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What do Gymnotiformes have in common with Siluriformes? Which authors include them in Siluriformes and why?

And what is the relationship, if any, between New World knifefishes (Gymnotiformes) and Old World knifefishes (Osteoglossiformes)?

Dinyar

Hi Dinyar,

im sure Heok Hee can give you a more detailed answer ;), but for starters:
Gymnotiformes are like Characiformes (Tetras), Cypriniformes (Carps, Barbs and loaches) and Siluriformes Ostariophysi, they share a common ancestor. The members of the superorder Ostariophyshi have the weberian apparatus in common.
Old world knifefishes, they are like you already mentioned Osteoglossiformes, are not Ostariophysi and have except for being Teleostei nothing in common with the Gymnotiformes.

Achim

What do Gymnotiformes have in common with Siluriformes?

The gymnotiforms are the sister group of catfishes within the Ostariophysi (forming what is called the Siluriphysi; the characiforms and cyprinids each form the Characiphysi and Cypriniphysi respectively). The Cypriniphysi, Characiphysi and Siluriphysi in turn form a group within the Ostariophysi known as the Otophysi (the other ostariophysan group is the Anotophysi, which includes the Chanidae, Gonorynchidae, Phractolaemidae and Kneriidae as its only living members). Relationships within the Otophysi are (((Siluriformes, Gymnotiformes), Characiformes), Cypriniformes).

As Achim mentioned, Old World notopteroids are not related to gymnotiforms. All they share is a knife-like morphology of the body.

Thank you, gentlemen. I guess I failed to explain my question clearly.

I gather that some scholars (eg, husband and wife team whose name I forget) class Gymnotiformes within Siluriformes. Why? Or put another way, is the Siluriformes / Gymnotiformes relationship closer than the relationship of Siluriformes to Characiformes and Cypriniformes, and if so, why?

The second part of my question, why do knifefishes (presumed to be one set since they have one common name) belong in two different orders (divisions, even) was in retrospect a stupid and self-contradictory question. If they belong in different divisions, obviously they wouldn't have a whole lot in common. Somehow it seemed to me that if they were all called "knifefishes", they should have more in common than just being knife shaped.

Can you think of any other examples of fishes that share a common name but are phylogenetically far apart?

Dinyar

Dinyar wrote:Can you think of any other examples of fishes that share a common name but are phylogenetically far apart?

Dinyar,

Wolf fish (i.e. the nasty Atlantic dwelling fish and the nasty Amazon dwelling fish <I>Hoplias</I>) was the first to spring to mind but then butterfly fish, angel fish to name a few if you went looking I guess. Hmm, pattern emerges... What about silver fish? Now that's not even a fish!

I'm sure this is leading somewhere and I'm sure we're all dying to find out...

Jools

husband and wife team whose name I forget

Are you referring to Bill and Sara Fink? Bill is my advisor and Sara I meet now and then when we have social functions.
I am very cetrtain that Bill and Sara did not state that the Gymnotiformes lie within the Siluriformes, however, they did show that the Siluriformes and Gymnotiformes are sister groups (the Siluriphysi). There is a fair body of evidence for this relationship, including, interestingly, the electrosensory system.

As for wolf fish (Anarhichas lupus, isn't it also called a catfish?

Yup, Anarhichas lupus is often called catfish. If you look up "catfish" in a norwegian - english dictionary, you will probably find it translated to "steinbit", which is the norwegian word for this fish. A local shop that imports food from the far east had some hermetic catfish. Due to norwegian law, all kinds of edibles are required to have a declaration of what it contains, in norwegian, so the shop had translated "catfish" to "steinbit" on the can. The "strange" thing is that this hermetic was imported from Thailand, and "steinbit" only lives around here (northern europe).

Probably my first contribution in this forum