Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 October 2023 | 15(10): 24032–24042
ISSN 0974-7907
(Online) | ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.8595.15.10.24032-24042
#8595 | Received 16
June 2023 | Final received 07 September 2023 | Finally accepted 09 October 2023
Taxonomy and conservation status
of swamp eels (Synbranchiformes: Synbranchidae)
of West Bengal, India
Ram Krishna Das
Department of Industrial Fish and
Fisheries, Asutosh College, 92, S. P. Mukherjee Road,
Kolkata, West Bengal 700026, India.
Editor: R. Ravinesh,
Centre for Marine Living Resources and Ecology, Kochi, India.
Date of publication: 26 October 2023 (online & print)
Citation: Das, R.K. (2023). Taxonomy and conservation status of swamp eels
(Synbranchiformes: Synbranchidae)
of West Bengal, India. Journal of
Threatened Taxa 15(10):
24032–24042. https://doi.org/10.11609/jott.8595.15.10.24032-24042
Copyright: © Das 2023.
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: West Bengal Biodiversity Board ( Memo No. 1221/3K(Bio)- 5/2019
Competing interests: The author declares no competing interests.
Author details: Dr.
Ram Krishna Das is an assistant professor in Industrial Fish and Fisheries at Asutosh College, Kolkata, West Bengal. His research interests include animal taxonomy, fish nutrition and toxicology.
Acknowledgements: The author extends his gratitude
to the West Bengal Biodiversity Board for financial support(Memo
No. 1221/3K (Bio)-5/2019). Special thanks are owned to Dr.
Subhadip Gupta, assistant professor, Department of Geography, Asutosh College for creating the study area map.
Furthermore, the author appreciates to the principal of Asutosh
College for the permission granted to carry out the research. Lastly, sincere thanks
are extended to all the fishermen for their invaluable field support.
Abstract: In a comprehensive study spanning
January 2019 to April 2023 within the state of West Bengal, the research focused
on elucidating the taxonomy and conservation status of swamp eels in the state.
Swamp eels were harvested using traditional fishing techniques, and sampling
sites were randomly selected across nine districts: Cooch Behar, Alipurduar, Jalpaiguri, Uttar
Dinajpur, Purba Bardhaman,
Nadia, Purba Medinipore,
North 24 Parganas, and South 24 Parganas, accounting for variations in climatic
zones and topography. Through meticulous examination involving X-ray
radiographs and morphometric measurements, two distinct swamp eel species, Ophichthys cuchia
(Hamilton, 1822) and Ophisternon bengalense McClelland, 1844, were identified, both
falling under the ‘Least Concern’ category according to the IUCN Red List of
Threatened Species. Rapid population decline of swamp eels in West Bengal is
primarily attributed to habitat degradation and the indiscriminate use of
pesticides and chemical fertilisers.
Keywords: Bengal Mud Eel, diagnosis and
description, Gangetic Mud Eel, Ophichthys
cuchia, Ophisternon
bengalense, Synbranchiform
fishes.
Introduction
The swamp eel, a distinctive
eel-like percomorph fish, belongs to the Synbranchidae
family. These eels are found across tropical and sub-tropical regions globally,
excluding Antarctica (Rosen & Greenwood 1976; Bera
2007; Britz et al. 2021a,b).
According to Praveenraj et al. (2021), the Synbranchidae family comprises four genera and
approximately 26 species, with 12 residing in India (Gopi et al. 2017; Praveenraj et al. 2021), including Monopterus
eapeni Talwar, 1991, M. albus (Zuiew, 1793), Ophichthys
cuchia (Hamilton, 1822), O. fossorius (Nayar, 1951), O.
hodgarti (Chaudhuri, 1913), O. ichthyophoides (Britz, Lalremsanga, Lalrotluanga & Lalramliana, 2011), Rakthamichthys
digressus (Gopi, 2002), R. indicus (Silas & Dawson, 1961),
R. roseni (Bailey & Gans,
1998), R. rongsaw (Britz, Sykes, Gower & Kamei, 2018), R. mumba Jayasimhan, Thackeray,
Mohapatra & Kumar, 2021, and Ophisternon
bengalense McClelland, 1844 (Gopi et al. 2017; Britz et al. 2020, 2021a,b)
The state of West Bengal contains
diverse habitats ranging from the eastern Himalaya in the north to the Bay of
Bengal in the south (Das et al. 2020; Bera et al.
