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The identity of Osteobrama cotio, and the status of “Osteobrama serrata” (Teleostei: Cyprinidae: Cyprininae)


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Osteobrama cotio is considered to be a widespread species in India and Bangladesh. Mitochondrial DNA (COI, 16S rRNA) shows that populations from the Meghna River, Karnafuli and Sangu Rivers, Narmada River, and Godavari River are genetically distinct from each other. No morphological differences were found to separate Meghna and Karnafuli+Sangu populations, however. A putative new species, “Osteobrama serrata” has been described from the Barak River basin, stated to be distinguished from O. cotio by the presence of a serrated third dorsal-fin ray. The description of “O. serrata” does not fulfil requirements of the International Code of Zoological Nomenclature, (International Commission on Zoological Nomenclature 1999) and the name is thus unavailable. Published DNA sequences of “Osteobrama serrata” are identical to sequences of O. cotio from Bangladesh. As mentioned already in the original description, O. cotio has a serrated third dorsal-fin ray.
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Accepted by R. Pethiyagoda: 22 Aug. 2018; published: 23 Oct. 2018
ISSN 1175-5326 (print edition)
(online edition)
Copyright © 2018 Magnolia Press
Zootaxa 4504 (1): 105
The identity of Osteobrama cotio, and the status ofOsteobrama serrata”
(Teleostei: Cyprinidae: Cyprininae)
Department of Zoology, University of Dhaka, Dhaka-1000, Bangladesh.
Department of Zoology, Swedish Museum of Natural History, PO Box 50007, SE-104 05 Stockholm, Sweden.
Corresponding author. E-mail:
Osteobrama cotio is considered to be a widespread species in India and Bangladesh. Mitochondrial DNA (COI, 16S rR-
NA) shows that populations from the Meghna River, Karnafuli and Sangu Rivers, Narmada River, and Godavari River are
genetically distinct from each other. No morphological differences were found to separate Meghna and Karnafuli+Sangu
populations, however. A putative new species, “Osteobrama serrata” has been described from the Barak River basin, stated
to be distinguished from O. cotio by the presence of a serrated third dorsal-fin ray. The description of “O. serrata” does
not fulfil requirements of the International Code of Zoological Nomenclature, (International Commission on Zoological
Nomenclature 1999) and the name is thus unavailable. Published DNA sequences of “Osteobrama serrata” are identical
to sequences of O. cotio from Bangladesh. As mentioned already in the original description, O. cotio has a serrated third
dorsal-fin ray.
Key words: Asia, DNA barcode, freshwater, morphometrics, phylogeny, taxonomy
Species of Osteobrama Heckel, 1843 (type species Cyprinus cotio Hamilton, 1822), are laterally compressed,
silvery fishes with an elevated dorsum, keeled abdomen, and long anal fin (Figs 1–2). They are common and often
abundant throughout their range, which encompasses primarily lentic habitats in Bangladesh, India, Myanmar, and
Pakistan (Hora & Misra 1940; Talwar & Jhingran 1991; Vishwanath & Shantakumar 2007). Recorded maximum
total length ranges from 11cm in O. bakeri (Day, 1873) to 38 cm in O. belangeri (Valenciennes, 1844) (Talwar &
Jhingran 1991).
In the most recent revision of the genus, Hora & Misra (1940), using Rohtee Sykes, 1839 as the generic name,
distinguished seven species, one with two subspecies, and provided descriptions and a key. Talwar & Jhingran
(1991) provided an updated list of species with established synonyms, short diagnoses, and a key that differs
slightly from that of Hora & Misra (1940). Vishwanath & Shantakumar (2007) revised northeastern Indian species,
and Jadhav et al. (2011) analysed nominal species from peninsular India.
Three species have been recorded from Myanmar and the Irrawaddy drainage in India and China, viz.,
Osteobrama feae (Vinciguerra, 1890); O. cunma (Day, 1888), with synonym Rohtee roeboides Myers, 1924; and
O. belangeri (Valenciennes, 1844), with synonyms Rohtee blythi Bleeker, 1860, O. brevipectoralis Tilak & Husain,
1989, and Systomus microlepis Blyth, 1858.
Osteobrama cotio, with the objective junior synonym Leuciscus gangeticus Swainson, 1839, is reported to
have a wide distribution from Pakistan eastwards to Assam and Bangladesh (Talwar & Jhingran, 1991). Hora &
Misra (1940), Talwar & Jhingran (1991), and Menon (1999) considered O. cunma to be a subspecies of O. cotio,
but it was ranked as a separate species by Vishwanath (2000, 2002) and later authors. Osteobrama cotio
peninsularis Silas, 1952, has rarely been reported, but was treated as a valid subspecies of O. cotio by Talwar &
Jhingran (1991), and Jadhav et al. (2011).
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Osteobrama vigorsii (Sykes, 1841), with synonyms Leuciscus alfredianus Valenciennes, 1844, Leuciscus
duvaucelli Valenciennes, 1844, O. rapax Günther, 1868, O. bhimensis Singh & Yazdani, 1992, and Rohtee dayi
Hora & Misra, 1940, occurs in the Godavari and Krishna River drainages (Jadhav et al. 2011) .
Osteobrama neilli (Day, 1873) and O. bakeri are present in the extreme south of peninsular India (Talwar &
Jhingran, 1991; Jadhav et al. 2011).
FIGURE 1. Adult specimens of Osteobrama cotio sensu lato. A) NRM 68948, 58.6 mm SL. Bangladesh: Meghna River
drainage, Kushiyara River at Fenchuganj. B) NRM 40578, 63.9 mm SL. India: Brahmaputra River drainage, Dibrugarh Market.
C) NRM 67707, 74.4 mm SL, Bangladesh: Karnafuli river drainage, Kaptai Lake.
The phylogenetic position and monophyly of Osteobrama is uncertain. In a molecular phylogenetic analysis,
Tang et al. (2013) consistently recovered O. cotio and O. cunma as sister species, but not forming a monophyletic
group with O. belangeri. Osteobrama belangeri and other Smiliogastrini, Rohtee ogilbii Sykes, 1839, Pethia ticto
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(Hamilton, 1822), and Enteromius trimaculatus (Peters, 1852) varied among themselves in relative position in
different analyses. The results of Tang et al. (2013) suggest that Osteobrama is not monophyletic. Osteobrama was
never the subject of a morphological phylogenetic analysis, and no synapomorphies have been recorded as such.
FIGURE 2. Subadult specimens of Osteobrama cotio sensu lato. A) NRM 68828, 49.1 mm SL. Bangladesh: Meghna River
drainage, Surma River at Kheaghat Point. B) NRM 40331, 42.9 mm SL. India: Brahmaputra River drainage, Sessa River, 30
km from Dibrugarh. C) NRM 67707, 50.5 mm SL, Bangladesh: Karnafuli River drainage, Kaptai Lake.
