External Characters and Karyotypes of the Captive Tamaraws, Bubalus (B.) mindorensis, at the Gene Pool in the Island of Mindoro, Philippines

Abstract

Measurement values of sixteen external characters and karyotypes were described for one female and five males of the adult captive tamaraws, Bubalus (B.) mindorensis endemic to the island of Mindoro. Principal component analyses among bubaline species, using nine or ten of the characters as variables, derived more than 95% of total variance on the first component axis, in which the tamaraw was located almost at the midpoint of two distant bubaline groups : the dwarf water buffaloes of Sulawesi (Anoa depressicornis and A. quarlesi) and the Asiatic water buffaloes (the swamp and the river types of Bubalus bubalis) . All the six tamaraws had 46 chromosomes in diploid form (2N) and 58 as the fundamental number (FN) including the sex chromosomes. In contrast, all the bubaline species of Syncerus, Bubalus and Anoa were reported to have FN=60 with exception of the swamp type of the Asiatic buffalo (FN=58 but 2N 48) . The X chromosome of the tamaraws was the largest acrocentric, and the Y was also acrocentric, probably among the smallest acrocentrics. The karyotype of the tamaraws differs from that of the swamp type buffalo both by one additional pair of metacentrics and the two decreased pairs of acrocentrics in the autosomes.