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lease note that all images of preserved specimens are copyright of the institution to which the specimen belongs / the photographer; for photographs of live specimens and the drawing of M. pelusius the copyright is that of the photographer or the institution mentioned. This is an updated and amended version of an article which appeared with the same title in Cat Chat, The Journal of the Catfish Study Group (UK), Volume 5 Issue Number 2, pages 5-17, June 2004, and of the first web based version of 2006.

This article has been written for interested aquarists (or, to a much lesser degree, ichthyologists), to contribute towards resolving the identity and validity of the striped bagrid catfishes of the genus Mystus Scopoli, 1777.
Having disregard to the species that belong in Hemibagrus, Mystus is currently a genus containing at least two, possibly more, groups of species that will probably be split into separate genera at some point. Roberts (1994) split the genus into two groups based on several features. The ones that can be used for living fishes were the relative height and length of the adipose fin, length of the maxillary barbels, the shape of the caudal fin, and whether or not the fontanel (a gap/space in the structure of the top of the skull) is split by an “epiphyseal” bar (basically making it look like one, or two elongated grooves on the top of the head). The split can be a complete split or the bar can appear as an indent that does not fully split the groove (see image below).

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Roberts restricted Mystus to the species with long and high adipose fins, long maxillary barbels, deeply forked caudal fins (with upper lobe being longer) and with the split fontanel. He did not propose any generic name(s) for the remaining species. Jayaram & Sanyal (2003) felt that more of the species could be included in the sensu stricto group to the ones included by Roberts, and felt that some of his characteristics were unreliable.

There is a generic name that already exists which could be resurrected in the future for some of the remaining species: Aspidobagrus Bleeker, 1862. Recent authors have mentioned Hypselobagrus Bleeker, 1862, but if one follows Roberts (1992) work on the synonymy of its type species, this genus would be a synonym of Mystus. Looking at the morphology of what is currently considered to be the type species of Mystus, I personally doubt how it can be included as belonging to the same morphological group as the species Roberts (1992) lists in sensu stricto. Basically it is still a bit of a mess and I think that for the time being they will have to be referred to as Mystus, but I wouldn’t bet against Hypselobagrus and/or Aspidobagrus being resurrected.

With all the species I have tried to get images of the preserved type specimens and/or reproduced the original drawing if one was provided. The reason I have done this is that I have found that unless one refers to the type specimens or drawings of them, one cannot be 100% sure that you are talking about the species in question. I appreciate that for some people images or drawings of dead, sometimes now colourless, fish may not be the best way to assist in identification but misidentifications have been made previously and I feel this is the safest way. However, even with type material to refer to, some of the multi-striped species are still difficult to tell apart when looking at live fish, and sometimes one has to use the morphology of the fontanel (which is not easy in live fish) and supra-occipital process (a bony extension of the skull which extends towards the ‘basal bones’ of the dorsal fin – see image below).

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Hara malabarica Day, 1865(b)
Macrones malabaricus nec Jerdon, Day 1877
Mystus malabaricus nec Jerdon, Jayaram & Sanyal, 2003
Mystus malabaricus nec Jerdon, Easa & Shaji, 2003
Mystus malabaricus nec Jerdon, Jayaram, 2006
Mystus malabaricus nec Jerdon, Pethiyagoda et al, 2008This name was described by me as a replacement name for Hara malabarica Day, 1865(b) as that species belongs in Mystus and in my opinion it is not a junior synonym of Mystus malabaricus (Jerdon, 1849) (see further discussion under Mystus oculatus).

The type specimen (see discussion below) of M. canarensis (AMS B.7624) measures 11.1 cm SL and originates from the district of Canara (or Kanara), Karnataka State, India and is probably from Mangalore (see Ferraris et al, 2000 for information on another AMS Day specimen listed as Macrones armatus - but not representing that species in my opinion - also listed as being from ‘Canara’). The coordinates given in my description were taken from the specimen label but must be in error as the coordinates given are much further north and away from the Canara region. Although Mangalore is in Day’s view of what is meant by Malabar, in the description of Hara malabarica he mentions receiving some specimens from Travancore. Travancore is still in the Malabar region but is further south than Mangalore. However, it is not clear if all the syntypes were from Travancore, and in any case Jayaram & Sanyal (2003:71) found M. canarensis specimens in Travancore (under the account of M. malabaricus), and AMS B.7624 was labelled as Hara malabarica by Day himself. It is probable that AMS B.7624 is the specimen figured by Day (1877, Plate CI fig. 2) as “Macrones Malabaricus” (but it is important to note that Day captioned it as his species, not Jerdon’s Bagrus malabaricus), showing a fish with a tympanic semi-ocellus, a dark stripe along the lateral line, and spots on the fins making the upper portion of the dorsal fin and lower third of the anal fin appear blackish. The original drawing of Hara malabarica is not a good one. In fact in the copy that I was originally provided with the adipose fin wasn’t even showing. However, it does show in the reprint that I now have. In my opinion Fig. 12 in Jayaram & Sanyal (2003), and Fig. 119 in Easa & Shaji (2003) show M. canarensis, captioned as M. malabaricus.

