Journal of Threatened
Taxa | www.threatenedtaxa.org | 26 February 2025 | 17(2): 26479–26486
ISSN 0974-7907 (Online)
| ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.9156.17.2.26479-26486
#9156 | Received 25 May
2024| Final received 03 January 2025 | Finally accepted 21 January 2025
Morphological
characterization and ecological insights of Pseudonapaeus
cf. candelaris (L. Pfeiffer, 1846) in the Pir Panjal Range of western
Himalaya
Hilal Ahmed 1, Imtiaz
Ahmed 2 & N.A. Aravind 3
1,2
Fish Nutrition Research Laboratory, Department
of Zoology, University of Kashmir, Hazratbal,
Srinagar, Jammu & Kashmir 190006, India.
3 SM Sehgal Foundation
Centre for Biodiversity and Conservation, Ashoka Trust for Research in Ecology
and the Environment (ATREE), Royal Enclave, Srirampura,
Bengaluru, Karnataka 560064, India.
1 hilalahmed1991@gmail.com,
2 imtiazamu1@yahoo.com (corresponding author), 3 aravind@atree.org
Editor: Mandar Paingankar, Government Science College Gadchiroli,
Maharashtra, India. Date of publication: 26 February
2025 (online & print)
Citation: Ahmed, H., I. Ahmed & N.A. Aravind (2025). Morphological characterization and ecological
insights of Pseudonapaeus cf. candelaris (L. Pfeiffer, 1846) in the Pir Panjal Range of western
Himalaya. Journal of Threatened Taxa 17(2):
26479–26486. https://doi.org/10.11609/jott.9156.17.2.26479-26486
Copyright: © Ahmed et al. 2025. 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: The work was supported by Council of Scientific and Industrial Research (CSIR), Government of India, New Delhi with the reference to file number 09/251(0137)/2019-EMR-I for awarding fellowship to Hilal Ahmed, a senior research fellow, Department of Zoology, University of Kashmir.
Competing interests: The authors declare no competing interests.
Author details: Hilal Ahmed, a senior research fellow at the Department of Zoology, University of Kashmir has been engaged in fisheries and molluscan studies since 2019. Dr. Imtiaz Ahmed, a professor at the Department of Zoology, University of Kashmir focuses his teaching and research efforts on fish diversity, nutrition, physiology and molluscan biodiversity since 2006. Dr. Neelavar Ananthram Aravind, a professor at ATREE, Bengaluru brings 25 years of expertise in land and freshwater molluscs in India, focusing on ecology, systematics, biogeography, and conservation. His research employs molecular, spatial and citizen science tools to address pertinent questions in molluscan studies.
Author contributions: HA led the entire field sampling, data collection and preparation of the manuscript. IA and Dr. NAA gave study conceptualization, design, manuscript review,
editing and supervision. Their significant contributions were crucial for the improvement of the overall quality of the manuscript.
Acknowledgments: The authors express gratitude to the head, Department of Zoology, University of Kashmir for providing required laboratory facilities. Special appreciation to the Freshwater Ecology and Conservation Lab, ATREE Bangaluru for offering access to various equipment and for enhancing our practical work. The authors would also like to extend their sincere appreciation to CSIR, New Delhi for providing financial support to Hilal Ahmed, senior research fellow in advancing the research goals.
Abstract: Pseudonapaeus cf. candelaris
is a terrestrial snail species belonging to the Enidae
family, specifically inhabiting the Pir Panjal Range of the western Himalaya. This species displays
a unique shell morphology with prominent features including deep furrows, a
smooth outer surface, cylindrical form, gradually tapering apex, spiral bands
and axial ribs. This study examines the morphometric characteristics of shell
and distinct structural patterns observed in specimens from various sites
within the region. By documenting these morphological attributes, the research
enhances our taxonomic understanding of P. cf. candelaris,
addressing aspects of its classification and ecological role. The findings
present critical information for conservation efforts aimed at protecting this
regionally significant, endemic snail species.
Keywords: Biodiversity,
endemic, gastropods, high altitude, molluscs, shell
morphology, snail, terrestrial.
