Mitsuru Aimi

Taxonomy and distribution ofPresbytis melalophos group in Sumatera, Indonesia

Taxonomy of thePresbytis melalophos group in Sumatera has been based solely on the distinction in the pelage coloration and has been a subject of controversy. In the present study, extensive field observations were undertaken. Three species, i. e.P. melalophos, P. thomasi, andP. femoralis, are recognized in Sumatera based on the cranial morphology, pelage coloration, and vocalization. Subspecies of each species are revised, a new classification is proposed, and a new subspecies,Presbytis melalophos bicolor, is described. A detailed distribution map of species and subspecies is presented. No sympatry occurs between the species. Finally, a cladistic analysis is presented for the three species, based on the cranial characters; the branching sequence is first between theP. melalophos clade and theP. femoralis- P. thomasi clade and second between theP. femoralis clade and theP. thomasi clade.

Distribution and deployment ofPresbytis melalophos group in Sumatera, Indonesia

Pelage color and pattern, facial markings, cranial morphology, and vocalization have been studied comparatively in thePresbytis melalophos group in Sumatera. Pelage coloration of fetuses and neonates were described forP. melalophos andP. femoralis. Based on this study, three species —P. thomasi, P. melalophos, andP. femoralis — are recognized. Using field data that have been gathered since 1981, the distribution of these three species has been mapped. The resultant map reveals that no sympatry is known and that rivers form the interspecific boundaries. However, rivers apparently are not barriers to the dispersal of species in this group. Instead, distributions appear to be limited ecologically, by competitive exclusion. Historically, it appears that the ancestral stock initially dispersed throughout this area, then theP. melalophos stock split from theP. thomasi-P. femoralis stock, theP. thomasi stock split from theP. femoralis stock, and, finally, theP. femoralis stock dispersed to eastern Sumatera. It appears unlikely that the centrifugal speciation hypothesis based on the principle of metachromism applies to deployment of theP. melalophos group.

FossilMacaca nemestrina (Linnaeus, 1766) from Java, Indonesia

This is a description of the fossil macaque specimen registered as G. M. B. K 102 at the Geological Museum in Bandung. It is consisted of a left half maxilla and a mandible. The fossils are assigned toMacaca nemestrina (L., 1766) being a large macaque with long mandibular symphysis, big canines and marked lateral flares in molars. They were unearthed from Sangiran, near Surakarta, Central Java, Indonesia. The horizon is unknown. It is, however, most likely to be the Kabuh Formation, Middle Pleistocene, based on the colouration and matrix of the specimen. This is the first valid record ofMacaca nemestrina (L., 1766) from Java, where now the species is absent.

Macaca fuscata develops thin enamel on lingual sides of lower incisors

Among the cercopithecids, papionins were believed to have unique lower incisors without enamel on the lingual surfaces based on analyses by light microscopy. We examined unerupted lower permanent incisors ofMacaca fuscata with scanning electron microscopy and found a lingual thin enamel layer. This seems to be the case for all papionins. Thus, all cercopithecines can be regarded to share this trait which distinguishes cercopithecines from colobines who have substantial enamel layer on the lingual sides of lower incisors. Further study will support this hypothesis. This trait produces self-sharpening chisel-like edges on lower incisors. And the adaptive significance of this chisel-like edged incisor could be understood for scraping and cutting to prepare foods for consumption.

Initial calcification of the upper permanent incisor in Japanese macaques

Fifteen laboratory-born Japanese macaques,Macaca fuscata (Blyth, 1875), were examined radiographically for the timing of initial crown calcification of the permanent upper first incisors. The mean age of initial calcification was 199.8 days in females and 204.7 days in males; the sexual difference was significant (p<.05). Precocious incisor calcification in females inM. fuscata resembles that inM. nemestrina andHomo sapiens.