Please ignore the information in the description about the number of gill rakers as this is a mistake. Ferraris (2007) does not accept my neotype designation. He considers that the absence of types and nomenclatural need was not clearly demonstrated. Whitehead & Talwar (1976) found no types (which included BMNH, NMW and ZSI – where all the purported syntypes are), and I could not trace them in the BMNH. Jayaram & Sanyal class NMW 45228 as a “topotype” of Hara malabarica. Thanks to Helmut Wellendorf I have had access to images of the NMW specimen (see link above). It seems too large to be a syntype (it measures approx. 12cm SL and 14.5cm TL and Day states that his specimens from Travancore were “rather less than 4 inches in length”). Also I have been informed by Helmut that the locality label on the specimen is “Canara”. This again appears to match that of AMS.B 7624 and is probably from the same batch; I do not consider the NMW specimen to be a syntype of Hara malabarica. It is topotypical with M. canarensis and matches that species. With hindsight I should have been more specific with the information rather than just use the bibliographic reference via Eschmeyer et al to searches by other authors. The identity of Day’s species is not straight forward. It was severely wound up in a problematic identification problem with Mystus malabaricus (Jerdon, 1849) and as such the identity of the species becomes very difficult and confusing if not based on an actual type specimen. Therefore I consider the neotype to be nomenclaturally and taxonomically required, and despite the partially valid criticism of the way in which the search for the types was expressed in the designation I consider it to be valid as it meets all the requirements of Article 75 of the ICZN. It gives a base to work from to compare it to Jerdon’s M. malabaricus and M. montanus and M. armatus (sensu Day, 1865) and M. oculatus from the same region.

It is my opinion that M. armatus is possibly a synonym of M. oculatus (see under that species for a further discussion). However, it is clear that there are at least 4 species in the ‘Malabar’ region:
M. montanus
M. oculatus (possible synonym - M. armatus)
M. canarensis (the species given the name M. malabaricus by Jayaram & Sanyal et al)
M. malabaricus (probably the species given the name M. armatus by Jayaram & Sanyal et al – see under M. malabaricus and M. oculatus for a further discussion)

Therefore when comparing M. malabaricus (using specimens under the account of M. armatus in Jayaram & Sanyal, and Pethiyagoda et al, and also AMS B.7573 and NMW 45165) it is clear that M. malabaricus and M. canarensis differ. M. canarensis has a much shorter supra-occipital process, a longer more slender body, the fontanel not reaching base of supra-occipital process (vs. almost reaching), different shaped teeth bands, and other morphometric differences. This mainly revolves around my view that Day (in his 1877 account) used a specimen not conspecific with his original type specimens, and this has led Jayaram and all others since to base what they consider M. armatus to be on a misidentification (see further discussion under M. oculatus). What would finally resolve the issue of whether M. canarensis is a different species to the true M. malabaricus is a neotype designation for Jerdon’s species. However, the identity of M. armatus must be resolved first as discussed under M. oculatus.

M. canarensis is also similar at first glance to Mystus dibrugarensis and Mystus rufescens (Vinciguerra, 1890) - see under species headings for differences. See images of a very small specimen of what appears to be M. canarensis (photographed by Rahul Kumar). This specimen was caught in leaf litter in a hill stream in Wayanad, a couple of hundred miles south of Canara district. In the first picture it measures around 2 inches Total Length, in the other images it is around 4 inches TL. Compare with the images under M. malabaricus.

Mystus carcio (Hamilton, 1822)   (Please see image of live specimen)

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There are no known preserved type specimens of this species which was described from the ponds of northern Bengal.In Hamilton (1822) there is no reference to any drawing but as per Hora & Law (1941), Plate 23, Figs. 60 of Hamilton (1822) are erroneously captioned as Pimelodus batasio (which is now Batasio batasio), and should have been captioned as Pimelodus carcio. It is quite obvious when one reads the description of B. batasio and M. carcio that Hamilton made a mistake with designating which fish figs 60 represented. Thus we can quite clearly see what M. carcio looks like. The specimen in my image matches exactly the written description and figures in Hamilton (1822).

This species is a dwarf one, only reaching approx. 5cm SL in captivity.

It can be differentiated from all others by its small adult size, very small adipose fin, a dark horizontal mark across the tympanum, greenish yellow colouration, large laterally placed eyes, and relatively long and wide fontanel which is distinctly split by a thick epiphyseal bar. Usually confused as representing M. vittatus or M. tengara.

Mystus colvillii (Günther, 1874)

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See images of type specimens and see further discussion under Mystus pelusius (Solander, 1794).