Introduction
The family Enidae comprises a group of pulmonate
gastropod molluscs that primarily inhabit terrestrial
environments. Woodward (1903) was the first to describe these land snails and
they are well known for their air breathing mechanism. Enidae,
a taxonomic family belonging to the phylum Mollusca, exhibits notable
diversification within this phylum, encompassing approximately 66 genera and
300 species (Molluscabase 2024). The family Enidae is native to India, comprises approximately 29
species. These species are classified into three genera: Mirus Albers, 1850 (consisting of five
species), Serina Gredler, 1898
(consisting of five species), and Pseudonapaeus Westerlund, 1887 (consisting of 19 species). Among these
species, 21 are found exclusively in India (Kobelt
& Mollendorff 1903; Gude
1914; Ray 1951; Solem 1979; Ramakrishna et al. 2010; Tripathy et al. 2018). With the progress of technology,
numerous taxa have undergone taxonomic redescriptions.
The genus Pupinidius Moellendorff belongs to the family Enidae
and has undergone comprehensive examination, resulting in the redescriptions of 14 out of the 16 known species and
subspecies (Wu & Zheng 2009). In a study conducted by Alonso et al. (2006),
it was reported that five previously unidentified species belonging to the
family Enidae of land snails were identified from La
Gomera, located in the Canary Islands. The findings of Wu & Wu (2009, 2013)
improves the
understanding about the characteristics of this family, which
still needs to be clarified in terms of its subdivision or make-up of
subgroups. The taxonomic classification of the family Enidae
has undergone thorough scrutiny and revision throughout its history. It has
also been reported that taxonomy of this species delineated several
subfamilies, including Pseudonapaeinae, Chondrulopsininae, Merdigerinae, Buliminusinae, Andronakiinae, Retowskiinae, Eninae, and Multidentulini (Schileyko 1998).
Furthermore, the following taxonomy by Bouchet et al.
(2017) tried to simplify things by narrowing the classification down to two
subfamilies: Eninae and Buliminusinae.
Bank & Neubert (2016) made improvements to the existing classification
system by dividing the Eninae into four distinct
tribes, namely: Enini, Multidentulini,
Merdigera, and Pseudonapaeini.
In addition to taxonomic factors, Enidae snails have
notable versatility in adapting to a wide range of terrestrial environments,
including forests, grasslands, and cold deserts (Ożgo
2014; Zhukov et al. 2019). The presence of adaptation in this species is
responsible for the intricate morphological and behavioural
characteristics identified within the taxonomic group. Additionally, their
evolution of a functional lung distinguishes them from their aquatic relatives
and allows them to thrive on land (Lodi & Koene
2016; Nandy et al. 2022). The family Enidae is a compelling illustration of evolutionary
flexibility among gastropod molluscs, including
around 20% of the overall population of land snails (Alonso et al. 2006).
The taxonomic
classification of the genus Pseudonapaeus,
as first proposed by Westerlund (1887), occupies a
notable position within the Eninae subfamily of the Enidae. According to Tripathy et
al. (2022), Pseudonapaeus encompasses
136 recognized species and exhibits a broad geographical distribution spanning
central, southern, southeastern Asia, and Japan. The distribution of this genus
in India is primarily limited to the western Himalaya, comprising 18 species
(Ahmed et al. 2023). The taxonomic complexity surrounding this genus has played
a significant role in advancing our knowledge of terrestrial gastropods. The
taxonomy of Pseudonapaeus has
faced difficulties, particularly in classification and species identification (Feruza 2017). The complexities occur due to the varied
physical traits of different species, posing challenges in accurately defining
separate taxonomic groups. The taxonomic classification of this group includes
multiple species, each of which poses distinct difficulties in accurate
identification. The challenges arise from nuanced variations in shell form,
coloration, and size, underscoring the importance for taxonomists to
demonstrate meticulousness in discerning distinguishing characteristics.
The Pseudonapaeus presents a
captivating subject for scholarly investigation, providing valuable
perspectives on the difficulties related to taxonomy, classification, and
species identification within the Enidae family and
the broader realm of terrestrial gastropods.
