Need for
further research on the freshwater fish fauna of the Ashambu Hills landscape: a
response to Abraham et al.
Rajeev Raghavan1, 2
1Conservation Research Group (CRG),
St. Albert’s College, Kochi, India
2Durrell Institute of Conservation
and Ecology (DICE), University of Kent, Canterbury, United Kingdom
Email: rajeevraq@hotmail.com
Date of publication (online): 26 May 2011
Date of publication (print): 26 May 2011
ISSN 0974-7907 (online) | 0974-7893 (print)
Manuscript details:
Ms
# o2755
Received
08 April 2011
Citation: Raghavan, R. (2011). Need for further research on the freshwater
fish fauna of the Ashambu Hills landscape: a response to Abraham et al. Journal of Threatened Taxa 3(5): 1788–1791.
Copyright: © Rajeev Raghavan 2011. Creative Commons Attribution 3.0 Unported
License. JoTT allows unrestricted use of this article in any medium for
non-profit purposes, reproduction and distribution by providing adequate credit
to the authors and the source of publication.
Acknowledgements: I thank Neelesh Dahanukar (IISER, Pune, India), Siby Philip
(CIIMAR, University of Porto, Portugal), Anvar Ali (CRG, St. Albert’s College,
Kochi, India) and Ambily Nair (University of Hasselt, Belgium) for their
critical comments, and suggesting necessary changes to the draft manuscript.
The updated checklist of
the freshwater fish fauna of Ashambu Hills including an undescribed species of
the genus Puntius, and range extension of four cyprinids (Abraham et al. 2011) is
continuing testimony to the fact that ichthyofauna of Western Ghats (WG) is
poorly understood and is still influenced by the ‘Linnean shortfall’ (lack of knowledge of how many, and what kind of, species exist) and ‘Wallacean shortfall’
(inadequate knowledge on the distribution of species). Ashambu Hills landscape,
south of the Shencottah Gap is one of the least explored areas for freshwater
fish diversity in Kerala, and so the work of Abraham et al. (2011) is an
important first step in filling the knowledge gap. The authors need to be commended for carrying out field
surveys for a year in as many as five rivers of this eco-region and collecting
58 species belonging to 16 families, including a species hitherto unknown to
science. One of the highlights of
this paper is the information provided by the authors on the major threats
faced by different species (Table 1 of the article). Such species specific data will surely help policy makers
and biodiversity managers and lead to improved conservation action for
freshwater fish in the Ashambu landscape.
A very serious problem with
ichthyological literature (especially papers in the recent past) is that
authors uncritically rely on earlier data, the result that many reviews are
merely compilations of old and often incompatible information. Errors are thus propagated over long
periods of time (Kottelat & Freyhof 2007). Since the work by Abraham et al. (2011) has been
published as an updated and systematic checklist of fishes of a poorly known
region of the WG, the paper will surely be referred and cited by regional
ichthyologists for years to come.
In this context, I believe
that some of the results presented by Abraham et al. (2011) are ambiguous and
need additional discussion and deliberation by the ichthyological research
community of the WG. The paper has several cases of taxonomic inaccuracies,
erroneous remarks and redundant data that the authors have presumably
overlooked while preparing this manuscript in haste. As a peer researcher working on fish conservation in the
southern WG, I believe that it is my obligation to point out some of the issues
and shortcomings in this paper, to prevent future authors from citing
inappropriate information, as well as assist the present authors in realizing
their oversights.
The first point of interest
is that Abraham et al. (2011) does not include Hypselobarbus
thomassi (Day, 1874) in their updated checklist. This large cyprinid was recorded from the Kallada River at
Kulatupuzha (Kurup 2002; Kurup et al. 2004) and Thenmala Dam (Euphrasia et al.
2006). Since Abraham et al. (2011)
mention that their checklist is based on a compilation of previous literature
on fishes of the Ashambu Hills (in addition to their field surveys), there is a
need to understand whether this species was missed out accidentally from their
list, or excluded due to any specific reason. Further, as Abraham et al. (2011) have recorded three species
within the genus Hypselobarbus (H. curmuca, H. kolus and H. kurali) from Kallada River, it is reasonable to speculate that the
omission of H. thomassi from their list may also have been due to taxonomic reasons. A discussion on whether H. thomassi is distributed in Kallada
River is also timely as there is a current doctoral thesis work being carried
out at one of the Universities in Kerala titled ‘Life history and population ofH.
thomassi from Kallada River’.
