N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

CHAPTER – I

Introduction

Freshwater biodiversity constitutes a vitally important component of the

planet, with a species richness that is relatively higher compared to both

terrestrial and marine ecosystems (Gleick, 1996). The freshwater ecosystem

supports various orders of animals, plants and fungi contributing to a quarter

of vertebrate diversity and almost as much of invertebrate diversity described

to date.

Fish forms the most important wetland product on a global scale, and

is certainly the most utilized wetland resource. Asia accounts for 63% of total

fish production (Briones et al., 2004) and fish accounts for 30% of the typical

diet across Asia as a whole (World fish, 2010). It has great cultural and

psychological value to human beings. Freshwater fishes are defined as those

that spend all or a critical part of their life cycle in freshwaters. There are an

estimated 13,000 freshwater fish species in the world (Leveque et al., 2008).

IUCN Red list assessment of freshwater fishes of the Eastern Himalaya shows

that about 2% of fishes of the region are at high risk of extinction.

Northeast India which forms a part of the Eastern Himalaya extends

from Sikkim eastwards embracing the Darjeeling hills of West Bengal to

Arunachal Pradesh and to Mizoram in the south-east. It is a land of Blue

N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

2

Mountains, Green Valleys and Red River. It lies between 21°57´ and 29°23´ N

and between 87°58´ and 97°09´ E. The region extends over an area of about

2,62,230 sq. km. It comprises of the eight sister states, viz., Arunachal Pradesh,

Assam, Manipur, Meghalaya, Mizoram, Nagaland and Tripura and Sikkim.

Drainages of Northeast India

The fish faunal resources of northeast India may be subdivided into four

drainage based systems, viz., the Brahmaputra, the Barak-Meghna-Surma, the

Kaladan and the Chindwin.

The Brahmaputra drainage system. The Brahmaputra also called

Tsangpo-Brahmaputra, is a trans-boundary river and one of the major rivers of

Asia. From its origin in the southwestern Tibet as the Yarlung Tsangpo River,

it flows across the southern Tibet to break through the Himalayas in great

gorges and into Arunachal Pradesh where it is known as Dihang. It flows

southwest through the Assam Valley as the Brahmaputra and to the south

through Bangladesh as the Jamuna (not to be mistaken with Yamuna of India).

In the vast Ganges Delta it merges with the Padma, the main distributary of

the Ganges, then the Meghna, before emptying into the Bay of Bengal. The

river drains the Himalaya east of the Indo-Nepal border, southern-central

portion of the Tibetan plateau above the Ganges basin, the south-eastern

portion of Tibet, the Patkai-Bum hills, the northern slopes of the Meghalaya

hills, the Assam plains and the northern portion of Bangladesh.

Portions of the Brahmaputra drainage located in Arunachal Pradesh,

Meghalaya, and northern Bengal, together with parts of Assam and the

Himalayan foothills between Nepal and Bihar exhibit the most diverse fish

fauna. Species richness is highest in the Tista, Kameng, Dikrong, Subansiri and

Siang basins. The richness in those areas is due to the diversity of habitats and

environments existing between the plains of the Brahmaputra at a low altitude

(120-200 m) to the upland coldwater regions (1, 500-3, 500 m) in the hill ranges

N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

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in Arunachal Pradesh and also in Meghalaya and Assam within a short aerial

distance of 200-500 km. Similar levels of richness are expected in other basins

i.e., the Lohit and Dibang basins and those in Bhutan flowing to the

Brahmaputra drainage and headwaters of the Barak and Chindwin basins and

Kaladan drainage.

Fig. 1.1. Drainage map of Northeast India

The Barak-Meghna drainage system. The Barak River rises in the

Manipur hills and enters the plains near Lakhipur. The river flows southwards

on the eastern side of the Vangai range and then makes a U-turn at Tipaimukh

where it is joined by the Tuivai River, flowing westward between Manipur

and Myanmar. The Barak then flows northward on the western side of the

N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

4

Vangai range and then enters the Cachar district of Assam to finally enter

Bangladesh and join the Surma-Meghna basin.

The Kaladan drainage system. The Kaladan River is a drainage that

flows between the Ganga-Brahmaputra and Chindwin-Irrawaddy drainage.