The Pir Panjal Range, a significant
mountain range located in the northern section of the Indian subcontinent, has
a crucial role in shaping the distribution patterns of the Enidae
family and the genus Pseudonapaeus within
the area. Pseudonapaeus cf. candelaris, a unique species of the genus Pseudonapaeus, demonstrates a significant distribution
within the specified geographic area. The existing literature over the last two
centuries emphasizes the difficulties encountered in taxonomy and the
ever-evolving nature of scientific investigation. The progress in technology
and methods has made it easier to learn more about Pseudonapaeus
cf. candelaris and the Enidae
family, which is an essential contribution to the field of malacology. The
extensive body of literature on gastropod studies offers a significant basis
for present and future research, underscoring the enduring significance of
investigating these land-dwelling molluscs within
shifting scientific frameworks.
The scholarly
discourse surrounding the distribution patterns and ecological preferences of
the Pseudonapaeus cf. candelaris species in the western Himalaya has
undergone significant development, owing to the outstanding contributions made
by numerous workers. Huge Cuming, Esq. initially gathered the specimens, which
were subsequently documented by Pfeiffer (1846). Pfeiffer’s knowledge of the
species’ environment was limited, whereas Reeve asserted that it originated
from regions including Europe and Asia (Reeve 1849). Specimens of the species
were gathered by Thomas Thomson from Takht-i-Suleiman in Srinagar, India, during the exploration
conducted in 1847–48 (Woodward 1856; Benson 1857). The occurrence of the
species in the higher slopes of Kashmir was further investigated in subsequent
research conducted by Hanley & Theobald (1876). Later on, Nevill (1878) expanded the geographical range of this
family included Tandali from Himachal Pradesh, India.
Theobald (1878) expanded upon the existing studies by investigating the
elevated regions in Kashmir. Gude (1914) conducted an
extensive study encompassing Fort Lockhart in Pakistan as a habitat for the
subject under examination.
Conversely,
Ramakrishna et al. (2010) identified Kashmir as the location of occurrence
based on significant literature sources. Various geographical areas, such as Chandak from the Poonch District
of the Pir Panjal Range in
India (Ahmed et al. 2023), exemplify the inclusive scope of these
investigations. The body of literature, which spans over a century, encompasses
diverse research endeavours that have significantly
enhanced our comprehension of the distribution and ecology of Pseudonapaeus cf. candelaris
in the western Himalaya.
There is a
significant knowledge deficit on the variety and ecological aspects of land molluscs, specifically Pseudonapaeus
cf. candelaris, in the vicinity of the Takht-i-Suleiman type locality
situated on the eastern flank of the Pir Panjal Range. Even with the proximity of the species,
existing literature indicates a significant gap in detailed research about the
ecology and diversity of land molluscs within this
geographic region. Significantly, the research conducted by Ahmed et al. (2023)
underscores the necessity for further investigation and the dearth of periodic
evaluations of species by checklists. This study notably draws attention to the
inadequate focus on terrestrial molluscs such
as Pseudonapaeus cf. candelaris and their ecological significance. The
research holds great importance, mainly due to its proximity to the type
locality. It presents a distinct chance to acquire knowledge regarding habitat
preferences, population dynamics, and prospective conservation strategies for
this species. In addition, the need for more consideration of the ecological
aspects of land molluscs in the region gives rise to
apprehensions regarding the potential ramifications for the agricultural sector
at the local level. It is imperative to undertake a targeted research endeavour that examines the ecology of Pseudonapaeus cf. candelaris
and other terrestrial molluscs in the Pir Panjal Range. Addressing this
study would make a valuable contribution to the scientific comprehension of the
species while also carrying practical consequences for promoting local
agricultural sustainability and preserving biodiversity.
It is imperative to
adopt a multidimensional approach to effectively address the research gap in
precisely describing pupillid shell features. Using ultrastructure images of
the shell surfaces gives us a high-resolution picture that lets us look at many
different morphological features, like the structure of the sutures, the
structure of the tips, and the structure of the shell openings. The utilization
of this sophisticated imaging technology overcomes the constraints inherent in
traditional microscopy methods. Integrating molecular identification
techniques, particularly DNA barcoding, can enhance taxonomy classifications
with additional precision. The primary objective of molecular analysis will be
to investigate genetic markers, enhancing species identification’s precision.