Mystus dibrugarensis (Chaudhuri, 1913)

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See image of the holotype, which came from Dibrugarh, Assam, India and measures 6.8 cm total length. Colour and pattern described as: “Head grey, dorsal side dark brown, body brownish. The membranous covering of the air bladder behind the gill openings is black, and a black line from above this membrane extends through the middle of the side to the middle of the root of the caudal fin, ending in a black circular blotch. The barbels are black, except the inner mandibular, which, with the fins, is dull white.” This species was originally described as Macrones montanus var. dibrugarensis. Contrary to Jayaram (1954) and subsequent authors it is not a junior synonym of Mystus montanus (Jerdon, 1849). M. montanus was described by Jerdon from the Kabini River of the Kaveri (or Cauvery) system in south western India as: “greenish above and on the fins; yellow on the cheeks and beneath.” There is no mention of any stripe(s) on the body, or semi-ocellus. Jayaram & Sanyal (2003) give information on M. montanus from further south than the type locality and show that whilst in life it is silvery grey with light yellowish bands along the sides, it can exhibit greenish bands along the sides with a dark spot at the base of the caudal fin, and a dark mark near the tympanum. In M. montanus the caudal lobes are shaped differently, the adipose fin appears to have a longer base, and the body and fin patterns differ. In my opinion the different zoogeography should be taken into account, M. dibrugarensis being from the upper Brahmaputra River in north eastern India. M. dibrugarensis differs from M. canarensis by having the supraoccipital process raised, long, and touching the basal bones of the dorsal fin (versus not raised, very short, and not touching); body not elongated; caudal fin lobes being equal (versus upper lobe being longer than lower lobe). Also see notes on M. malabaricus, M. pulcher and M. rufescens.

Mystus gulio (Hamilton, 1822)  (Please see image of live specimen)

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This is the type species of Aspidobagrus. See image of an eyeless specimen.Originally described from “Higher parts of Gangetic estuaries”, this species lives in fresh and brackish waters. Sometimes when young it can exhibit pale stripes along the body. It is easily differentiated from the other species by the combination of its greyish silver colour and small adipose fin. Can reach approx. 40cm SL.See discussion under M. oculatus regarding the identity and zoogeography of the true M. gulio.

Mystus horai Jayaram, 1954

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See image of a type specimen.

It has been included here as it was originally described as a sub species of Mystus vittatus (Bloch, 1794), although according to the original description there are no stripes on the body of M. horai, just a faint black ‘shoulder’ mark. Preserved colouration said to be brownish yellow above, dull grey underneath. Type specimens originate from the Indus River, Kalabagh, Pakistan; the largest specimen being 8.4 cm SL.

Mystus keletius (Valenciennes, 1840)

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Bagrus albilabris (Specimens from Pondicherry, and possibly Sri Lanka) Valenciennes, 1840?
Mystus gulio nec Hamilton, Easa & Shaji, 2003?

M. keletius was originally described from Java, and Pondicherry. Ng (2002) examined the type specimens and concluded that the one from Java represents Mystus nigriceps (Valenciennes, 1840); and after a lectotype designation restricting the type locality for M. keletius to Pondicherry [Puducherry], India.See image of the lectotype (MNHN A.9011) from Pondicherry, India; the specimen measures approx. 9cm SL. In earlier versions of this article I said that Valenciennes stated that the colour and pattern was very similar to Mystus tengara (Hamilton, 1822) in its colouration and pattern, but differed due to the supraoccipital and humeral (cleithral) processes being more granulated, the supraoccipital process being longer, the dorsal fin appearing rounder and the maxillary barbels being shorter. This is an error. Valenciennes actually stated that (translated from French) “is a species very close to the preceding, and which is confused at Pondicherry under the same name”. The preceding species was Mystus cavasius (Hamilton, 1822) (although the ‘M. cavasius’ at Pondicherry is actually M. seengtee (Sykes, 1839) – see Chakrabarty & Ng (2005)), and at the end of that account Valenciennes refers to M. tengara of Bengal and that is why my error was made. Ferraris (2007) classed it as a junior synonym of M. vittatus; Pethiyagoda et al, 2008 tentatively agreeing with him. In the earlier versions of this article I said it was different to M. vittatus based on the more rugose bony plates, slightly different fontanel, and shorter barbels. Also, Baensch & Evers (2002) show a picture captioned as M. keletius and state that it has a yellow/silvery colouring, with a “dark shoulder mark”, two silvery to golden strips bordering the lateral line, and black marks near the dorsal and caudal fin. Jayaram & Sanyal (2003) state it is "Brownish turning dull white beneath. A dark shoulder spot and a light band along lateral line present. Dorsal and caudal fin tips tinged black, anterior portions of anal fin black". If this colour and pattern is correct for specimens from the type locality and they are conspecific with the lectotype then M. keletius is valid in my opinion. Jayaram & Sanyal also show a drawing of a specimen which is clearly different in its morphology to that of M. vittatus.Interestingly Easa & Shaji (2003: Fig. 118) picture a specimen that they caption as M. gulio (Hamilton, 1822).