This drainage is separated from the Barak-Brahmaputra basin in India by the

Chittagong hill tract and from the Chindwin- Irrawaddy basin in Myanmar by

the north-south extension of Arakan Yoma hill range.

The Chindwin drainage system. The Chindwin originates in the broad

Hukawng Valley of Kachin State of Burma, roughly 26°26′ N, 96°33′ E, where

the Tanai, the Tabye, the Tawan, and the Taron (also known as Turong or

Towang) rivers meet. It enters the Irrawaddy River at about 21°30′N, 95°15′E.

The extreme outlets into the Irrawaddy are about 35 km apart, the interval

forming a succession of long, low, partially populated islands. Chindwin -

Irrawaddy almost drains the heart of Myanmar. It consist of the Imphal River

and its tributaries, the lakes and marshes lying in the valley and the hill

streams of Ukhrul and Chandel districts which drain into the Chindwin in

Myanmar. Some part of it also reaches Nagaland as Tizu River. In the

meantime some part of Arunachal Pradesh is also drained by the Chindwin

drainage.

According to Abell et al. (2008) the region encompasses middle

Brahmaputra and parts of the Upper Brahmaputra, Himalayan foothills,

Ganga delta and plain, Chin-Arakan coast and the Sittaung-Irrawaddy

ecoregions.

Fish Diversity in Northeast India

Northeast India has rich freshwater fish diversity. Kottelat & Whitten’s (1996)

map of freshwater fish diversity hotspots in Asia included major parts of

Northeast India and Myanmar. The diversity is attributed to several factors,

N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

5

viz., habitat diversity, existence of different drainage basins, recent geological

history (the collision of Indian, Chinese and Burmese plates and the

Himalayan orogeny) which played an important role in the speciation and

evolution of groups inhabiting mountain streams (Kottelat, 1989). The

evolution of the river drainages in Northeast India and adjoining areas has

been the subject of several studies that utilize geological evidence to

reconstruct the palaeodrainage patterns (Clark et al., 2004). Phylogenetic

studies of fishes of the region have indicated vicariance events which may

have played important role in shaping the current distribution pattern of the

freshwater fishes of the region (He et al., 2001, Peng et al., 2006, Guo et al., 2005,

Ruber et al., 2004).

Fig. 1.2. Freshwater threatened fish species map of Eastern Himalaya © IUCN

After the breakup of the supercontinent Gondwanaland, about 140

million years ago, Indian plate attained a very high speed compared to other

continents probably because of its thin lithosphere. The lithosphere roots in

South Africa, Australia and Antarctica are between 180 and 300 km deep,

whereas the Indian lithosphere extends only about 100 km deep (Kumar et al.,

N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

6

2007). The vigorous collision with the Asian plate resulted in the Himalayan

orogeny and the consequent changes in drainage patterns, aquatic life, etc.

According to IUCN assessment, 2010, on eastern Himalayan region, majority

of threatened fishes are in Chindwin basin in Manipur, particularly the Imphal

River and its tributaries draining the surrounding hills and the central plain of

Manipur and the adjoining areas in Myanmar, i.e., the eastern part of the Chin

Hills and the Kabaw valley.

The diversity in north east India was thought to be due to the presence of

a ‘centre of origin’ of ostariophysan fauna in Southeast Asia, somewhere in the

Yunnan China, from where they distributed centrifugally to the east, west and

southeast; the distribution in the west via the northeast India corridor. The

dispersal theory considers that most advanced species would be found at the

centre of origin with more conservative or primitive species, the farthest from it.

This concept of Southeast Asia as the ‘centre of origin’ of freshwater

fish fauna by Darlington (1957), Menon (1973), Banarescu & Nalbant (1982)

and Briggs (1979) has been rejected as there is no evidence to support it

(Kottelat, 1989). The Satpura hypothesis has been reviewed by many authors

and found to be untenable for different reasons (Dilger, 1952; Mani, 1974;

Kottelat, 1989; Daniel, 2001 and Praveen, 2003) and hence the concept of fish

evolution, affinity of Indian and Southeast Asian freshwater faunae has

changed.

