Journal of Threatened
Taxa | www.threatenedtaxa.org | 26 December 2024 | 16(12): 26306–26311
ISSN 0974-7907 (Online) | ISSN 0974-7893
(Print)
https://doi.org/10.11609/jott.9376.16.12.26306-26311
#9376 | Received 23 August 2024 | Final
received 12 November 2024 | Finally accepted 17 December 2024
Pinnatella limbata (Bryophyta: Neckeraceae): reassessment of conservation status based on
recent findings
O.M. Sruthi 1,
C.N. Manju 2, K.P. Rajesh 3 & J. Enroth 4
1,2 Bryology Laboratory,
Department of Botany, University of Calicut, Malappuram district, Kerala 673
635, India.
1,3 Department of Botany,
The Zamorin’s Guruvayurappan College (Affiliated to the University of Calicut),
Kozhikode district,
Kerala 673614, India.
4 Botanical Museum,
University of Helsinki, P.O. Box 7, FI-00014, Helsinki, Finland.
1 sruthiradhabalan@gmail.com,
2 manjucali@gmail.com (corresponding author), 3 kprajesh.botany@gmail.com,
4 johannes.enroth@helsinki.fi
Editor: D.K. Singh, Botanical Survey of India,
Lucknow, India. Date of publication: 26 December 2024
(online & print)
Citation: Sruthi, O.M., C.N. Manju, K.P. Rajesh & J. Enroth (2024). Pinnatella
limbata (Bryophyta: Neckeraceae):
reassessment of conservation status based on recent findings. Journal of Threatened Taxa 16(12): 26306–26311. https://doi.org/10.11609/jott.9376.16.12.26306-26311
Copyright: © Sruthi et al. 2024. 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: University Grants Commission (UGC), New Delhi and the Core Research Grant project of the Science Engineering Research Board (SERB), New Delhi.
Competing interests: The authors declare no competing interests.
Acknowledgements: The authors are
thankful to the authorities of the Department of Botany, University of Calicut
and the Zamorins Guruvayurappan College, Kozhikode for the facilities and
support. Sruthi is thankful to the University Grants Commission (UGC), New
Delhi for financial assistance. The corresponding author acknowledges the
support from the Core Research Grant project of the Science Engineering
Research Board (SERB), the microscope procured from this project is utilized
for taking photographs. We are also thankful to the Kerala Forest and Wildlife
Department, and their staff members in Aralam
Wildlife Sanctuary for their support during the field studies.
Abstract: Pinnatella
limbata Dixon (Neckeraceae),
a rheophytic moss species with a bistratose
leaf margin unique in the genus was reported from Sampkhand
in Kanara district of Karnataka State in India. The species was subsequently
collected from two additional localities of Kodagu (Coorg) District in
Karnataka State and that P. limbata should be
removed from the threatened category of the IUCN World Red List of bryophytes
due to the new information of its distribution range. The present collection
from Aralam Wildlife Sanctuary, in the Kannur
District of Kerala is a range extension of this species in the Western Ghats
and the first report from Kerala. An attempt is made to reassess the IUCN Red
List status of P. limbata.
Keywords: Aralam
Wildlife Sanctuary, IUCN Red List, Kannur District, Karnataka, Kerala, mosses,
new record, taxonomy, Vulnerable, Western Ghats.
A world monograph of Pinnatella by Enroth (1994) gives a thorough and
insightful re-examination, clarifying all the taxonomic complexities that
existed in the genus and recognized 15 species. Recently, Manju et al. (2023)
added a new species P. enrothiana Manju, J.Muñoz, Sruthi, Mufeed & K.P.Rajesh, from the
Western Ghats of India to the list. Among the Pinnatella
species P. minuta (Mitt.) Broth. is the only
representative in the Neotropics and continental Africa. The greater diversity for Pinnatella
lies in southern and southeastern Asia (Enroth 1994).
