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Hi all; a long time

A new question about this fish



















This is captured in Orinico, betwen Puerto Ayacucho and San Fernando Atabapo

I'm no expert, but surely that's no Chaetostoma, but an Ancistrus.

Maybe ?

[Mod edit: Use clog-tags --Mats]

I'm no expert on Chaetostoma, but yes, I'm convinced that is some for of Ancistrus.

As to which Ancistrus, I couldn't say for sure.
this is a link to the search results of Rio Orinoco basic Ancsitrus.

--
Mats

Mike_Noren wrote:I'm no expert, but surely that's no Chaetostoma, but an Ancistrus.

Maybe Ancistrus macropthalmus?

Quite possibly. The eye on the first photo looks very large in proportion to the head. It also has a very broad head in proportion to SL, as in the A. macrophthalmus type:

http://acsi.acnatsci.org/base/getthumbn ... get=136308

Although the original description has this to say about colour/ pattern (from French): "The overall color is uniformly brown, the underside of
the head and belly are white."

The type is 8cm SL.

The.Dark.One wrote:

Mike_Noren wrote:Although the original description has this to say about colour/ pattern (from French): "The overall color is uniformly brown, the underside of the head and belly are white."

Is that explicitly said to be live coloration? Older descriptions often just described the color of the fish in alcohol.

Mike_Noren wrote: Is that explicitly said to be live coloration? Older descriptions often just described the color of the fish in alcohol.

Hi Mike

No, it doesn't say live so I think it will be in alcohol. However, I would have thought that some spotting would have showed up if the background colour had been retained? Unless only juveniles are spotted?

The.Dark.One wrote:I would have thought that some spotting would have showed up if the background colour had been retained?

The spots are pretty small, but I would think they'd be visible if the fish was well preserved. If on the other hand it was two days dead before being put in formalin, or had spent a year in a jar exposed to light before Pellegrin looked at it, or... Well, you get the picture.

However, I should say that I arrived at macrophthalmus by negative identification: it's the one species recorded from Orinoco I could not exclude, because I don't know what it looks like, so it's a very weak ID.

I'm trying to source the ACSI images to include in the Cat-eLog - and if we can determine that these images are indeed A. macrophthalmus, they should go in the Cat-eLog as well.

--
Mats

A. macrophthalmus ARE spotted (I think there is a picture of a live fish in Ingo Seidel's Catfish Atlas).

Pictures (and a breeding record) can also be found here (in German):
http://www.thomas-pritzkow.de/Fachbeitrag/LDA%2074.html
But I am not entirely sure whether the ID is correct.

When it comes to coloration first descriptions are not alsways very reliable as conservation was not always done very well and sometimes quite a lot of time elapsed between collection and description.

Based on coloration and body shape the only other alternative I arrived at is L255, but their distribution is way off.

Thanks all;

Is very similar to the picture the link of sunfish

A. macrophthalmus is very probable.

Thanks all.

PD. Sorry for my bad English

Mike_Noren wrote:I'm no expert, but surely that's no Chaetostoma, but an Ancistrus.

Maybe

Ancistrus macropthalmus

?

[Mod edit: Use clog-tags --Mats]

The link doesn't work as i think there is a spelling error? macrophthalmus

Spelling error now fixed in the original post, but not in the quote. Thanks Richard for pointing that out.

--
Mats

sunfish wrote:A. macrophthalmus ARE spotted (I think there is a picture of a live fish in Ingo Seidel's Catfish Atlas).
.

You're assuming that the ID in the book is correct. Even the scientists let alone the top hobbyists get things wrong from time to time. We are all human after all!

Sunfish raises a good point. I can't read French, and the description is old enough that it might not even mention it, but if the description is based off of preserved coloration, and this fish was preserved for a long time, or simply preserved poorly, than it could lose its live coloration. Even if properly preserved, very small, light spots typically disappear (apparently melanophores dilate because of preservation). For example, Pseudancistrus nigrescens has many tiny light spots in life, but I have seen over 60 specimens and not one of them shows these spots. Hypancistrus lunaorum also may lose its spots in preservation. A. macrophthalmus looks like it has small enough spots that this could happen.

This is not to say that the pictured fish is definitely A. macrophthalmus, but it seems plausible that a spotted fish such as this might become uniform with a pale belly in preservation.

Certainly, the body shape of the preserved fish in ACSI matches. That is certainly a good start.

--
Mats

Suckermouth wrote:Sunfish raises a good point. I can't read French, and the description is old enough that it might not even mention it, but if the description is based off of preserved coloration, and this fish was preserved for a long time, or simply preserved poorly, than it could lose its live coloration. Even if properly preserved, very small, light spots typically disappear (apparently melanophores dilate because of preservation). For example, Pseudancistrus nigrescens has many tiny light spots in life, but I have seen over 60 specimens and not one of them shows these spots. Hypancistrus lunaorum also may lose its spots in preservation. A. macrophthalmus looks like it has small enough spots that this could happen.

This is not to say that the pictured fish is definitely A. macrophthalmus, but it seems plausible that a spotted fish such as this might become uniform with a pale belly in preservation.

I agree with the point made by sunfish and yourself, in fact I also think it probably is A. macrophthalmus based on locality, body shape/proportions, eye size. But to say A. macrophthalmus "ARE" spotted, I'm not sure I can be so certain.

I'm not certain on this but it appears the type was collected in 1887. It was described in 1912. If so, 25 years preserved before description. Adequate time for spots to disappear then.

I am at work so do not have any fish books handy, but this is a very commonly exported fish from Puerto Ayacucho. I would be quite suprised to find it is not already assigned an L Number. If you look at almost any picture of collections taken in that area of the Orinoco, there are always several of these present. I am sure I have photos of them saved to a CD somewhere taken in Colombia.
As to if it is actually A. macrophthalmus I can not say. I agree that the general proportions are a good match, but that does not in itself make a proper identification.
-Shane

Hi Shane; How Are you?

This fish will can say A. cf macrophtalmus?

Estoy bien gracias.

This fish will can say A. cf macrophtalmus?

I think that would be a fairly safe name to go with.

-Shane

Thanks Shane; and thanks all

Me alegra que este todo bien por alla.