In their paper on the
fishes of Ashambu Hills, Abraham et al. (2011) extends the range of Garra mcclellandi (Jerdon, 1849) to the
Neyyar Wildlife Sanctuary (Neyyar River). G. mcclellandi was first described from
various locations in the Cauvery drainage (Nilgiri and Wayanad region of Tamil
Nadu and Kerala) (Jerdon 1849), and subsequently recorded by many workers from
the same or nearby drainages north of the Palakkad Gap. To the best of my knowledge, there are
only two drainages south of the Palakkad Gap from where G. mcclellandi has been previously
recorded, i.e., Periyar (Arun et al. 1996; Arun 1999; Minimol 2000; Easa &
Shaji 2003; Thomas 2004) and Chalakudy (Antony 1977 cited in Ajithkumar et al.
1999).
G. mcclellandi was recorded from the
Periyar Tiger Reserve (PTR) by Arun et al. (1996), Arun (1999) and Minimol (2000). Subsequently, Gopi (2000a) described a
new species, G. periyarensis (based on two specimens) from the PTR which closely resembles G. mcclellandi, but without providing any
information on whether any comparative material was examined. Nevertheless, in
the most recent publication on the fishes of PTR, Radhakrishnan & Kurup
(2010) suggests that G. periyarensis and G. mcclellandi have great similarity in body
morpho-meristics, and validates the presence of G. periyarensis (but not G. mcclellandi) inside the PTR.
Silas (1958) in his remarks
on the cyprinid fishes described by Jerdon, mentions that Pillay (1929), Hora
& Law (1941), and Silas (1951) have recorded G. jerdoni (synonym of G. mcclellandi) as occurring in the
rivers draining the Travancore Hills. Silas (1958) also mentions that the single specimen that he collected
from Peermed Hills (Periyar drainage) was different from the typical G. mcclellandi in many details and that G. mcclellandi appears to be restricted
to the Cauvery watershed. This
lends further support to the description of G. periyarensis by Gopi (2000a).
There are no known types for G.
mcclellandi (Eschemeyer & Fricke 2011) and hence it
would be interesting to know more about the specimens examined by Abraham et
al. (2011) for reporting its range extension to the Ashambu Hills. Similarly, it will also be worthwhile
to know whether Abraham et al. (2011) had examined the types of G. periyarensis housed at the Regional
Station of the Zoological Survey of India at Kozhikode (ZSI, CLT V/F 9426 and
9427). I
believe that examining types and/or other museum specimens of both these
species are crucial to confirming the actual identity of G. mcclellandi collected by Abraham et
al. (2011) from Neyyar.
I also wish to debate on
the record of the range extension of P. mahecola and G. hughi to the Ashambu Hills made
by Abraham et al. (2011). Pethiyagoda & Kottelat (2005) explicitly mentions collecting P. mahecola from the Kallada River and
Kallar Stream (possibly Vamanapuram River). The figure on page 147 of Pethiyagoda & Kottelat (2005)
showing the distribution of P. mahecola, has Kallada River as one among the main collection
locations. Therefore, it is
already known that P. mahecola occurs in the Kallada River and the Ashambu Hills landscape. The claim of range extension of P. mahecola to the drainages of the
Ashambu Hills (especially River Kallada, as mentioned in the second paragraph
of discussion) by Abraham et al. (2011) is therefore redundant, and cannot be
treated as a range extension record.
G. hughi was recorded from Kallar
tributary of Vamanapuram River (Ashambu Hills Landscape) by Johnson &
Arunachalam (2010). Although this has been mentioned by Abraham et
al. (2011) in their discussion, they still continue to treat their record of G. hughi as a range extension to
Ashambu Hills and southern Kerala. It is therefore not clear, what Abraham et al. (2011) mean by the term ‘range
extension’. Like the case of P. mahecola, one should also consider the information on the range
extension of G. hughi as redundant.
Abraham et al. (2011)
(citing Pethiyagoda & Kottelat 2005) also mentions that P. amphibius is a synonym of P. mahecola. This is an entirely wrong statement, as nowhere in the
original paper have the authors opined so. Pethiyagoda & Kottelat (2005)
(page 151; paragraph 3) only suggests that the “identity of P. amphibius remains in question and
warrants further investigation; but cannot, however, be resolved without fresh
collections from near the type locality”. Even the Catalog of Fish (Eschemeyer & Fricke 2011) retains P. amphibius as a valid species. It is indeed a reality that P. amphibius has a taxonomic ambiguity
and much of the confusion is because of misidentifications with, and incorrect
references to P. mahecola in current literature (Pethiyagoda & Kottelat 2005). It has also been suggested that the
species presently assigned to P. amphibius may in fact be distinct and possibly new (Pethiyagoda &
Kottelat 2005).
Abraham et al. (2011),
citing Gopi (2000b) mention that the southernmost record of Puntius (Hypselobarbus) jerdoni was previously from the
Chalakudy River. This is again a
wrong statement as this species was recorded by Kurup et al. (2004) and Kurup
(2002) from the Achenkovil River which is further south of Chalakudy and very
close to the Ashambu Hills landscape.