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Singh et al. (2018) and Maisnam et al. (2018) analysed phylogenetic relationships of species of Osteobrama,
based on the cytochrome c oxidase subunit 1 (COI), and 16S ribosomal RNA (16S rRNA) mitochondrial genes. The
latter paper also included a morphometric comparison. Singh et al. (2018) considered their sample from the Barak
River, a tributary of the Meghna River in Manipur, India, to represent a new species, for which they proposed the
specific name “Osteobrama serrata”. Comparing the information in Singh et al. (2018) with our data on
Osteobrama from Bangladesh, we noticed, besides the name “serrata” not being available under the International
Code of Zoological Nomenclature (International Commission on Zoological Nomenclature 1999), that “O. serrata”
does not represent a new species, and that there is unrecorded variability in what has been called Osteobrama cotio.
Here we present a complementary phylogenetic analysis of Osteobrama and review the taxonomic status of O.
cotio and “O. serrata” based on collections from Bangladesh, supplemented by DNA sequences available from
Materials and methods
Specimens were already available in museum collections, purchased from fishermen or markets; or collected in the
wild using a beach seine or hand net and euthanized through immersion in buffered tricaine-methanesulphonate
(MS 222) until cessation of opercular movements plus an additional 30 minutes, following the protocol in permits
from the Swedish Environmental Protection Agency (dnr 412-7233-08 Nv) and the Stockholm Ethical Committee
of the Swedish Board of Agriculture (dnr N 85/15). Collecting in Bangladesh was conducted under a permit to the
University of Dhaka. Voucher specimens are deposited in the collections of the University of Dhaka, Dhaka (DU),
and the Swedish Museum of Natural History, Stockholm (NRM).
Measurements and counts were taken as described by Fang (1997). Vertebral counts are given as
precaudal+caudal, where the first vertebra bearing a long haemal spine articulating with anal-fin pterygiophores
was recorded as the first caudal vertebra (Kullander et al. 2018). X-radiographs were made with a Kevex 130kVP
microfocus X-ray source and a Samsung/Rayence 17x17 inch DR panel. Statistics were calculated using SYSTAT
v. 13 (Systat 2013). Two specimens were digested in trypsin solution, counterstained with Alcian Blue 8GS for
cartilage and Alizarin Red S for bone, and cleared and stored in full strength glycerol, following the procedure of
Taylor & Van Dyke (1985).
For the genetic analysis, a 655 basepair (bp) fragment of the 5’ end of the mitochondrial COI gene and a 596
bp fragment of the mitochondral 16S rRNA gene were sequenced from morphologically identified specimens of
Osteobrama. Additional sequences of Osteobrama were downloaded from GenBank. DNA was extracted, and COI
sequences obtained as as described by Kullander et al. (2018) 16S rRNA was amplified using the primers
with a PCR cycle of 94°C 4 min; 35 * (94°C 30s; 55°C 30s; 72°C 30s); 72°C 8 min). The PCR products were
processed as described by Kullander et al. (2018). Geneious (Kearse et al. 2008) was used to calculate genetic
distances (uncorrected pairwise p-distance, as recommended by Srivatsan & Meier (2012), and the Geneious plug-
in Species Delimitation (Masters et al. 2011) was used to calculate the probability of reciprocal monophyly under a
model of random coalescence. Automatic barcode gap detection was performed with ABGD (http:// (Puillandre et al. 2011). A phylogenetic hypothesis was
constructed using MrBayes version 3.2 (Huelsenbeck & Ronquist 2001; Ronquist & Huelsenbeck 2003) (5 million
generations, GTR + Γ + I model), COI data partitioned by codon position; samples were taken every 1000
generations, and the first 25% of samples were discarded as ‘burn-in’. Convergence was checked with Tracer,
version 1.6 (Rambaut et al. 2014).
New sequences in this study are listed in Table 1. Sequences downloaded from GenBank are referred to in text
and figures by their GenBank accession numbers.
The distribution map was constructed in QGis ( with layers from Natural Earth (http://
Material examined. Osteobrama cotio sensu stricto: India. Brahmaputra River drainage: NRM 40331,
12, 26.7–43.3 mm SL; Assam, about 30 km SW of Dibrugarh, Sessa River close to Patiola village, 27°18ʹ47ʺN
94°49ʹ46ʺE; 21 Jan 1998. F. Fang & A. Roos (FANG-98-006).—NRM 40578, 3, 60.8–63.9 mm SL; Assam,
Dibrugarh Market, 27°29ʹ0ʺN 94°54ʹ0ʺE; 20 Jan 1998. F. Fang & A. Roos (FANG-98-005).—Ganga River
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drainage: NRM 40479, 8, 32.8–37.5 mm SL; Bihar, roadside ditch about 8 km on road Lukeesarai–Munger,
25°13ʹ52ʺN 86°3ʹ27ʺE; 28 Jan 1998, F. Fang & A. Roos (FANG-98-018).—Bangladesh. Meghna River drainage:
NRM 68828,1, 49.1 mm SL; NRM 68885, 8, 37.4–66.9 mm SL; Sylhet Division: Sylhet District: Golapganj:
Surma River left bank, at Kheaghat point, 1.5 km upstream from Golapganj, 24°51ʹ40ʺN 91°59ʹ37ʺE; 23 Mar 2016,
M.M. Rahman, et al. (SRL-2016-013).—NRM 66129, 1, not measured; DU 9031/NRM 69352, 1, not measured;
NRM 68929,1, 64.6 mm SL; Dhaka Division: Khishoreganj District: Ashuganj, Meghna River at Ashuganj Point,
24°2ʹ47ʺN 91°0ʹ20ʺE; 20 Mar 2016. M.M. Rahman, et al. (SRL-2016-005).—NRM 68904, 2, 53.9–47.4 mm SL;
NRM 69284, 1, 45.7 mm SL; NRM 69291, 1, not measured; NRM 68948, 2, 55.9–58.6 mm SL; Sylhet Division:
Sylhet District: Fenchuganj, Kushiyara River left bank in Fenchuganj at junction with Juri River, 24°42ʹ19ʺN
91°57ʹ16ʺE; 22 Mar 2016. M.M. Rahman, et al. (SRL-2016-008).—NRM 68918, 3, 43.7–46.2 mm SL; NRM
68995, 1, not measured; Sylhet Division, Sylhet District, Goyanghat, Piyain Goyan River near Goyanghat,
25°5ʹ18ʺN 91°58ʹ53ʺE; 25 Mar 2016, M.M. Rahman, et al. (SRL-2016-020).—Padma River drainage: DU 6149, 1,
41.6 mm SL Dhaka Division: Munshigonj district: Arial Beel, 23°34ʹ47ʺN, 090°16ʹ20ʺE; 10 Oct 2014, M.M.
Rahman.—NRM 67729, 4, 38.5–39.6 mm SL; Dhaka Division: Sreenagar: fish market in Shonbari, Sreenagar,
[23°32ʹ38ʺN 90°17ʹ47ʺE]; 2 Dec 2014. M.M. Rahman, et al. (SRL-2014-018).—Feni River drainage: DU 6112, 4,
33.8–61.4 mm SL; Chittagong Division, Feni District: Feni River and Shitakunda Hillstream: Kohua River,
22°54ʹ42ʺN, 091°30ʹ10ʺE; M.M Rahman, 29 May 2015 (SL-6). Osteobrama cotio sensu lato: Bangladesh.