The true M. gulio appears (in my opinion) to be restricted to north, and north eastern India, Nepal, and Bangladesh (and possibly Pakistan). The identity of the species distributed in Myanmar, Thailand, Vietnam, Malaysia, and Indonesia has not yet been proved (and there are several names already available if these do prove to be distinct). It is possible that the species captioned as M. gulio and present in south western India, and Sri Lanka is actually M. keletius. If this is the case the syntypes of M. albilabris from Pondicherry (and possibly Sri Lanka – if the type information in Eschmeyer, 2008 is correct – the original description does not mention Sri Lanka) may be synonymous with M. keletius; certainly they have similarly originally described colour patterns, overall shape and proportions, relatively short adipose fins, and similar cranial morphology (see images of some of the MNHN syntypes of M. albilabris on www.fishbase.org). M. keletius and M. albilabris were described in the same work. Because M. albilabris is based on syntypes that may not be conspecific with each other due to their differing localities, it may be an idea in the future to designate one of the specimens from “Ganges” as the lectotype.

If it came down to being the first reviser I consider that M. keletius should take precedence over M. albilabris.Based on Valenciennes showing that M. keletius is similar to M. seengtee; the information and drawing in Jayaram & Sanyal; the possibility of it being what has been incorrectly captioned as M. gulio in south western India; and the lectotype of M. keletius being different to the holotype of M. vittatus, M. keletius should remain as a valid species until further specimens can be studied and compared to M. vittatus. Although the pattern is more like M. seengtee it clearly differs from that species in morphology, the obvious difference being in the length of the adipose fin (longer in M. seengtee) and the much longer fontanel of M. seengtee (see images above of a non type specimen, and the possible holotype of M. seengtee). Although there are zoogeographical differences to M. gulio, morphological differences need further work. It differs from the similarly patterned M. oculatus (and therefore M. armatus) by the shape and structure of the fontanel (longer and broader, and split in M. oculatus). See under M. ankutta for differences to that species.

Mystus malabaricus (Jerdon, 1849)  (Please see images of live specimens)

? Mystus armatus nec Day, Day 1877
? Mystus armatus nec Day, Jayaram, 1954, 2006, and Jayaram & Sanyal, 2003
? Mystus armatus nec Day, Easa & Shaji, 2003
? Mystus montanus nec Jerdon, Easa & Shaji, 2003
? Mystus armatus nec Day, Pethiyagoda et al, 2008 (not including the listing and figure of the syntype of M. armatus)
See discussion under M. ankutta, M. canarensis and M. oculatus.
Described from “Mountain streams in Malabar, India”. There are no known preserved type specimens therefore the original description of the colour and pattern is important: “blueish leaden above, silvery beneath; fins yellowish.” No semi-ocellus, or stripe(s) on the body are mentioned.

I wondered if based on the locality and that colour and pattern if it was possible that Jerdon’s species is a synonym of M. armatus and/or M. oculatus, the latter being the senior synonym. However, Jayaram & Sanyal (under the account of M. armatus) state that although it is brownish on top, and becoming lighter beneath, freshly collected specimens have a dark band on the sides along the lateral line ending in a dark blotch at the base of the caudal fin. Also a dark band along the anal fin and upper half of the dorsal fin. This would make it very close to M. dibrugarensis in terms of colour and pattern, although that species has a definite tympanum spot, more vivid black markings (with some in caudal fin), and different zoogeography. I doubt that the specimen from Kenchong River, Myanmar listed in Jayaram & Sanyal (2003) is M. malabaricus, I think it will possibly be M. dibrugarensis or even M. castaneus Ng, 2002 in view of the zoogeography. I am aware of at least 2 new species from Myanmar so it is unlikely that the Myanmar specimen is M. malabaricus.

Please see my images of a specimen that is very close (if not identical) to the erroneous identification of M. armatus (= M. malabaricus of Jerdon in my opinion – see under M. oculatus). This specimen of unknown origin is 102mm SL, and stopped growing some time ago therefore I consider it an adult. I consider the AMS and NMW specimens shown here represent M. malabaricus. *See images by Hayath of specimens from the southern states of Kerala, Tamilnadu and Karnataka in the western ghats.

Very similar to M. ankutta; see that species account for differences. Similar to M. rufescens, but that has a more slender body; the head shape when viewed from above in M. rufescens is more angular; and the fontanel is more triangular at its front portion in M. rufescens.

? Mystus misrai Anuradha, 1986

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See discussion under Mystus pelusius (Solander, 1794).

Mystus montanus (Jerdon, 1849)

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The original description states “Colour greenish above and on the fins; yellow on the cheeks and beneath” and this was the colour and pattern at about 6 inches. See further discussion under M. dibrugarensis about the colour and pattern in live/fresh specimens from different localities as found by Jayaram & Sanyal (2003). Jerdon stated that he “only found it in the river at Manantoddy in Wynaad” which I think is now called Mananthavady, and the river the Kabini (or Kabbani), but Jayaram & Sanyal found it in other localities in Kerala and Tamil Nadu.At first glance it is also similar to M. pulcher but that species has a much more distinctly round tympanic spot, as well as morphometric differences and zoogeography.

