Ornatum or Gephyrum

[DRE]

I remember the fun thread we had years back regarding some gephyrum. I manage to get those identified as gephyrum together with Sven Kullander when we compared with conserved speciments at Naturhistoriska riksmuseet in Stockholm. My Gephyrum:
https://www.ciklid.org/artregister/art.php?ID=1468

Since then I have come a across another set of speciments, but thistime from Rio Cajambre (so he said...) and they look slightly different to me. These are much more yellow on their upper halv of their flanks.
Does the links work?
https://www.dropbox.com/s/jgdfhjmf0yab3 ... 0.JPG?dl=0
https://www.dropbox.com/s/f48lmp2v5j54j ... 1.JPG?dl=0


What do you think, are they both gephyrum or could it be that I got ornatum this time?

[Mark Smith]

I think they may be the same species. The C. gephyrum looks larger than the other two with more yellow.

It is also good to know that Kullander has confirmed that the one in the first image is actually C. gephyrum. The only image I am aware of that might possibly be a live C. ornatum is from Willem Heijn's. There is a photo by him on this site, and I think it is of a sub-adult.

I am aware of various wholesalers giving differing collecting locality data to suggest that what they are now selling is the true C. ornatum, such as on Jeff Rapps Tangled Up in Cichlids site. However, they are still the same C. gephyrum, and I cannot tell yet if it is Mr. Rapps that is saying this organically, or the collectors themselves, in an attempt to market and sell more fish.

[DRE]

I too doubt that there is anything else than gephyrum on the market.

[DRE]

Do you have a link to Heijn's ornatum?

[Mark Smith]

http://www.cichlidae.com/species.php?id=928

I think the yellowish ones you posted are just from another river system?

[blackghost]

I thought gephyrum wasn't valid yet? Is Dr Sven working on this?

[DRE]

Why would it not be valid? It has been described long time ago as far as I understand.

[DRE]

http://www.cichlidae.com/species.php?id=928

I think the yellowish ones you posted are just from another river system?

Yes maybe, for me the differences are very small.

[Rico Morgenstern]

Provided the locality Rio Cajambre is correct, these fish are of particular interest because this river is located between the known ranges of Mesoheros ornatus and M. gephyrus. Which would not exactly facilitate their determination.

[DRE]

Provided the locality Rio Cajambre is correct, these fish are of particular interest because this river is located between the known ranges of Mesoheros ornatus and M. gephyrus. Which would not exactly facilitate their determination.

Haha, typical. Since I kept the gephyrum from Rio San Juan I rather soon saw that these are much more yellow, hard to see on the photos though. The photos I have of gephyrum had flash towards the fish while for the Cajambre the flash is from above. This is why I perhaps thought they could be ornatum?

I think location is to 90% certainty correct. I spoke with the collectors, but the risk is perhaps that they want to hide the exact location?

[Bas Pels]

Do I understand correctly that these fish, collected in the area where gephyrum is replaced by ornatum, look a bit like ornatum?

In many cases this is an argument for considering the two groups as conspecific. I know nothing about these, but still

[DRE]

What do you mean by area where gephyrum is replaced by ornatum? I guess the location is "between" the type localities at least.

[Bas Pels]

I mean, if you go from the ornatum type locality to the gephyrum one, there will be a place where you will not find ornatum anymore. Either there is no fish to fill in the ecological nice, or there will be another species, most likely gephyrum. This is what I meant with replacing. However, not knowing the localities, festae could be between them.

Generally speaking, animals living close to where one finds another species (which replaces them) do not resemble the other species. Lions from Asia are not striped as tigers are, for instance.

If the areas of ornatum and gephyrum touch, and the fish in the middle resembles both ornatum and gephyrum, this is generally considered as an argument for considering them as 1 species.

Most likely the resembling bodies will also have resembling DNA

[fevelasco]

Perhaps it's the different lighting used in the photographs, but the base color of the specimen photographed by Willem Heijns looks different from David's. However, in the same CRC species profile of ornatum are photos of two other fish from Seiichi Hamada. These were the specimens that attracted a lot of attention from cichlid hobbyists in 2009. David's male from Rio Cajambre bears a strong resemblance to Seiichi's male.

