Redescription of Batasio
merianiensis, a catfish (Teleostei: Bagridae) from northeastern India
Heok Hee Ng
Raffles Museum of Biodiversity Research, Department of
Biological Sciences, National University of Singapore, 6 Science Drive 2, #
03-01, Singapore 117546
Email: dbsnhh@nus.edu.sg
Date of online publication 26 May 2009
ISSN
0974-7907 (online) | 0974-7893 (print)
Editor: W. Vishwanath
Manuscript
details:
Ms
# o2177
Received
08 April 2009
Final
received 15 April 2009
Finally
accepted 19 May 2009
Citation:Ng,
H.H. (2009). Redescription of Batasio merianiensis, a catfish
(Teleostei: Bagridae) from northeastern India. Journal of Threatened Taxa1(5): 253-256.
Copyright: © Heok Hee Ng
2009. 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.
Author
Details: Heok Hee Nggraduated with a PhD from the University of Michigan in 2006 and has
been working on the taxonomy of Asian catfishes since 1994. Now at the Raffles
Museum of Biodiversity Research in Singapore, his current research focus is on
sisoroid taxonomy and systematics.
Acknowledgments:I
am grateful to Andrew Rao for help in obtaining specimens of B. merianiensis,
and the following for permission to examine material under their care: David
Catania (CAS), Andrew Bentley (KU), Anthony Echelle (OSUS), Douglas Nelson
(UMMZ), Kelvin Lim (ZRC) and A. K. Karmakar (ZSI). This study was partially supported by the
Raffles Museum of Biodiversity Research.
Abstract: The bagrid catfish Batasio
merianiensis was described from only the holotype collected in the
Brahmaputra River drainage, Assam, northeastern India. This poorly known catfish is rediagnosed and
redescribed on the basis of fresh material in this study. Batasio merianiensis is diagnosed from
congeners in having a combination of the following characters: length of
adipose-fin base 16.9–22.2 % SL, dorsal fin when appressed not reaching
anterior origin of adipose fin, body depth at anus 15.2–18.4% SL, caudal
peduncle depth 9.7–11.5% SL, eye diameter 18.3–25.9% HL, vertical dark brown
bars on head and body, and absence of dark mid-dorsal stripe.
Keywords: Brahmaputra River, Siluriformes, South Asia
For Figure, Images & Table
– Click here
Introduction
Members
of the genus Batasio are small, laterally compressed bagrid catfishes
generally found in fast-flowing streams and rivers throughout South and
mainland Southeast Asia. They are
diagnosed from other confamilials in possessing large sensory pores on the
head, narrow mental region, a pair of prominent posterior processes on the
anterior part of the vomer, transversely elongated, bar-like entopterygoid, and
the close contact of the metapterygoid with the quadrate (Mo 1991). They have a (sub-Himalayan) distribution
ranging from the Indus River drainage to the west, the short, coastal rivers draining
the eastern face of the Annam Cordilleras to the east, and the Perak River
drainage to the south. Recent studies
(Ng 2008) have recognized sixteen valid species of Batasio: B.
batasio, B. tengana, B. affinis, B. fluviatilis, B.
dayi, B. merianiensis, B. travancoria, B. pakistanicus,B. tigrinus, B. elongatus, B. sharavatiensis, B.
macronotus, B. fasciolatus, B. spilurus, B. feruminatus,
and B. procerus. Of these sixteen
species, half of them have been described within the last ten years,
highlighting the amount of hidden diversity within the group.
Batasio
merianiensis(Chaudhuri 1913) is a species from the Brahmaputra River drainage in Assam
(northeastern India) that is known only from the holotype. Recently, I was able to obtain fresh material
from the Brahmaputra River drainage in Assam referable to this species. As the original description of this poorly
known species is only based on the holotype, I rediagnose and redescribe Batasio
merianiensis on the basis of this material.
Material and methods
Measurements
were made point-to-point with dial calipers and recorded to 0.1 mm. All
measurements and counts follow Ng & Kottelat (2001). Asterisks after
meristic data indicate value for holotype. Institutional codes follow Ferraris (2007). Meristic values with an asterisk indicate
those for the holotype.
Batasio
merianiensis (Chaudhuri,
1913)
(Image
1 & Fig. 1)
Macrones
merianiensisChaudhuri, 1913: 253, Pl. 9 (Figs. 1, 1a–b) [type locality: pond at Mariani
Junction]
Material
examined: holotype, 65.7mm SL; India: Assam, pond at
Mariani Junction, Assam, India, ZSI F7781/1. UMMZ 248780 (13) 46.8–75.5mm SL;
ZRC 51880 (7), 49.5–59.8mm SL; India: Assam, Gurfhula River, approximately 16
km NW of Kokrajhar, in the vicinity of Kumapara.