With the new concept of fish evolution and distribution in this part of

the world, there are three distinct adjacent faunae corresponding to the three

plates and drainages as follows:

1. Indian, constituted by the species of India, the Irrawaddy and the

Salween,

2. Southeast Asian, by the Chao Phraya, Mekong and Sunda Islands, and

3. Chinese, by those of China and the Red River.

N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

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Out of the 34 biodiversity hotspots listed by Conservation International

(Roach, 2005), two, viz., the Himalaya and Indo-Burma lie in north east India.

The Himalaya is the home of the world’s highest mountains and deepest

gorges. The mountains rise abruptly, resulting in a diversity of ecosystems.

The Indo-Burma, also called Indochina bioregion covers the area from eastern

India to Vietnam. The whole of Arunachal Pradesh and Assam, north of

Brahmaputra, and Sikkim belong to the Himalaya while Mizoram, Assam,

south of the Brahmaputra, Meghalaya, Nagaland and Manipur belong to the

Indo-Burma. Kottelat & Whitten’s (1996) map of freshwater biodiversity

hotspot also covers areas of north east India.

Catfishes

Catfishes are characterized by having naked body, barbels usually four pairs:

one each of nasal, maxillary and two pairs mandibular; adipose fin usually

present. Body often covers with bony plates. The order also characterized by

the absence of parietal, symplectic, suboperculum, and intermuscular bones.

The second third and fourth vertebrae were fused to a single ossification called

a “complex vertebrae”. Principal rays of the caudal fin fewer than 10+9, with

upper principal rays equal to, or fewer than, the lower rays.

Catfishes (order Siluriformes) are a wonderfully diverse clade with

over 3000 valid living species (Ferraris, 2007; Eschmeyer et al., 2004). In the

first six years of the 21st century 332 new catfish species were described, and

among these are the first representative of nine new genera and one new

family (Ferraris, 2007; Eschmeyer et al., 2004). This high rate of discovery

shows no sign of diminishing. Ferraris (2007) also recognized 3,093 species of

catfishes as valid, and are found to be distributed among the 478 genera and

36 families. He recognized major changes in the membership of some of the

higher level taxa and also stated that the current emphasis given to catfish

N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

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taxonomy at present is likely to result in a dramatic increase in the total

number of valid taxa.

Freshwater Fish Inventory

Ichthyological research in the northeast region started with the pioneering

works of Hamilton (1822), followed by Day (1878). S. L. Hora made

tremendous contribution to the ichthyology of the region till the middle of 20th

century. However, works on the Burmese forms became almost standstill after

Hora’s (1941) report on the Vernay-Hopwood Upper Chindwin expedition. In

the later part of the 20th century and in the beginning of the 21st century,

scientists from all over the world have focused their research on the

ichthyofaunal exploration in south-east Asia. Many new species have been

discovered and many taxa have been reviewed. More than 75 research papers

have been published and as many as 139 species of fishes have been described

new from the region. J. E. Gray, J. McClelland, J. Muller & F. H. Troschel, R.L.

Playfair, B. L. Chaudhuri, S.L. Hora, D.D. Mukherji, E. Ahl, A.G.K. Menon, K.

C. Jayaram, P. Banarescu, T. Nalbant, G.M. Yazdani, R.P. Barman, W.

Vishwanath and co-workers, P. Nath & S. C. Dey, R. Tilak, A. Hussain, J.

Vierke, T. K. Sen, N. Sen, S. P. Biswas, L. Arunkumar, P. Musikasinthorn, S.

Kullander & R. Britz, H. H. Ng, D. R. Edds, K. Nebeshwar et al., contributed to

the descriptions (Vishwanath, 2009).

Vishwanath et al. (2007) listed 90 species of catfishes under 38 genera

and 11 families from northeast India. Among the catfishes, maximum diversity

is found among the superfamily Sisoroidea and in the family Bagridae.

