I found this piece in Pursuit dealing mountain lions with melanism.
ps: Poor photocopy so there will be garble
Member #210 promptly came through with two references, noting that .. Stanley P. Young and Edward A. Goldman's ~ (Dover Edition, 1964) mentions a couple of sources black pumas. A specific case of just such a cat having been killed in 1843 in the carandahy River section of Brazil is cited. as well as a vague reference to specimens of South American pumas (black, of course) being taken 'from time to time'. In Victor H. Cahalane's Mammals Qf North Ameril (Macmillan Co., 1961) this great one liner is found on page 272: 'Melanistic or black cougars are known; cougars of Florida seem to run strongly to that "freak" color'."
"No black specimen of Felis concolor has ever been collected in North America [Unless you count Costa Rica], but one has been shot in Brazil (Young and Goldman. 1946, p. 58).
The repeated mention of black specimens seen in daylight at close range demands some explanation. I once believed they were caused by the specimens being wet. To test this I went to Vancouver: Island and followed a government cougar hunter until he killed a large male. I took the fresh hide and suspended it by its edges and filled it with water and left in overnight. The next morning I photographed it in color from all angles. I could not make it appear black.
"My next thought was that they must be backlighted. However. a check on the position of the sun at the time of these reports proved this theory ,untenable.
"I have now no alternative but to accept the word of the eye-witness that there are black specimens of Felis concolor in northeastern North America and that they are not particularly rare (about 7% in New Brunswick and Nova Scotia.)"
Terry W. Colvin
[I probably DO need to reiterate, reports of known species do not qualify as subjects for Cryptozoology, whether you admit to the colour phase they come in or not. or whether they seen are outside their normal range or not. And also I should mention that black jaguars are known to cross over the border of the US and Mexico occasionally. -DD.]