Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 January 2021 | 13(1): 17554–17560
ISSN 0974-7907 (Online) | ISSN 0974-7893
(Print)
https://doi.org/10.11609/jott.6133.13.1.17554-17560
#6133 | Received 11 May 2020 | Final received
15 January 2021 | Finally accepted 18 January 2021
Assessment of threat status of
the holly fern Cyrtomium micropterum (Kunze) Ching (Polypodiopsida: Dryopteridaceae)
in India using IUCN Regional guidelines
C. Bagathsingh
1 & A. Benniamin
2
1,2 Fern Tissue Culture Laboratory,
Botanical Survey of India, Western Regional Centre, No-7, Koregaon
Road, Pune, Maharashtra 411001, India.
1 rcbagath007@gmail.com (corresponding
author), 2 fernsbenni@gmail.com
Abstract: During the field survey in
central Western Ghats of India, an interesting dryopteridoid fern species was collected from Nellikathrupodu Range of Billigiri
Rangaswamy Temple (BRT) Tiger Reserve of
Karnataka. After a critical study of
literature, the specimen was identified as Cyrtomium micropterum (Kunze) Ching. In India, this species is known only from its type
locality Nilgiri and Palani hills of Tamil Nadu. The present collection from the BRT Tiger Reserve shows its extended distribution
and forms the first report for the state of Karnataka. The present paper deals with the assessment
and conservation status of Cyrtomium micropterum (Kunze) Ching in India in accordance with IUCN guidelines for the application
of Red List Criteria at regional and national Levels, 2012, Version 4.0. Detailed descriptions, photographs,
microphotographs are provided for easy identification of this species.
Keywords: Categorization, GeoCAT, Nilgiris,
threatened pteridophytes, Western Ghats.
Editor: V. Irudayaraj, St. Xavier’s College
(Autonomous), Palayamkottai, India. Date
of publication: 26 January 2021 (online & print)
Citation: Bagathsingh,
C. & A. Benniamin (2021). Assessment of threat status of
the holly fern Cyrtomium micropterum (Kunze) Ching (Polypodiopsida: Dryopteridaceae) in India using IUCN Regional guidelines. Journal of Threatened Taxa 13(1): 17554–17560. https://doi.org/10.11609/jott.6133.13.1.17554-17560
Copyright: © Bagathsingh
& Benniamin 2021. Creative Commons Attribution
4.0 International License. JoTT allows unrestricted use, reproduction, and
distribution of this article in any medium by providing adequate credit to the
author(s) and the source of publication.
Funding: Science and
Engineering Research Board (SERB), Government of
India (File No. EMR/2017/0003856).
Competing interests: The authors
declare no competing interests.
Acknowledgements: The authors wish to express
their sincere thanks to the Director, Botanical Survey of India, Kolkatta for his support. We extend our sincere thanks to
Principal Chief Conservator of Forests (Wildlife Division), Karnataka Forest
Department for granting permission to carry out the research. The first author is thankful to Mr. V. Thirumurugan and Mr. Muthukrishnan,
Wildlife Institute of India, Dehradun and
Mr. Nenjae Gowda, ATREE Community Conservation
Centre, BR Hills for their assistance during fieldwork. Special thanks to Mr.
Caroline Loup, Curator Université de Montpellier – Herbier (MPU) for sending the isosyntype image.
The seed-free vascular plants
of pteridophytes, which include ferns (10,578 species) and lycophytes
(1,338 species) are the second most species-rich group of vascular plants
composing of ca. 11,916 species globally (PPG I, 2016). It has, however, received little conservation
effort than other plant groups and most species of ferns have not yet been
evaluated for their conservation status (IUCN 2017). A huge number of ferns and lycophytes have become threatened (Arcand & Ranker
2008) and the decline is probably due to habitat destruction and loss of mature
individuals (IUCN 2019). In India, about 1,107 species of
ferns and lycophytes were reported (Fraser-Jenkins et al. 2017) of which nearly
about one-third of total Indian populations (337 taxa) are considered to be
threatened (Fraser-Jenkins 2012). The
Western Ghats, one of the global hotspots of the world, harbors 349 species of
ferns and lycophytes (Benniamin & Sundari
2020) among which
38 species are assessed as threatened (Benniamin et al. 2008).