Mystus multiradiatus Roberts, 1992   (Please see image of live specimen)

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See holotype (CAS 76119) which originates from Prachinburi market, Thailand, and live specimen by Kamphol. Largest type specimen is 12.8 cm SL. The small gap between supra-occipital process and basal bones of dorsal fin spine help visually differentiate this species from the similar M. atrifasciatus. It is also distinguished from the similar M. bleekeri by the much less conspicuous and non-indented fontanel, and the lack of dark tympanic spot.

Mystus mysticetus Roberts, 1992   (Please see image of live specimen)

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See holotype (CAS 76121) which originates from Nakorn Phanom market, Thailand, and live specimen by Allan James. Largest type specimen is 12.9 cm SL. This species has a humeral semi-ocellus, and the tympanum is darkly pigmented but is not a semi-ocellus. Tips of anal and caudal fin often black.

The laterally placed eyes (visible when viewed from above or below), and the combination of small adipose fin, humeral semi-ocellus, and dark tympanum differentiate this from all other species.

Mystus oculatus (Valenciennes, 1840)

Junior synonym: ? Macrones armatus Day, 1865

Type locality for M. oculatus is “Malabar Coast”, India. This is on the south western coast, covering parts of modern day Karnataka, Kerala, and Tamil Nadu states. Day (1865b:v) classed his “denomination” of Malabar as the coastal region from Mangalore (in Karnataka state) to Cape Comorin [Kanyakumari town] in Tamil Nadu state, and inland into the Western Ghats (a mountain range). This includes Cochin (now known as Kochi), which is the type locality of M. armatus It has been kindly pointed out to me that the historical Malabar region does not cover the large area used by Day (including Cochin) but it is clear that Day’s use of Malabar did and this is important when discussing the species he described or covered.

See holotype (MNHN 1195) of M. oculatus. According to the original description by Valenciennes, and Day (1877) there is no stripe present on the body in M. oculatus. The colour/pattern is said to be grey at the top, silvery on the sides, lighter beneath. The reason I have included it here is that Jayaram & Sanyal (2003) state it is dark brown above, yellowish beneath with a dark shoulder spot, a dark spot at the base of the dorsal fin (spine), a dark band along the middle of the dorsal fin, and a dark broad band along the lateral line. I’m not sure if this is from observations of the specimens they used, or from the figure in Day (1877), which in my opinion is just trying to illustrate the lateral line itself, not any band of colour or pattern along it. However, they did have four recently preserved specimens so this may be from them and if so it is possible that the body spot and bar quickly fade in older or less well preserved specimens? However, in Easa & Shaji (2003) and Mercy et al (2007) no stripe is present along the lateral line.

In the 2004 and 2006 versions of this article I included M. armatus (Day, 1865) as a valid species. However, I raised the point that M. armatus needed checking against M. oculatus as they might be conspecific. Day described M. armatus as new in 1865a from “rivers and backwaters of Cochin, India”, but did not include any details regarding its colour or pattern, but did thankfully say (amongst other morphological details) that the base of the adipose fin equalled that of the anal fin, the supra-occipital reached the basal bones of the dorsal fin, and the fontanel almost reached the origin of the supra-occipital process (which he showed in a drawing).

In 1865b he used the same morphological information but went on to say that the colour and pattern was “Bright leaden silvery, lightest along the sides and with a purplish gloss over the cheeks. A black spot just anterior to the root of the dorsal spine. Fins finely dotted with minute black points.” He then stated that the adipose fin commenced a short distance anterior to that of the anal fin.

Unfortunately no figure was published of the whole fish and as yet the type specimens have not been definitely identified. However, in my opinion BMNH 1865.7.17.21 does constitute one of the syntypes (one of a number of type specimens originally used by Day), alternatively it may be a specimen used by Day in 1865b (although they were probably one and the same, even taking into account the slightly different statements about the adipose fin). According to the BMNH website the locality for the specimen is “Malabar”. Looking at the descriptions by Day in 1865, the BMNH specimen certainly seems to match. In particular the bony plates on the head (cranium); the size, shape and placement of the fontanel; the size and length of the supra-occipital process; the dorsal and pectoral fin spine morphology; and the darkish mark near the dorsal fin spine base (which on the BMNH specimen looks like it is on the anterior and median nuchal plates) all match. I have compared the BMNH specimen with the holotype of M. oculatus. Although the MNHN specimen is not as well preserved the two specimens appear to closely match in all these factors. In particular the morphology of the bony plates of the head and nuchal plates are virtually identical. The size, shape, and placement of the fontanel match, and the supra-occipital process matches. Although one could be mislead by Day (1877) into thinking that the maxillary barbels of M. armatus are shorter than that of M. oculatus, in 1865a and b it is clear that the maxillary barbels reach the anal fin (in fact in the original description it states that they reach the caudal fin), as they do in M. oculatus. The main possible difference is the size of the eyes. In M. oculatus at first glance they appear larger, however (using images) in the holotype of M. oculatus the eye goes into the head length 3.4 times, and in the syntype of M. armatus it goes in 3.57 times. This is very close. It is my tentative opinion that based on the locality details and the colour, pattern, and morphology that M. armatus is a junior synonym of M. oculatus. Hopefully an ichthyologist will resolve this problem once they have definitely defined the true M. armatus, although unfortunately even in 2008 this still doesn’t appear to be happening. Thanks to Mark Sabaj Peréz and Kyle Luckenbill I have also been able to compare the BMNH syntype with NMW 45165 (see images above) which has previously been highlighted as a possible syntype of M. armatus. The NMW specimen does not match the original description of M. armatus or of the BMNH syntype. Notable differences are in the fontanel. In the BMNH (syntype) the fontanel is very long and narrow, commencing anterior to the eyes and ending near the base of the supra-occipital process, whereas in the NMW specimen it stops well short of the base of the supra-occipital process and its anterior portion is wider than the posterior portion. In the BMNH syntype it is partially split by an epiphyseal bar near the anterior rim of the eye, whereas in the NMW specimen it is not split at all (although there is a slight indentation in the shape). For these reasons I do not consider NMW 45165 as a syntype of M. armatus.