During a field survey
in the deep forest of the Aralam Wildlife Sanctuary
in the Kannur District of the Peninsular Indian state of Kerala, an intriguing
moss species was discovered. It was found attached to a large rock surface in a
streamside and hanging down like a loose green curtain covering the entire rock
surface. Through careful examination and detailed study, the species was
identified as P. limbata of the family Neckeraceae. P. limbata
can be distinguished from other Pinnatella
species by its bistratose leaf margin which is a
unique feature of the species. It was first described by Dixon (1921) from the
Kanara district of Karnataka State based on the collection by Mr. L.J. Sedgwick
during 1919. Later, Raghavan in 1960 collected the species from Agumbe of Karnataka and observed that it is a fairly common
species on moist rocks in association with Papillaria
fuscescens (Hook.) A.Jaeger (Raghavan & Wadhwa 1968). Subsequently,
Schwarz (2013) based on the collections of Frahm, Schwarz, & Schumm in 2012
reported it from other two localities of Karnataka. The present collection
proved to be the first report of the species from the state of Kerala and it
implies a range extension of the species in the Western Ghats. The present
collection showed variability in the stem length and texture of the plant as
compared to previous reports. Usually, it has a shorter stem, maximum up to 15
cm. Here relatively larger species were found, reaching twice the length of
those reported earlier.
Pinnatella limbata was assessed as a
‘Critically Endangered’ species in the IUCN World Red List of bryophytes (id
39178; Bryophyte Specialist Group, 2000; https://www.iucnredlist.org/species/39178/10167017).
Schwarz (2013) based on the new information gathered on its distribution
suggested that P. limbata should be removed
from the threat category of the IUCN Red List of bryophytes. The present
collection from Kerala is a record of its further range extension in the
Western Ghats. The IUCN Red List status of P. limbata
Dixon is further reassessed here (Images 1,2).
Materials and Methods
The present
collection was made from the Aralam Wildlife
Sanctuary, a protected evergreen forest in the Western Ghats of Kannur District
in Kerala in peninsular India. The collections were made in two different
seasons from different localities. A combination of microscopes was used to
study the characteristics of the specimen, a Leica Sapo
Stereo Microscope was used for morphological observations, and an Olympus
CX21liLED microscope for anatomical examinations. Magnus Analytics MagVision software (version: x64, 4.8.15674.20191008) was
used to measure the plant parts and cells. An updated description of the species
was prepared based on the present collections. The collected specimens were processed and the herbarium packets of standard size are
deposited in the Calicut University Herbarium (CALI) and Central National
Herbarium (CAL).
The distribution data of this species has been
tabulated based on previous records as well as the present observations. The
area of occupancy (AOO) and extent of occurrence (EOO) were assessed using GeoCat (Bachman et al. 2011; https://geocat.iucnredlist.org/editor).
The threat status was assessed according to the IUCN Red List criteria (Version
3.1).
Results
Taxonomic treatment
Pinnatella limbata Dixon, J. Indian
Bot. 2: 184. 1921. – Type: India, Karnataka, Leonard John Sedgwick, #6437 1919
(BM).
Plants gregarious,
pendent, up to 30 cm long, irregularly pinnately branched, older parts dark
green to brownish green, younger parts and branches pale green, flagelliform branches present; stolons
in cross-section oval-round, cortical cells small, in 2–3 layers, thick-walled,
inner medullary cells in several layers, comparatively larger, thin-walled.
Stolon leaves small, closely appressed, loosely imbricate, 0.7–0.9 x 0.4–0.5
mm, triangular in shape, gradually ending to an acute tip, margin serrulate
except at extreme base; costa reaching above half of the leaf. Stipe short, 1–2
cm long, 0.4 mm diameter in cross-section, with 6–9 layers of cortical cells
surrounding several layers of rounded to hexagonal medullary cells, central
strand absent; stem pale yellow, up to 27 cm long, with 6–7 layers of small,
thick-walled cortical cells in cross-section, medullary cells thin-walled,
larger than cortical cells, rounded to hexagonal, central strand absent. Stem
leaves comparatively larger than stolon leaf, ovate-lanceolate, 1.7–2.3 x
0.9–1.2 mm, loosely imbricate, twisted when dry, nearly symmetrical, leaf apex
sub-acute–obtuse, sometimes mucronate, margin entire below, serrulate at apex,
leaf cross-section adaxially flat, abaxially convex, bistratose
margin ends near extreme tip, leaf tip cells rhomboidal, 8–14 x 3–7 µm, median
laminal cells slightly elongated than tip cells, 11–27 x 3–5 µm, basal cells
elongated vermicular, 19–50 x 3–6 µm, extreme basal juxta costal cells porose; costa ending below apex. Stem leaf base wider than branch
leaf, 1.7–2.1 x 0.8–0.9 µm, leaf apex obtuse, sometimes mucronate, margin
entire below, serrulate apex, bistratose margin
vanishing near tip. Cells at leaf tip rhomboidal, 8–13 x 3–8 µm, median laminal
cells slightly elongated than apex cells, 13–27 x 2–4 µm, basal cells elongated
vermicular, 25–46 x 3–4 µm, extreme basal cells porose
near the costa. Sporophyte not observed (Image 3).