The previous assessments, however, could not meet the guidelines of IUCN Red List
Categories and Criteria neither at the regional nor national Level (IUCN 2012).
Hence, the threatened status of most ferns and lycophyte species in
India remains under-evaluated. The present study is an attempt to assess the
threat status of Cyrtomium micropterum (Kunze) Ching. (Dryopteridaceae) in India, in accordance with the IUCN
Guidelines for application of Red List Criteria at regional and national
Levels, 2012, Version 4.0.
During the field survey
(2017–2020) the first author collected an interesting dryopteridoid fern species from Nellikathrupodu Range of Billigiri
Rangaswamy Temple (BRT) Tiger Reserve, Karnataka
(11.91180°N & 77.20776°E). After
making detailed studies on morphological characters along with consultation of
relevant literature (Manickam & Irudayaraj 1992, 2003; Rajagopal & Bhat 2016; Benniamin & Sundari 2020) and herbarium (BSI, RHT, JCB, MPU), this species was identified as
Cyrtomium micropterum (Kunze) Ching. On perusal of literature surveys and herbarium
consultation, it became apparent that this genus has not been reported in
Karnataka. Hence the genus Cyrtomium forms a new addition to the
pteridophytic flora of Karnataka State, with the single species C. micropterum (Kunze) Ching. The
paleotropical species C. micropterum (Kunze)
Ching is distributed in eastern and southern Africa, Madagascar, and southern
India. In India this species is known
only from its type locality in Nilgiri Hills and from
Palani Hills of Tamil Nadu (Figure 1).
The present record with previous
studies shows that the habitats of this species, somewhat high altitude on the
eastward offshoots of the Western Ghats like Palni
Hills, Nilgiri Hills, and BRT Hills are more suitable
for this species when compared to Munnar Hills and Tirunelveli Hills on the
main tract of the Western Ghats. As far
as the Dryopteridaceae members are concerned, most of
the species are altitude specific, i.e., 1,300–1,800m. Since the altitude of northern Western Ghats
is less than 1,300 m (Maharashtra, Goa, and Gujarat), it is not possible for
this species to grow there. This may be due to the requirement of a highly
specific ecological niche for this species, which prefers ever-green or
partially-exposed semi-evergreen forests at high altitudes. It has also been confirmed that no such
specific habitat has been observed on the roadsides of Palni
Hills, Nilgiris, and Nellikathuru
Podu in the BRT Tiger Reserve, Karnataka. Apart from the altitudinal and physiographic
characteristics mentioned above, other climatic factors, in particular the
proportion of maritime and land moisture and temperature, also play an
important role in the distribution of this threatened fern as shown in the distribution
map (Map 1). In general, all the
populations are present on the eastern side of the Western Ghats to get more
continental air mass and less maritime air mass as in Africa (Bostock et al.
1998). From the distribution pattern of
this species, it is well understood that this species prefers high altitude
locations along the eastern border of the main tract of Western Ghats, as
opposed to unfavorable regions/localities on both the
eastern and western slopes. It is
expected to be present in Meghamalai, adjacent to Palni Hills, but due to lack of high altitude, it does not
grow there (Mr. Amirtham, pers.comm.
15.11.2020).
All the 31 species of Cyrtomium are maritime-moisture-loving ferns common
in Japan to Africa where all the species are strictly restricted to the
easternmost coastal border. But the
Indian diploid and triploid apogamous species of Cyrtomium shows the difference in the requirements
of maritime and land moistures. Thus the
triploid C. caryotideum requires more moisture
with the coolest climate in contrast to the diploid apogamous
C. micropterum which requires a cooler climate
with comparatively less moisture. With
the above details on the global distribution of the genus Crytomium,
the present gatherings of Cyrtomium micropterum from BRT Tiger Reserve is a very important
record for its complete distribution range in India.
Materials and Methods
Extensive field exploration was
carried out between 2017 and 2020 in different seasons of the year and
geographical coordinates were recorded using geographical positioning system
(GPS). Plant identification was done by
consulting relevant literature (Manickam & Irudayaraj 1992, 2003; Benniamin
& Sundari 2020) and herbaria consultation (BSI,
RHT, JCB, MPU). Photomicrographs were
taken using an Olympus stereo microscope SZ61.