There is no mention of stripes in the original description of M. armatus, but in Day (1877, Plate CI fig. 3.) a drawing is shown of a fish with a mid-lateral stripe terminating in a blotch on the body near the base of the caudal fin, and the adipose fin being much longer than the anal fin base. In my opinion this is probably AMS B.7573, which Ferraris et al. (2000) have correctly stated is not a type specimen of M. armatus. AMS B.7573 is from Canara district and as such could represent M. canarensis or M. malabaricus, thus accounting for the differences in pattern and morphology. Thanks to Shobnom Ferdous I have been sent images of AMS B.7573 (see above). It matches exactly with the drawing and account in Day (1877). In the text in Day (1877) he states that M. armatus doesn’t always show the dark lateral line or dark shoulder mark. Unfortunately AMS B.7573 is not conspecific with M. armatus as originally described by Day in 1865. Bearing in mind that BMNH 1865.7.17.21 does match M. armatus as originally described, if one compares AMS B.7573 with that BMNH syntype one can see that not only is the general shape of the head and body different, but that the fontanels are a completely different shape, but more importantly a different length (bearing in mind the drawing and information about this in the original description of M. armatus). The differences between the BMNH specimen and the NMW specimen are mirrored here; the AMS specimen appearing conspecific with the NMW specimen. In my opinion this misidentification in Day (1877) (using a non type and non conspecific specimen) has led to Jayaram (1954) and subsequently (Ng 2002), Jayaram & Sanyal (2003), Eas & Shaji (2003), Jayaram (2006), and Pethiyagoda et al (2008) considering M. armatus as having a dark stripe along the body. Day’s 1877 account of M. armatus (and therefore Jayaram’s et al) shows the maxillary barbels as only reaching around the ventral (pelvic) fins, whereas as stated above it is clear from the 1865 accounts that they are longer. Also, it is clear that as originally described M. armatus has the dark mark around the base of the dorsal fin spine (also present in M. oculatus), and this is missing in the Day (1877) account and therefore in the subsequent accounts by Jayaram et al. My theory is that the M. armatus as originally described is a synonym of M. oculatus, and that Day’s 1877 account (and therefore all accounts since) of M. armatus are actually M. malabaricus of Jerdon. As an example, compare the cranium of the specimen figured in Pethiyagoda et al (2008: fig. 6a) as representing M. armatus with that of the syntype of M. armatus (BMNH 1865. 7.17.21) and you will see that the fontanels are of a completely different shape, placement, and length.

See image of a live specimen under M. malabaricus that appears conspecific with the NMW and AMS specimens, but not the BMNH one. As mentioned previously, a final and definite determination and then examination of a syntype of M. armatus and then a comparison with that of the holotype of M. oculatus, with then a comparison with the specimens identified as M. armatus by Jayaram et al, then in turn a comparison with the type of M. canarensis will resolve this issue one way or another. Until then I consider M. armatus a tentative junior synonym of M. oculatus.

Mystus pelusius (Solander, 1794)

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Junior synonyms: Bagrus halepensis Valenciennes, 1840
                            Macrones aleppensis Günther, 1864
                           ? Mystus misrai Anuradha, 1986

M. pelusius is currently considered to be the type species of Mystus but the earliest designation has not yet been fully resolved. Solander described the species in 1794, from Kowick (Coic?) River, Aleppo, Syria based on earlier invalid names proposed by Russell in 1756 and Gronow in 1763.

Roberts (1994) tentatively considered M. colvillii (from the Tigris River at Baghdad, Iraq) and M. misrai (from Lake Antioche, Syria) to be junior synonyms of M. pelusius, although he did note that in the future M. colvillii may prove to be distinct. Thanks to Anthony Troncale of the American Museum of Natural History I have now managed to see the original drawing of M. pelusius from Solander (1794), and the text of the description, which is very basic in terms of colour and pattern information, just saying it was predominantly dark silver. The colour pattern of the alleged junior synonym M. misrai (see image of a type specimen) is (in alcohol): pale yellowish brown with head slightly lighter. No spots or stripes present.

