Lake Quillen (39º25'S, 71º19'W) is located at 975 m (3,200 ft.) above sea level deep inside the Andes in the province of Neuquén, Argentina.
It is, like al Patagonian lakes, cold and oligotrophic (very transparent and low in nutrients and cloprophyll), so the chances that it can be home to some carnivorous animal are small. See my post on the Sustainability issue.
With a surface area of 24 km2 (9,2 sq.mi.) it is quite small; it is also relatively shallow with a maximum depth of 155 m (508 ft.). It is on the Atlantic Ocean side of the Continental water divide, and it drains towards the east through the Quillen River into the Aluminé River, a tributary of the Limay - Rio Negro basin.
Quillen, which in the language of the Mapuche natives (Mapudungun) means strawberry, is protected by the Lanín National Park.
Gregorio Alvarez wrote about a "cuero uñudo or "hide with claws" seen at the River, at Quila Chanquil (Mapudungun for "where three rivers meet") by a local named Eusebio Cisternas.
Cisternas also saw the creature by the Quillen River, shortly after it leaves Lake Quillen. It was slightly smaller than the hide of a yearling calf and was holding on to a tree trunk by the river.
This clawed creature, a kind of manta ray with claws along its body, is described in detail in our post on "cuero".
It drags itself out of the water and lies flat on the ground, when someone walks over it, it quickly wraps around its victim and captures it with its claws. Tightly rolled up, it rolls back into the river or lake where it eats its prey safely inside its lair.
The following map shows the area where the cuero was seen. The upper red dot shows Quila Chanquil, and the lower one, Lake and River Quillen.
To the south of the map, by San Martín de los Andes is Lake Lacar, home to a "lake bull" and above it Lake Huechulafquen, home to another lake creature, Huechulito.
Copyright © 2009 by Austin Whittall
 Image from: www.argentinaviajera.com
 Sistema Nacional de Información Hídrica / Información General. Lago Quillen
 Alvarez, Gregorio, (1981). El tronco de oro: folklore del Neuquén. Neuquén: Ed. Siringa Libros. pp. 116+
 Map original source: Instituto Geográfico Nacional
Copyright 2009 by Austin Whittall ©