Karnafuli River drainage: DU 9031/NRM 66545, 1, not measured; NRM 67721, 1, 59.0 mm SL; Chittagong
Division: Rangamati District: Rangamati, town fish market, fish from Kaptai Lake; 22°38ʹ59ʺN 92°11ʹ1ʺE. 27 Nov
2014. M.M. Rahman, et al. (SRL-2014-001).—NRM 67707, 9, 52.0–74.4 mm SL; NRM 70222, 9, 29.6–53.9 mm
SL; NRM 70230, 2, 43.0–50.0 mm SL, cleared and stained; Chittagong Division: Rangamati District: Rangamati,
fish landing pier, fish from Kaptai Lake, 22°39ʹ0ʺN 92°11ʹ9ʺE; 27–28 Nov 2014, M.M. Rahman et al. (SRL-2014-
002).—Sangu River drainage: NRM 67175, 48.2 mm SL; Chittagong Division: Bandarban District: Sangu River at
Dhopachari, 22°12ʹ22ʺN 92°8ʹ2ʺE. 13 May 2015. M.M Rahman et al. (SRL-2015-025).
TABLE 1. New DNA sequences produced for this paper.
Our new COI sequences combined with those available from GenBank in May 2018, identified as Osteobrama
cotio or “O. serrata”, and including those published by Maisnam et al. (2018) and Singh et al. (2018), show two
major clades (Fig. 3), correlating with the geographical distribution of samples (Fig. 4). For clarity, we refer to
Species Catalogue /Voucher
Locality GenBank
Accession No.:
Accession No.:
16S rRNA
Systomus sarana DU 0101086 Bangladesh, Meghna basin: Jaflong MH708075
Systomus sarana DU 1101128 Bangladesh, Ganga basin: Atrai River MH708074
Labeo gonius NRM 67602 Bangladesh: fish market in Dhaka MG895641 MG920325
Osteobrama belangeri NRM 58399 Myanmar: Kyaikto market MG895642 MG920320
Osteobrama belangeri NRM 58873 Myanmar, Chindwin basin: Monywa MG895643 MG920321
Osteobrama cotio
sensu lato
DU 9032/NRM
Bangladesh, Karnafuli basin: Rangamati
fish market
MG895647 MG920323
Osteobrama cotio
sensu lato
NRM 67175 Bangladesh, Sangu River at Dopachari MG895646 MG920324
Osteobrama cotio
sensu stricto
NRM 69291 Bangladesh, Meghna basin: Kushiyara
River at Fenchuganj
MG895645 MG920326
Osteobrama cotio
sensu stricto
DU 9031/NRM
Bangladesh: Meghna River at Ashuganj
MG895644 MG920327
Osteobrama cunma NRM 59480 Myanmar, Chindwin basin: Kalaymyo MG895648 MG920322
Osteobrama cunma NRM 58233 Myanmar, Irrawaddy basin: near Yangon MG895649 MG920319
Zootaxa 4504 (1) © 2018 Magnolia Press
these groups as clade A, comprising all O. cotio from the Karnafuli, Narmada, and Sangu, drainages, and one sub-
clade inferred to represent the Godavari drainage; and clade B, comprising all O. cotio from the Barak,
Brahmaputra, Meghna, Surma, and Yamuna (Ganga) drainages and including all specimens identified in GenBank
as O. serrata”. Within clade A, there are three sub-clades, suggesting strong population structure or possibly
cryptic species: O. cotio from Karnafuli and Sangu drainages; O. cotio from the Narmada drainage; a group of O.
cotio with origin stated only as “India” (KF550101–KF550103), but 99% identical with BOLD sequences from the
Godavari River drainage (BOLD identifiers GDK340-13.COI-5P and GDK559-13.COI-5P, not yet published in
GenBank as of 16 May 2018); and KX550004, with origin “India”, but according to Raja, M. & Perumal, P. (2017)
(DNA barcoding and phylogenetic relationships of selected freshwater fishes based on mtDNA COI sequences.
Journal of Phylogenetics & Evolutionary Biology, 5: 5 pp.), listing the voucher as PUMNH23/2014, it is from a
study sampling in the Kaveri and Bhavani River systems in southern India.
Pairwise uncorrected p-distance is the number of different homologous positions between two sequences,
expressed in percent. Empirically, pairwise p-distances for the COI gene greater than 1–2% suggest that the
compared sequences belong to different species (Ward 2009). Closest uncorrected p-distance between clades A and
B was 11.9%. The within-clade longest uncorrected pairwise p-distance was 0.5% for clade B, and 6.6% for clade
A. The uncorrected p-distance between all three sub-clades in clade A was >2%, suggesting they may represent
three distinct species. However, p-distance is sensitive to artefacts such as ambiguities or missing data in the data
Automatic Barcode Gap Detection (ABGD) (Puillandre et al. 2012) groups sequences based on the distribution
of pairwise distances, given a prior intraspecific divergence estimate. Our ABGD analysis of the COI barcode data
finds two distinct groups, corresponding to clades A and B, throughout the prior pairwise distance range 1–3%,
where empirically groups have been found to best correspond to species (Puillandre et al. 2012). ABGD finds four
distinct groups, with clade A dissolving into three groups, at prior pairwise distances lower than 0.5%. This
suggests that clade A and B are separate and distinct species, and that clade A has strong population structure.
Rosenberg’s P
(Rosenberg, 2007) test rejects the hypothesis that the clades A and B are artefacts caused by
random coalescence (p = 3.4*10
). P ID(Liberal) (Masters et al. 2011) is a comparison of the intraspecific
variation in a putative species, the interspecific distance to its closest relative, and the intraspecific variation in that
relative, providing an estimate of the probability that an unknown sequence from the putative species would be
correctly identified as a member of the species. P ID(Liberal) for clade A is 0.96; for clade B = 0.99.
The phylogram based on 16S rRNA sequences (Fig. 4) is similar to the COI tree (Fig. 1), with two major clades
reflecting clades A and B in the COI tree, but the number of sequences and distinct localities is smaller, with 14
sequences from the Barak River, two from the Meghna River, and one each from the Karnafuli and Sangu Rivers.
Separation of Osteobrama cotio and “O. serrata” is not supported.