Putting these methods together and linking morphological and molecular
approaches creates a strong foundation for fully understanding the features of
the pupillid shell. The comprehensive nature of this technique addresses the
deficiency in morphological analysis and establishes a foundation for the
following research endeavours, encompassing
ecological investigations. The objective is to enhance our comprehension of
these species, aiding in the evaluation of damage, development of conservation
measures and implementation of management methods that are well-informed and
grounded in a more comprehensive and precise understanding of pupillid land
snails. The present study significantly enhances our comprehension of
terrestrial snails’ biodiversity and ecological processes within the demanding
topographies of the Pir Panjal
Range and the wider Himalayan region besides provide us significant
opportunities for enhancing the understanding of the complex interplay
between these gastropods and their alpine habitats.
Material and Methods
Field sampling
From April 2021 to
March 2023, the
specimens of Pseudonapaeus cf. candelaris were meticulously collected in the Rajouri and Poonch Districts of
the Pir Panjal Range
(Figure 1). Monthly surveys, following an active visual search strategy.
Specimens underwent photographic documentation and precise shell measurements
in the laboratory using a Leica M205 stereo microscope and Mitutoyo digital calliper. Identification was confirmed through
morphological examination and comparison with type specimens. Preserved at the
ATREE Biodiversity Laboratory, this research significantly enhances the understanding of
terrestrial mollusc taxonomy in the region.
Morphological
analysis
The collected
individuals were morphologically examined for standard conchological characteristics
such as shell shape, size, aperture shape, width, architecture on the shell,
etc. The shell morphology was compared with earlier descriptions (Pfeiffer
1846; Benson 1857). The photos of the syntype from the Natural History Museum
London and other voucher specimens (ZMA.MOLL.34612 at Naturalis Biodiversity
Center) were compared for identification.
Results
Systematic position
Order: Gastropoda
Subclass: Heterobranchia
Order: Stylommatophora
Family: Enidae B.B. Woodward, 1903 (1880)
Subfamily: Eninae B.B. Woodward, 1903 (1880)
Genus: Pseudonapaeus Westerlund,
1887
Pseudonapaeus cf. candelaris
Shell morphology
The shell of this sinistral gastropod exhibits a cylindrical morphology
characterized by a sleek outer surface and faintly pigmented bands. On average,
it is 25.2 mm in length and has a diameter of 5.8 mm (Image 1). Deep grooves
and a top that gradually narrows to a sharp point distinguish the shell. It
displays slightly slanted stripes over an off-white base colour.
The terminal one exhibits a series of nine flat bends, gradually decreasing in
obliquity, culminating in a rounded base. The semioval
aperture has an interior characteristic of bright white coloration. A peristome
with enlarged white folds encircles the opening, harmoniously connecting them
with a delicate callus along the borders. Significantly, the columellar region
exhibits a pronounced dilation, contributing to the complexities inherent in
the morphological characteristics of this snail shell. On examining the ultrastructure
images of the shell (Image 1a), the surface is smooth with a slowly obliquely
slight band without horizontal streaks, the groove is not too wide and the shell tip is concentrated bluntly without a
sharp tip.
Ecological habitat
By methodically collecting
79 specimens, it was possible to ensure a complete representation of the
species’ range across various environments. A rigorous assessment was carried
out to examine the species’ ecological intricacies, focusing on its habits and
environment. The study on Pseudonapaeus
cf. candelaris in the Pir Panjal Range of the western
Himalaya has provided a detailed understanding of species preferences for
several environmental and habitat factors in the terrestrial ecosystem. The
species exhibited a consistent occurrence in environments defined by soils with
good drainage, particularly red clay, located beneath a thick layer of fallen
leaves and within regions with abundant vegetation that get limited direct
sunlight (Image 2b). The altitude distribution of P. cf. candelaris, which spans from 900 to 1,500 m, has been
identified as a crucial element that highlights its ability to adapt to
specific elevational ranges within the Pir Panjal Range (Image 2a). The soil study indicated a pH
range of 6.5–7.8, with a distinct inclination towards habitats with a
substantial calcium content of 7.9–9.8 mg/g. This preference is particularly
evident in locations that experience semi-arid climatic conditions. Observing
dead specimens within the sandy mud and loamy soil indicates the possibility of
these locations serving as potential hibernation places during high
temperatures and aridity. Field observations showed a notable increase in
specimen abundance from August to mid-September. This time frame accounted for
approximately 75% of the studied population. The ecological study provides a
complete overview of the essential climatic and ecological elements that play a
crucial role in regulating the distribution patterns of P. cf. candelaris. These parameters, identified as critical
determinants, include humidity, altitude, soil type, and temperature.