Diagnosis: Batasio
merianiensis is distinguished from congeners in having a combination of the
following characters: length of adipose-fin base 16.9–22.2% SL, dorsal fin when
appressed not reaching anterior origin of adipose fin, body depth at anus
15.2–18.4% SL, caudal peduncle depth 9.7–11.5% SL, eye diameter 18.3–25.9% HL,
vertical dark brown bars on head and body, and absence of dark mid-dorsal
stripe.
Description: Morphometric
data as in Table 1. Body moderately
compressed. Dorsal profile rising evenly
and somewhat steeply from tip of snout to origin of dorsal fin, then sloping
gently ventrally from there to end of caudal peduncle. Ventral profile flat to anal-fin base, then
sloping gently dorsally from there to end of caudal peduncle. Skin smooth.
Lateral line complete and midlateral. Vertebrae 18+18=36 (n=1), 18+19=37 (n=1), 19+18=37 (n=14) or 19+19=38
(n=4).
Head
compressed and narrow. Bony elements of
dorsal surface of head covered with thin skin. Anterior nostrils tubular, separated from posterior nostrils by distance
of two-thirds eye diameter. Eye ovoid,
horizontal axis longest; located entirely in dorsal half of head.
Mouth
inferior, premaxillary tooth band not exposed when mouth is closed. Oral teeth small and villiform, in irregular
rows on all tooth-bearing surfaces. Premaxillary tooth band rounded, of equal width throughout. Dentary tooth band much narrower than
premaxillary tooth band at symphysis, tapering laterally.
Barbels
in four pairs. Maxillary barbel short
and slender, extending to half of distance between its base and base of
pectoral spine. Nasal barbel slender,
extending to anterior orbital margin. Inner mandibular-barbel origin close to
midline, extending to vertical through anterior orbital margin. Outer mandibular barbel originating
posterolateral of inner mandibular barbel, extending to vertical through middle
of orbit.
Dorsal
fin with spinelet, spine, and 7 (n=21) rays. Origin of dorsal fin at point
through anterior two-fifths of body. Dorsal-fin margin convex. Dorsal-fin spine short, straight and slender,
posterior edge with low irregular serrations.
Pectoral
fin with stout spine, sharply pointed at tip, and 7* (n=2) or 8 (n=19)
rays. Anterior spine margin smooth;
posterior spine margin with 6–7 large serrations along entire length.
Pectoral-fin margin straight anteriorly, convex posteriorly.
Pelvic-fin
origin at vertical through posterior end of dorsal-fin base, with i,5 (n=21)
rays and slightly convex margin; tip of appressed fin not reaching anal-fin
origin. Anus and urogenital openings
located at vertical through middle of appressed pelvic fin.
Adipose
fin with slightly convex margin for entire length, fin base approximately same
length as anal-fin base. Origin of
anal-fin base slightly posterior to origin of adipose-fin base, with iii,9
(n=1), iv,8* (n=8), iv,9 (n=10), iv,10 (n=1) or v,8 (n=1) rays and convex
distal margin.
Caudal
peduncle of moderate depth. Caudal fin deeply forked, with i,7,8,i (n=21)
principal rays; upper and lower lobes slightly rounded. Procurrent rays extend
only slightly anterior to fin base.
Coloration: In 70% ethanol:
body and head light grayish brown, with four vertical dark brown bars: one on
head passing through eye; second running obliquely anterior to dorsal fin,
terminating just below lateral line; third below adipose-fin origin,
terminating at lateral line; last at base of caudal fin. Faint dark, saddle-shaped patches present
between dorsal-and adipose-fin bases, and on caudal peduncle immediately below
posterior end of adipose-fin base. Ventral surfaces paler in color. Humeral region in area of swimbladder
with scattered melanophores, conferring a slightly darker appearance. Pectoral, pelvic and anal fins hyaline, with
scattered melanophores on fin rays. Dorsal
fin hyaline, with dark brown subdistal ovoid patch covering spine and parts of
first 3–4 branched dorsal rays.
Distribution: Known from the Brahmaputra River drainage in
Assam, northeastern India.
Discussion
Four
other species of Batasio are recorded from the Brahmaputra River
drainage (Ng 2006): B. batasio, B. fasciolatus, B. spilurus,
and B. tengana. Batasio
merianiensis is distinguished from all of these species except B.
fasciolatus in having dark vertical bars on the head and body (vs. such
marks absent). It differs from B.
fasciolatus in having a shorter adipose-fin base (16.9–22.2% SL vs.
24.5–25.3; dorsal fin when appressed not reaching vs. overlapping the anterior
origin of the adipose fin) and fewer vertical bars (four vs. six) on the
body. Other characters that may be
useful in distinguishing the two species include a more slender body (depth at
anus 15.2–18.4% SL vs. 18.1–20.3) and larger eye (diameter 18.3–25.9% HL vs.
16.5–18.8) for B. merianiensis, although these two characters are
slightly overlapping and may not be useful all the time. Batasio merianiensis further differs
from B. batasio in having a shorter adipose-fin base (16.9–22.2% SL vs.
