Fishes of the genus Botia in the Indian Region - part 1

 by Steven Grant (The.Dark.One)

Introduction

In recent years there have been numerous works on fishes of the family Botiidae (I use Botiidae rather than Cobitidae as per Šlechtová et al 2006); but most of them discuss nomenclature of the names of genus rank and above, or are descriptions or synonymies of the genera and species that inhabit waters of China, Laos, Thailand, Cambodia, and Indonesia. In the last few years, only Kottelat (2004) and Ng (2007) have discussed species of the genus Botia in any detail, describing new species from Myanmar. Nalbant (2002) discusses Botia, but this is more about the interrelationships with other Botiidae (phylogeny).

I will mainly discuss here the Botias of the ‘Indian region’ (see comments under ‘Distribution’). The only recent work that has tried to resolve the identities and synonymies of ‘Indian region’ Botia is that of Menon (1993). However the results have still left some doubt in the minds of ichthyologists and aquarists alike. The synonymies proposed for the species have little or no discussion about the reasons for them; and the photographs are of poor quality. Having said this, Menon does provide some useful information that would not be available otherwise. Before Menon’s review, the literature on Botia in this region has been patchy, and much has relied on views of earlier authors, or misidentifications.

After discussions with a fellow aquarist (Andy Rushworth) we decided further clarification was needed as we were becoming frustrated with the use of various names for similar looking fishes that appear in the aquarium hobby, and the lack of clarity for identification and discussion in scientific works. So a decision was made to try and see if anymore light could be shed on the problem.

Building on the work of Menon, I will bring together here the myriad of papers on these fishes, and combine this with information from preserved and live specimens, to provide some (hopefully) useful information. However, I have found that although the status and identity of some species has hopefully been resolved, I have also found this study has produced more questions that cannot be fully resolved here. Rather than simplify and reduce the number of names in usage, it has actually had the opposite effect as it is my opinion that there are numerous species or subspecies within the genus that have historically been lumped under one name. Although I accept that this work has perhaps complicated the picture, I think this is more satisfactory than just lumping names together when it appears that there are differences that should be recognised. The recent work of Ng & Edds (2005) and Ng (2006) on Pseudecheneis catfish has shown that what was once thought to be a few species spanning Nepal, India, Bangladesh, Myanmar Laos and China are actually numerous species. Based on my interim findings I see a similar picture with Botia.

As mentioned previously it is important to note that this is by no means an attempt to thoroughly and finally review the genus as that is beyond my knowledge, time and capabilities. The scarcity of specimens in collections, and the age and quality of them makes it almost impossible to say with any absolute confidence that the results of this study reflect a true picture of the genus. To do this, collections would have to be made across the whole region, and fishes of differing ages and gender compared with that of other localities; and what would be useful would be to capture the specimens and keep them alive, observing their pattern changes as they grew. Menon (1993) did the former to a degree, and is the only attempt so far to show this; but as stated previously he failed to show or discuss reasons for his synonymies. He was better placed than most, having easy access to important specimens in Indian collections, to show the variances in pattern and colour across different distributions and the changes that happen as certain species groups grow, or become sexually mature (also including morphological changes associated with this). See ‘Identification by pattern’ for a further discussion of this point. Mitochondrial DNA analysis may also be useful in any future studies, particularly for the B. almorhae complex.

As well as access to important museum specimens, and information on them, the information from those involved in the export, retail, and keeping of these fishes has been invaluable. I consider that that information is a prime example when aquarists and aquarium exporter/retailers can provide a valid and useful role in the study of fishes.

