Nemacheilus stigmofasciatus, a new species of nemacheiline loach (Cypriniformes: Balitoridae) from
the Western Ghats, India
M.Arunachalam 1 & M. Muralidharan2
1,2Sri Paramakalyani Centre for Environmental Sciences, Manonmaniam SundaranarUniversity, Alwarkurichi, Tamil Nadu 627412, India
Email: 1 arunacm@gmail.com
Date
of publication 26 March 2009
ISSN 0974-7907
(online) | 0974-7893 (print)
Editor: Rema Devi
Manuscript
details:
Ms # o1942
Received 09
February 2008
Finally accepted
12 March 2009
Citation: Arunachalam, M. & M. Muralidharan(2009). Nemacheilus stigmofasciatus,a new species of Nemacheiline loach (Cypriniformes: Balitoridae) from
the Western Ghats, India. Journal of Threatened Taxa1(3): 147-150.
Copyright: © M. Arunachalam & M. Muralidharan2009. Creative Commons Attribution 3.0 UnportedLicense. 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.
Author Details: Dr. M. Arunachalam has more than 20
years of resesrch experincein stream and stream fish ecology. Dr.
M. Muralidharan has 8 years experience in the same fields.
Author
Contribution: The
authors were equally involved in field work, analysis of data and writing.
Acknowledgement:MA is grateful for financial assistance from NATP under the mission mode programme of Germplasm Inventory and
Gene Banking of Freshwater Fishes (Sanction No. 27 (281/98/NATP/MM-III 18) dt. 23.12.1999). We thank Drs. D. Kapoorand S.P. Singh of
NBFGR, Lucknow.
Abstract:A new nemacheiline loach is described
from the Seethanathi riverof the Western Ghats, Karnataka. The new species differs from others of the
genus in having an incomplete lateral line extending up to the end of the
pelvic fin, shorter snout (35.9 -39.4% of HL) and bigger eyes (28.1-31.3% of
HL). Notable colourvariation is present in the bands on the back (11-13) and blotches (6-8) evenly
spaced along the lateral line.
Keywords:Karnataka, Nemacheiline loach,
Peninsular India, Seethanathi, Western Ghats
Abbreviations:SL - Standard length; HL - Head length.
For
Images & Table – click here
Introduction
The rich biodiversity
and pristine habitats of many of the westward-flowing rivers of peninsular
India have attracted many researchers for the exploration of new taxa. The area is
especially significant for icthyologists as is
evident from the discovery of two new nemacheilineloaches, Schistura shravathiensisand Schistura nagodiensis(Sreekantha et al. 2006) from the Shravathi river. The
discovery is significant as these species have been collected from two streams
of the same river basin. Also recently,
the research team from Zoological Survey of India, Western Regional Station,
Kozhikode, reported the collection of a new sisoridfish species from a stream inside Kudremukh National
Park (to be published).
During our
recent fish habitat survey in the main stream of the Seethanathi river in Karnataka, a few nemacheilineswere collected having features distinct from known species; herein we describe
a new species. The subfamily Nemacheilinae is readily distinguished from Balitorinae in having paired fins not inserted horizontally
and with rounded abdomen. This genus has
more than 450 species with distribution in southern China, South and southeast Asia, Baluchistan, western Iran and northeastern
Africa (Kottelat et al. 1993). Fish of the genus Nemacheilusare characterized by a rather short dorsal fin (7 or 8 branched rays), a
longitudinal stripe, which may be of lateral black band or black spots
coalescing to form a band extending to caudal fin or distinct moniliform spots along the lateral line in the middle of body,
large eyes, and a dark spot on the middle of the caudal base (Banarescue & Nalbant1995). The genus Nemacheilusrepresents three valid species, namely Nemacheilus corica from northern India, and N. anguilla and N. monilis from southern India (Arunachalam& Muralidharan 2007). Nemacheilus anguilla Annandale was
described from Medha river in Maharastrastate and Nemacheilus monilis (Hora 1921) was described from Bhavani river near Mettupalayam,
which is endemic to the streams of NilgiriHills. Nemacheilus poonaensis (Menon 1950)
described from Moola-Mootha river of Krishna drainage
is placed in synonymy with Nemacheilus anguilla (Menon1987). Also Menon(1987) considers N. corica as belonging to Schistura, another related genus, whereas Banarescue & Nalbant (1995)
include it under the genus Nemacheilus, which
has also been followed by Jayaram (1999).
