Lets talk about Stingray Identification

[Nic]

they look like the orb. that alex had brought in before.... store by me brought blue motoros in from tfd that looked like them as well

 

[Zoodiver]

I think as of late, ray ID has become harder due to two big things:

1) Hybrids. People are trying to pass of some new hot selling pattern or morph, and we are getting polluted DNA. So it might not really be a particular species.

2) Geographical morphs aren't well documented in some cases. A motoro from one area will look vastly different than a motoro from another. But if one looks close to a second species, it will be labled as that or maybe even a new species instead.

 

[Miles]

I think as of late, ray ID has become harder due to two big things:

1) Hybrids. People are trying to pass of some new hot selling pattern or morph, and we are getting polluted DNA. So it might not really be a particular species.

2) Geographical morphs aren't well documented in some cases. A motoro from one area will look vastly different than a motoro from another. But if one looks close to a second species, it will be labled as that or maybe even a new species instead.

1) I think the polluted DNA is more of a problem with the black rays.. Obviously they are a specific species, and hybridizing them is a bad idea.

2) Would you assume that some geographical morphs are a product of wild hybridization? That is why I would be less concerned with selectively breeding the P. sp. Peru morphs, as it seems like it's a regular occurance anyways..

 

[Itaituba2003]

Some motoros in the picture an the one on the right is a P.Schroederie P40.
Regards
Frank

 

[Zoodiver]

Miles, I agree on both. We know for a fact that these rays will mix in the wild.
It's the strongest point those who think all potamotrygon spp should be listed as one, with them all just being morphs. I'm not of that group. I think there are very key differences between the main species.

 

[Miles]

So.. let's compile a species list..

P. sp. Motoro
P. sp. Castexi
P. sp. Reticulata
P. sp. Hystrix
P. sp. Scobina
P. sp. Orbignyi
P. sp. Humerosa
P. sp. Schroederi
P. sp. Falkneri
P. sp. Leopoldi
P. sp. Henleii


Now there is quite a bit more.. please add to the list.

Variants would fall under each species category..
Nazca, Mantilla, Chainlink, Marbled, Peru Motoros....
Otorongo, Motello, Star, Hawaiian Castexi..
P14, Eclipse, Black Isle Leopoldi..

Let's here arguments now..

 

[amazongirl]

Miles, I agree on both. We know for a fact that these rays will mix in the wild.
.

This is not true. It 2 rays never coexist in the wild they will not interbreed- they don't have the chance. Some of these species have very limited ranges and they do not occur together- this is the case with leopoldi and henlei- they occur in different rivers in the Amazon river system.

If you think about it, these stingrays may not be very 'old' on the evolutionary time scale. Perhaps we are glimpsing that moment in time when species are starting to develop and a lot of the variation that we see is based on geographical variation rather than adaptation to different niches.

Think about the variation that you see in motoro for example. This is a very wide ranging (goegraphically) species that also exhibits a lot of polymorphism (members of this species can look very different, lots of variety). Yet if you look at the species within a small portion of their range in the wild they look much more similiar. A motoro from Peru of Columbia closer to the headwaters of the Amazon is not breeding with a motoro from Brazil much farther down, at least no scientific evidence that I am aware of documents large migrations of members of this family. This to me is a classic example of a ring species.

One more thing to note when it comes to captive breeding, and I'm going to borrow an example from the herp world. Many dart frogs also exhibit a lot of variation in appearance across it's range. A good example of this is Dendrobates tinctorius. Look it up on the web- this species has a ton of different color morphs all found in different localities. That said, when most people try to propogate this species in captivity, especially places like zoos, they keep the different morphs seperate and wouldn't dream of interbreeding them. They also will interbreed with other species in a captive environment.

Animals that never see each other in the wild will often interbreed in a captive environment. There may be no evolutionary advantage to recognizining members of your species as being different from others if you never/rarely encounter that other species in the wild. The small amount of hybrids that do naturally occur may be mostly ellimiated because they are less vigorous and do not survive often to reproduce, of maybe there is the occasionaly small amount of intermingling of DNA between 2 species. Maybe they have different times of year that they breed so do not for the most part interbreed in the wild but in our home aquariums we give them cues for both species at once so they interbreed. The possibilities are almost endless. That is part of why this is so much fun- there is still so much to learn.