The drawing of M. pelusius looks more similar to M. colvillii than it does to M. misrai, although the profile of the dorsal fin is different in M. colvillii than the drawing of M. pelusius. The image here of BMNH BMNH 1955.6.25.1 (a syntype of B. halepensis, and possibly of M. pelusius also) looks very different to M. colvillii.

M. colvillii is said to be olivaceous in colour, with three narrow, white, parallel, longitudinal stripes, one along, one above, and one below the lateral line. The type specimens are “9 inches long”. According to Ferraris (2007) BMNH 1955.6.25.1 is a syntype of M. halepensis (a junior synonym of M. pelusius). If you compare the M. halepensis specimen with the syntypes of M. colvillii you will see that the whole body, head, and fin shape is different. In addition the fontanel in M. colvillii appears to extend much further forward anteriorly. Based on these points and the different locality data, I consider that M. colvillii is probably valid. M. misrai appears to be a junior synonym of M. pelusius.

Mystus pulcher (Chaudhuri, 1911)   (Please see images of live specimens)

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Described from four small specimens (6.7cm total length) from near the Yunnan border, upper Myanmar. See image of a type specimen, and a live specimen by Kamphol.

Described as “Dorsal and upper part of the body dark brown, with lighter or paler whitish brown stripes: one median, from the tip of the snout to the base of the dorsal spine, and two lateral longitudinal on each side, one above and the other below the middle line, which is distinguished by being dotted black for the openings of the lateral organs.” “…nasal and maxillary barbells blackish brown, adipose fin dark brown, dorsal, anal and caudal fins are brownish with black spots on the membranes between the rays.”

It has an intensely black tympanic spot/semi-ocellus, and also a spot near the caudal peduncle, followed by a thin white band. Its supraoccipital process meets the basal bones of the dorsal fin.

The difference in length of the supra-occipital process differentiates it from M. canarensis. The light body stripes differentiate it from M. dibrugarensis. Differs from M. rufescens by the fact that its fontanel is not split by an epiphyseal bar, and it has a shorter adipose fin.

Mystus rhegma Fowler, 1935   (Please see image of live specimen)

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See drawing and image of holotype ANSP 61748 which originates from Bangkok, Thailand, and measures 4.96cm SL; and a live specimen by Kamphol. Roberts (1994) lists specimens up to 10.6cm SL.

As per original description: “Very light or pale brown, lower or under surfaces more or less whitish. Upper surface of head and back sprinkled with dark grey dots. Band of dark dots along lateral line and broader one along lower side of trunk and tail parallel. Iris greyish, also maxillary barbell, other barbells whitish. Outer edge of adipose fin dusted with dark grey dots. Caudal dark grey. Other fins pale or whitish.”

This is a small and graceful looking species, which reminds me of species of the South American pimelodid genus Pimelodella Eigenmann & Eigenmann, 1888.

The lack of any semi-ocellus, the thin dark band across the lateral line, and large gap between the small supraoccipital process and basal bone of the dorsal fin spine differentiate this species from all the others.

Mystus rufescens (Vinciguerra, 1890)   (Please see images of live specimens)

The type specimen measures 7.4cm (which is SL), and originated from Meetan, Tenasserim Provinces, Myanmar. See drawing and photograph of the type. I understand that ‘Meetan’ equates to the Mitan Chaung, a rivulet flowing south from the summit of Mulayet Taung (16°11'N 98°32'E) (information taken from Heok Hee Ng, an ichthyologist who specialises in catfish). The Mitan Chaung is part of the Gyaing River drainage, in southern Myanmar. In the earlier versions of this article I included the above CAS specimen as a M. rufescens, due to the identification in Roberts (1994). However, after looking at an image I have of a live specimen that matches the CAS specimen (see above) and a discussion with Kamphol, I do not think that the live specimen in my image or the CAS specimen are M. rufescens. To start with the CAS specimen is from the Sittang River drainage at Hlegu, Myanmar. This river system is currently unconnected to the Ataran. The other reason is that the CAS specimen and mine have a much longer and deeper adipose fin than the holotype of M. rufescens (although that is a smaller specimen). The pattern also looks different. Also, please see the image by Kamphol of a live specimen from the Irrawaddy drainage (which is closer to and connected in places to the Sittang). Kamphol’s specimen could be the same as mine but on the other hand it could be a different species as I know that a species of Botia and a species of Syncrossus in the Sittang are very similar to but different to species in the Irrawaddy (in my opinion). My specimen and Kamphol’s may be one or two of the undescribed species of Myanmar. Either way it is also does not match the holotype of M. rufescens. Kamphol has an image of an Ataran River drainage Mystus that could be the true M. rufescens (see above). Again however, this specimen has a deeper body and a much longer adipose than the holotype, and the Mitan Chaung is not part of the Ataran drainage (although they lie close). The Ataran specimen may represent a third undescribed species. So, at this moment in time the true M. rufescens may be a mystery in terms of a photograph of a live specimen.