Herbarium specimens were deposited at the Botanical Survey of India, Western Regional Centre
Herbarium (BSI). A distribution map was
constructed using open-source software QGIS Ver. 3.12.0. Assessment of threat status was carried out according
to the IUCN Red List Criteria at Regional and National Levels, 2012 (version
4.0). Mature individuals were also
counted as per the guidelines of IUCN 2010.
The area of
occupancy (AOO) and extent of occurrence (EOO) were calculated using the
open-source online software GeoCAT (Geospatial
Conservation Assessment Tool, Bachman, et al. 2011), available at http://geocat.kew.org/
Results
Cyrtomium micropterum
(Kunze) Ching
Icon. Fil. Sin. 3: t. 127. 1935.
Image 1. Benniamin & Sundari,
Pteridophytes of Western Ghats-A
Pictorial guide: 41. f. 113. 2020; Fraser-Jenk. et al., Annot.
Checkl. Indian. Pterid. 2:
215. 2018. Aspidium anomophyllum f. micropterum
Kunze, Linnaea 24: 278–279. 1851. Phanerophlebia
caryotidea var. micropteris
(Kunze) C.chr., Manickam, Fern Fl. Palani Hills,
132. 1986; Manickam & Irudayaraj, Pterid. Fl.
West. Ghats, S. India: 272. t. 209. 1992; Manickam & Irudayaraj, Pterid. Fl. Nilgiris S. India:
157. 2003.
Isosyntype:
India, Tamil
Nadu, Nilgiris, Hohenacker #913 (MPU image!).
Herbs perennial; rhizome erect,
densely covered with persistent leaf base and scales; scales lanceolate,
fimbriate at margins, long acuminate at apex, brownish-black; stipes tufted, 15
̶18 cm long, brown at base, green towards above, densely scaly at base, grooved
above. Leaves unipinnate; lamina oblong with trilobed
terminal pinna, 50 ̶ 60 cm long, dark green; pinnae 10–12 pairs, slightly
ascending, subopposite, ovate to lanceolate, c. 7 × 2.5 cm, auriculate at acroscopic end, blunt auricle, serrate at margin, acute at
apex, petiolate, widely spaced, brown unicellular hairs on both surfaces; veins
anastomosing with included veinlets; rachis as for stipe; sori
indusiate, indusium fimbriate at margins, reniform, orbicular, scattered,
seated on free veinlet, 32 spores per sporangium; spores bilateral, monolete, laesura long, exine thick, perine highly folded to form tubercle like structues all over the spore, darkish brown, 18 ̶ 20 µm
long.
Specimen examined: 205936 (BSI), 29.xi.2018, India,
Karnataka state, BRT Tiger reserve, Nellikathurupodu
range, 11.91180°N, 077.20776°E, 1,370m,
coll. C. Bagathsingh (Image 4). 17687 (RHT!), 03.v.1981, India, Tamil Nadu State, Palani
Hills, on the slopes of Perumal Peak, 1,800m, coll. V.S.Manickam.
Phenology: Fertile from August to January.
Habitat & Ecology: This species was found growing in
a terrestrial habitat as small colonies on fully shaded evergreen forest
floors, between 1,600 and 1,800 m.
Global distribution: Ethiopia, Kenya, Lesotho,
Malawi, Madagascar, South Africa, Tanzania, Uganda, and India; India: Nilgiris and Palani Hills of Tamil Nadu and BRT Tiger
Reserve of Karnataka (present report).
Threat status assigned: Endangered (B2ab(iii,v)).