Morphometric data, summarized in Table 2, did not separate our Karnafuli and Sangu samples from those of
the Meghna basin in Bangladesh. No specimens were available from the Narmada or Barak River drainages for a
morphometric comparison. Ontogenetic shape change was noticeable, with young specimens more elongate than
adults, but this transition was shared among samples (Figs 1–2). Fin-ray counts were taken from 10 specimens
from the Meghna and 11 from the Karnafuli+Sangu drainages. All specimens had the dorsal-fin count iii.8½ and
the pelvic-fin count i.9. Number of branched anal-fin rays varied: Meghna: 29½ (2), 31½(5), 32½ (3);
Karnafuli+Sangu 28½ (1), 30½ (4), 31½ (4), 32½ (2). Pectoral-fin rays: Meghna: i.12 (1), i.13 (7), i.14 (2);
Karnafuli+Sangu: i.13 (4), i.14 (5), i15 (1). Vertebral counts were nearly invariant: 15+19 in three Meghna basin
specimens, 15+18 (1), (15+19 (2), and 15+20 (1) in four specimens from Kaptai Lake.
The morphometric and meristic data from Bangladeshi specimens identified as Osteobrama cotio show no obvious
difference between the Karnafuli, Sangu, and Meghna drainages. The sample sizes are small, however, and largely
based on specimens sampled from markets and not in optimal condition. The fin counts are very conservative, with
minor variation in the pectoral and anal fins. Due to abrasion, none of the specimens retains a complete lateral line
scale series. Transverse and circumpeduncular scale counts could not be obtained with accuracy due to loss of
scales. Attempting to count lateral line scales based on scale pockets gave low numbers down to 47, whereas the
Zootaxa 4504 (1) © 2018 Magnolia Press
better preserved specimens had counts up to 58–61. With the exception of scale counts, our meristic data are
compatible with those of Hora & Misra (1940), Maisnam et al. (2018), and Vishwanath & Shantakumar (2007) for
O. cotio, and Singh et al. (2018) for “O. serrata”. Singh et al. (2018) recorded two unbranched and eight or nine
branched pelvic-fin rays in “O. serrata”, but, this may be in error, as no cyprinine cyprinids are known to have two
unbranched anterior pelvic-fin rays, or the last pelvic-fin ray was somehow considered to be unbranched.
The reported count of scales in the lateral line for Osteobrama cotio varies slightly between authors. Hora &
Misra (1940) counted up to 70 lateral-line scales. Maisnam et al. (2018) counted 65 lateral-line scales in their five
specimens. Vishwanath & Shantakumar (2007) reported 66 lateral-line scales. Singh et al. (2018) did not provide
lateral-line scale counts for “O. serrata”.
Kumar & Goswami (2013), using a traditional taxonomic set of measurements, did not find any morphometric
differences between samples of Osteobrama cotio from the Brahmaputra (Gauhati), Tista, and Barak rivers.
Measurement data of Osteobrama cotio from Bangladesh (Meghna, Karnafuli) and corresponding data from
Vishwanath & Shantakumar (2007), Kumar & Goswami (2013), and Maisnam et al. (2018) are given in Table 2,
showing similar variation between different authors and data sets. Vishwanath & Shantakumar (2007) did not state
number of specimens measured, but 75 specimens were listed as material examined. The mean length of the pelvic
fin was reported by them as 17.4% of SL, which is longer than the maximum (16.5%). In Kumar & Goswami's
(2013) data it is not clear whether “caudal peduncle” mentioned in their table summarizing the measurement data
refers to caudal peduncle depth or length. Caudal peduncle measurements were not mentioned in the text. The text,
however mentioned “caudal fin length”, a measurement not present in the measurement table. The proportional
measurement "caudal peduncle" is interpreted here as caudal peduncle length. Dhanze & Dhanze (2018) give
similar values to those in Table 2, but their head depth measurement is too low to be homologous.
In their phylogenetic analysis of Osteobrama, Singh et al. (2018) presented altogether 15 new sequences of
COI , and 14 new sequences of 16S rRNA from three species, namely Osteobrama belangeri, O. cunma, and their
proposed new species O. serrata. In addition, they used selected sequences from GenBank representing other
species of Osteobrama. The sequences were used to build separate phylogenetic trees with the COI and 16S rRNA
sequences using a Maximum Likelihood approach. In their COI tree (fig. 2), sequences from the Narmada River
River basin (JQ667557, JX983423, 983425, 983427, 983429) and one without locality (EU417780) were labelled
as O. cotio, whereas their own four sequences from Jiribam, Jiri River, Meghna River basin (KU867238–
KU867241), and one GenBank sequence from Tanguar Haor, Sunamganj, Bangladesh, in the Meghna River basin
(KT762359) were assigned to “O. serrata”. The 16S rRNA tree (fig. 3) only contains sequences assigned to “O.
serrata”. Singh et al. (2018) distinguished “ O. serrata” from Osteobrama cotio by K2P distance, but also
morphology, based on a comparison with data in Hamilton (1822): presence vs. no mention of serrations along the
third dorsal-fin ray, 11–12 vs. 10 dorsal-fin rays, three vs. two unbranched dorsal-fin rays, 29–33 vs. 36 anal-fin
rays, 10–11 vs. 12 pelvic-fin rays, 14–15 vs. 16 anal-fin rays, 4 vs. 3 branchiostegal rays, absence vs. presence of
black spots on anterior part of lateral line. In the morphological comparison Singh et al. (2018) note that there is no
mention of serrated dorsal-fin rays in Hamilton’s description of O. cotio, but in the text, p. 362, they mention that
“As the individuals of new species has serrated dorsal spine (an adjective), so it was named as Osteobrama serrata
sp. nov.”. Whereas Singh et al. (2018) apparently derived some descriptive data from specimens identified asO.
serrata in their molecular analysis, the identification of O. cotio was based exclusively on specimens that were not
In the original description of Osteobrama cotio, Hamilton (1822: 340) states clearly that the second dorsal-fin
ray [apparently, the very short anteriormost ray was overlooked] is “indented behind”, and in his field notes this is
expressed in Latin as “simplex, posterius denticulatus” [undivided, with small teeth posteriorly] (R. Britz, personal
communication). Hamilton (1822) repeatedly used the term indented to describe serially repeated sharp projections
along the rear margin of the third dorsal-fin ray in cyprinids, a condition commonly described as serrated in current
literature. In Osteobrama, the first dorsal-fin ray is extremely short, and tightly attached to the second ray, and may
easily be overlooked. Consequently, a serrated dorsal-fin ray does not distinguish “O. serrata” from O. cotio. Also
Singh et al.’s (2018) more explicit comparison of “O. serrata” with O. cotio, summarized above, is of doubtful
value. Data in Hamilton (1822) must be viewed as observed without advanced magnification tools, X-radiographs,
or even an advanced understanding of fish morphology. There is nothing in the comparison provided by Singh et
al. (2018) that cannot be explained by methodological differences. The colour character may need particular
consideration, however. Hamilton described a row of 5–6 black spots “below the fore part of the lateral line, around
Zootaxa 4504 (1) © 2018 Magnolia Press
FIGURE 3. Phylogram of relationships of species of Osteobrama, based on mitochondrial COI sequences, with emphasis of
samples identified as O. cotio or O. serrata”. Other branches were collapsed. Sequences of “O. serrata” are duplicated, as
obviously these sequences were first submitted as O. cotio (KT896700, KT896701, KT896702, KT896703), and again as “O.
serrata” (KU867239, KU867238, KU867240, KU867241). Branches are annotated with GenBank Accession number, clade
designation (A, B), and river drainage. Collapsed branches include Osteobrama belangeri (KT921838–921849, KU867233–
867237, KX245099, MG895642–43, MG895247, NC_036232); O. cunma (KF029669; KT921850–921860, KU867242–
KU867247, KX245100, MG895648–895649, NC_031559); O. feae (KT921871–921873, NC_031560); O vigorsii
(KF550094–550100). Numbers at branches show Bayesian posterior probabilities. The scale bar shows number of expected
substitutions per site.
