X.eiseni "San Marcos" identification

Illustrator posted: 16.03.2011

Dear all,

I understand that there are 2 sites with X. eiseni "San Marcos", usually labelled as I and II. Besides fish from known origin, there are also some known simply as "San Marcos" bred in aquaria, and for these the origin appears lost. Several members, including me, have such "Lost-Locality" fish. I wonder what is whise with these fish:

- is there any way to identify the "Lost Locality" fish, meaning, is there any visible difference between locality/strains I and II?

- how often is the species collected? Was this only once for either locality? In that case, "Lost Locality" fish are unlikely to preserve any genetic variation that is not also present in I and II. Meaning that, ultimately, it could be better to replace these "Lost Locality" fish with the ones from known locality/collection dates ...

 

Grigri posted: 22.03.2011

From our data we identified two strains :

The historic one, "San Marcos Road" collected various time from a small stream between Ezatlan and san Marcos (if my memory is good)
For what I know it is the first location the "San Marcos" was identified. last news give them extirpated i think...

The second one is "San Marcos est" from a trip by Brian Kabbes in 1999. "Kabbes location 2". Have a description of the site in dutch.
it was a small lac Est from the town of San Marcos.
For what I know this second strain is quite rare, and only referenced here in France (and Andorra !)

I will have to check it but I remember that Kabbes durring his trip find other location for the "san marcos" type.

Visually the two strains are really similars, there is no significative variations.

 

MIchael Koeck posted: 23.03.2011

Hi Alain and Paul,

my information concerning this form is the same, two collection-sites, one with the first collections in 1982 by Radda et al, small stream, sometimes called "localita 1" or "San Marcos road" and a second by Kabbes in 1999, called "localita 2" or "San Marcos East", from another location, a tiny lake - as far as I know together with X. melanosoma. About the distribution of the strains in the hobby, I don't know much, but I have a list from Zoo Plock, Poland, including San Marcos 2, coll. Kabbes 2000.
So, all strains older than 1999 should be loc.1, I presume.

Greetings, Mike

 

Christian posted: 25.03.2011

Hi,
the first collection report I found (until now) is from Radda. But I still have not reviewed all registered DGLZ stocks before 2000.

Radda et al. collected the fish in 1982 next to the road, the description published with picture was "small creek (dry watercourse) with remaining puddles, 10 km at road from Ezatzlan (sic! - picture labeled Ezatlán!) to San Marcos."
[SO 14/82 Kleiner Bach (ausgetrockneter Wasserlauf) mit Restwasserpfützen, 10 km an der Strasse Ezatzlan nach San Marcos; Jalisco (Schreibweise "Ezatlán" in Bilduntertitel)]

The next collection information I found so far is from Brian Kabbes:
"Granja Sahuaripa, Jalisco. Mexico Brian Kabbes 1999": "Ditch, located about 3000m east of San Marcos. The ditch is located at the right side about 20 m from the road from Etzatlan and turn-off to Granja Sahuaripa."
[Graben, etwa 3000 Meter östlich von San Marcos gelegen. Der Graben liegt an der rechten Seite etwa 20 Meter von dem Weg entfernt, der von Etzatlan kommt und nach Granja Sahuaripa abzweigt. - www.goodeiden.de ]

The same site is also found as
"2000 Kees de Jong"
and
"Ranja San Isidro, San Marcos, Jalisco - Mexiko 2000" [Ivan Dibble's registration at DGLZ]
"San Isidro Farm; Etzatian-San Marcos" [ http://www.goodeids.com/Goodeidae-Taxa.html ]

Ivan wrote in his 2000 Morelia trip report (10th February): "From here [Teuchitlan] we went across to another old friend the El Palo Verde looking for Allotoca maculata. ... We then carried on the road towards San Marcos and between 3 & 4klms latter we found a newly cleaned out stream on the right of the road at the sign for the Rancho San Isidro. Investigating here we think we have found were the fish from the El Palo Verde go to when it’s waters get low, as here we found Allotoca maculata. Xen, eiseni. Xen, melanosoma. and Poeciliopsis infans. The water temp was 17c the air temp 18c the Ph 8-0. Kh 10. Gh 8.