Specimens examined: India, Kerala,
Kannur District, Aralam Wildlife Sanctuary, Meenmutty waterfalls (400 m), 11.947N, 75.882E, on a large
rock near stream, 28 September 2022, Sruthi O.M. 14898 (CALI); Chavachi waterfalls (280 m), 11.929N, 75.901E, on a large
rock surface near stream, 11 January 2023, Sruthi O.M. 14262 (CALI); Meenmutty thodu (664 m), 11.950N,
75.890E, on a rock near streamside, 12 January 2023, Sruthi O.M. 14303 (CALI).
Distribution: Karnataka, Kanara
District, Sampkhand (Dixon 1921; Enroth 1994), Shimoga District, Agumbe
(Raghavan & Wadhwa 1968); Kodagu (Coorg) District, Kabbinakad,
the area around Kabbe Holiday Homestay and the area
around Honey Valley Homestay (Schwarz 2013); Kerala (present study).
Habitat: This species grows as
a mat or curtain on moist large rocks near stream sides which is not inundated
by overflowing waterfalls but is always wet due to the flow of water. The type
specimen was also reported from a similar habitat.
IUCN Red List
reassessment: Pinnatella limbata is known only from a small area in the Brahmagiri region of the Western Ghats, with an EOO of
2,413.644 km2 and an AOO of about 24 km2. As per the
major criteria (B1 and B2) of the IUCN Red List (ver. 3.1) it thus qualifies
for consideration as Endangered (EN). It also meets sub-criteria B1a and B2a,
as it is known from less than 10 locations. Since the area is protected and located
in interior forest there are no other direct threats to the species.
Observations on other sub-criteria such as trends of population decline are not
available at present. Although restricted in EOO and AOO, it does not qualify
for Endangered (EN) due to more than five locations that are not severely
fragmented. However, it does not qualify for Vulnerable (VU) either due to no
known threats which are impacting the area, extent, quality, locations, or
mature individuals. The species is categorized as Near Threatened as it misses
the criteria for VU narrowly.
Discussion
In the genus Pinnatella, P. limbata
is unique in having the bistratose leaf margin. The
species is known to grow on moist rocks in the streams and streamlets of
evergreen forests in a small area in the Brahmagiri
region of the Western Ghats of Karnataka and Kerala. The bistratose
margins may be an adaptation for the rheophytic
habitat, as it makes the leaves stronger (Enroth 1999). Thulasi
et al. (2024) based on Ecological Niche Modelling (ENM) analysis of Elaphoglossum beddomei,
a Southern Indian endemic fern, predicted sharp decline of evergreen habitats
in the Western Ghats of India. This trend of loss of quality of habitats will
also affect other Southern Indian endemics, especially those adapted to the
moist habitats. P. limbata was assessed as
Critically Endangered (Bryophyte Specialist Group 2000), as it was known only
from the type collection from the Western Ghats of Karnataka. In the present
re-assessment, based on updated distribution data from Karnataka (Dixon 1921;
Raghavan & Wadhwa 1968; Schwarz 2013) and Kerala (present observations) the
current status of the species has been categorized as Near Threatened due to
its no known threats which are impacting the area, extent, quality, locations,
or mature individuals.
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