G. ctenocephalus

[Jim Powers]

Very interesting, Martin. That is the first time I have heard anyone, outside of the aquarium hobby, mention the distinct blue caudal. That is something that always troubled me about the original species descriptions I have read. Another characteristic missing in the descriptions is the prominant barbels that are larger and more visible on the above pictured fish, than on any of the other species we have seen in the hobby. It is this kind of thing that makes the original descriptions somewhat ambiguous.

If this fish has been extensively wrongly indentified, it wouldn't be the first time. Remember that Linaparhomaloptera disparis was pictured as Homaloptera zollengeri for many years. In fact, it still is in one of the more popular fish identification books on the market.

[Martin Thoene]

More.......

http://www.petfrd.com/forum/showthread. ... ge=1&pp=15

Martin.

[Jim Powers]

Interesting...but why does this differ from the original species descriptions?

[Martin Thoene]

The whole thing is in a pickle Jim...which might be half the problem.....



Martin.

[Jim Powers]

All those pickled hillstreams make me sad

[Hendra]

Big possibly the preserved fishes in pic above (Martin’s post) is G. sp “SK01” which I send to Heok Hui (Betta and Borneo sucker (Balitoridae) expert). Sorry Jim if that made you sad, but that is the procedure for Ichthyology contribution, meanwhile scientist or anyone mustbe can not count or observe the details of the fish in live condition.

But there is one thing which maybe made you more sad. The stream where I found them is in very bad condition now because uncontroled logging and steel and gold mining near the stream.

Here pic of the stream.



Several years ago it’s a beautiful clearwater stream, you can see some Gastromyzon move slowly scrapping algae on surface of rocks, schooling of Paracrossocheilus vitatus in big number, also fastswimming Rasbora spp. But now the water is very cloudy, many sedimentation from drain soil covered the surface of rocks, so you must be thinking how fishes especially Gastromyzon can survive in this condition.

[Mark in Vancouver]

Alas, I think this is the fate of many - if not most - streams in Borneo.

[Jim Powers]

That is, indeed, very sad. Its hard to imagine gastromyzons surviving long in that type of water.

[Hendra]

From “Freshwaterfishes of western Indonesia and Sulawesi” by Maurice Kottelat et.al


Gastromyzon ctenochephalus
SL (Standard Length) 45 (mm)
Distinguished from all other Gastromyzon by having only 8-12 papillae on lower lip; gill opening strongly angular, ctenoid tubercles on head and pectoral base of mature males.
Distribution: Borneo W.
Roberts (1982a) p.505



Gastromyzon punctulatus
SL 54
Snout relatively truncate when seen from above (in large specimens only); dorsal surface of the head and body with relatively large, round, pale spots, a transverse row of papillae posterior to lower lip
Distribution: Borneo W
Inger and Chin (1961) p.173; Roberts (1982a) p.515

[Tony T.]

Inger and Chin (1961); Roberts (1982a)
Maybe someone can get these ODs and check with descriptions and figures [if there are ones] and compare with the fish avaliable now?

[Martin Thoene]

Tony T, those probably are the fish you sent Heok Hui. The pic was taken at Raffles.

I've been exchanging mails with Dr Tan in the past few days. What a pleasant gentleman! He has two new papers coming out soon with descriptions of new species and a monograph is currently under work before publishing hopefully later this year. It relates descriptions of new and existing species to pictures of live fish, so that finally there is a correlation between live specimens and preserved material.

Set to become the definitive Gastromyzon ID literature .

Martin.

[Tony T.]

I do not know Heok Hui in person or send anything

[Tony T.]

Martin: wondering who is Tony T. you mentioned sending fishes to Heuk Hui?

I had received copy of Inger & Chin [OD for G. punctulatus] from Hendra, and after browsing through it was stated that G. borneensis has dark spots while G. punctulatus has light spots.

[Hendra]

Thats the problem, since C. ctenocephalus also have light spots. Really need to see the live specimens of G. punctulatus. But from pic of preserved specimen of C. punctulatus, they quite different at head shape and pattern of the caudal fin. I guess (if there is pic of live fish) G. punctulatus will easily separate with G. ctenochepalus.

[Tony T.]

Is the pic of preserved G. puntulatus ones that was ID as such by Inger and Chin or used as types? If not we need to be careful. Anyway from Inger and Chin [OD] we know that G. puntulatus has light-color spots and not dark-color spots.

The irridescent coloration in general won't stay that way in preservation. In the case of Barilius cyprinid often the blue bars stay dark in preservation, but often the bars simply fade or disappear. If such coloration cover other patterns in life, its disappearance may reveal the pattern under it.

In one thread below I had said that head shape, fin size/shape and some other difference in body parts and shape can be sex-related. Also the variation within population need to be taken into account too, since it is unlikely that all fish in the same population would be of the exact same shape and size. It took a very long time for ichthyologists to confirm that 2 different looking Barilius is actually male and female of the same species, B. bendelisis.