Zootaxa 4504 (1) © 2018 Magnolia Press
TABLE 2. Osteobrama cotio. Comparison of morphometric data. Ten specimens from two localities in Bangladesh (Meghna River basin, NRM 68904, 68918, 68929, 68948,
68858: Karnafuli River basin: NRM 67707, 67721), corresponding data of O. cotio from Maisnam et al. (2018), from Barak River; Vishwanath & Shantakumar (2007), from
Barak and Brahmaputra rivers; and Kumar & Goswami (2013), from Brahmaputra, Barak, and Tista Rivers.
O. cotio Meghna
O. cotio Karnafuli Maisnam et al. Vishwanath & Shantakumar
Kumar & Goswami 2012
min max mean
min max mean
SD min max SD N min
mean SD
SL (mm) 10
54.7 7.8
55.8 10.3
67.2 75.4 71.8 3.8 52.3 74.9 220
31 65 44.1 5.8
Body depth 10
40.4 2.8
40.1 2.0 5
31.6 38.7 37.1 3.1 39.3 44.9 2.0 220
33 48.6
39.6 2.7
Head length 10
23.7 0.7
24.4 0.9 5
18.7 23.7 22.1 2 23.8 26.3 0.7 220
21 29.3
24.3 1.3
Snout length 10
5.8 6.5 6.2 0.2
5.9 7.1 6.5 0.5 5
4.8 6.4 5.9 0.7 220
3.8 8.8 5 0.6
Head depth 10
19.2 0.9
18.1 0.3 5
17.2 18.6 17.9 0.5
Head width 10
13.6 0.5
13.4 0.6 5
8.7 12.6 11.6 1.6 13.4 15.3 0.5
Upper jaw length 10
6.4 7.0 6.7 0.2
6.9 8.2 7.4 0.4
Lower jaw length 10
8.6 10.6
9.7 0.5
9.5 11.7
10.6 0.6
Orbital diameter 10
9.3 11.2
10.1 0.6
9.5 11.0
10.3 0.4 5
6.4 8.7 8.0 0.9 220
6.8 12.9
9.8 0.7
Interorbital width 10
9.1 9.8 9.4 0.2
8.7 10.5
9.3 0.5 5
7.6 8.7 8.2 0.4
Caudal peduncle length 10
8.5 12.6
11.4 1.2
11.3 0.7 5
9.2 11.8 10.9 1 9.0 10.6 0.5 220
9.4 15.8
11.6 0.9
Caudal peduncle depth 10
9.9 11.3
10.6 0.5
9.1 10.9
10.1 0.5 5
9.5 11.0 10.4 0.6 10.3 11.5 0.5
Dorsal-fin base length 10
11.6 1.0
11.8 0.6 11.3 12.6 0.4
Anal-fin base length 10
39.9 0.9
39.0 1.8
Predorsal length 10
52.1 1.6
52.3 1.5 5
42.3 51.6 48.9 3.8 47.2 50.7 1.2 220
49.6 2.2
Preanal length 10
55.5 1.9
55.7 2.8 5
45.2 53.7 51.4 3.5 52.3 58.2 2.1
Prepelvic length 10
40.8 1.8
41.7 1.8 5
34.4 41.5 39.4 2.8 37.4 42.2 1.5
Pectoral-fin length 10
19.2 1.2
20.1 0.8 18.3 20.4 0.7
Pelvic-fin length 10
18.1 1.0
17.9 1.0
14.0 16.5 0.7
Zootaxa 4504 (1) © 2018 Magnolia Press
which is a bluish shining depression”. Hamilton’s figure of O. cotio, pl. 39, fig. 95, shows four black spots beneath
the anterior lateral line scales. The bluish shining depression apparently refers to the pseudotympanum, which is
not shown on Hamilton’s figure. We have not observed the black spots in any specimens of O. cotio, and there is no
mention of them in later literature describing O. cotio. Black spots as shown and described by Hamilton, however,
are shown on photos of O cunma and O. cotio in Maisnam et al. (2018: fig. 1, b,c), and O. vigorsii in Jadhav et al.
(2011: image 2b,d).
The sequences identified as O. cotio by Singh et al. (2018), are from a study of the fishes of the Narmada River
in Madhya Pradesh (Khedkar et al. 2014: GenBank Accession numbers JX983423, 983425, 983427, 983429);
from Barna, also in the Narmada basin in Madhya Pradesh (GenBank Accession number JQ667557); or without
locality (GenBank Accession number EU9417780). According to Singh et al. (2018), referring to the publisher,
Lakra et al. (2016), the locality of EU9417780 is Kanpur (Uttar Pradesh, Ganga basin), but no locality information
is given in Lakra et al. (2016). The poorly documented sequences indicated to be from southern India, KF55101–
55103 (sister group of Narmada samples), and KX550004 (nested with O. cotio sensu stricto) add complexity to
the tree (Fig. 4), but for now one can only consider them as questionable.
Consequently, Singh et al.’s concept of O. cotio mainly refers to a population from the Narmada River. The
type locality of O. cotio, however, is “ponds and ditches of Bengal”. The Presidency of Bengal at the time
corresponded roughly to the present state of West Bengal in India and present-day Bangladesh (Meyer et al., 1908:
FIGURE 4. Map of Bangladesh and adjacent India and Myanmar showing localities of Osteobrama cotio in the wide sense,
and restricted to samples used in the present analysis. The reported distribution of O. cotio covers a much wider area in northern
If accepted that the published sequences of both O. cotio and “serrata” are correct, they potentially represent
two distinct species. Singh et al.’s samples of “serrata”, however, are from the Meghna basin in Manipur and
Bangladesh, draining to the Bay of Bengal, whereas the Narmada runs westward to the Arabian Gulf. It is not
possible that Hamilton’s locality “ponds and ditches of Bengal” would have included the Narmada basin or any
Zootaxa 4504 (1) © 2018 Magnolia Press
river in the Deccan or western peninsular India. His concept of Bengal may at most have included the lower Ganga,
Brahmaputra and Meghna basins, and adjacent smaller drainages; and perhaps even the Mahanadi drainage; but see
below for Hamilton localities.
Singh et al.’s (2018) sequences of “O. serrata” are from the Jiri River in the Barak drainage in Manipur. The
Barak River drains to the Meghna River. Singh et al. (2018) also included in “serrata” a sequence, KT762359, from
northern Bangladesh: Tanguar Haor, Sunamganj.