Vinciguerra described the colour and pattern as body tawny reddish, with one spot near the humeral region and one on the caudal peduncle. If one looks at the figure of the holotype there appears to be a thin black stripe along the lateral line.

Differs from the similar M. canarensis, M. dibrugarensis and M. pulcher by having its fontanel split by an epiphyseal bar.

Mystus vittatus (Bloch, 1794)

Junior synonyms: ? Pimelodus tengara Hamilton, 1822

Bloch described the colour and pattern as head, ‘back’ fins, and caudal chestnut brown. Other fins steel coloured. Stripes light blue, with yellow interspaces. The plate of the holotype shows the general shape of the body and fins but the accuracy of its pattern is doubtful. See images of the holotype of M. vittatus: ZMB 2939 that originates from Tranquebar, Tamil Nadu, India.Since its description in 1822 from “Ponds of India”, M. tengara has been discussed as being very similar to or perhaps a junior synonym of M. vittatus. Jayaram & Sanyal (2003) have classed them both as valid but they did not have access to the holotype of M. vittatus and as such they may have been using non type specimens and information from years of wrongly identified specimens which has just added to the confusion. They may have used misidentified specimens of M. carcio as representing M. tengara, and therefore incorrectly distinguishing M. vittatus as distinct from M. tengara.

If one looks at the original drawings of M. tengara (see images) and compares them with the images of the holotype of M. vittatus, you will see that the structure of the fontanel and supraoccipital process are very similar, the only difference being that in the drawing of M. tengara the front portion of the fontanel is thin, the second is wider, whereas this is the opposite in the holotype of M. vittatus. This could be a mistake in the drawing. Everything else from the description of M. tengara appears to fit M. vittatus. If one looks at the images of ANSP 85780 from Bombay [Mumbai], India (which definitely represent M. vittatus in view of the exact same fontanel and supra-occipital morphology when compared to the holotype) you will see that the pattern, and shape of the body, especially relating to the high back and adipose fin matches that of the drawing of M. tengara. The adipose fin on the holotype of M. vittatus has shrunk in size due to its age.

The only possible evidence I have seen so far for classing M. tengara as possibly valid is that of specimen CAS-SU 34858 from Calcutta [Kolkata], India (see images). If you look at the lateral image of this specimen it appears visually very similar to that of ANSP 85780. But if you compare the fontanels of each specimen you will see that the fontanel of the CAS specimen is long and evenly portioned, unlike that of the holotype of M. vittatus and of the ANSP specimen. I feel that for the validity of M. tengara to be properly determined, future ichthyologists need to bear in mind that validity and identity of M. carcio when comparing lots of specimens from different localities. Until then, I feel that M. tengara should be classed as a questionable synonym of M. vittatus. I say questionable because of the possible aforementioned differences, and because M. vittatus comes from southern India, M. tengara possibly representing the Ganges population (but with M. carcio distinct from both).

M. vittatus will reach at least 8 to 9cm SL.
M. vittatus differs from most species (except M. carcio) by the higher number of dark body bands, but can also be differentiated from the most similar species by:
M. atrifasciatus differs due to M. atrifasciatus having less dark lines on the body and having a thinner, non indented fontanel.
M. bleekeri differs due to M. bleekeri’s more elongated body, adipose fin and fontanel.
M. carcio differs due to M. carcio’s distinctly separated fontanel, much smaller adipose fin, and laterally placed eyes.
M. montanus by the distinct shape of the fontanel in M. vittatus.
M. multiradiatus differs due to M. multiradiatus having a humeral semi-ocellus and having the fontanel not as visible.
M. mysticetus differs due to M. mysticetus’s large laterally placed eyes.

Acknowledgements

Thanks to Shobnom Ferdous of Auburn University, USA; Jon Fong of the California Academy of Sciences, California, USA; Mark Sabaj and Kyle Luckenbill of the Academy of Natural Sciences, Philadelphia, USA; Mark McGrouther & Sally Reader, and Mark Allen (formerly) of the Australian Museum, Sydney, Australia; Rémi Ksas of the Muséum National d’Histoire Naturelle, Paris, France; Dr Peter Bartsch of the Institut fuer Systematische Zoologie, Museum fuer Naturkunde der Humboldt-Universitaet zu Berlin, Helmut Wellendorf, Naturhistorisches Museum Wien, Austria for the provision of the images of preserved specimens. Rohan Pethiyagoda for his opinions and information. Anthony Troncale of the American Museum of Natural History, New York, USA for the drawing of M. pelusius. Rahul Kumar for permission to use his images; Kamphol Udomritthiruj of AquariCorp for allowing use of his images and for his opinions; Rohan Pethiyagoda for the image and description of M. ankutta, Allan James for the use of his images and his efforts to post this on ScotCat; Roy Blackburn for the opportunity to photograph his fish.

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