Discussion
The rediscovery
of Pseudonapaeus cf. candelaris, a species belonging to the Enidae family and native to the Pir
Panjal Range in the western Himalaya, represents a
significant achievement in malacological research. This species has been
challenging to find since it was documented 170 years ago at Takht-i-Suleiman in Srinagar,
Kashmir (Woodward 1856). Many scholars from different periods have been
interested in studying this species, including Reeve (1849), Woodward (1856),
Hanley & Theobald (1876), Nevill (1878), Theobald
(1878), Gude (1914), Ramakrishna et al. (2010), and Tripathy et al. (2018). Old records do not always have
solid proof; they often rely on lists or collections of historical writings (Gude 1914; Ramakrishna et al. 2010; Tripathy
et al. 2018) that do not give essential details like reference numbers and
pictures, or drawings that are needed to confirm the specimens that were
reported. Reeve’s (1849) early claim that the species was limited to Asia and
Europe, which was later withdrawn, introduces a level of intricacy to the
historical account. The problem worsens because specimens still need to be
correctly identified as Zootecus sp. even
though they have apparent physical features that make them easy to spot. The
persistent uncertainty and lack of modern reports highlight the rarity of P.
cf. candelaris in the Pir Panjal Range, as emphasized
in recent studies (Ahmed et al. 2023). The clear connection of the species with
its original location in Kashmir is an undeniable aspect of its importance,
both in the past and present.
The shells of Pseudonapaeus cf. candelaris
in the Pir Panjal range
exhibit unique traits specific to the species. Typically, these shells have a
cylindrical shape with a pointed tip that resembles a candle. The oval-shaped
aperture and the spire height, which is around half of the shell’s overall
height, are distinctive characteristics of the species. Certain shells exhibit
chromatic differences and development lines, indicating the possibility of
variety within the population. P. cf. candelaris can
be distinguished from similar species like P. domina and P.
arctuatus based on its distinctive physical
characteristics (Table 1). These include a sinistral
shell, a smooth surface, a thick aperture shell without horizontal streaks and
3–4 middle whorls that are almost the same width. According to historical
records by Nevill (1878) and Theobald (1878), many sinistral shells were recorded, while dextral shells were
less commonly seen. The lack of visual evidence and preserved specimens in
historical literature raises doubts about the occurrence of dextral shells.
This scepticism is particularly relevant considering
the extensive surveys conducted by multiple expeditions and authors over the
past two years (Ahmed et al. 2023). Theobald (1878) also talks about how the sinistral and dextral shells are very different in size and
suggests that the dextral shells might be Pseudonapaeus
domina with close-type locations. Discernible
distinguishing characteristics have yet to be found between the two.
This study provides a
comprehensive analysis of shell morphology for Pseudonapaeus
cf. candelaris in the Pir
Panjal range of the northwestern Himalaya. In
addition, it includes a succinct ecological investigation specific to this
species. By combining traditional taxonomic methods with ecological assessment,
the understanding
of this mollusc species is significantly improved in
this ecologically crucial region. Future research should prioritize an in-depth
exploration of the ecological implications of P. cf. candelaris
and its role within the Pir Panjal
ecosystem.
This research
underscores the need for extensive biodiversity studies in the western
Himalayas, inspired by the rediscovery of P. cf. candelaris—a
species initially documented by scientists over 170 years ago during several
expeditions. This rediscovery emphasizes the pressing need to investigate and
preserve the region’s rich biodiversity.
For
figure & images - - click here for full PDF
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