SURVEYS ON PROPITHECUS-VERREAUXI-DECKENI, A MELANISTIC VARIANT, AND PROPITHECUS-VERREAUXI-CORONATUS IN NORTH-WEST MADAGASCAR

Propithecus verreauxi is currently divided into three of four subspeci es. Decken's sifaka, P. v. deckeni, and the crowned sifaka, P. v. coro natus, are believed to be synonymous by some authors, while others reg ard them as separate subspecies. The results of a survey on an isolate d melanistic population of Decken's sifaka, known from museum specimen s collected in Ambararatabe, as well as the results of additional surv eys carried out within the ranges of P. v. deckeni and P. v. coronatus are presented. A detailed description and photographs of the melanist ic variant are provided. The data are employed to argue the case for r ecognition of the subspecific status of the endangered P. v. coronatus . The consistency of sightings of P. v. coronatus to the east of the r iver Mahavavy and to the west of the river Betsiboka, and sightings of P. v. deckeni to the west of the Mahavavy indicate clear separation o f the two subspecies in the lower reaches of the two rivers. Clarifica tion of the status of the enigmatic museum specimens from Ambararatabe , representing a melanistic form rather than hybridization of P. v. de ckeni and P. v. coronatus, lends further support to this argument.