Materials and Methods
Methods
for taking measurements were followed from Menon(1987) & Kottelat (1990). Morphometric values
are expressed as percentage of standard length or of other values (head length,
etc). The examined materials are
deposited in the Zoological Survey of India, Southern Regional Station, Chennai
(ZSI/SRS) and Manonmaniam SundaranarUniversity Museum of Natural History (MSUMNH), Alwarkurichi,
Tamil Nadu.
Nemacheilus stigmofasciatus sp. nov.
(Image 1)
Holotype: 22.ii.2002,
37.7mm SL, Thuttinjet, Seethanathi,
Karnataka State, (13023’54.3’’N & 75001’18.2’’E), coll. M. Arunachalam, F7599, ZSI SRS Chennai.
Paratypes: 4 ex.,
31.60-37.66mm SL, other details same as holotype,
MSUMNH 19.
Diagnosis
Nemacheilus stigmofasciatus sp. nov. is distinguished from
the other two peninsular Indian species N. anguilla and N. monilis by its colourationand a set of morphometric characters. The new species differs in having a lateral
line that extends to the pelvic fin base below (vs. reaching up to anal fin in N.anguilla and complete in N. monilis), shorter snout length (35.9–39.4% HL vs 46.8% HL in N. anguillaand 40.5–48.1% HL in N. monilis), bigger eye
(28.1–31.3% HL vs 23.0% HL in N. anguilla and 15.9-19.9 % HL in N. monilis), caudal peduncle shorter than N. anguilla (12.4–13.1% SL vs15.5% SL) and shallower than N. monilis (9.5–10.2%
SL vs 12.0–14.5% SL). Vent to anal distance is reduced compared to N. anguilla (29.7–34.5% vs40.6% Pelvic to anal distance) and greater than N. monilis (29.7–34.5% vs 16.9–25.9% Pelvic to anal
distance). Notable colourvariations are the lesser number of bands on dorsal (back) 11–13 (vs 19-20 in N. anguilla and N. monilis), 6–8 blotches evenly
spaced along the lateral line (vs. band formed of coalescing blotches extending
to caudal base in N. anguilla and moniliform band in N. monilis).
Description
The general body
shape and appearance are shown in Fig. 1. Morphometric data of the holotypeand paratypes are given in Table 1. Body sub-cylindrical, dorsal profile slightly
arched, dorsal region raises gradually from tip of snout to dorsal fin origin,
followed by a gentle sloping for some extent and then evenly proceeds to caudal
base. Ventral profile
fairly convex. Depth of body (12.1–13.5 % in SL), head of moderate size and its
length 23.5–24.8 % in SL. Snout
short, blunt anteriorly, shorter than postorbital
distance and its length 8.4–9.7 % in SL and 35.9–39.4 % in HL. Eyes large, placed dorsally in the mid of
head length and not visible from ventral view. Nostrils close to each other with short flap, tubular but not extended
as barbels. Mouth semicircular, lips moderately fleshy, deeply furrowed, upper lip
with a pair of barbel like process at the arch,
interrupted with a median incision, lower lip with small lobes and a median
notch similar as in N. anguilla(Image 2). Dentiformprocess moderately developed. Barbels long and
simple, two pairs rostral and one pair maxillary. Outer rostral pair,
longest among barbels, extends almost to the anterior
margin of eye. Maxillarybarbels reaching to middle of eye. Entire body surface with
uniformly small imbricate scales, except on the ventral side. Dorsal fin, slightly less than length of
head, with four simple and eight branched rays, its origin well in advance to
the perpendicular of pelvic fin origin, slightly ahead of midway between tip of
snout and caudal base.
Pectoral fins
with one simple and 12–13 branched rays, extending to half way beyond the
distance to pelvic origin. Pelvic fins with one simple and seven branched
rays. Unculiferouspads on ventral surface of both paired fins, distinct in anterior most
rays. Anal fin with three simple and
five branched rays, its origin very far posterior, however, when compressed not
reaching caudal fin base. Vent nearer to
anal fin than to pelvic fin origin, which is overlapped by distal end of pelvic
fin. Caudal fin deeply forked with well-developed
upper and lower lobes, of equal length with 19 rays. Procurrent rays,
beyond the caudal principal ray, 10 in upper lobe and seven in the lower
lobe. Caudal peduncle
short, its length 12.4–13.1 in percent of SL and its depth 75.0–76.8 percent in
its own length.