24.8–26.5) and deeper caudal peduncle (9.7–11.5% SL vs. 8.2–8.8), and from bothB. spilurus and B. tengana in having the adipose-fin base longer
than (vs. shorter than) the anal-fin base (16.9–22.2% SL vs. 12.6–17.5) and the
absence (vs. presence) of a dark mid-dorsal stripe.
In
previous comparisons with only the holotype of B. merianiensis, the
length of the pectoral-fin spine was used as a diagnostic character in
distinguishing this species from B. fasciolatus (16.3% SL vs. 12.7–14.3;
Ng, 2006). However, data from the fresh
material of B. merianiensis (12.2–15.0% SL) does not support the
diagnostic value of this character.
Although
the locality from which the fresh material was obtained is nearer the type
locality of B. fasciolatus (160 km to the west-northwest) than that of B. fasciolatus (400 km to the east), it is diagnosable as being conspecific
with B. merianiensis when compared to the illustration in the
original description (Fig. 2), as the color pattern and size of the adipose fin
indicates.
Among
congeners outside of the Brahmaputra River drainage, the color pattern of B.
merianiensis is most similar to B. affinis (from the Irrawaddy,
Sittang and Ataran River drainages in Myanmar) and B. tigrinus (from the
Mae Klong River drainage in western Thailand). However, B. merianiensis can be distinguished from both species
in having a shorter adipose-fin base (16.9–22.2% SL vs. 23.9–29.1). The appressed dorsal fin in B.
merianiensis also does not reach (vs. overlapping in B. affinis) the
anterior origin of the adipose fin. Batasio
merianiensis further differs from B. tigrinus in having a more
slender body (depth at anus 15.2–18.4% SL vs. 18.4–20.8).
Comparative
material
Batasio
batasio:
CAS-SU 34847 (3), 58.2–69.0 mm SL; India: West Bengal, Mahananda River at
Siliguri. UMMZ 209009 (1), 54.8mm SL;
Bangladesh: Chittagong, Koilla Khal (creek), 9.7km E of Feni-Chittagong highway
on road to Ramgarh, 22°55’N & 91°36’E. ZRC 40570 (10), 53.4–67.8mm SL; India: Assam, Dibrugarh.
B.
fasciolatus:
UMMZ 244798 (holotype), 67.0mm SL; UMMZ 244799 (1 paratype), 70.6mm SL; India:
West Bengal, market at Malbazar, 26°32’30”N & 88°44’17’’E. BMNH 1988.4.11.14 (1 paratype), 50.1mm SL;
India: West Bengal, Balason River at Digana, near Panighata, 20km from
Siliguri. UMMZ 244797 (1 paratype),
57.5mm SL; India: West Bengal, Tista River at Tista barrage, 26°45’10”N &
88°34’11”E.
B.
tengana:
UMMZ 244796 (neotype), 43.4 mm SL; India: West Bengal, Tista River at Tista
barrage; 26°45’10”N & 88°34’11”E. KU
28534 (1), 31.5 mm SL; KU 35240 (5), 30.4–39.4 mm SL; KU 35256, 53.5mm SL;
Nepal: Saptari/Sunsari, purchased at Kosi barrage, 26°31’30”N &
86°56’00”E. KU 28685 (1), 36.0mm SL;
Nepal: Kanchanpur, Chandhar River, confluence of three rivers (Chaudhar,
Bahuri, Gobraiya) at Royal Shuklaa Phantaa Wildlife Reserve, 28°43’00”N &
80°12’00”E. OSUS 17365 (2), 35.8–36.6mm
SL; Nepal: Nawalparasi, Narayani River at Toadi Ghat. OSUS 15812 (2), 43.8–45.9mm SL; Nepal:
Nawalparasi, borrow ditch west of Tribeni.
B.
spilurus:
ZRC 49133 (holotype), 42.0 mm SL; ZRC 50201 (1 paratype), 40.5 mm SL; India:
Assam, Dibrugarh district, 27°29’N & 94°54’E.
Additional
material examined is listed in Ng (2006), Ng & Kottelat (2007) and Ng
(2008).
References
Chaudhuri, B.L. (1913). Zoological
results of the Abor Expedition, 1911–12. XVIII. Fish. Records of the Indian
Museum 8(3): 243–257, Pls. 7-9.
Ferraris, C.J. Jr. (2007). Checklist of
catfishes, recent and fossil (Osteichthyes: Siluriformes) and catalogue of
siluriform primary types. Zootaxa 1418: 1–628.
Mo, T.-P. (1991). Anatomy,
relationships and systematics of the Bagridae (Teleostei: Siluroidei) with a
hypothesis of siluroid phylogeny. Theses Zoologicae 17. Koeltz,
Koenigstein, 216pp.
Ng, H.H. (2006). The identity ofBatasio tengana (Hamilton, 1822), with the description of two new
species of Batasio from north-eastern India (Teleostei: Bagridae). Journal
of Fish Biology 68(Supplement A): 101–118.
Ng, H.H. (2008). Batasio
procerus, a new species of catfish from northern Myanmar (Siluriformes:
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495–511.
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