Lake Huechulafquen (39°46' S, 71°23' W) is located in the Andean region of Neuquén province. I have already posted about its lake creature, Huechulito which was sighted in 2009, and also posted on a very old sighting (before 1922).
The 1922 sighting describes it as similar to the "Black lake Plesiosaur":
many times I heard respectable neighbors of Junín de los Andes say […] that in the Lake Huachi-Lauquen, at dusk, an animal often appears on its surface, which has more or less the same features of the one that is said to have been seen in Esquel. Very long neck, lizard head, body that must be enormous, because when it submerges it produces a sort of “boiling” in the waters.
This weekend I came across another reference on this creature. It is a very short comment by Argentine folklorist Gregorio Alvarez in which he casually mentions among several other strange animals which he calls zoomorphs. This animal is the "cow at Lake Huechulafquen".
Unfortunately Alvarez gives no description of the beast and I have not been able to find any other articles or books mentioning this creature.
 Juárez, F. Historias patagónicas. Online.
 Alvarez, G., (1968). El tronco de oro. Neuquén: Ed. Pehuen. pp. 114.
Copyright 2009-2010 by Austin Whittall ©
Patagonian Monsters Cryptozoology, Myths & legends in Patagonia