Reference for the loss of hypertrophied lips

[Adrian Indermaur]

Hy everyone,

I'm currently looking for a good scientific reference for the fact that A. labiatus loses its thick lips over time once in captivity.
Does this actually corespond with the findings you guys have made over the years ?
So far I "only" have the pers. comment from Loiselle
(Loiselle, Paul V.. (November 07, 1998). "The Amphilophus labiatus Species Complex". The Cichlid Room Companion. Retrieved on June 05, 2012, from: http://www.cichlidae.com/article.php?id=106.)
on this subject.
If any of you know good work or articles dealing with that matter, I`d be very happy for a hint.


Greets Adrian

[Rico Morgenstern]

The following 'classical' works are certainly of interest:

Villa, J. (1976): "Systematic Status of the Cichlid Fishes Cichlasoma dorsatum, C. granadense and C. nigritum Meek"

http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1025&context=ichthynicar

Barlow, G. W. (1976): "The Midas Cichlid in Nicaragua"

http://digitalcommons.unl.edu/ichthynicar/23

Balow, G. W. & J. W. Munsey (1976): "The Red Devil-Midas-Arrow Cichlid Species Complex in Nicaragua"

http://digitalcommons.unl.edu/ichthynicar/24

Please note that the nomenclature is somewhat outdated, particularly with respect to the numerous species recently described from Lakes Xiloa and Apoyo, of which only a single one was recognized then.

[Adrian Indermaur]

Hy Rico,

thanks a lot for the links, I didn't know the work by Villa so far.
I am really surpised there is no more recent work on such an intersting trait.

Well, there will be...

Thanks again

Adrian

[RD.]

I don't believe that you are going to find any type of in-depth scientific reference on this subject.

It seems that most researchers are in agreement that the large fleshy lips found on labiatus (along with some A. citrinellus types) is due to their specialized feeding technique of feeding on invertebrates and crustaceans found within the rock crannies. Being that this physical trait is a product of their environment, when one removes those fish from that environment, and removes that specialized feeding behaviour, the lips will not become hypertrophied (such as in F1 offspring) and the wild adults can also lose some of the fleshy build up over time. Of course this may vary among individual fish kept in captivity, and I would think that this would be largely dependent on how hypertrophied the lips are when the fish is collected, the age of the fish, their feeding techniques & diet in captivity, etc.

In citrinellum, the jaw structure has been shown to also be different between the same species found in the different crater lakes, again due to their feeding techniques.

The Midas cichlid species complex: incipient sympatric speciation in Nicaraguan cichlid fishes? MARTA BARLUENGA and AXEL MEYER

Department of Biology, University of Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany

http://www.evolutionsbiologie.uni-konst ... 2/P159.pdf

Two different types of pharyngeal jaws have been described in A. citrinellus: papilliform and molariform. For both A. labiatus and A. zaliosus only papilliform pharyngeal jaws have been described previously in the literature (Meyer 1989, 1990a,b). All A. citrinellus individuals sampled in L. Managua, Tisma Pond and L. Masaya had papilliform pharyngeal jaws (see also Meyer 1990a). All A. citrinellus individuals collected in Ometepe in L. Nicaragua had molariform pharyngeal jaws. Among samples of A. citrinellus that were collected from L. Xiloá, L. Apoyo (A. zaliosus) and Isletas, L. Nicaragua both trophic morphs were found in sympatry. This study provides the first evidence of molariform pharyngeal jaws on fish from Lake Apoyo.

More in this paper ..........

Cost of morphological specialization: feeding performance of the two morphs in the trophically polymorphic cichlid fish,Cichlasoma citrinellum

http://www.evolutionsbiologie.uni-konst ... 2/P006.pdf

The pharyngeal jaw structure in C. citrinellum is correlated with differences in external morphology (Fig. 1, Meyer 1988). Molariform morphs have blunter, shorter snouts, larger eyes, wider heads, and deeper shorter bodies than papilliform morphs.

[dogofwar]

A buddy and I were discussing how someone could use the new Repashy superfood (gel) to coat rocks and the like for more realistic mbuna feeding. I wonder if the same could be useful for developing fleshy lips in CAs?

Matt

[RD.]

Matt, my understanding is that the fleshy lips develop from sucking invertebrates from within the rock crannies, just as it does with some of the cichlids found in the Rift Lakes, such as Placidochromis milomo. http://www.malawicichlids.com/mw08083.htm

Once developed those lips create a vacuum of sorts when pressed tightly against the cracks & crevices within the rock piles.Those types of hypertrophied lips will not develop from sucking gel, or algae from the surface of a rock.

[RD.]

Another interesting read on this subject, and while the info is based on another Malawi cichlid, the author of this article adds a new twist to the fleshy lip discussion.

http://www.malawicichlids.com/mw09004.htm

However, Matt Arnegard and I had to disagree with Ribbink and Konings about the function of the soft, enlarged lips. We believe they may be too delicate for constant friction against rocks. Our discovery that the lips are densely packed with taste buds suggests an alternative explanation; these lips, much like the barbels of catfishes, may allow A. labrosus to sense prey items deep in dark cracks by tasting them. Or, perhaps the two proposed functions are not mutually exclusive. A well-designed experiment could settle the matter.

I would guess that it's a bit of both, due to the number of feeding observations that have been made by Konings etc.