermocol solution applied on the selected colonies, carefully thinned with the help of a fine brush without disturbing the colonies. Colonies with hyperparasites (wooly nature) were avoided. The treated colonies along with their host plants kept in dust free chamber for half an hour. When the applied solution dried, a thin colourless "film" or "flip" was formed with the colonies firmly embedded in it. For soft hostparts, flip was lifted up with a slight pressure on the upper side of the leaves and just below the colonies or an edge of the flip eased and subsequently the entire flip peeled-off by using the thumb nail and ring finger of the left hand. In case of hard host parts, the flip was eased-off with the help of a razor or scalpel. A drop of DPX was added on clear slide and the flip was spread properly on it. Care was taken to avoid air bubbles while mounting. One or two more drops of DPX was again added on the flip and clean cover glass was placed over it and gentle pressure on the cover glass brings out the excess DPX and it was removed after drying. These slides were labeled and placed in the dust free chamber for one to two days for drying.
In some species, the septa were not visible due to heavy pigmentation. In such cases, scrape was taken directly from the infected host and mounted in 10% KOH solution. After 30 minutes, KOH was replaced by lacto phenol (Rangaswamy 1975). Both the mountants worked well as clearing agents and made the septa visible.
The individual material was assigned to its taxonomic rank and prepared for herbarium carrying the details of fungus name, host name, date of collection, locality, name of the collector, expert who identified the specimen and its herbarium number. The envelopes were serially arranged in a rack based on their collection number. Part of the herbarium material is deposited in the Herbarium Cryptogamae Indiae Orientalis (HCIO), IARI, New Delhi and part of it in the Jawaharlal Nehru Tropical Botanic Garden Travancore herbarium (TBGT), Thiruvananthapuram, Kerala.

BLaCK MILDeWS
Black or dark mildews, in contrast to Powdery mildews, are obligate but mostly ectoparasites produce black colonies on the surface of the host plants. The term "sooty moulds" was loosely applied to the entire black colony forming fungi. Hughes (1976) clearly made a distinction between "sooty moulds' and "black mildews". Sooty moulds are totally distinct from these in their nutritional habit, grow on insect secretion or on nectar produced by the plants and spread on entire surface (irrespective of leaf, petiole, stem or dead bark) of plants. When handled, such colonies stick-on to hands and clothes. Close observation of these uniformly spread dense colonies reveal their association with ants, thrips or nectar glands of the plants. In contrast to these, black mildews are obligate parasites and are specific in infecting their compatible hosts. In short, black mildews are obligate parasites, while, sooty moulds are saprophytes. These fungi flourish well in tropics and have extended their distribution to sub-temperate to temperate regions of the World. Since these fungi do not cause any appreciable pathogenicity on the staple food producing crop plants, attention has not been paid much to this group. Economically, like other biotrophs, these fungi increase the temperature in the areas covered by the black colonies, initiate more respiration, reduce the efficiency of the chlorophyll, reduce total sugars, etc. Hosagoudar et al. (1997). Hence, Wellman (1972) stated that "nowhere are these black mildews being made a subject of major pathological study, although agriculturists who observe their crops well, know that at times these fungi are very damaging in their effects" (Hosagoudar 2010). Parasitic on vascular plants; mycelium mostly superficial; appressoriate, phialidic. Ascomata flattenedglobose to globose, ± ostiolate, peridium with conoid cells, larviform and striated appendages, or with repent or strong setae. Asci unitunicate, 2-4-spored, clavate to cylindrical, evanescent; ascospores 3-4-septate, brown at maturity.
Type genus: Meliola Fries To identify the meliolaceous fungi up to species level, it is essential to know: the identity of the host and its family. Further, the description in digital form.

Digital formula
Beeli formula consists of eight digits. The first four digits before the stop (left side to the stop) represent the morphological characters like ascospore septation, presence or absence and the nature of the perithecial setae or appendages, presence or absence and the nature of the mycelial setae and the arrangements of appressoria, respectively. The second 4 digits, after the stop, represent the measurements such as length and breadth of ascospores, diameter of perithecia and length of mycelial setae, respectively. The species having both simple and dentate setae is denoted by ⅓, while species having straight and uncinate setae are designated as ½. The Beeli formula is modified here to accommodate the genus Armatella having 1-2 septate ascospores. Further, for Prataprajella, the second digit becomes ¾ or so. straight to undulating, branching alternate to opposite at acute angles, closely reticulate, forming solid mycelial mat and impart thalloid appearance, cells 13-16.6x6-8 µm. Appressoria alternate to unilateral, very closely arranged, antrorse, straight to curved, 13-16.5 µm long; stalk cells cuneate, 3.5-5 µm long; head cells globose, entire, 10-13 x10-11.5 µm. Phialides mixed with appressoria, alternate, ampulliform, 13-16.5x6.5-8 µm. Perithecia mostly aggregated, flattened-globose, glabrous, black, up to 281µm in diam.; ascospores cylindrical to obovoidal, 4-septate, constricted, 36-43x13-16 µm.

aSTeRINaLeS
These fungi characterized by the presence of external mycelium; orbicular thyriothecium stellately dehisced at the centre, elongated or X or Y-shaped thyriothecium with central sutures, asci globose to oval.  (Fig. 71).

The genus Sarcinella
This is the form genus of the genus Schiffnerula, producing sarciniform, dark conidia.  (Fig. 109).
Colonies amphigenous, mostly epiphyllous, crustose to velvety, up to 2mm in diameter, confluent and covering the entire upper surface of the leaves. Hyphae straight, flexuous, often crooked when solitary, branching alternate to irregular at acute angles, several hyphae running closely parallel and forming a compact mycelial mat, cells 9-15.5x4.5-7.5 µm. Appressoria alternate and produced only on the outer surface of the compact hyphae, mostly straight but rarely curved, unicellular ovate to globose, entire, 6-12.5x6-9.5 µm. Pycnothyria numerous, loosely crowded, circular in outline, often ovate, 130-190 µm in diameter, covering membrane initially brown, later becoming dark and opaque, splitting stellately at the center or having a wide opening. Pycnothyriospores oval, ellipsoidal, pyriform, acute at one end and broadly rounded at another, cinnamon brown, 19-22.5x14-16 μm, wall smooth, germ pore distinct in some spores.  (Fig. 125).