2018). This geographic diversity underscores the state’s significance in terms
of biodiversity. Surprisingly, no comprehensive study on the taxonomy and
conservation status of swamp eels in West Bengal, India, has been conducted by
any previous author. These fishes inhabit a variety of environments, including
subterranean waters and mud holes in swamps and caves, making their harvesting
challenging with conventional fishing methods. Additionally, their superficial
anatomy lacks distinctive features, and the limited external characteristics
are highly variable, posing identification challenges. Consequently, this study
seeks to investigate the taxonomy and conservation status of swamp eels in West
Bengal, India, including the identification of major threats to facilitate
effective conservation strategies.
Materials
and Methods
The research spanned January 2019
to April 2023 in West Bengal (Figure 1), involving the collection of swamp eel
specimens from nine districts of West Bengal (Cooch Behar, Alipurduar,
Jalpaiguri, Uttar Dinajpur, Purba
Bardhaman, Nadia, Purba Medinipore, North 24 Parganas and South 24 Parganas; Table
1). Sampling sites were systematically chosen to ensure representation across
diverse climatic and topographical conditions. Traditional fishing techniques
such as Shuli, kodal-assisted digging, and
handpicking were used in rice fields and marginal water areas, while drag nets
and mosquito nets were employed in weed-infested wetlands like oxbow lakes.
Additionally, baited hooks on hand lines were used to capture species in
ditches and fish ponds. Post-harvest, specimens were photographed and preserved
in 10% formalin solution, each assigned a museum voucher/accession number for
documentation.
Detailed morphometric
measurements were conducted using a digital caliper to measure various
morphometric measurements like total length (TL), head length (HL), snout
length (SL), pre-anal length, gape length, the distance between
anterior-posterior naris, the width of the body at vent and depth of the body
at the vent. The meristic character, like vertebral count, was also undertaken.
The vertebrae counts were determined through X-ray radiography and examined
various anatomical features, such as fins, scales, gill cleft, soft tissue
around the upper jaw, branchiostegal membrane, holobranchs, suprapharyngeal
pouches, and afferent and efferent blood vessels of 4th gill arch.
Fishes were identified as per the standard taxonomic keys (Rosen &
Greenwood 1976; Jayaram 2010).
The assessment of species threat
status adhered to the criteria outlined by the IUCN Red List of threatened
species (Dahanukar 2010; Dahanukar
et al. 2019). Additionally, the frequency of each species’ occurrence was
determined by calculating the number of times it was collected during the
sampling process. This determination was facilitated by employing a standard
catch frequency chart, as presented by Tamang et al. (2007), where catch
frequencies were categorized as follows: 91–100% (common), 81–90% (abundant),
61–80% (frequent), 31–60% (occasional), 15–30% (sporadic), 05–14% (rare), and
less than 5% (extremely rare).
Results
The study revealed the occurrence
of two species of swamp eel, Ophichthys cuchia (Hamilton, 1822) and Ophisternon
bengalense McClelland, 1844 in the study area
(Table 2).
Taxonomic account
The recorded swamp eels belong to
the family Synbranchidae, which is characterized by
anterior and posterior nostrils widely separated; gill openings united to form a single pore or
slit under the head or throat, so they are named Synbranchidae,
which means fused gills; the dorsal and anal fins are reduced to ray less skin
folds, and the caudal fin is reduced, pectoral and pelvic fins absent; scales
may be present or absent; eyes small or
vestigial; 4th aortic arch is
complete and swim bladder is absent.