 

[rayman]

Hi Miles,

your list is not ok because these are all true species. The sp. stands for rays that may be a undescribed species. So my try, all valid species according to Rosa 1985:

Paratrygon aiereba

Plesiotrygon iwamae

Potamotrygon brachyura
Potamotrygon castexi
Potamotrygon constellata
Potamotrygon dumerilii
Potamotrygon falkneri
Potamotrygon henlei
Potamotrygon histrix
Potamotrygon humerosa
Potamotrygon leopoldi
Potamotrygon magdalenae
Potamotrygon motoro
Potamotrygon ocellata
Potamotrygon orbignyi
Potamotrygon schroederi
Potamotrygon schuemacheri
Potamotrygon scobina
Potamotrygon signata
Potamotrygon yepezi

Potamotrygon sp. A (similar coloration to motoro, differs in dentition and some other morphometrics, from Amazonas Peru/Brazil)

Potamotrygon sp. B (ocelli similar to motoro and ocellata but very dark background coloration (nearly black), smaller teeth than motoro and higher number of pectoral fin radials than motoro and ocellata, from Corantijn river drainage Surinam)

Since Rosas work something has changed, there was a new description in 2006:
http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=16797454&dopt=Citation

Potamotrygon marinae


And in fishbase you find this:
"Therefore, the approach adopted here has been to not recognize certain species that are inadequately defined at present, or that lack adequate material for proper characterization (e.g. Potamotrygon dumerilii,Potamotrygon humerosa)"
http://www.fishbase.org/Summary/FamilySummary.cfm?ID=21


Then we have some rays we know very well because we keep them in our tanks. But if they belong to the above species or they are undescribed species is questionable, these are the P. sp., I add in parenthesis some possible species these rays may belong to:

Plesiotrygon sp. blacktailed
Potamotrygon sp. tiger (menchacai (Aqualog), falkneri (Rosa), schroederi?)
Potamotrygon sp. reticulata (magdalenae?, orbignyi (Rosa))
Potamotrygon sp. pearl
Potamotrygon sp. itaituba/P14 (Potamotrygon cf. leopoldi)
Potamotrygon sp. mantilla
Potamotrygon sp. peru
Potamotrygon cf. histrix (the histrix from Rio Negro, Potamotrygon sp. C)

Potamotrygonidae sp. china (China ray)

There are some more sp. in new scientific work, but without pictures these names will not help here because these rays are not kept in aquaria.

 

[rayman]

It 2 rays never coexist in the wild they will not interbreed- they don't have the chance. Some of these species have very limited ranges and they do not occur together- this is the case with leopoldi and henlei- they occur in different rivers in the Amazon river system.

That's true. But we do not know what happens at flood, maybe there is a way for leopoldi and henlei to meet. A rumor is that the nice Sao Felix leopoldi could be hybrids. I don't know if this is possible, but some captive breed leopoldi x henlei hybrids look very similar to Sao felix leopoldi.

Another source for strange hybrids is to release captured rays in the false river system. I was told that in Peru were pearl rays released. And some exporter in Brazil who hoped that the ban could be lifted soon did release now all the leos, henlei and whatever they had collected in the next river, and that is not Xingu or Tocantins ...

 

[Miles]

That's true. But we do not know what happens at flood, maybe there is a way for leopoldi and henlei to meet. A rumor is that the nice Sao Felix leopoldi could be hybrids. I don't know if this is possible, but some captive breed leopoldi x henlei hybrids look very similar to Sao felix leopoldi.

Another source for strange hybrids is to release captured rays in the false river system. I was told that in Peru were pearl rays released. And some exporter in Brazil who hoped that the ban could be lifted soon did release now all the leos, henlei and whatever they had collected in the next river, and that is not Xingu or Tocantins ...

I was going to say..

When the Amazon floods, the possibility of rays migrating into different tributaries is very possible. This is how some of those 'rare' wild hybrids or undescribed species could be forming, such as the Mantilla motoro we sometimes see.. or that thread a while back where a Leo/Pearl cross made some offspring, looking nothing like the parents while other litter mates were distingiushed as black rays.


Rayman, thanks for the confusion and clearing up the list..

However, some of the species I have never heard of as their own individual.. Signata for example. I have this only in my asian ray book, it looks very similiar to some other species..

I am assuming tail structure, eye placement, and a number of other physical characteristics play the primary part in SPECIES identification, while pattern style is just a guessing game for morphs within the species.