David's male

Seiichi's male

[fevelasco]

For comparison, here is a photo of my male Mesoheros gephyrum (Rio San Juan) when he was about 5 to 6 inches long. (I'm guessing he was a little more mature than David's male at the time I took the photograph.)

It might be possible to get a better idea of the coloration from this video of the group.

https://youtu.be/0YbR61ECW6Y

While perhaps not as much yellow in the base coloration as the ones from Rio Cajambre, the difference is very subtle and may be age-related. My impression is that this is likely the same species as gephyrum.

[DRE]

Perhaps it's the different lighting used in the photographs, but the base color of the specimen photographed by Willem Heijns looks different from David's. However, in the same CRC species profile of ornatum are photos of two other fish from Seiichi Hamada. These were the specimens that attracted a lot of attention from cichlid hobbyists in 2009. David's male from Rio Cajambre bears a strong resemblance to Seiichi's male.

David's male

David Rejdemhyr Mesoheros gephyrum or ornatum, Rio Cajambre.jpg

Seiichi's male

Seiichi Hamada Mesoheros ornatum Feb. 2009.jpg

Yes. Too be honest I don't see a difference between mine and Seichiis.

I also got these photos from Reff Rapps, fish caught in Rio Patia, even further south.
https://www.ciklid.org/artregister/art.php?ID=1470

Map: https://upload.wikimedia.org/wikipedia/ ... Dos%29.svg

[DRE]

For comparison, here is a photo of my male Mesoheros gephyrum (Rio San Juan) when he was about 5 to 6 inches long. (I'm guessing he was a little more mature than David's male at the time I took the photograph.)

exCichlasoma gephyrum male.jpg

It might be possible to get a better idea of the coloration from this video of the group.

https://youtu.be/0YbR61ECW6Y

While perhaps not as much yellow in the base coloration as the ones from Rio Cajambre, the difference is very subtle and may be age-related. My impression is that this is likely the same species as gephyrum.

This one looks very similar to mine from Rio San Juan:
https://www.ciklid.org/artregister/art.php?ID=1468

[Mark Smith]

What would be splendid is if some enterprising ichthyologist(s) would traverse and collect all Mesoheros from this general region of South America, collect in all river systems, compare and contrast what is caught with the original descriptions, and hopefully uncover what is truly going on with this interesting, almost Central American-like group of cichlids. Until then, small pieces of this interesting puzzle may only trickle out over the course of many years, if not decades.

[Rico Morgenstern]

Yes of course, Mark. Nevertheless the the genus Mesoheros might be regarded as fairly well known compared to other cichlid genera of the region. Andinocara is still a big problem; and nobody knows how many species the Caquetaia umbrifera complex contains, not to mention the enigmatic 'Cichlasoma' microlepis.

The question remains whether there are consistent differences between M. ornatus and M. gephyrus. The original description (Eigenmann 1922) of the latter is not overly convincing in this respect, especially since it is reported to be a quite variable form showing considerable overlap with M. ornatus. Consequently, he regarded gephyrus only as a subspecies. Indeed, Eigenmann took the possibility into account that the holotype was a hybrid between M. atromaculatus (which occurs sympatrically in the Rio San Juan drainage) and M. ornatus. At one stage I thought that the interuption of bars above the lateral line could be a distinguishing character, but there are intermediate specimens, and if the fishes of Jeff Rapps are really from Rio Patia (from where only M. ornatus is reported; Eigenmanns specimens of ornatus where all from that drainage), then this distinction would anyway not hold. Of course we have yet to see life M. ornatus from the type locality (Rio Durango) in the Rio Santiago drainage of northwestern Ecuador.

I mean, if you go from the ornatum type locality to the gephyrum one, there will be a place where you will not find ornatum anymore. Either there is no fish to fill in the ecological nice, or there will be another species, most likely gephyrum. This is what I meant with replacing. However, not knowing the localities, festae could be between them.

The species of that genus do not occur strictly allopatric, since both M. atromaculatus and M. gephyrus are found in the Rio San Juan drainage. However, it is very unlikely that M. festae occurs in the area between M. ornatus and M. gephyrus, because that species is only recorded from the Rio Esmeraldas system (where it seems to be quite rare) in Ecuador southward to Rio Tumbes in Peru, i.e. the range would be south of that of M. ornatus.

[Mark Smith]

Great points to consider, Rico. Hopefully, more sense will come out of this area soon.