Class: Actinopterygii
Order: Synbranchiformes
Family: Synbranchidae
Ophichthys cuchia (Hamilton, 1822) (Image 1)
Unibranchapertura cuchia
(Hamilton,
1822)
Amphipnous cuchia
(Hamilton,
1822) Muller 1839
Monopterus cuchia
(Hamilton,
1822) Rosen & Greenwood 1976
Monopterus (Amphipnous)
cuchia (Hamilton, 1822) Talwar & Jhingran
1991
Ophichthys cuchia (Hamilton, 1822) Britz
et al. 2020
Materials examined
2 exs.,
03.iii.2019, 750–860 mm TL, Rice field (17.4291 N, 83.1805 E), Paschim Nararthali, Hindupara, Alipurduar, West Bengal, India, Coll. R.K.Das,
Reg. No. AABM/IFF/AC/Fish/Synbranchidae/1-2; 1 ex.,
20.vi.2019, 380 mm TL, an oxbow lake (Beel)
(26.2822N, 89.4345E), Madhuvasa, Alipurduar,
West Bengal, India, coll. R.K. Das, Reg. No. AABM/IFF/AC/Fish/Synbranchidae/3; 1 ex., 13.i.2019, 710 mm TL, small ditches
(26.2400N, 89.2993E),Kaljani, Baneswar,
Cooch Behar, West Bengal, India, Coll. R.K. Das, Reg. No. AABM/IFF/AC/Fish/Synbranchidae/4; 1 ex., 04.xi.2020, 460 mm TL, Bochamari beel (26.2500N,
89.4400E), Tufangunge, Cooch Behar, West Bengal,
India, coll. R.K. Das, Reg. No. AABM/IFF/AC/Fish/Synbranchidae/5;
2 exs., 25.xi.2020, 680–700 mm TL, ditches
(26.2048N,89.2876E), Gosaierhat, Sitalkuchi,
Cooch Behar, West Bengal, India, Coll. R.K. Das, Reg. No. AABM/IFF/AC/Fish/Synbranchidae /6–7; 1 ex., 06.xi.2020, 630 mm TL, Beel (ox-bow lake) (26.2292N, 89.2557E), Kharija Kakribari, Cooch Behar,
West Bengal, India, coll. R.K. Das, Reg. No. AABM/IFF/AC/Fish/Synbranchidae /8; 2 exs.,
8.xii.2020, Beel (25.4410N, 88.1260E), Balliadighi, Hemtabad, Uttar
Dinajpur, West Bengal, India, coll. R.K. Das, Reg. No. AABM/IFF/AC/Fish/Synbranchidae /9–10; 2 exs.,
22.ii.2021, 520–550 mm TL, Beel (23.5500N, 87.5932E),
Jamalpur, Balarampur, Purba
Bardhaman, West Bengal, India, coll. R.K. Das, Reg. No. AABM/IFF/AC/Fish/Synbranchidae
/11–12; 2 exs., 10.iii.2022, 715-770 mm TL, seasonal
fish pond (23.3319N, 88.3510E), Chapra, Padmamala, Nadia, West Bengal, India, coll. R.K. Das, Reg.
No. AABM/IFF/AC/Fish/Synbranchidae /13–14; 2 exs., 25.xii.2022, 600-630 mm TL, fish pond (22.5070N,
88.3652E), Habra, Ashokenagar, North 24 Parganas,
West Bengal, India, coll. R.K. Das, Reg. No. AABM/IFF/AC/Fish/Synbranchidae /15-16; 2 exs.,
20.iv.2023, 465–565 mm TL, fish pond (22.3007 N, 88.6671 E), Canning, South 24
Parganas, West Bengal, India, coll. R.K. Das, Reg. No. AABM/IFF/AC/Fish/Synbranchidae /17–18.)
Common name Gangetic mud eel.
Local name Kuchia, Kuichha,
Kuche.