As mentioned previously,
errors in taxonomy and nomenclature of freshwater fish keep appearing in recent
checklists, even if they have been corrected in the scientific literature years
(sometimes decades) ago. One example of this is Mystus cavasius, which is currently known
to be restricted to Godavari River and drainages north of it. The species previously recorded as M. cavasius in Krishna and rivers
south of Krishna, are currently known to be M. sengtee (Chakrabarty & Ng
2005). I understand that the authors
have not collected this species from the Ashambu Hills but mention M. cavasius in their checklist based
on previous studies. I recommend that the authors should change the species
name to M. sengtee based on the updated taxonomy, so that future workers referring
to Abraham et al. (2011) will not repeat the same mistake.
Abraham et al. (2011)
mentions Tor malabaricus as the only species of Mahseer present in the Ashambu Hills
landscape. Previous workers
including Johnson & Arunachalam (2009) have recorded only T. khudree from this landscape. A discussion on why T. khudree was not mentioned by
Abraham et al. (2011) even in the checklist is therefore necessary. Similarly, Johnson &
Arunachalam (2009) have recorded Botia striata, Puntius melanampyx, and Pterocryptis (Silurus) wynaadensis from Kallar Stream of
Vamanapuram River, while Kurup (2002) has recorded Glyptothorax lonah and Mystus gulio from Kallada River. However, Abraham et al. (2011)
does not mention these species in their checklist. Hence, a discussion on why these species were omitted from
the checklist is also required.
An earlier study on the
fishes of the Neyyar Wildlife Sanctuary (Thomas et al. 2000) has presumably
been overlooked by the authors. This is evident from the fact that the Abraham
et al. (2011) have missed out listing Nemacheilus guentheri which was collected by
Thomas et al. (2000) from this protected area.
There are also several gaps
in the information on endemism that has been presented in Table 1 of the paper
by Abraham et al. (2011). These
authors have mentioned that Aplocheilus blockii is an endemic species of WG. However, this
species was first described from Sri Lanka (Arnold 1911) and later recorded
from Pakistan (Mirza 2003). Probably, the records from Pakistan might need verification, but the
fact remains that there are existing records of A. blockii from outside the WG. On the other hand, Pangio goaensis,
Horalabiosa joshuai and Garra surendranathanii are endemic to the WG (Dahanukar et al. 2004)
but the authors do not indicate this.
One of the main drawbacks
of this paper is the lack of information (size, sex of the fish, diagnostic
characters, number of samples collected) on the samples of the species whose
range extension have been reported, as well as on the comparative material that
the authors have (?) examined. The importance of comparative material either
from museum collections, or even personal collections of the authors or their
colleagues becomes important when reporting range extensions of species that
have taxonomic ambiguity (like in the case of G. mcclellandi).
There has also been a lack
of integration of some key literature on freshwater fishes of Kerala (for e.g.
Thomas et al. 2000; Kurup et al. 2004). Two of the additional references that I mention here (Kurup 2002;
Euphrasia et al. 2006) have been published in proceedings of conferences and so
may not be available for easy access. This could have been one reason why these were not referred to by
Abraham et al. (2011). However,
Kurup et al. (2004) is one of the most comprehensive reviews on freshwater fish
fauna of Kerala that is widely cited. Although it is also part of a published conference proceeding, it is
available open access online (ftp://ftp.fao.org/docrep/fao/007/AD526e/ad526e12.pdf) and so easily available
to most authors. On the other
hand, the paper on the fishes of Neyyar Wildlife Sanctuary (Thomas et al. 2000)
has been published in an easily accessible and reputed national journal. By
missing key references, Abraham et al. (2011) have been unsuccessful in
presenting a checklist of the fishes of Ashambu Hills that is ‘updated’ and ‘systematic’
as they claim.
Nevertheless, I still
believe that the paper by Abraham et al. (2011) is an important ichthyological
work from the southern WG with regard to the data on species richness vis-à-vis
four important rivers, stream microhabitats and elevational gradients; and the
very important additional information on species specific threats. I would therefore suggest that the
authors attempt to integrate the references that were missed, include the
species that were overlooked, discuss the reasons why they think specific
species are absent (even though it was recorded by previous workers) and
prepare an updated list of fishes of the landscape.
I sincerely hope that
Abraham et al. (2011) take my comments and suggestions in the right spirit and
engage in a meaningful discussion on various aspects mentioned in this
response, so as to further the science of fish taxonomy and conservation in the
Western Ghats.
Note: The views expressed here
are solely of the author, and in no way mirrors that of the institution(s) he
represents.
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