Singh et al. (2018: table 2) listed specimen catalog numbers MUMF 4501–14506 as “O. serrata”, but the
publication does not contain the explicit fixation of a holotype, or syntypes, and consequently the name is not
available under the International Code of Zoological Nomenclature (International Commission on Zoological
Nomenclature 1999: Articles16.4, 16.4.1, 72.3, 73.2, 73.21, 732.1.1). Actually, the number of specimens is
uncertain. The number collected is stated to be four on p. 361, corresponding to the GenBank numbers in table 1,
but table 2 has data for six specimens. Four sequences where submitted to GenBank both as O. cotio and as “O.
FIGURE 5. Phylogram of relationships of species of Osteobrama based on mitochondrial 16S rRNA sequences, with emphasis
on samples identified as O. cotio or O. serrata”. Other branches were collapsed. Branches are annotated with GenBank
Accession number, and river drainage. Numbers at branches show Bayesian posterior probabilities. The scale bar shows
number of expected substitutions per site.
Dhanze & Dhanze (2018) reported specimens identified as Osteobrama cunma from the Gumti River at
Indiranagar, in the Barak River drainage in Tripura (India), apparently syntopic there with O. cotio. They suggested
that the samples of “O. serrata” described by Singh et al. (2018) “may be the habitat dependent morphological
Zootaxa 4504 (1) © 2018 Magnolia Press
variant of O. cunma”, basing their argument partly on the presence of serrations on the third dorsal-fin ray present
in all species of the genus. They also referred to a publication by Kumar, S.K. [as Konthoujam] & Goswami, U.C.
(2011) [Nucleotide sequences variation of Osteobrama (Heckel) freshwater fish species of North-east India on
mitochondrial COI gene. Archives of Applied Science Research 3, 437–442], dealing with COI variation in O.
belangeri, O. cotio, and O. feae, but that paper contains no sample metadata, and the sequences were not published
by GenBank or other publicly accessible nucleotide sequence repository. Osteobrama cunma is a relatively deep-
bodied species, similar to O. cotio. The specimen figured by Dhanze & Dhanze (2018: fig. 18) as O. cunma, is
strikingly slender in comparison with O. cunma of the same length from the Ayeyawaddy basin, suggesting a need
for revision of Dhanze & Dhanze’s (2018) determination.
Understanding which species is the “real” Osteobrama cotio requires either an unambiguously unique
character in the original description, a name-bearing type specimen, a precise type locality, or a decisive
combination of the preceding criteria. No specimens are known to have been preserved of species described by
Hamilton (Day 1873, 1877), and consequently no type specimens are in existence for any of Hamilton’s species.
Hamilton’s (1822) description of O. cotio is not detailed, and in case of the existence of several similar species, it
may not be sufficient to enable recognition of the species among several candidates. The stated type locality,
“Ponds and ditches of Bengal”, is imprecise. Based on Hamilton’s notes published by Day (1877: 30, 52, 63, 78,
100), Hamilton observed O. cotio in Dinájpur District [Dinajpur District, now divided between India and
Bangladesh], where it was called Koti and Sangpuyi; in Góálpárá [Goalpara, Assam, India], where it was called
Ghilá-chándá; Laksmípur [Lakshmipur, southern Bangladesh], where it was called Bokri; Purniah District [Purnea
District, Bihar, India], where it was called Guttá; Monghir [Munger, Bihar, India], where it was called called
Pĭthárí and Gordá, as well as in Gorakhpur District [Gorakhpur, Uttar Pradesh, India], where it was called Patuki.
Hamilton (1822) mentions only Koti as the common name, from which one might deduce that the description was
mainly based on specimens from Dinajpur. Osteobrama cotio, however, was already described under a different
manuscript name in his field notes, made before the Bengal survey 1807–1813, but without precise locality (R.
Britz, personal communication).
Because of the congruence with localities at which Hamilton observed Osteobrama cotio, and compatibility
with the original description, we conclude that “O. serrata” of Singh et al. (2018), and O. cotio of Vishwanath &
Shantakumar (2007) and Maisnam et al. (21017), as well as most other records of O. cotio, represent O. cotio sensu
Hamilton, i.e., in a strict sense. Based on our analysis of mtDNA sequences (Fig. 1), the populations in the
Narmada, Godavari and Sangu+Karnafuli rivers apparently represent undescribed cryptic species or distinct
populations. In the case of the Karnafuli+Sangu population, no morphological characters were found to
differentiate it from O. cotio. We have not examined specimens from the Narmada or Godavari drainages, and
cannot comment on their morphology. Osteobrama cotio in the wide sense has a very wide distribution in India,
Bangladesh and Pakistan (Talwar & Jhingran, 1991), and studies with wider geographic coverage may be more
instructive in evaluating the taxonomic status of populations of O. cotio.
The haplotype group represented by the sequences from the Narmada, Karnafuli, Sangu, and Godavari
drainages may represent a distinct species but not necessarily undescribed. Based on the very brief description
(Silas, 1952) and data on topotypes in Jadhav et al. (2011), the oldest alternative available name may be O.
peninsularis Silas, with type locality Pune (Maharashtra, India) in the upper Krishna River drainage.
In conclusion, Osteobrama cotio of authors includes two genetically distinct species or populations. Samples
from the Barak, Meghna, Ganga and Brahmaputra Rivers represent Osteobrama cotio in the strict sense.
Genetically distinct populations from the Narmada and Sangu+Karnafuli Rivers, as well as unidentified localities,
represent one or more genetically distinct populations or cryptic species. “Osteobrama serrata” is not an available
Research on Bangladeshi freshwater fishes was supported by the project “Genetic characterization of freshwater
fishes in Bangladesh using DNA barcodes” funded by the Swedish Research Council, contract D0674001 to Sven
Kullander and Abdur Rob Mollah. We thank Ralf Britz, editor Rohan Pethiyagoda, and an anonymous reviewer for
careful reading and insightful comments on our manuscript, and Ralf Britz also for valuable unpublished
information on Francis Hamilton’s manuscripts.
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... OBUs 126, Osteobrama cotio, and 127, O. cf. cotio, differed in coi and mt-rnr2 sequences 22 . Samples from the Karnafuli and Sangu drainages were slightly different from those from the Meghna drainage, including published sequences from the Barak River. ...
... Samples from the Karnafuli and Sangu drainages were slightly different from those from the Meghna drainage, including published sequences from the Barak River. No morphological differences were found and they might be cryptic species 22 . Because O. cotio is a widespread species, it should be re-analyzed with inclusion of representation of the entire geographical distribution 23 . ...
... Consequently, "cryptic OBUs" require taxonomic assessment, and evolutionary analysis, and in the meantime remain ghost OBUs. Whereas many of our sequences cannot be linked to a particular species, only few cases of sibling or cryptic species were demonstrated in cyprinids and badids so far 18,20,22 , and the unidentified OBUs should not be assumed to represent cryptic species or undescribed species in the absence of taxonomic analysis. Nation-wide or regional barcoding surveys, have been proposed to accelerate DNA barcode coverage 43 , and some have been attempted, such as the one reported here. ...