Colour
Head
and body pale yellow with little greenish tinge. Head with numerous brownish
patches distinct in inter-orbital and inter-nasal region. Dorsal region with 11–13 dark brown vertical
bands of varied thickness mostly as wide as interspaces (Image 1). Bands usually 3-4 in the predorsal region between occiputand dorsal region, four in the dorsal fin region (origin to distal end of the
fin) and 4-5 in the post-dorsal region beyond the dorsal fin extension up to
caudal base. Bands darker in the
back, except for the two anterior most bands on lateral side, probably branched
extensions of dorsal bands, first one as an elongated dot over upper angle of
operculum and the second one as curved band from little above lateral line to
half way along the anterior branched rays of pectoral fin diminishing
afterwards. Rest others fade as they
descend downward as incomplete bands, distinct uptolateral line beyond which they are less clear. Body with 6–8 longitudinally elongated dark brown blotches along the
lateral line distributed in array upto caudal base,
which end with the black spot a characteristic feature of genus Nemacheilus. The blotches along the lateral line are found to overlap or placed in
between the forked bands. Dorsal fin has three black bands and caudal fin with
melanin pigmentation as transverse rays in the median region. The sexual dimorphism as such is not
exhibited, neither sub orbital flaps nor any form of colourindications have been noted.
Etymology
The specific namestigmofasciatus is a combination of the Greek
words stigmo for blotch and fasciatus for band, due to the regularly sized
blotches alternating with bands.
Distribution and
habitat ecology
N. stigmofasciatus is represented only in the Seethanathi river at Thuttinjet. The Seethanathi is a small west-flowing river in Karnataka with
many cascades and waterfalls in the upstream portion. The elevation of the stream at the type
locality is 199m above sea level. The
habitat in the study area is dominated by the presence of pebbles and boulders,
gravels are lesser, sand constitutes about 5% of the total substrate. Riparian cover is about 20% and gradient is
3% and the banks are highly stable, left bank with thick vegetation while right
bank is sparsely vegetated. Feeding was
not observed in the field and gut contents were not examined due to the lesser
number of specimens collected.
Comparison of
species
Of the two valid
species N. anguillaand N. monilis from peninsular India, the new species
has more features in common with N. anguilla. The new species resembles other congeners
with regards to prominent characters of the genus: blotches along mid-lateral
line, bands on the dorsal region, long barbels and
occurrence of a dark spot on the median lobe of the caudal fin. N. monilisdiffers from the new species in having a bigger body, smaller eyes, a lateral
line that reaches to the caudal base, prominent moniliformblack spots, and also in having a mouth with upper lip poorly furrowed (Image
2). N. anguilla shows a closer resemblance, but the new
species differs in several features: a lateral line that extends up to the
pelvic fin, shorter snout, bigger eye diameter, shorter caudal peduncle, and
pelvic fin extending beyond vent. Variation is also found in body colouration,
with 6–7 roundish blotches along the mid lateral line along with a peculiar
pattern of 10–14 vertical bands varying in number and extension along the back
to the lateral line. Both N. anguilla and N. stigmofasciatus sp. nov. have a pair of barbel-like
processes interrupted with a median incision in their upper lip. However, the
shape of the mouth opening differs a little, the tip of mouth is sharp in the
form of inverted V shape in N. anguillawhereas it is curved and bell-shaped in N. stigmofasciatussp. nov. Also
the inner rostral barbelsare not as short (Image 2) and the barbels are not as
thick and fleshy as compared to those found in N. anguilla.
Materials
examined
Nemacheilus anguilla: ZSI, KolkattaF 9692/1 Holotype (45.4mm SL), Yenna river at Medha, Satara Dist, Annandale. No date; MSUMNH 25, 1 ex., 48.8mm
SL, Krishna river, near Koyna Dam, Pune, M. Arunachalam, 1998;
MSUMNH 27, 2 ex., 35.3-39mm SL, Bhadra river,
Karnataka. M. Arunachalam& J.A. Johnson 18.i.1998; MSUMNH 22, 1 ex., 45.3mm SL, Ponnambalamedu,Pamba river, Kerala, M. Arunachalam02.xi.2003; MSUMNH 26, 1 ex., 38.3mm SL Syntherirock, Kanneri river, tributary of river Kali,
Karnataka, M. Arunachalam, 10.i.2003.
Nemacheilus monilis: MSUMNH 32, Topotype 4
ex., 64-72.9mm SL, Chengal, Bhavaniriver near Mettupalayam, M. Arunachalam& team, 01.ii.2001; MSUMNH 36, 5 ex., 65.4-72. 7mm SL, Bommeenmaduvu,Bhavani river, M. Arunachalam& team 03.ii.2001; MSUMNH 31, 2 ex., 59.8-67.6mm SL, Gugalthurai,Moyar river, tributary of Bhavaniriver, M. Arunachalam, 25.iii.2000.
No type
materials available in ZSI Calcutta, ZSI/SRS, Chennai and ZSI/WRS, Kozhikode
for this species.
References
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