Rancho San Isidro and Granja Sahuaripa seem to represent the same collection site.
See: James Langhammer. De historie van Allotoca maculata in de V.S. Poecilia nieuws nr. 4 - 2007 p.15-18. [ http://www.poecilia.nl/boekje/boekje_in … a16-17.asp ]

Brian also collected in 1999 at:
"pond, about 1500m east of San Marcos. The pond is at the right side on a pasture in about 30m distance from the road from Teuchitlan to San Marcos. This pond is close to a bridge over a dry watercourse."
[Teich, etwa 1500 Meter östlich von San Marcos. Der Teich liegt an der rechten Seite auf einem Weideland in etwa 30 Meter Abstand von der Straße, die von Teuchitlan nach San Marcos führt. Dieser Teich liegt in unmittelbarer Nähe einer Brücke, die über einen ausgetrockneten Wasserlauf führt. - www.goodeiden.de ]

Thus, Brian's collection sites east of San Marcos and Granja Sahuaripa are only about 2 km away from each other. To get an impression of the valley, just type in the coordinates below in Google maps and check out using Google street view or satellite.

Another collection site: Mejía-Madrid, Domínguez-Domínguez & Pérez-Ponce de León (2005): Río San Marcos (20°53'28.7'', -104°01'17.2''); [ http://www.bioone.org/doi/full/10.1654/4169 ]

For pictures and descriptions from Kees and Brian have a look at:
http://www.goodeiden.de/html/san_marcos.html (german)
http://www.goodeiden.de/html/san_marcos1.html (english)
http://www.goodeiden.de/html/_san_marcos_.html (norwegian?)
Information on each website vary, also check out X. melanosoma and A. maculata for further pictures and information.

Christian

 

Grigri posted: 25.03.2011

Impressive work Christian !
I think Kees goes there, he could certainly help with all this...
By the way, is the san marcos status still "sp." or could it be assimilated to eiseni  ?

 

Michael Koeck posted: 25.03.2011

My congratualtions, Christian!!
Absolutely impressive!!!

I asked Omar a few months ago about the status of some "uncertain populations". He answered me, concerning San Marcos fish, that they will probably have to be decribed as a separate species. However, such things depend on the author sometimes (see also Hubbsina, Zoog. purhepechus, the Allotoca-diazi group aso), so we will have to wait for results. Remembering Shanes studies, the genetic differnce between these populations had not been so big, on the other hand, these both types differ a lot, and the Etzatlán-fish are isolated, too.
Me for my part, until further studies are taken, denote them as "Xenotoca" sp. "San Marcos".

Cheers, Mike

 

Illustrator posted: 25.03.2011

The current trend is the phylogenetic species concept, which is in practice suspiciously similar to the morphological species concept (with genetics added if convenient).

In theory any form which is evolving independently on an evolutionary timescale should be considered as a separate species. In practice this means that if fish are recognisably different in any way, and it is clear that they don't mix with related fish (either because they co-occur and hybrids are rare or because from geology of the area it is clear that there is a barrier which has also existed before we started to change the world), then they can be described as a different species. For some time these were subspecies, but it is often difficult to say what should be a subspecies and what should be a species, so the concept of "subspecies" is largely abandoned (and is not a part of the phylogenetic species concept). It is nice when there is a clear genetic difference, but this is not nessesary in order to describe a different species.

So in the case of the San Marcos Xenotoca, all that is needed is that someone studies the whole X. "eiseni" complex and identifies which forms are historically isolated AND clearly separable.

 

mandrade posted: 27.03.2011

Salut Alain
Hi everyone,

Alain, once all the " San Marcos " we currently have in Portugal are descendents of yours ( if I am not mistaken ), could you be so kind and confirm the original location of collection regarding our fish ?
Thank you very much for your help on this issue.
Allow me also to congratulate Christian for the impressive data revealed about this topic.

Kindest regards

 

Grigri posted: 29.03.2011

Bom dia Miguel ;-P
So they are from the Kabbes 1999 collection : San Marcos Est, Kabbes loc. 2.

See you !
Alain