Materials and methods

Descriptions of colour and pattern and some meristics and morphometrics are by a combination of live (or unpreserved) specimens (some with accurate locality data), and any preserved specimens mentioned. Unfortunately I have not been able to physically examine the preserved specimens myself, I have had to rely on images, x-rays, and thankfully the staff that I have listed in the acknowledgements have kindly provided me with any other information needed. Counts for caudal fin rays do not include the procurrent or outermost principal rays. Counts for fin rays will class a ray as separate, even if it shares the same pterygiophore as the preceding one. For dorsal rays, the last two rays (sometimes counted as 1 ray or ½ ray by some workers) are split down the middle, or are unbranched, and they usually do not have a normal or any pterygiophore. However, I have counted them as 2 rays as when people are counting rays on live specimens they will usually just see them as 2 rays, rather than 1 or ½ ray. Counts for principal rays may not be accurate as some counts have been taken from references, or un-x-rayed material, whereas some are from x-rays which usually shows some rays under the flesh. I have used the term ‘sp.’ if I consider that this represents an undescribed species/subspecies that I can also provide some specific information on their zoogeography and how it differs from other species. I have used the term ‘form’ if the differences are more subtle or their zoogeography is not as demarcated, but in either case the names or labels attached to them are not intended to form available species or subspecies names. For the B. histrionica complex I have used the term ‘form’ because of ongoing work by others more qualified than I. Material used is in: BMNH (Natural History Museum, London); USNM (Academy of Natural Sciences, Philadelphia); CAS (California Academy of Sciences, California); MNHN (Museum National d'Histoire Naturelle, Paris), AMS (Australian Museum), MCZ (Museum Comparative Zoology, Harvard), KU (Kansas University), OSUS (Oklahoma State University, Stillwater), NHSB (Bombay Natural History Society). Some specimens only have circa measurements if they are taken from images with scale bars as the institution has not been able to provide the information. Unfortunately I have not had access to specimens in Indian or Pakistani museum collections, some of them being types. However, based on the limited use of morphological and meristic data in fishes of the genus (and the information provided by Menon and the original descriptions) this has not been unduly problematic when discussing validity of some of the species.

Distribution / zoogeography

By the term ‘Indian region’ I mean Nepal, Bhutan, Pakistan, India, and Bangladesh. I will discuss connected areas: Myanmar (but not in too much detail as I am aware of work ongoing on Botias of Myanmar), the region of Yunnan in China, and Thailand, as they too have species of Botia within their borders. Based on what is known about the Tibetan origin of some of the major rivers or tributaries which Botias do occur in (Negi, 1994), one would think that Botias may occur in southern (Himalayan) Tibet (the Yarlung Tsangpo [Brahmaputra system], and the Sengge Chu [Indus system]) However, Wu & Wu (1992) and Zhang et al (1995) did not report any Botia from Tibet [Xizang], and Edds (1993 & 2007) did not report any loaches in the upper waters of Nepalese rivers. The waters there may be too cold and this may act as a natural barrier (see Petr 1999, and Petr & Swar 2002). Rather than dwell on countries and their man drawn borders, I should expand more on the distribution in waters of the region; as I can say with certainty that fish do not require passports to pass through different countries! The findings of Menon (pgs. 12-13 - although not explicit on the point), and comments from Kottelat (2004) led me to consider whether each major river system (and/or perhaps major river) has its own species of Botia, and if this is the case, if this could contribute towards formulating the identity and validity of the species in question.

I would have preferred to be able to include graphs with distribution markers for each species or form, but I have not been able to access any that I could reproduce. The major river systems or rivers that Botias are currently known to occur in are the following (only certain and relevant tributaries or distributaries, and states/countries will be mentioned and by no means does it infer that they are restricted to the ones mentioned here):

Indus River System: The Indus River rises in the Tibetan plateau and enters the Himalayas in Ladakh. Thereafter it flows through the Ladakh region of Jammu and Kashmir (India) before entering the plains of Pakistan. It has several tributaries that drain the western Himalayas, the important ones being Jhelum River (originating in Jammu and Kashmir), Chenab, Ravi, and Beas (all originating in Himachal Pradesh, India). The Sutlej (or Satluj) River rises in southern Tibet, cutting through the main Himalaya into the plains of Punjab (India) (Negi, 1994). Kabul River is a tributary. See Rafique (2000) for more details.

Ganges River System: The Bhagirathi and Alaknanda rivers join to form the Ganges River (all in the Uttarakhand Himalayas of India). The river then flows south east through Himalayan valleys into the north India plains. The Gangetic Plains form a major river basin and delta. Its tributaries include the Kosi, Sone, Karnali / Ghaghra and Gomti rivers, and a major river, the Yamuna. The Yamuna joins the Ganges in Uttar Pradesh (India). The River Hooghly branches off from the Ganges and drains into the Bay of Bengal after passing by Calcutta [Kolkata]. The main stream of the river enters Bangladesh (where it is known as the Padma river), where it meets with the Jamuna River of the Brahmaputra system. They combine with the Meghna River and drain into the sea in the Bay of Bengal.

