Masahito Natori

A cladistic analysis of interspecific relationships ofSaguinus

The dental and cranial morphologies of all species ofSaguinus, S. oedipus, S. geoffroyi, S. leucopus, S. nigricollis, S. fuscicollis, S. labiatus, S. mystax, S. imperator, S. bicolor, andS. midas are examined. The following hypotheses are developed by cladistic methodology, using only synapomorphic characters to assess the interspecific relationships ofSaguinus.Saguinus are divided into two main groups; one consists ofS. oedipus, S. geoffroyi, andS. leucopus, and the other includesS. inustus, S. nigricollis, S. fuscicollis, S. labiatus, S. mystax, S. imperator, S. bicolor, andS. midas. In the former group,S. oedipus is more closely related toS. geoffroyi than either is toS. leucopus. In the latter group,S. labiatus, S. mystax, andS. imperator are classified into one group, andS. bicolor andS. midas form one monophyletic group.

An analysis of interspecific relationships ofSaguinus based on cranial measurements

The interspecific relationships of the following nine forms ofSaguinus were analyzed applying the multivariate analysis to the cranial measurements;S. oedipus, S. geoffroyi, S. leucopus, S. nigricollis, S. fuscicollis, S. labiatus, S. mystax, S. midas midas, andS. midas niger. Penroses size distance was used to express the size factor among the nine forms; and for the shape factor, Q-mode correlation coefficients were utilized. The shape distance betweenS. oedipus andS. geoffroyi was almost equal to that betweenS. nigricollis andS. fuscicollis which are recognized as different species based on biogeographical evidence. Furthermore, the Penroses size distance betweenS. oedipus andS. geoffroyi was quite large. Therefore, the results of this study support the hypothesis thatS. oedipus andS. geoffroyi are valid species.The analysis of the phylogenetic relationships among the nine forms was based on the shape factor only. The forms were divided into two main clusters: (1)S. oedipus, S. geoffroyi, andS. leucopus; (2)S. nigricollis, S. fuscicollis, S. labiatus, S. mystax, S. midas midas, andS. midas niger. In the former cluster,S. oedipus was more closely related toS. geoffroyi than either was toS. leucopus. The latter cluster was subdivided in two subclusters based on the degree of their affinity: (2a)S. nigricollis, S. fuscicollis, S. labiatus, andS. mystax; and (2b)S. midas midas andS. midas niger. In the former subcluster, [S. nigricollis, S. fuscicollis] and [S. labiatus, S. mystax] were classified into clusters, respectively.The ancestor of theS. nigricollis group differentiated intoS. oedipus, S. geoffroyi, andS. leucopus with the narrowing of the maxilla in the facial region, andS. midas midas andS. midas niger with the downward movement of rhinion.

Variations in Dental Measurements between Saguinus Species and Their Systematic Relationships

Multivariate analysis is applied to dental measurements of Saguinus species to analyse their systematic relationships. The shape distance between Saguinus midas midas and S. midas niger is larger than that between S. nigricollis and S. fuscicollis, both of which are generally recognized as valid species. In dental form, S. bicolor is the closest relative of S. midas. S. inustus is not linked to S. leucopus. S. geoffroyi and S. leucopus, as S. inustus shows closer affinity with S. labiatus and S. mystax than with the former 3 species.

Preliminary analysis of numerical taxonomy of the genusSaguinus based on dental measurements

Although several investigations have been made from different viewpoints, the classification or interspecific relationships ofSaguinus still remain uncertain.In the present study, we applied multivariate analysis methods to dental measurements of part ofSaguinus populations of sufficient sample size and obtained the following conclusions.Saguinus can be classified into two main groups: one consists ofS. oedipus andS. leucopus, and the other ofS. fuscicollis, S. nigricollis, S. labiatus, andS. mystax. Concerning the former group, the two subspecies ofS. oedipus, S. o. oedipus, andS. o. geoffroyi, show a close affinity with each other and also a close relationship toS. leucopus, while the latter group consists of two subgroups of species, one includingS. fuscicollis andS. nigricollis, and the other includingS. labiatus andS. mystax. The biological distance betweenS. oedipus oedipus andS. o. geoffroyi is slightly larger than that between the pairs ofS. fuscicollis andS. nigricollis and ofS. labiatus andS. mystax. Factor analysis revealed significant factors which could explain the differences among the seven maleSaguinus populations.Taking all the results into account, it seems necessary to reconsider the phylogenetic relationships within the genusSaguinus.

A revision of Tetraconodon (Mammalia, Artiodactyla, Suidae) from the Miocene of Myanmar and description of a new species

ABSTRACT We describe five new dentognathic specimens of Tetraconodon, a genus of Miocene tetraconodontine suid (Mammalia, Artiodactyla), discovered in Myanmar (= Burma). In Myanmar, we recognized three distinct species of Tetraconodon (T. minor, T. intermedius and T. malensis sp. nov.) and one specifically undetermined specimen, which is here named Tetraconodon sp. cf. T. intermedius. The new species, T. malensis, has characteristics of Tetraconodon, such as extremely enlarged P4 and simple and relatively small M3. It is distinct from the other Tetraconodon species in being much smaller, suggesting that it is the most primitive known Tetraconodon species. The dental size and characteristics of T. malensis suggest that Tetraconodon was derived during the late middle Miocene from the early middle Miocene Conohyus sindiensis, which was discovered in the Siwalik Group of Indo-Pakistan and Nepal and has also been found in the middle Miocene deposits of Thailand, or a close relative. The discovery of the most primitive form in Myanmar suggests that Tetraconodon may have originated in Myanmar.

Numerical analysis of sexual dimorphism inSaguinus dentition

Among New World monkeys, more or less sexual dimorphism exists in the dentition, especially in the Cebidae. On the other hand, the Callitrichidae includingSaguinus are said to be characterized by a broad lack of sexual dimorphism with the exception of the reproductive organs.In the present article, sexual dimorphism in the dentition of someSaguinus species was reconfirmed using univariate and multivariate analytical methods. The results of the analysis were as follows: (1) there is no sexual dimorphism in the canine tooth size, except for the upper canine ofS. geoffroyi and lower canine ofS. mystax; (2) the overall tooth size difference between males and females is slight or none inS. geoffroyi, S. leucopus, andS. fuscicollis, relatively small inS. oedipus andS. mystax, and rather larger inS. midas; (3) an overall difference in shape factor between both sexes exists in all species ofSaguinus to a greater or lesser extent; (4) although only slight sexual dimorphism is recognized in the canine tooth itself, sexual dimorphism does exist in some adjacent teeth of the canine in a few species; and (5) there are some interspecific differences in the magnitude of the sexual dimorphism of theSaguinus dentition and these differences are more evident in species inhabiting the peripheral regions of the distribution areas of this genus.Taking all the evidence obtained into account, the sexual dimorphism in theSaguinus dentition must be re-investigated in comparison with other genera of the Callitrichidae.

Dental eruption sequence and eruption times in Erythrocebus patas

Erythrocebus patas has a short inter-birth interval, juveniles become independent from their mother early, females are young at first birth, and adult females have a high mortality rate. According to Schultz’s rule, the molars of fast-growing and shorter-lived primate species erupt early relative to the replacement teeth. Based on the life history of E. patas, we hypothesized that the molars would erupt before the replacement teeth and/or that the eruption time of its molars would be early. The purpose of the present study was to determine the dental eruption sequence and eruption times for E. patas and to test our hypothesis. The eruption sequence for the permanent teeth of E. patas is

Evolutionary trends of the hairy-faceSaguinus in terms of the dental and cranial morphology

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