Description
The body is elongated, eel-shaped
with a rounded/oval abdomen but laterally compressed at the caudal peduncle;
upper lip with a characteristic overhanging or jowl-like structure (Image 2);
fins absent; very minute cycloid scales at the posterior part of the body;
pre-maxilla with a single row of teeth with 2–3 rows of teeth at symphysis, the
maxilla is equal to pre-maxilla in length, without any teeth,
palatine/ectopterygoid with a row of teeth, each half of mandible is with more
than one row of teeth anteriorly but a single row of teeth in posterior part;
branchiostegal rays six in number; the triangular gill opening which is
internally attached with isthmus (Image 3); a single layer of gill filaments
are present in 2nd and 3rd gill arches; 1st, 4th,
and 5th gill arches are without any gill filaments, 5th ceratobranchial with
several teeth-like structures. In the morphometric measurement, the head
length 7.35–9.16 % of the total length, pre-anal length is 70.83–78.87 % of the
total length, depth of the body at vent 2.08–4.65 % of the total length, the
width of the body at vent 1.25–2.20 % of the total length, snout length 13–20 %
of head length, the distance between anterior and posterior naris 15.71–22.50 %
of head length, snout length 40–50 % of the gape length. The total vertebral
count was 165 to 167 in which abdominal vertebrae was 97–98 and caudal
vertebrae was 68–69 (Image 4). Morphometric measurements of the species are
presented in Table 3.
Colour
In living conditions, the dorsal
side of the O. cuchia was
yellowish/greenish/brownish with black spots. Whereas the ventral side was
yellowish or whitish in colouration. However, the
formalin preserved specimens were dark/blackish in colour.
Remarks
O. cuchia
(Hamilton, 1822) differs from all the species of synbranchidae
except O.
hodgarti (Chaudhuri, 1913), O. ichthyopthoides (Britz, Lalremsanga, Lalrotluanga & Lalramliana, 2011), O. fossorius
(Nayar 1951), O. indicus (Silas & Dawson,
1961) and O. desilvai (Bailey & Gans, 1998) by the presence of scales. O. cuchia differs from the latter five species having
scales in the posterior part of the body. It also differs by having the highest
vertebral count (165–167) compared to the remaining species of the genus Ophichthys.
Habitat
The study revealed the occurrence
of O. cuchia in diverse aquatic habitats in
the study area. They were found to live in the mud holes of rice fields in the Alipurduar and Purba Medinipore districts (Image 5a–c). However, most of the
specimens were found to inhabit the marginal areas of ditches in Cooch Behar
and Uttar Dinajpur districts (Images 6a–f). Some individuals were also found to
live in the weed-infested wetlands in Alipurduar and
North 24 Parganas districts (Oxbow lake) (Image 7), and fish ponds in Nadia and
South 24 Parganas district (Image 8). Higher density of the individual was
observed in the clayey soils and weed-infested water bodies. During drying
seasons, they move to a greater depth of soil, having a very small amount of
water. Some specimens were also observed to live in subterranean water. They
create a characteristic canal located in deep soils in the marginal areas of
water bodies (Image 9). All of the O. cuchia were
collected from the freshwater region of the study area.
Distribution
India (West Bengal, Assam);
Bangladesh; Nepal; Myanmar; Pakistan; and USA.
Status
According to catch frequency, the
species can be categorised as an abundant species
(Table 2). On the other hand, the species is recognized as a ‘Least Concern’
(LC) category as per the IUCN Red List of Threatened Species (Dahanukar 2010).
Ophisternon bengalense
McClelland,
1844 (Image 10)
Materials examined
1 ex., 20.iv.2023, 330 mm TL,
Tidal creek of Matla river estuary (22.3007 N,
88.6671 E), Canning, South 24 Parganas, West Bengal, India, coll. R.K. Das,
Reg. No. AABM/IFF/AC/Fish/Synbranchidae /19; 2 exs., 22.iv.2023, 381–487 mm TL, Tidal creek of Matla river estuary (22.3007 N, 88.6671 E), Canning, South
24 Parganas, West Bengal, India, coll. R.K. Das, Reg. No. AABM/IFF/AC/Fish/Synbranchidae /20–21.
Common name: Bengal Mud Eel.
Local name: Nona kuchia,
Kuchia.