Brahmaputra River System: The Yarlung Tsangpo River rises in the Tibetan Himalayas. The river enters India in Arunachal Pradesh, after its confluence with two other rivers it becomes the Brahmaputra River. It stretches through Assam (India). In Bangladesh it splits into two branches. The larger branch is called the Jamuna which joins with the Ganges (Padma). The other branch (Old Brahmaputra River) meets the Meghna (which a tributary of are the Surma and Barak rivers). Both branches meet and then flow into the Bay of Bengal. The Teesta (or Tista) is a tributary.

Salween River basin: Rises in Tibet, and flows through Yunnan (as the Nujiang River). It runs south through Myanmar (as the Thanlwin), and then enters the sea. The Suriya River is a tributary. The Ataran (or Kasat) River drains towards the Salween, where it enters the Andaman Sea. They appear to be connected via the Gyaing River.

Irrawaddy [Ayeyarwaddy] River basin: Rises in the north east of Myanmar near the border with China, and runs south west towards the ocean. In Yunnan it is known as the Daying Jiang River; the Longchuan Jiang River in Yunnan (called the Shweli River in Myanmar), also drains into the Irrawaddy. The Chindwin River of Myanmar flows into it, and the Chindwin has connected rivers that enter into Manipur (India). Although the Sittang River is not connected, it is theorised that the lower course of the Irrawaddy occupied the valley, pre-Pleistocene era. I class the Pegu (or Bago) River as part of the Sittang system. The Myitmaka River of the Irrawaddy drainage meets the Pegu River at Yangon.

The results of this study (albeit far from being the full picture) have led me to believe thatgenerally one should pay close attention to the river system or drainage that Botia specimens are found in, as it appears that species may be restricted to certain ones rather than the very wide almost all encompassing ranges that have been given for them in various publications over the years. As Kottelat (2004) states (when discussing phylogeny of genera), zoogeography has to be derived from phylogeny, so I am not trying to propose any phylogenetic tree using zoogeography, merely commenting that zoogeography can be useful tools when considering identity or validity of species.

Because some of the river systems now merge, or have merged in the past, some species will be present in more than one system or river. However, generally for the currently described species the zoogeography when looking at major systems or rivers appears (on a simplistic level) like this:

Indus system - B. birdi

Upper Ganges system - B. almorhae

Mid course of the Ganges & the Himalayan drainage to it - B. lohachata, B. dario

Lower Ganges - B. dario, B.rostrata

Upper Brahmaputra - B. dario

Lower Brahmaputra - B. dario, B. rostrata

Surma - B.dario, B. rostrata

Krishna - B. striata

Sittang - B. histrionica* (*see notes under B. histrionica regarding which river system actually houses the true B. histrionica)

Ataran - B. kubotai

Tenasserim - B. udomritthiruji

The occurrence of B. striata in the Krishna, which is some distance from any of the other systems/rivers above, and without any current hydrographic connection is discussed in Menon (1993:24), where he also discusses ‘waves’ of species distribution.

Identification by pattern and/or colour

Aquarists know that the patterns of some Botia can change dramatically as they grow, and can vary even in fish of the same size. Because of similarities in morphological and meristic information between species, pattern can give us an important comparator to help try and differentiate species. Using patterns alone has usually been frowned on by some as methods of separating species; however Menon (pg. 13) stated that he had relied mostly on colouration to distinguish the Botiidae species. Also Kottelat (2004) felt (with some reservation) that for at least two types of species in this genus pattern was “conspicuously diagnostic”. His comparison with another species was predominantly based on the differences in pattern in ontogeny (as well as distribution). I have struggled to come up with other factors that are as useful. Having witnessed the different patterns of many specimens (live and some preserved) from different river systems or major rivers, I agree that in this genus pattern is an important factor to use as a diagnostic tool. As aquarists we are well placed to see in live specimens the colours and more importantly the patterns that these fish exhibit at various growth stages, and aquarists and exporters like the groups that frequent Internet forums such as Loaches Online and Petfrd, have played an important role in obtaining visual and anecdotal information on the varying patterns of specimens, be it due to ontogeny, variations, or aberrant patterns. Bogdan Janiczak, and Mark Duffill have taken photographs of varying specimens as they grow, and these have contributed to this article.I have found that although patterns do have variations (and in the B. almorhae complex this becomes more problematic), and there are aberrant patterns, in some species the number and positioning of bars is almost always constant. The problem is when the bars start to anastomose** due to ontogeny, but I also feel that in some species they can ‘disintegrate’. By this I mean when the solid dark bars end up with pale (colour depends on species/form) spots within them. As well as or instead of anastomosis and ‘disintegration’, the dark bars can start to reduce or break off to form smaller dark particles and end up being unconnected dark spots, blotches, bars or reticulations (depending on the species); and/or in at least two species, some or all of the bars split to form two separate bars. I will call this fragmentation. Based on what I have observed, I agree with Kottelat that patterns can be very useful and/or diagnostic when trying to identify and separate Botia species. However it is not failsafe as some species have a very variable pattern. For the similar B. almorhae complex, colour differences (albeit subtle) can also play a role.