Linnaeus (1758) reported 1 species of catfish from northeast India. Several

workers have added more to the list: Bloch (1794) [4 species], Schneider (1801)

[1], Hamilton (1822) [28], Burchell (1822) [1], Sykes (1839, 1841) [3], McClelland

(1842) [4], Muller & Troschel (1849) [1], Blyth (1860) [1], Day (1870, 1877) [3],

Vinciguerra (1890) [1], Boulenger (1894) [1], Regan (1905) [1], Chaudhuri (1911,

N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

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1912, 1913) [3], Prashad & Mukerji (1929) [1], Hora (1923, 1936, 1937) [5],

Menon (1954) [1], Jayaram (1966a) [1], Datta et al.. (1987) [1], Nath & Dey

(1989) [2], Sen & Biswas (1994) [1], Roberts & Ferraris (1998) [1], Ferraris &

Runge (1999)[1], Vishwanath & Kosygin (1999, 2000c) [2], Arunkumar (200d)

[1], Ng & Lahkar (2003b) [1], Chakrabarty & Ng (2005) [1], Ng (2005c, 2005d,

2006a, 2006b) [6], Vishwanath & Joyshree (2006) [1], Vishwanath & Nebeshwar

(2006) [1], Vishwanath & Darshan (2005, 2006, 2007) [4] and Vishwanath &

Linthoingambi (2007a) [3].

Hora (1921a) reported 10 species of catfishes from Manipur, viz., Ompok

bimaculatus, Mystus bleekeri, Clarias batrachus, Wallago attu, Batasio affinis,

Glyptothorax dorsalis, G. minutus, Gagata cenia, Erethistes hara and Erethistoides

elongata. Menon (1954) described Glyptothorax manipurensis from Barak

drainage of the state. Vishwanath & Tombi (1986) recorded Hemibagrus

microphthalmus (Day) and Selim & Vishwanath (1999) recorded Mystus pulcher

(Chaudhuri) from Manipur. Vishwanath & Kosygin (1999) newly described

Myersglanis jayarami; Vishwanath & Kosygin (2000), Hara serratus; Vishwanath

& Darshan (2005 & 2006), Sisor barakensis and Batasio niger; Vishwanath &

Linthoingambi (2005), Glyptothorax ventrolineatus; Vishwanath & Nebeshwar

(2006), Pterocryptis barakensis; Vishwanath & Linthoingambi (2007a);

Glyptothorax chindwinica, G. granula, G. ngapang and Vishwanath & Darshan

(2007), Pseudecheneis ukhrulensis. They also described P. sirenica from

Arunachal Pradesh.

Many new forms of catfishes have been newly described from Nepal,

North East India, Bangladesh and Myanmar. Those from Myanmar are: Gagata

dolichonema (He, 1996); Batasio elongatus (Ng, 2004); Glyptothorax panda from

Myanmar (Ferraris & Britz, 2005); Psudolaguvia tenebricosa (Britz & Ferraris,

2003) and Mystus falcarius (Chakraborty & Ng, 2005). Species described from

Brahmaputra basin in Assam are: Sisor chennuah (Ng, 2003); Pseudolaguvia

foveolata (Ng 2005a); Erethistoides sicula (Ng, 2005b); Pseudolaguvia ferula (Ng,

N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

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2006b) and Conta pectinata (Ng, 2005c). Batasio spilurus and B. fasciolotus have

been described respectively from Assam and North Bengal (Ng, 2006b).

Pseudolaguvia inornata and P. muricata (Ng, 2005d) and Gogangra laevis (Ng,

2005e) are also described from Bangladesh. Erethistoides infuscatus is also

described from the Brahmaputra and Meghna basins in north East India and

Bangladesh (Ng, 2006c).

From Kosi drainage of Nepal and North Bengal, Batasio macronotus (Ng

& Edds, 2004), Erethistoides ascita and E. cavatura (Ng & Edds, 2005a);

Pseudecheneis crassicauda and P. serracula (Ng & Edds, 2005b), and Pseudecheneis

eddsi (Ng, 2006d) are described.

