Redescription of Vieja hartwegi (Taylor & Miller 1980)

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DRE
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Redescription of Vieja hartwegi (Taylor & Miller 1980)

Post by DRE » Wed Jan 24, 2018 11:54 pm

Redescription of Vieja hartwegi (Taylor & Miller 1980) (Teleostei: Cichlidae) from the Grijalva River basin, Mexico and Guatemala, with description of a rheophilic morph

Gómez-González AE, Álvarez F., WILFREDO A. Matamoros WA, Velazquez-Velazquez E, Schimitter-Soto JJ, Gonzalez-Diaz AA, McMahan CD (2018).

http://www.mapress.com/j/zt/article/vie ... a.4375.3.5

Abstract

Vieja hartwegi was described by Taylor and Miller in 1980 based on 45 juvenile and sub-adult specimens, but this species shows an enormous variation in coloration patterns during ontogenic development and between individuals. Additionally, morphological data have demonstrated the existence of two forms in V. hartwegi: the typical morph of a moderately deep to slightly elongated body shape with midlateral band, and a rheophilic morph with an elongated to slightly deep body shape and lack of midlateral band. Herein we redescribe V. hartwegi adding adults and individuals from broad geographic ranges, as well as a rheophilic morph recently discovered in the upper reaches of the Grijalva River basin in Mexico. The set of characters include coloration, meristic, morphometric and osteological features. Vieja hartwegi is a polymorphic species whose forms may be segregating because of habitat preferences and food habits.
If anyone have the pdf, I'd love a copy
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Re: Redescription of Vieja hartwegi (Taylor & Miller 1980)

Post by Mark Smith » Mon Jan 29, 2018 10:48 am

That rheophilic morph sure looks like a different species, but I guess not.

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Re: Redescription of Vieja hartwegi (Taylor & Miller 1980)

Post by Juan Artigas » Mon Jan 29, 2018 11:30 am

Very likely with time it will keep differing and isolating in reproduction, that is a way for new species to develop, exploiting niches. I thought that it was probably rapids that had isolated V. hartwegi and V. breidohri, if it were so, are now rapids isolating a new species? or was it a geographical barrier before for the two species to form?
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Re: Redescription of Vieja hartwegi (Taylor & Miller 1980)

Post by Mark Smith » Tue Jan 30, 2018 1:23 pm

I wonder if that question could ever be answered. Perhaps depending on the ichthyologist working with this rapids dwelling form, some might have described it as a new species.

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Re: Redescription of Vieja hartwegi (Taylor & Miller 1980)

Post by Rico Morgenstern » Thu Feb 01, 2018 12:06 pm

The unusual 'rheophilic morph' maybe nothing but a natural hybrid between V. hartwegi and C. grammodes. Such hybrids have occurred in aquarium (Buchhauser 1999) and looked much the same. The possibility that it is a hybrid has not been considered in the paper. The differences between 'normal' V. hartwegi and the new 'morph' are so striking that the latter needed a separate diagnosis. The only reason for the authors to place it within V. hartwegi appears to be the result of the molecular analysis (cytochrome b only). As the cytochrome b gene is part of mtDNA, the analysis would not reveal hybrids. Those between a V. hartwegi female and a C. grammodes would fall within V. hartwegi as the 'rheophilic morph' did.

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Re: Redescription of Vieja hartwegi (Taylor & Miller 1980)

Post by Juan Artigas » Thu Feb 01, 2018 12:43 pm

That is a very interesting view! Thank you Rico! They have collected eight specimens of the form in several areas upstream from La Angostura dam, which would indicate it is a common hybrid there.
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Re: Redescription of Vieja hartwegi (Taylor & Miller 1980)

Post by Rico Morgenstern » Fri Feb 02, 2018 4:49 am

All specimens fof the 'rheophilic morph' are from only three localities, two of them so close to each other (near a river confluence) that the specimens from both could well stem from a single hybridation event.

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Re: Redescription of Vieja hartwegi (Taylor & Miller 1980)

Post by cichla » Fri Feb 09, 2018 11:59 am

Rico Morgenstern wrote:
Thu Feb 01, 2018 12:06 pm
...As the cytochrome b gene is part of mtDNA, the analysis would not reveal hybrids. ...
Any source available?

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Re: Redescription of Vieja hartwegi (Taylor & Miller 1980)

Post by Rico Morgenstern » Sat Feb 10, 2018 12:36 am

I should perhaps have expressed this somewhat different. What I mean is that mtDNA is inherited by the mother only, therefore the hybrid bears the mtDNA of the maternal species. Consequently it would not be separable from that species in this respect.

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Re: Redescription of Vieja hartwegi (Taylor & Miller 1980)

Post by cichla » Sun Feb 11, 2018 5:19 am

Thank you.
Yes, it is very possible that these specimens are hybrids. The 'rheophilic morph' looks very similar to the hybrids between grammodes and hartwegi pictured by Buchhauser (DCG-Informationen, 1999).

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Re: Redescription of Vieja hartwegi (Taylor & Miller 1980)

Post by Florent » Tue Mar 13, 2018 2:00 pm

Hybrids, not a new rheophilic morph of Vieja hartwegi


https://www.researchgate.net/publicatio ... a_hartwegi

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Re: Redescription of Vieja hartwegi (Taylor & Miller 1980)

Post by cichla » Wed Mar 14, 2018 1:01 pm

Thanks for the link. Well, Rican and Morgenstern make good points. It is most likely that these are hybrids, indeed.

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