(**To connect, or branch together. This word appears to have first been used by Hora (1932), but has also been used by Menon, and Kottelat).

Morphology & morphometrics

Menon (pg. 13) used the following morphological and morphometric characters to help differentiate the species: body depth, length of the snout, length of ventral fins in relation to anal opening, and depth of caudal peduncle in relation to its length. I have found that the majority of these generally unhelpful as they can all fluctuate depending on size and gender. Hora (1922) used the length of snout in relation to the distance between the eye and the opercle (snout length compared to remaining part of measurement for head length), and then the position of the eye as to which portion of the head it was placed. Again, I find these factors unreliable for the same reasons. He then drilled down further using the position of the dorsal fin, eye size, and pattern. I have found that lateral head length in SL is so close and overlapping (all specimens I used 3.1 – 4.6) in all Botias to not be of any use. Out of any of the proportionate morphology measurements, proportionate body depth can be useful, and proportionate snout length more useful, when used in conjunction with other factors (colour, pattern, distribution). However, depending on the number of specimens used, and the proportion of gender in the specimens, results can be misleading so they should not be given too much weight on their own. When using proportionate body depth in SL it has to be borne in mind that smaller fish will be not as deep bodied, even when taking into account their SL, and female specimens will have a deeper body in SL. Snout length as a proportion of SL also seems to vary, and appears to be attributed to gender (males with proportionately longer snouts).

Hora also stated that in two similar species the swimbladder was of different relative size, and that the anterior chamber differed in the proportion of it that was enclosed in bone. He (1935) again commented on this and provided some drawings. Menon did not mention this character for Botia, but on page 14 mentioned it for Cobitids and stated it was not of any use. Of the Botia specimens that I have seen x-rays of, they almost all have a very similar if not the same structure to the bony portion of the swimbladder. The only one specimen with a notable difference is that of BMNH 1860.3.19.910, which has the anterior portion encased in a narrow tubular shape. Unfortunately this specimen has no identifiable locality data but is possibly B. lohachata, although I have been unable to compare it with x-rays of topotypical B. lohachata.

Incidentally, I have compared the morphology of the swimbladder of numerous Botia specimens from BMNH , USNM and AMS, with that of some Syncrossus, and some Yasuhikotakia (USNM 107853) and found that, they are all more encased in bone (anterior chamber) than in Syncrossus and Yasuhikotakia. This is something that Taki (1972) discussed in some detail.

Meristics

Menon (pg. 13) mentions the number of branched dorsal fin rays as a character to aid segregation of species but this is probably because he included Syncrossus berdmorei in Botia. I have noticed that some populations, forms or species have a certain consistent range of dorsal fin ray counts when compared to other species or forms or populations of them. However, the differences are only small and the counts will sometimes overlap, therefore as a character I consider that on its own it is unreliable.

Meristics of other fins are similar and vary within the same species, population, or form. The only possible difference is that of a higher ventral ray count, but this is only one or two extra rays.

Vertebral counts are usually within 3-4 of counts for other species, with the range being the same or very similar. The average count can be different albeit usually by only a low number.

To summarise I have found that the major river system and/or particular ranges, or tributaries/distributaries of systems can be a good starting point to differentiating species because those found in them tend to have different (albeit only subtle) base colours, and also patterns in terms of the number and placement of them, and the way in which the bars anastomose, disintegrate, and fragment, to specimens found in other systems etc. Whether this is enough to justify considering them as different species or subspecies needs further work using methods such as mitochondrial DNA analysis, as the factors discussed here may not be enough.