Description
Body elongated, eel-like, abdomen
rounded; eyes visible through skin (Image 11), vent in the posterior part of
the body; head short, compressed; mouth wide, terminal, the gap of mouth
extending to some distance behind the posterior border of the eye (Image 11);
both the jaws equal with villiform teeth; four branchial arches with
well-developed gills; scales absent; pectoral and pelvic fins absent; dorsal,
anal, and caudal, fins are rudimentary; dorsal originates ahead of anal;
dorsal, caudal and anal fins are confluent with each other. The snout length
(SL) is 40% of the gape length; the head length is 9.65–9.71 % of the total
length; the pre-anal length is 74.01–75.75 % of the total length, the depth of
the body at vent 2.87–3.67 % of total length, the width of the body at vent
1.43–2.36 % of total length, snout length 9.4–10.8 % of head length, the
distance between anterior and posterior naris 12.50–16.21 % of head length,
snout length 44.40–45.45 % of the gape length. The total vertebral count was
128–132 in which abdominal vertebrae was 73–75 and caudal vertebrae was 55–57
(Image 12). The morphometric measurements of the species are presented in Table
3.
Colour
In living conditions, the dorsal
side of the fish was deep brownish, and the ventral side was light brownish
with small spots. Whereas the formalin preserved specimens were
reddish/brownish in colour.
Remarks
O. bengalense
McClelland differs from all the species of the genus Ophisternon,
having caudal vertebrae of 55–57, and a snout length of 40% of the gape length.
In O. bengalense, pectoral and pelvic fins are
absent; dorsal, anal, and caudal fins are rudimentary; dorsal originates ahead
of anal; dorsal, caudal and anal fins are confluent with each other.
Habitat
The specimens of O. bengalense were collected from the mud holes located in
the marginal areas of the tidal creek of the Matla
River estuary (Image 13), Canning, South 24 Parganas, West Bengal, India. Thus,
the results of the present study reveal that O. bengalense
is a brackish water swamp eel.
Distribution
India (West Bengal); Sri Lanka;
Bangladesh; Indo-Malayan region; Philippines.
Status
According to catch frequency, the
species can be categorized as a rare species (Table 2). On the other hand, the
species is recognized as a ‘Least Concern’ (LC) category as per the IUCN Red
List of Threatened Species (Dahanukar et al. 2019).
Discussion
The swamp eel species, O. cuchia, was originally described as Unibranchapertura
cuchia by Hamilton in 1822 using the type
locality of the Ganges river in southeastern Bengal. Later, Muller (1839)
transferred the species U. cuchia to the genus
Amphipnous. Rosen & Greenwood (1976), in
their well-known revisionary work on the taxonomy of swamp eels, placed the
species in the genus Monopterus.
Recently, Britz et al. (2020) again revised the
taxonomy of this fish, placing the species in the genus Ophichthys.
On the other hand, O. bengalense was
described by McClelland in 1844 with the type locality of Hooghly River, West
Bengal, India. The swamp eels identified in the present study are in accordance
with the holotype of the species. In an earlier study, Mishra et al. (2003)
recorded the O. cuchia in the rivers Kansai,
Subarnarekha, and Shilabati of West Bengal. Recently,
Mishra & Gopi (2017) recorded both species in the Sundarban
Biosphere region of West Bengal, India.
The results of the present study
showed that O. cuchia is widely distributed in
the state of West Bengal. The adaptive features like air breathing organs, the
ability to tolerate a wide range of salinity, the capacity to withstand extreme
draught and cold by living in burrows, the ability to survive without feeding
for considerable periods, and the crawling type of movement are evident in the
swamp eel species O. cuchia, which possibly
caused the wide distribution of the species in the state of West Bengal (Nico
et al. 2019). However, O. bengalense has been
recorded only in the tidal creek of the Matla River
estuary, demonstrating brackish water of living habit, thus showing a very
restrictive distribution of the species in the state compared to the O. cuchia.
Swamp eels occur in a variety of
habitats, both freshwater and brackish water. Although some species live in
clear flowing streams, most inhabit sluggish or standing waters, often with low
oxygen content, like swamps or marshy areas, ponds, and lakes, where borrowing
and amphibious habits are commonly displayed. They are admirably adapted for
cave life, and some species from both the New World and Old World are cavernicolous (Rosen & Greenwood 1976; Bailey & Gans 1998). In addition, some species, like M. eapeni Talwar and R. roseni
(Bailey & Gans 1998), are blind cavernicoles living in subterranean waters (Gopi 2002).