Cyrtomium micropterum
(Kunze) Ching
is placed under the Endangered (ER) category in the present assessment as the
species is restricted to only three locations in India. The extent of occurrence is 7,152.25 km2 which is more than
threshold value for Endangered category, so it’s not applicable for category
assignment and the area of occupancy is estimated to be about 12.00km2,
which meets criterion B2 for Endangered category. The continuous decline in the quality of
habitat (an increase of temperature, and a decrease of air humidity) and the
number of mature individuals was observed due to extension of patrol roads,
invasions of weeds, poor spore viability & germination rate, increased
transport inside the reserve, and other anthropogenic activities which qualify
for the Endangered category under sub-criteria B2a,b(iii,v). Due to the lack of adequate information on the number
of mature individuals in localities and estimation & reduction in the size
of the population, we couldn’t able to apply Criteria A, C, D, and E. Since the distribution of these species is
restricted only to the southern Western Ghats of India, the influences of
colonization from African countries is not possible. It is still unpredictable
for the reason for its diminished capacity for colonization of new habitats in
the Western Ghats, though the species is apogamic (development of sporophyte
without fertilization). So the threat
status of these species will get upgraded if the same trends continue (Detailed
justification for this assessment is given in Appendix I)
For
figure & images - - click here
Appendix I
Extent of Occurrence (EOO): EOO for the species was estimated to be 7,152.25km2,
calculated by using GeoCAT software (Bachman et al.
2011).
Area of Occupancy (AOO): AOO was calculated based on the cell width (2km ×
2km) recommended by IUCN and it is estimated to be 12 km2 by using GeoCAT software (Bachman et al. 2011).
Number of locations and its information: Based on the field experience by
the second author for the last 20 years (1999–2020) in different seasons in
India, the species is reported from only three localities, i.e., Perumal Peak of Palani Hills (Manickam 1981; Pounraj 2020), Nilgiris Guliar Reserve, Pachaikadu Shola,
Kodanadu Valley in Tamil Nadu (Manickam 1991, 1992), Nellikathuru Podu range in BRT
Tiger Reserve, Karnataka (2020, present report). As this species grows nearby roadsides, due
to the widening of roads and tourist activities, the locations are severely
fragmented. This is also one of the
reasons for the rarity of the species. Active searches for the species
from additional localities in the Western Ghats have been unsuccessful.
Population numbers and its trends: As far as the population numbers
are concerned there are no early reports on mature individuals in any locality
(Manickam & Irudayaraj 1992, 2002; Manickam 1994). Dr. V. Irudayaraj
and Pounraj (pers. comm. 10.09.2020) have collected
this species recently (2020) in Palani Hills and they have found only three
mature individuals. While studying the
fern diversity of Western Ghats (2004), the senior author (AB) could not
relocate this species in Nilgiris and Palni hills in Tamil Nadu except in Kodanadu
Valley. Continuous field survey, during
the last five years (2016–2020) in different parts of Western Ghats, by the
senior author (AB), has resulted in the observation of 25 individuals in the
year 2016 and they were reduced to 10 mature individuals in 2019 and recently
on 2020 they have been further reduced to only five individuals. Due to the widening of road and tourist
activities, the number of individuals is gradually declining. A quite high number of mature individuals
(25) were encountered in BRT Tiger Reserve, Karnataka (in 2018) and now it has
reduced to 11 individuals. Nearly 70%
and 45% population got decreased on the Nilgiris and
in the BRT Tiger Reserve, respectively.
Threats: In general,
all the populations in all the three localities are growing along shaded
roadsides with an easy approach to human beings with periodic roadside
cleanings by the local government. In
the BRT Tiger Reserve, increased transport activities to the coffee estates
within the reserve pose a serious threat to the population and impedes the
growth of mature individuals, and most of the matured individuals were uprooted
last year, during the expansion of patrol roads in the Reserve. Apart from the anthropogenic pressure, the
habitat of C. micropterum in the Reserve has
been invaded by notorious weeds such as Chromolaena
odorata (L.) R.M.King
& H.Rob., Ageratina
riparia (Regel) R.M.King
& H.Rob.
The vigorous growth of these weeds often interrupt the growth of
individuals by covering them all over.
Moreover,
when compared to the common triploid apomictic Cyrtomium
caryotideum (Chromosome count database), this
diploid apomictic species does not require a humid atmosphere and it prefers to
grow at high altitude on the eastward side (Nilgiris,
Palni Hills, BRT), more or less on the same longitude
of the Western Ghats, with the presence of more continental air masses with
less humidity. With the climate change
and increase of atmospheric temperature, this species struggles for survival in
the existing locations without being able to spread to other localities.
Through this
assessment, we strongly recommend conserving this species by both in vivo and
in vitro (biotechnological) methods, since it has a high ornamental valve. These species have been introduced in the
botanical garden of Botanical Survey of India (BSI) Western Regional Centre,
Pune as a part of ex situ conservation (Image 3).
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