National Science Foundation of United States of America launched “All

Catfish Species Inventory Project” in 2003 with its headquarters at Florida

Museum of Natural History, Florida. It is a mission to facilitate the discovery,

description and dissemination of knowledge of all catfish species by a global

consortium of taxonomists and systematists. Dr. Lawrence M. Page was the

principal investigator of the project. Nearly three hundred scientists all over

the world were engaged in the project. The objective was to find out the

approximate global distribution of catfishes, repositories of siluriform types

field and museum projects, phylogenetic studies on catfishes and catfish

oddities. The project on its completion expected discovery of about 1,750 new

species of catfishes, 2,300 to 4,600 new species of freshwater fishes (Annon,

2006). However, the study did not cover Northeast India which has diverse

catfish fauna. During the project, 37 families of catfishes were recognized from

the world of which 12 are found in India. Out of the 12 families, 10 families are

recognized from northeast India.

The works of Hamilton (1822), Gray (1832), and McClelland (1842)

covered certain areas of W. Bengal and western parts of Assam, Arunachal

Pradesh and Meghalaya only. Surveys and description of Dr. S. L. Hora were

mostly from Nagaland, Manipur till 1940’s. These precious pieces of works

N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

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were mostly based on small collections because of inaccessibility. It is difficult

to arrive at a phylogenetic relationship of the siluroid fishes based on these

data. Interrelationships of the fishes of the order Siluriformes are poorly

known. Despite numerous recent papers on the morphology of catfishes, no

satisfactory arrangement of families, generic status is at present possible due

to lack of data of many fishes.

Anatomical Study and Phylogeny

Phylogenetic study is based on the morphology, anatomy especially the

osteological features and the molecular data, now-a-days. Several workers

consider that the only phyletically significant characters in distinguishing

higher taxa of vertebrates are the osteological ones (Banarescu & Nalbant,

1995; Chen & Lundberg, 1995; de Pinna, 1996). Actually all characters

including external morphology, rays, scales etc. have phyletical significance.

Knowledge on the osteological structures of all the available catfishes

are necessary for comparison with the fossil and to make an attempt at

understanding the evolutionary history of catfishes. The external morphology,

especially the skeleton is the only complete organ system available for detailed

comparison with fossils (Greenwood et al., 1966). But till date, there is no true

phylogenetic classification for any group of animals, except (to some extent)

that of horses. This is due to incomplete fossil records and also because the

comparative data collected through other approaches fail to possibly give a

clear picture by itself (Kapoor, 2001). In the history of systematics, more

published materials on fish phylogenies have been found over the last decade.

Worldwide projects tackling the relationships of enormous taxonomic groups

such as the siluriformes and cypriniformes, along with more general surveys

employing DNA barcoding have directed substantial resources into data

collection and phylogeny reconstruction. However fish systematics is found to

be in crisis. Over the last decade or two, molecular approaches have come to

N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

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dominate phylogenetics. This, of course, is not bad in and of itself; the more

data, the better. But processing this volume of data has moved workers away

from an intimate understanding of character distribution, homology and

meaning of evidences. Phylogenetic relationships have been studied based on

molecular data by several workers (Rüber et al., 2004, 2007; Jiang et al.., 2011;

Liao et al., 2011). However, the results based on molecular and morphological

and anatomical data are often found to contradict each other, mainly

regarding proper identification of species. Mooi & Gill (2010) also could find

many contrasting characters during the comparison of molecular and

morphological results.

The fundamental trends of cladistics are that common ancestry can

only be inferred from derived character states. Two methods of distinguishing

primitive and derived character states have been promoted vigorously in the

literature, the ontogenetic method and the out-group comparison (Farris, 1982;

Maddison et al., 1984). Of these, the latter is more widely used because it is

often difficult to obtain adequate ontogenetic series for most taxa and

characters.

Maddison et al. (1984) have shown that if two or more of the in-group

character states occur among the out-groups, and the relationships among the

out-group taxa are unresolved; the primitive in-group character state cannot

be determined by parsimony. They have also shown that if the relationships

among the out-group are known, polarization may be possible, even in the

face of such out-group variability. Out-group comparison is thus most

effective when out-group relationships are as broad and resolved as possible.

Osteological character provides valuable data as it does not fluctuate

physiologically, rhythmically or seasonally throughout the post-embryonic life

of the fish (Jayaram & Anuradha, 2003).

McClelland (1842) was a pioneer worker who made use of osteological

studies in separating the tribes and group of fishes in family Cyprinidae.