Full-text available
We sequenced the standard DNA barcode gene fragment in 694 newly collected specimens, representing 243 species level Operational Barcode Units (OBUs) of freshwater fishes from Bangladesh. We produced coi sequences for 149 out of the 237 species already recorded from Bangladesh. Another 83 species sequenced were not previously recorded for the country, and include about 30 undescribed or potentially undescribed species. Several of the taxa that we could not sample represent erroneous records for the country, or sporadic occurrences. Species identifications were classified at confidence levels 1(best) to 3 (worst). We propose the new term Operational Barcode Unit (OBU) to simplify references to would-be DNA barcode sequences and sequence clusters. We found one case where there were two mitochondrial lineages present in the same species, several cases of cryptic species, one case of introgression, one species yielding a pseudogene to standard barcoding primers, and several cases of taxonomic uncertainty and need for taxonomic revision. Large scale national level DNA barcode prospecting in high diversity regions may suffer from lack of taxonomic expertise that cripples the result. Consequently, DNA barcoding should be performed in the context of taxonomic revision, and have a defined, competent end-user.
... Species of Osteobrama are frequent and abundant in lentic habitats throughout their range in Bangladesh, India, Myanmar, and Pakistan (Hora & Misra 1940;Talwar &Jhingran 1991 andVishwanath &Shantakumar 2007). Rahman et al. (2018) recognized eight species of Osteobrama, viz., O. belangeri (Valenciennes 1844); O. feae Vinciguerra (1890) and O. cunma (Day 1888) from the Chindwin-Irrawaddy drainage of India and Myanmar; O. cotio (Hamilton 1822) from the Barak-Meghna and Ganga-Brahmaputra drainages of India and Bangladesh; O. neilli (Day 1873) from the Cauvery drainage of India; O. bakeri (Day 1873) from west-flowing rivers in Kerala; and O. vigorsii (Sykes 1839) and O. peninsularis Silas (1952) from the Godavari and Krishna drainages of India. Hora & Misra (1940) described Osteobrama dayi from the Godavari River based on three specimens. ...
A new species of the genus Osteobrama is described from the Mahanadi River, Tikarpada, Angul District, Odisha state, India. Osteobrama tikarpadaensis, new species, differs from its congeners in having two pairs of minute barbels; iii–iv unbranched dorsal-fin rays with 25–33 serrae on the last unbranched ray; 15–16 branched pectoral-fin rays, and 25–27 branched anal-fin rays. The status of Osteobrama dayi is discussed and shown to be a valid species. A key to the species of the genus is provided.
... It is unlikely that it represents an undetected species that has hybridized with B. pallidus in the Sangu River, but this hypothesis is open for testing. Observations of other species in southeastern Bangladesh show that the Sangu and Karnafuli Rivers share a distinct fish fauna (e.g., Rahman et al. 2018). Kullander et al. (2017) reported on introgression in Devario anomalus Conway, Mayden & Tang, 2009, a species restricted to the Sangu and Matamuhuri Rivers and coastal streams near Cox′s Bazar, by Devario aequipinnatus (M′Clelland,1839), a common species in the Karnafuli and more western drainages, but not recorded from the Sangu River. ...
Five species of Badidae are reported from Bangladesh, with morphological diagnoses and mitochondrial DNA sequences (cytochrome b, cytb; and cytochrome c oxidase subunit I, coi). Dario kajal is recorded from Bangladesh for the first time with a precise locality. Badis badis is reported from several localities in central Bangladesh. Badis chittagongis is redescribed on the basis of samples from the region of Cox′s Bazar, including Maheskhali Island. Badis pallidus, new species, is described from the Sangu and Karnafuli River drainages in Bangladesh. It is most similar to B. chittagongis, but differs slightly in colouration and meristics, and is separated by 3.8% uncorrected p-distance in coi from B. chittagongis. Badis chittagongis and B. pallidus are almost identical in morphology, colour pattern and meristics, but occupy different habitats and are reciprocally allopatric. Pronounced genetic difference but similar morphology in these two species may be due to strong stabilizing selection for cryptic colouration in Badis. Badis rhabdotus is a new species from northeastern Bangladesh and adjacent Meghalaya in India. It is distinguished from congeneric species by the colour pattern, including well-defined narrow vertical bars; posterior bars curved; and meristics. Species delimitation analysis of an alignment comprising all coi sequences available from GenBank longer than 600 bp and attributed to species of Badidae (21 June 2018) plus our coi sequences and outgroup sequences of Nandus nandus, using pairwise p-distance and the computer software GMYC, ABGD, and bPTP, produced similar results. Among 103 coi sequences of Badidae, unidentified or tagged with one of 18 valid species names, uncorrected p-distance suggests 27 OTUs at 2% difference threshold; ABGD found between 15 and 55 OTUs; GMYC with single evolutionary rate 33 OTUs, with multiple evolutionary rates 32 OTUs; PTP, mPTP and bPTP 27–28 OTUs. Phylogenetic analysis based on coi and cytb sequences support previous analyses and previously proposed species groups. Inadequate recent species descriptions and many misidentifications or provisional identifications of published DNA sequences hamper progress in species-level systematics in Badis. Based on published morphological data, Badis triocellus cannot be distinguished from B. singenensis; Badis dibruensis and B. pancharatnaensis cannot be distinguished from B. badis; Badis andrewraoi, B. autumnum, B. kyanos, and B. soraya are insufficiently well distinguished from each other.
Full-text available
Osteobrama cunma (Day) has hitherto been considered to be restricted to the eastern parts of Manipur in India (Chindwin drainage system) besides its type locality, Moulmein, in Myanmar. While confirming the identity of fish species collected from the Gumti, a tributary of the Barak-Meghna river system in Tripura, India, several specimens of Osteobrama tentatively identified as O. cotio (Hamilton) and housed in the Museum of the Central Agricultural University, Tripura, India, were observed to belong to O. cunma. This forms the first record of O. cunma from the Barak-Meghan drainage, which is geographically isolated from the type locality of this species.
Full-text available
Laubuka tenella is a new species characterized by the colour pattern, consisting of short dark vertical bars anteriorly on the side, and a dark lateral band posteriorly on the side, combined with a relatively short pelvic fin and 29–30 lateral-line scales. It is separated from other Laubuka analysed by minimum 9 % uncorrected p -distance in the mitochondrial COI gene. The type series is composed of specimens from small streams in the Cox’s Bazar District in Bangladesh (the type locality), and the Thandwe River drainage in western Myanmar. Laubuka brahmaputraensis is strongly indicated to be a junior synonym of L. laubuca , the second known species of Laubuka in Bangladesh. Eustira ceylonensis , currently in the synonymy of Devario malabaricus , is a valid species of Laubuka .