Overall, swamp eels are not
usually considered to be heavily threatened or endangered. So, that is the
reason IUCN is listed as the ‘Least Concern’ category. However, the populations
of both species are declining rapidly in the state. Habitat loss due to urbanisation, agricultural expansion, and pollution of
freshwater systems is probably responsible for the reduction of the population
of swamp eels in West Bengal. Barman (2007) also considered habitat loss to be the chief threat
to the fish in West Bengal. Overexploitation for food and trade can also impact
local populations of these fish. As agricultural land or rice fields are considered one of
the habitats for swamp eel, the indiscriminate use of pesticides and chemical fertilisers also causes the decline of the swamp eel
population in West Bengal. Thus, localised threats
such as habitat loss, water pollution, and overexploitation can affect the
populations of swamp eels, especially in areas where human activities
significantly impact their habitats.
Conclusion
The present study documented two
species of swamp eels, O. cuchia
(Hamilton, 1822) and O. bengalense McClellands, 1844 within the region of West Bengal, India.
These swamp eels inhabit diverse environments, including mud holes of the rice
field, ditches, fish ponds, wetland or oxbow lakes, and tidal creeks. Based on
the catch statistics, O. cuchia is notably
abundant, whereas O. bengalense is relatively
rare species. Nevertheless, it is noteworthy that both species are categorized
as ‘Least Concern’ category as classified by the IUCN Red List of Threatened
Species. The decline in swamp eel populations in West Bengal can be attributed
to habitat loss due to urbanisation, and
indiscriminate use of pesticides and other agro-chemicals.
Further studies endeavors are warranted to delve into the biology of the swamp
eels for the development of commercial swamp eel fisheries in West Bengal.
Table 1. Details of the sampling
sites.
|
District |
Block |
Village |
GPS Readings |
Type of water bodies |
|
Cooch Behar |
Tufanganj II |
Bochamari |
26.2500°N, 89.4400°E |
Bochamari Beel (ox-bow lake) |
|
Cooch Behar II |
Kharija Kakribari |
26.2292°N, 89.2557°E |
Beel (ox-bow lake) |
|
|
Baneswar |
26.2400°N, 89.2993°E |
Ditches |
||
|
Sitalkuchi |
Gosaierhat |
26.2048°N, 89.2876°E |
Beel (ox-bow lake) |
|
|
Alipurduar |
Kumargram |
Hindupara |
17.4291°N, 83.1805°E |
Rice Field |
|
Madhuvasa |
26.2822°N, 89.4345°E |
Beel (ox-bow lake) |
||
|
Uttar Dinajpur |
Hemtabad |
Balliadighi |
25.4410°N, 88.1260°E |
Beel (ox-bow lake) |
|
Purba Bardhaman |
Jamalpur |
Balarampur |
23.5500°N, 87.5932°E |
Beel (ox-bow lake) |
|
Nadia |
Chapra |
Padmamala |
23.3319°N, 88.3510°E |
Fish Pond |
|
North 24 Parganas |
Habra II |
Ashokenagar |
22.5070°N, 88.3652°E |
Fish Pond |
|
South 24 Parganas |
Canning II |
Canning |
22.3007°N, 88.6671°E |
Tidal Creek, Matla River estuary |
|
Purba Medinipore |
Bhagbankhali |
Chandipur |
22.1406° N, 87.8715° E |
Paddy field |
|
Jalpaiguri |
Ambari |
Rajgunge |
26.6388° N, 88.4971° E |
Wetland |
Table 2. The list of swamp eels
recorded from West Bengal.
|
Swamp eel species |
English name /Common name |
Local name |
Catch frequency |
IUCN category |
|
O. cuchia
(Hamilton, 1822) |
Gangetic Mud Eel |
Kuchia, Kuichha, Kunche |
Abundant (85.71%) |
LC |
|
O. bengalense
McClelland, 1844 |
Bengal Mud Eel |
Nona Kuchia,
Kuchia |
Rare (14.28%) |
LC |
Table 3. Selected morphometric
data for Ophichthys cuchia
and Ophisternon bengalense.