N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

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Sagemehl (1885) observed the cranium and Weberian apparatus of several

Characids for phylogenetic study. Sorenson (1890) examined the Weberian

apparatus of Siluroid, Cyprinoid, Characids and Gymnotid eels. Bridge &

Haddon (1894) described in detail the Weberian apparatus of Siluriformes.

Boulenger (1904) studied teleostean skeletons in the British Museum and gave

a classification of the suborders and families of the bony fishes reflecting their

phylogenetic lines. His observations on the osteological parts included

Weberian ossicles, anterior vertebra, osteocranial feature regarding the

articulation of the posttemporal bones with the skull, parietals with

supraoccipital etc. Regan (1909, 1911) laid down for the first time a firm basis

for the classification of catfishes based on osteological characters. His work

raised the sub-family Bagrinae to the rank of a family Bagridae. Gibian (1912)

studied hyobranchial skeleton of the cartilaginous fishes.

Hubbs (1920) enumerated many of the important evolutionary changes

in the branchiostegal of living fishes. He also noted the tendency for decrease

in branchiostegals during evolution and the differences in shape and

arrangement of the branchiostegals of Malacopterygeans and

Acanthopterygeans. Woskoboinikoff (1932) commented on the branchiostegal

series and hyoid arch in a general study of the respiratory apparatus of fishes.

Corsy (1933) studied the evolution of the hyoid arch of vertebrates which

included the structure found in teleosts.

Bimachar (1934) was the first Indian who showed the utility of

osteocranial studies in portraying interrelationships and affinities of various

families and genera of Indian freshwater catfishes. Allis (1935), while studying

some teleostean skulls, had mentioned various modifications found in the

sensory canal system in snout.

Eaton (1945) gave a detailed account of the skeleton supports of the

median fins in fishes. He reported that as a general rule, the skeletal supports

of median and paired fins are of the same nature. The two primary functions

N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

14

of the series of their pterygiophores are: support of the dermal fin rays by

articulation distally and provision of an area for attachment of the radial

muscles which erect and depress those rays.

Harry (1953) described the osteology of Amphilius longirostris

(Boulenger). He pointed that this African catfish have many common

characters with Sisoridae and Amblycipitidae and Bagridae. He also

hypothesized that Amphiliidae might be an intermediate form between

Bagridae and the two Asiatic families: Sisoridae and Amblycipitidae.

Khanna (1960) described the hypobranchial skeleton of some fishes,

viz., Pangassius pangassius, Rita rita, Sperata seenghala and Wallago attu. He

showed variability in the number and shape of pharyngo-branchials among

siluroid fishes.

Alexander (1962) analyzed the structure of Weberian apparatus in

Bagridae, Malapteruridae, Siluridae, Clariidae, Callichthydae and Loricariidae.

Tilak (1963) studied osteocranium and the Weberian apparatuses of Ailia coila,

Clupisoma garua, Neotropius navalchor, Pangasius pangasius, Pseudeutropius

atherinoides and Silonia silondia and compared with those of Eutropiichthys and

the members of the family Bagridae. He mentioned that Neotropius navalchor

and Pseudeutropius atherinoides closely resemble bagrid fishes and suggested to

put them in the family. He showed their great difference from schilbeids.

Saxena et al. (1963) observed osteocranium and vertebral column of

Mystus seenghala in detail and reported that the specialization in the skull

structure went far greater in Siluriformes than that of Cypriniformes. Jarvik

(1963) reviewed the intermandibular bones of some early teleosts.

Alexander (1965) felt that catfishes might have evolved from an

ancestor resembling primitive Characinoidei. He also verified Diplomystes to

be more primitive than other known catfish based on the forms of its maxilla,

pectoral girdle and position of dorsal fin.

N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

15

Tilak (1966) observed the osteocranium and the Weberian apparatus of

Amblycep mangois and compared with those of Bagridae and Schilbeidae.

Gauba (1966) also gave a detailed osteological structure of the skull of

Glyptothorax cavia.

Jayaram & Bimachar (1967) observed osteological structures of Mystus

bleekeri, M. cavasius, M. lecucophasis M. gulio, M. vittatus, M. tengara. Sperata aor

and S. seenghala. They made attempts to analyse the basic osteological patterns

that reflected phylogeny. They also mentioned that osteological characters

have immense value in clarifying the systematic status and affinities among

the species.