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DNA barcoding is a promising technique for species identification using a short mitochondrial DNA sequence of cytochrome c oxidase I (COI) gene. In the present study, DNA barcodes were generated from 72 species of freshwater fish covering the Orders Cypriniformes, Siluriformes, Perciformes, Synbranchiformes, and Osteoglossiformes representing 50 genera and 19 families. All the samples were collected from diverse sites except the species endemic to a particular location. Species were represented by multiple specimens in the great majority of the barcoded species. A total of 284 COI sequences were generated. After amplification and sequencing of 700 base pair fragment of COI, primers were trimmed which invariably generated a 655 base pair barcode sequence. The average Kimura two-parameter (K2P) distances within-species, genera, families, and orders were 0.40%, 9.60%, 13.10%, and 17.16%, respectively. DNA barcode discriminated congeneric species without any confusion. The study strongly validated the efficiency of COI as an ideal marker for DNA barcoding of Indian freshwater fishes.
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This study describes the species diversity of fishes of the Narmada River in India. A total of 820 fish specimens were collected from 17 sampling locations across the whole river basin. Fish were taxonomically classified into one of 90 possible species based on morphological characters, and then DNA barcoding was employed using COI gene sequences as a supplemental identification method. A total of 314 different COI sequences were generated, and specimens were confirmed to belong to 85 species representing 63 genera, 34 families and 10 orders. Findings of this study include the identification of five putative cryptic or sibling species and 43 species not previously known from the Narmada River basin. Five species are endemic to India and three are introduced species that had not been previously reported to occur in the Narmada River. Conversely, 43 species previously reported to occur in the Narmada were not found. Genetic diversity and distance values were generated for all of the species within genera, families and orders using Kimura's 2 parameter distance model followed by the construction of a Neighbor Joining tree. High resolution clusters generated in NJ trees aided the groupings of species corresponding to their genera and families which are in confirmation to the values generated by Automatic Barcode Gap Discovery bioinformatics platform. This aided to decide a threshold value for the discrimination of species boundary from the Narmada River. This study provides an important validation of the use of DNA barcode sequences for monitoring species diversity and changes within complex ecosystems such as the Narmada River.
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The cyprinid subfamily Oxygastrinae is composed of a diverse group of fishes that has been taxonomically and phyloge- netically problematic. Their great variation in appearance, life histories, and trophic diversity resulted in uncertainty re- garding their relationships, which led to their historical classification across many disparate subfamilies. The phylogenetic relationships of Oxygastrinae are resolved based on sequence data from four loci: cytochrome b, cytochrome c oxidase I, opsin, and recombination activating gene 1. A combined data matrix consisting of 4114 bp for 144 taxa was compiled and analyzed using maximum likelihood and parsimony optimality criteria. The subfamily Oxygastrinae is recovered as a monophyletic group that includes Ancherythroculter, Aphyocypris, Candidia, Chanodichthys, Ctenopharyngodon, Culter, Distoechodon, Elopichthys, Hainania, Hemiculter, Hemiculterella, Hemigrammocypris, Hypophthalmichthys, Ischikauia, Macrochirichthys, Megalobrama, Metzia, Mylopharyngodon, Nicholsicypris, Nipponocypris, Ochetobius, Opsariichthys, Oxygaster, Parabramis, Parachela, Paralaubuca, Pararasbora, Parazacco, Plagiognathops, Pseudobrama, Pseudohe- miculter, Pseudolaubuca, Sinibrama, Squaliobarbus, Toxabramis, Xenocyprioides, Xenocypris, Yaoshanicus, and Zacco. Of these genera, the following were found to be monophyletic: Aphyocypris, Distoechodon, Hypophthalmichthys, Nip- ponocypris, Opsariichthys, Parachela, Paralaubuca, Plagiognathops, Xenocyprioides, and Xenocypris. The following genera were not monophyletic: Metzia, Hemiculter, Toxabramis, Ancherythroculter, Chanodichthys, Culter, Megalobra- ma. The remainder are either monotypic or were represented by only a single species. Four genera not examined in this study are provisionally classified in Oxygastrinae: Anabarilius, Longiculter, Pogobrama, and Rasborichthys.
Four species of the genus Osteobrama collected from five different sampling sites of Chindwin and Barak river basin of North-East India, namely O. belangeri, O. cotio, O. cunma and O. feae, were characterized. Meristic study showed differences in anal fin rays count and lateral line scales. Morphometric analysis revealed significant differences among Osteobrama species. In Truss analysis, a clear pattern of differentiation was observed among the four species with discriminant function analysis assigning 100% correctly to the particular species. In molecular analysis, four Osteobrama species collected were barcoded with COI and 16S rRNA sequences and phylogenetically these four species formed two distinct clusters, O. belangeri form one separate cluster, from the other three species i.e. O. cotio, O. cunma and O. feae. High-resolution clusters generated (NJ trees) aided the groupings of species corresponding to their genera and families which are in confirmation to the values generated by COI Automatic Barcode Gap Discovery bioinformatics platform.
Genus Osteobrama Heckel is characterized by strongly compressed, fairly deep body with abdominal edge sharp and trenchant entirely or from the pelvic fin base to vent; anal fin long with 14-36 rays, of which 11-13 are branched rays. The fishes of this genus are distributed in Pakistan, India, Bangladesh, Burma, and Yunnan (China). Present study involve six Osteobrama species viz. O. belangeri, O. cotio, O. cunma, O. feae, O. serrata sp. nov., and O. vigorsii. Out of the 655 positions analyzed in the COI sequence dataset, 171 positions (26.1%) were variable, and 151 positions (23%) were parsimoniously informative. The genetic distance between Osteobrama species ranges from 7.10% (between O. cotio and O. serrata sp. nov.) to 22.86% (between O. belangeri and O. feae) for COI sequences and 3.04% (between O. serrata sp. nov. and O. cunma) to 9.89% (between O. serrata sp. nov. and O. belangeri) for 16S sequences. Osteobrama belangeri show very high interspecies K2P distance with all other Osteobrama species for COI and 16S datasets. Best fit models for COI and 16S rRNA dataset were HKY + G + I and K2 + G, respectively. The maximum-likelihood (ML) phylogenetic trees were constructed using the COI and 16S rRNA sequences.
Osteobrama cunma, originally described from Moulmein, Myanmar, has so far been considered a subspecies of Osteobrama cotio. Based on examination of specimens from Brahmaputra and Chindwin basins, O. cunma has now been given species status. The species differs from its nearest congener, O. cotio, in having less numbers of branched anal fin rays (26 vs. 31); lateral line scales (48 vs. 66); predorsal scales (20 vs. 27); scale rows between dorsal fin base and lateral line (9 vs. 14); scale rows between pelvic fin base and lateral line (8 vs.12) and circumpeduncular scales (20 vs. 28). Osteobrama feae Vinciguerra, originally known from upper Myanmar has been collected from the Maklang river of Manipur, and is reported as a new record for India. Brief descriptions of O. belengeri, O. cotio, O. cunma and O. feae are given in this paper.