|
|
O. cuchia (n = 18) |
O. bengalense (n = 3) |
||
|
|
Range |
Mean±SD |
Range |
Mean±SD |
|
Total Length (TL) in mm |
340–860 |
600.27±141.60 |
330–487 |
399.33±80.08 |
|
In percent of total length |
||||
|
Head length (HL) |
7.35–9.16 |
8.49±0.48 |
9.65–9.71 |
9.68±0.03 |
|
Pre-anal length |
70.83–78.87 |
74.82±2.26 |
74.01–75.75 |
75.03±0.91 |
|
Body depth at the vent |
2.08–4.65 |
3.39±0.57 |
2.87–3.67 |
3.19±0.42 |
|
Body width at the vent |
1.25–2.20 |
1.60±0.25 |
1.43–2.36 |
1.76±0.51 |
|
In percent head length |
||||
|
Snout length |
13.33–20.00 |
16.77±1.52 |
9.37–10.81 |
10.27±0.78 |
|
Distance anterior-posterior
naris |
15.71–22.50 |
19.20±1.82 |
12.50–16.21 |
13.82±2.07 |
|
In percent gape length |
||||
|
Snout length(SL) |
40–50 |
44.17±4.61 |
44.40–45.45 |
44.93±0.50 |
|
Ratio |
||||
|
Depth/Width of body |
1–1.66 |
1.23±0.22 |
1.00–1.06 |
1.02±0.03 |
|
Total length/Head length |
10.90–13.60 |
11.80±0.71 |
10.29–10.36 |
10.32±0.03 |
|
Total length/Body depth |
20–28.88 |
23.19±2.41 |
30.43–33.00 |
31.72±1.28 |
|
Vertebrae |
||||
|
Abdominal |
97–98 |
97.5±0.70 |
73–75 |
74±1.41 |
|
Caudal |
68–69 |
68.5±0.70 |
55–57 |
56±1.41 |
For
figure & images - - click here for full PDF
References
Bailey,
R.M. & C. Gans
(1998). Two synbranchid fishes, Monopterus
roseni from peninsular India and M. desilvai from Srilanka. Occasional
Papers of the Museum of Zoology, The University of Michigan 726: 1–18.
Barman, R.P.
(2007). A review of
the freshwater fish fauna of West Bengal, India with suggestions for
conservation of threatened and endemic species. Records of the Zoological
Survey of India, Occasional Paper 263: 1–48.
Bera, M., S. Paloi,
A.K. Dutta, P. Pradhan, A. Roy & K. Acharya (2018). Contribution to the Macromycetes of West Bengal, India: 23–27. Journal of
Threatened Taxa 10(9): 12270–12276. https://doi.org/10.11609/jott.3875.10.9.12270-12276
Berra, T.M.
(2007). Freshwater
Fish Distribution. The University of Chicago Press, Chicago and London, 615 pp.
Britz, R., A. Standing, B. Kumar, M. Kripakaran, U. Katwate, R.L. Sundar & R. Raghavan (2021b). Ophichthys fossorius, a poorly known South Indian
swamp eel (Teleostei: Synbranchidae).
Ichthyological Ex-ploration of Freshwaters
1173: 1–14. https://doi.org/10.23788/ief-1173
Britz, R., H. Sudasinghe,
D. Sykes & R.R.H. Tharindu (2020). Ophichthys desilvai, a poorly known synbranchid eel from Sri Lanka (Teleostei:
Synbranchidae). Ichthyological Exploration of Freshwaters
30: 1–16. https://doi.org/10.23788/IEF-1139
Britz, R., N. Dahanukar,
A. Standing, S. Philip, B. Kumar & R. Raghavan (2021a). Osteology of ‘Monopterus’ roseni
with the description of Rakthamichthys, new
genus, and comments on the generic assignment of the Amphipnous
Group species (Teleostei: Synbranchi-formes).
