Pyxicephalus Differences

[tgampper]

Here is the link to the African Amphibian Conservation Research Group:

AACRG

[Malachi]

Perhaps mine isn't the "true" Edulis because he is defiantly round bodied like the pictures ive seen.
His legs are pretty small too, the Edulis in the book picture has American Bullfrogish legs

[onedge30]

Ok, my head hurts. And I am most likely too dense to understand all this, so help me out. These are the emails from a conversation. I will try to post all the links that match.


Dear Jeff,
You are correct - identification and species boundaries in Pyxicephalus are confused and are currently subject to research by several groups (although in general the biology of this group is well studied). There is no question that P. adspersus and P. edulis are different species, however, immatures and smaller individuals can be very difficult to identify. Also, it is likely that multiple species are hiding under each of these names, occurring in different parts of Africa, contributing geographic variation to the difficulties of identification. In general, in southern Africa, P. edulis occurs in the lower lying coastal and river valley savanna, with P. adspersus in the high-lying (>1000m asl) grasslands, inland savanna and semi-arid areas.

I suggest that you find a copy of:

DuPreez L & Carruthers V (2009) A complete guide to the frogs of Southern Africa. Struik-random House, Cape Town ISBN: 978-1-77007-446

for the latest overview (P. edulis & P. adspersus).

Also another great site for the sort of information you might need is AmphibiaWeb
http://www.amphibiaweb.org/index.html

for the link to Pyxicephalus see...


http://www.amphibiaweb.org/cgi-bin/a...re-submittedby

this extracts information from authoritative books.


regards,
michael

Dr Michael Cunningham
University of the Free State, Qwaqwa
Private Bag X13, Phuthaditjhaba 9866, SOUTH AFRICA
phone: +27-(0)58 718 5327, fax: +27-(0)58 718 5444

My comments back:

Michael,

Thanks for the heads up. Yes, the variation of the species populations across Africa could be a real problem in identification. And babies and juveniles are a nightmare to look for specific traits. Traits which may not be there yet or may be there but will fade to adulthood. Tough call.

Great info on the geographic location. I will make note of that. Any thoughts on P. obbianus?

Your last link leading to CalPhotos even shows some of the problems occurring with identification. In the first link, this photo is neither adspersus or edulis?
http://calphotos.berkeley.edu/cgi/im...1111+1111+1200

And in this second link, the photo on the left is very different from the photo on the right. What I am finding is the photo on the left is what is called edulis in the states, and the photo on the right is what is called edulis in Africa. What a mess.
http://calphotos.berkeley.edu/cgi/im...el-lifeform=ne

Thank you for your time.

Sincerely,

Jeff

Comments back: That I guess I don't see that they can be the same.

Hi Jeff,
At least in Southern Africa it isn't so hard to separate the two species - including the juveniles.

DuPreez & Carruthers give the following characters...
edulis usually has a white mark on the tympanum which is absent in adspersus
edulis has a pale interorbital bar (with pale transverse marks on the dorsal eyelid) which is absent in adspersus
edulis has the tympanum about 1 eye-width from the eye, in adspersus it is closer to twice this distance
edulis has irregular pale vertical bars on the upper lip which are absent from adspersus

in addition adspersus tend to have the orange axillary marks and mouth and elongate white marks along the dorsal skin folds

On all these characters the photos from CalAcad check out pretty well - I don't see that the edulis photos are necessarily from different species...it looks more like different individuals being photographed under different conditions and all correctly IDed.

P. adspersus is the type species of the genus (which is type genus of the family).

The type locality for P. adspersus is Cape Town (Cape of Good Hope) - which is actually ~400km SW of their distributional limit - meaning that this is where they were shipped or where the collectors were based (as were all collectors in Southern Africa of that period). At the time of description (1838) a few collectors had just reached as far as the Tropic of Capricorn but it is likely that this particular collection was made around Port Elizabeth on the South Coast.

The type locality for P. edulis is Tete on the Zambezi R in NW Mozambique.

These are the populations that must define the names and they are consistent with the above differences. The captive populations could be from anywhere and so their IDs may be dubious. I notice that one of the photos is referenced to Central South America - which is in error.

P. obbianus is an obscure taxon from Somalia - I've never read the literature on it and don't really know how it would compare.

The real problem is to discover whether P. anchietae from Mozambique near the Zambezi mouth is a valid species different from P. edulis and whether the species from Southern Africa are the same as those from North and West African savannas that are assigned to the same names.



End: Please let me know if there are any clarifying question you all would like me to send back.

[tgampper]

Hi Jeff:

Thanks for all your hard work. I do have a copy of du Preez and Carruthers book that was mentioned in your last post. Other than clearing up the obbianus situation, I think we have all the info we need to put the guide together.

I was interested in Dr. Cunningham's explanation that its not too difficult to tell the difference between the species, so why all of this discussion

I wonder if these "unknown" species are obbianus or some new species making its way into the pet trade? I know obbianus has a small range and only found in Somalia, but evidently has a stable population.

[Malachi]

Possible that edulis in South Africa look different than the "Tanzanian" edulis?

Angola, Botswana, Kenya, Malawi, Mozambique, Namibia, Swaziland, Tanzania, Zambia, Zimbabwe, and Democratic Republic of the Congo.

How well are these frogs documented in the countries above? I am sure people in those countries would love to sell frogs to us under any name

So in south Africa there are two easy to distinguish frogs, but now pyxies from other regions are being sold either as the giant or dwarf.

[tgampper]

Possible that edulis in South Africa look different than the "Tanzanian" edulis?

It is quite possible that there are color morphs among different population groups, so what may be distinctively different in South Africa are more similar elsewhere.

Angola, Botswana, Kenya, Malawi, Mozambique, Namibia, Swaziland, Tanzania, Zambia, Zimbabwe, and Democratic Republic of the Congo. How well are these frogs documented in the countries above? I am sure people in those countries would love to sell frogs to us under any name

I think for the most part, the genus Pyxicepahalus is well documented, especially adspersus and edulis (obbianus is another story). P. edulis has two discontinuous ranges: the eastern range overlaps that of adspersus and its western range is also discontinuous: Nigeria, Senegal and Mauritania. I really like the picture of P. edulis in Roedel's book, looks a lot different than in other books.

So in south Africa there are two easy to distinguish frogs, but now pyxies from other regions are being sold either as the giant or dwarf.

Roedel, du Preez, Channing, and Carruthers has done a great job in describing the species, however, the name "pyxie" refers to frogs in the genera Pyxicepahalus and Tomopterna. Here in the U.S., we often refer to adspersus as a "pyxie". Popular names often lead to confusion.

[Malachi]

An adspersus looks like adspersus.

An edulis can look a lot different from edulis.

This is what is weird/confusing, not just color but shape it seems too.

And then you have the frogs that seem to be a mix

It would be nice to be able to match all the edulis morphs to the region they are from.

[Malachi]

kingsnake.com Classifieds: BRILLIANT PIXIE FROG!

another edulis being sold as a giant

[tgampper]

kingsnake.com Classifieds: BRILLIANT PIXIE FROG!

another edulis being sold as a giant

Sad, very sad

[tgampper]

I have uploaded the rough draft of the African Bullfrog Identification Guide on my personal website. I would appreciate any comments or input you may have. There are a few things that still need to be completed. Since we had access to many photos, I thought I would do the guide in a photo essay style. Please PM me if you have any thing you would like contribute. The link is:

http://xenopus.freeshell.org/abig1.doc