Rosen & Patterson (1969) described various osteological features of the

upper jaw, hyoid arch, and occipital region of the neurocranium, median fin

and caudal skeleton of Myctophids in their discussion of familial and ordinal

relationships. Rosen & Greenwood (1970) studied the origin of the Weberian

apparatus and the relationships of the Ostariophysean and Gonorynchiform

fishes. Sorescu (1972) compared the Weberian apparatus in the sub-families

Danioninae and Cultrinae.

Gosline (1971) discussed the relationships of a number of lower teleost

families including Myctophids, in the light of osteological features. Characters

of the skull, pelvic girdle and caudal skeleton were discussed.

Roberts (1973) observed the interrelationship of Ostariophysan by

studying their morphology including osteology. He proposed subfamilies

Siluroidei, Cyprinoidei and Characoidei respectively for catfishes, carps and

characins.

Lundburg (1975) reviewed the problem of the homologies of the two

bony elements between cleithrum and roof of skull in Siluriformes. He

concluded these bones to be hightly modified supracleithrum and post-

temporal. Lundberg (1982) described the skeleton and soft anatomy of the

toothless blind catfish Trogloglanis pattersoni and discussed relationships with

N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

16

Amiurus, Noturus, Prietella, Pylodictis and Satan. He concluded subgenus

Ictalurus to be a sister group of all other living Ictalurids and considered to be

monophylectic.

Kobayakawa (1989) studied osteology of seventeen species of the genus

Silurus in his revision of this genus. From the phylogenetic analysis, he

divided the species of the Silurus into cochinchinensis group and glanis group.

Bornbusch (1991) hypothesized the monophyletic nature of family

Siluridae by observing many derived character states in the osteological

structure. He commented the absence of distal radials in the dorsal fin support

has not observed in other siluriforms and interpreted as a synapomorphy of

the Siluridae.

Mo (1991) discussed on the anatomy and the phylogeny of the Bagrid

fishes. He used eighty-six morphological characters in the analysis using

cladistic methodology. He removed Horabagrus from Bagridae and placed

within Schilbeidae and Neotropius to Bagridae. His studies suggested the

monophyletic nature of Bagridae.

Kobayakawa (1992) also studied the shape and development of bony

elements of neurocranium and suspensorium in Silurus asotus, S. biwaensis and

S. lithophilus. Srinivasachar (1958) observed the development of skull in

Heteropneustes fossilis.

de Pinna (1993) examined bagrid phylogeny using 239 morphological

characters from 27 species. His studies suggested that monophyly of Bagridae

was not strong enough. Further, de Pinna (1996) used 112 characters to study

the relationship among the Sisoridae, Akysidae, and Amblycipitidae.

de Pinna & Ng (2004) reported the existence of second ural centrum in

the caudal skeleton of certain catfish families, viz., Akysidae, Amblycipidae,

Amphilidae, Aspredinidae, Auchenipteridae, Cetopsidae, Erethistidae,

Mochokidae, Pimelodidae and Sisoridae. They suggested that the inclusion of

N. Anganthoibi : Inventory and Systematic Studies of Catfishes of Northeast India

17

neotropical Aspredinidae into Asian clade was supported by the presence of

second ural centrum.

Literature shows that very little work has been done on the inventory

and systematic study of catfishes of northeast India. Most of the publications

are based on preliminary surveys. Identification and studies on the

relationships between species, genera and families based on anatomical

examinations have not been done. When the world has become very keen in

the inventory and conservation of freshwater habitat and biodiversity and

scientists from other countries have taken pains to visit remote and

inaccessible water bodies, many of our workers are unaware of the facts.

So, a detail survey of the catfishes was carried out and studied in

respect to taxonomic status, species diversity and phylogenetic relationships

among them were taken up. Thus, the present work has the following

objectives:

1. To carry out detailed inventory of catfish fauna of the major

river drainages of northeast India and to establish correct

identity of species.

2. To describe new taxa (many new species and genera) are

expected.

3. To carry out phylogenetic analysis of some groups of

catfishes based on morphometric and anatomical studies.