Ichthyological Exploration of Freshwaters 30: 221–236. https://doi.org/10.23788/ief-1163
Dahanukar, N. (2010). Monopterus
cuchia. The IUCN Red List of Threatened
Species 2010: e. T166554A6235213. Accessed on 05 May 2023. https://doi.org/10.2305/IUCN.UK.20104.RLTS.T166554A6235213.n
Dahanukar, N., S. de A. Goonatilake, M. Fernado & O. Kotagama (2019). Ophisternon bengalense. The IUCN Red List of
Threatened Species 2019: e.T166410A1131667.
Accessed on 05 May 2023. https://doi.org/10.2305/IUCN.UK.20193.RLTS.T166410A1131667.en
Das, D., E. Tarafder, M. Bera, A. Roy &
K. Acharya (2020). Contribution to the Macromycetes of West
Bengal, India: 51–56. Journal of Threatened Taxa 12(9): 16110–16122. https://doi.org/10.11609/jott.5115.12.9.16110-16122
Gopi, K.C.
(2002). A new synbranchid fish, Monopterus
digressus from Kerala, peninsular India. Records
of the Zoological
Survey of India 100(Part 1–2):
137–143.
Gopi, K.C.,
S.S. Mishra & L. Kosygin (2017). Pisces, pp. 527–570. In: Chandra,
K., K.C. Gopi, D.V. Rao, K. Valarmathi & J.R.B.
Alfred (eds.). Current Status of Freshwater Faunal Diversity in India.
Zoological Survey of India, Kolkata, 624 pp.
Hamilton, F.
(1822). An Account of the Fishes
Found in the River Ganges and
its Branches. Archibald Constable and
Company, Edinburgh, UK, 405 pp.
Jayaram, K.C.
(2010). The Fresh
Water Fishes of the Indian Region. Narendra Publishing House, New Delhi, 616 pp + XXIV
pl.
McClelland,
J. (1844). Apodal fishes of Bengal. Calcutta Journal of Natural
History 5: 150–226.
Mishra, S.S.
& K.C. Gopi (2017). Fish diversity of Indian Sundarban and its
resource and research prospects. In: Chandra, K., J.R.B. Alfred, B. Mitra & B.R. Chowdhury (eds.). Fauna of Sundarban Biosphere Reserve. Zoological Survey of
India, 229 pp.
Mishra, S.S.,
P. Pradhan, S. Kar & S.K. Chakrabory (2003). Ichthyofaunal diversity of
Midnapore, Bankura and Hooghly Districts, South West Bengal. Records of the
Zoological Survey of India 220: 1–65
Muller, J.
(1839). Vergleichende anatomie der Myxinoiden,der
Cyclostomen mit durchbohrtem Gaumen. Ueber das gefasssystem. Abhandlungen
der Königlichen Akademie der Wissenschaften zu Berlin 175–304.
Nico, L.G.,
A.J. Ropicki, J.V. Kilian & M. Harper (2019). Asian swamp eels in North
America linked to the live-food trade and prayer-release rituals. Aquatic
Invasions 14: 775–814. https://doi.org/10.3391/ai.2019.14.4.14
Praveenraj, J., T. Thackeray, A. Mohapatra
& A.P. Kumar (2021). Rakthamichthys mumba, a new species of Hypogean Eel (Teleostei: Synbranchidae) from Mumbai, Maharashtra, India. Aqua,
International Journal of Ichthyology 27(3): 93–102.
Rosen, D.E.
& P.H. Greenwood (1976). A fourth Neotropical species of syn-branchid
eel and the phylogeny and systematics of synbranchi-form
fishes. Bulletin of the American Museum of Natural His-tory 157: 1–69.
Talwar, P.K.
& A.G. Jhingran (1991). Inland fishes of India and
adjacent countries. Volume 2. Oxford & IBH Publishing Co., New Delhi,
Bombay, Calcutta, India, 615 pp.
Tamang, L., S. Chaudhury & D.
Chaudhury(2007). Ichthyofaunal contribution to
the state and comparison of habitat contiguity on taxonomic diversity in Senkhi stream, Arunachal Pradesh, India. Journal of the
Bombay Natural History Society 104(2): 170–177.