The skin of primates. 38. The skin of the red uacari (Cacajao rubicundus)

The role of piloerection in primate thermoregulation

The insulating properties of the primate integument are influenced by many factors, including piloerection, which raises the hair and insulates the body by creating motionless air near the skin's surface. The involuntary muscles that control piloerection, the musculi arrectores pilorum (MAP), are mostly absent except on the tail in most strepsirhines, and are entirely absent in tarsiers and some lorisids. The absence of piloerection and the reduced effectiveness of pilary insulation in preventing heat loss affected the evolution of behavior and metabolic thermoregulation in these animals. In lemurs, this situation contributed to the use of positional and social behaviors such as sunning and huddling that help maintain thermal homeostasis during day-night and seasonal temperature cycles. It also contributed in many lemurs and lorises to the evolution of a wide variety of activity patterns and energy-conserving metabolic patterns such as cathemerality, daily torpor, and hibernation. The absence of functional MAP in strepsirhines and tarsiers implies the absence of effective piloerection in early primates, and the reacquisition of whole-body MAP in ancestral anthropoids prior to the separation of platyrrhine and catarrhine lineages. © 2013 S. Karger AG, Basel.

Phylogenetic significance of the skin of New World monkeys (order primates, infraorder Platyrrhini)

The combined properties of a given cutaneous system, like other characters classically employed by systematic zoologists, are useful criteria in the assessment of primate taxonomy and phylogeny. From the synthesis of all available data, it is also concluded that (1) the results define a baseline regarding the normal histology and histochemistry of the skin of most genera and many species of New World monkeys; (2) intrageneric and intraspecific subtleties in cutaneous variation exist in primate integument; (3) single and multiple cutaneous traits contribute to the characterization and accurate identification of most levels of taxa within the primate hierarchy; (4) some traits, however, negate recent taxonomic practices, e.g., the familial position of Callimico; (5) basic cutaneous patterns confirm currently accepted concepts of taxonomy and phylogeny; and (6) the various cutaneous signatures of extant platyrrhines record a history of adaptive radiation in isolation, and suggest that the designation of at least two distinct families is warranted.

The skin of primates. XLII. The skin of the silvered sakiwinki (Pithecia monachus)

The following characteristics indicate that the skin of the silvered sakiwinki (Pithecia monachus, E. Geoffroy, 1812) is not only basically similar to other primitive cebids, but also remarkably close to that of callithricids: a thin epidermis with diminished monoamine oxidase activity; a poorly-developed dermis, paucity of elastic fibers, and scant adnexal blood supply; hair follicles arranged in linear perfect sets; grouped hairs present on the cheek; an absence of glycogen and phosphorylase in most sebaceous glands; apocrine glands present throughout most haired body regions, but totally absent from the dorsum; and poorly-differentiated eccrine glands, confined to volar friction surfaces, which are characterized by unusual glycolytic properties. Other noteworthy cutaneous traits include: concomitant epidermal and dermal pigmentation in the face and scalp; Merkel-like disks in the friction surfaces; moderately well-developed Haarscheibe, associated with large, dorsal guard hairs; small, discrete sebaceous glands throughout the dorsum; a 1:1 ratio of apocrine glands to hair follicles in the facial, gular and anogenital areas; and numerous cholinesterase-reactive nerves around eccrine but not apocrine secretory coils. Although previous comparative studies on the skin of New World monkeys suggest that the systematic designation of two familial taxa is warranted, information regarding five of the fifteen genera which comprise the families Callithricidae and Cebidae is totally lacking. Given that three of these genera (Leontopithecus, Chiropotes and Brachyteles) can no longer be obtained from animal dealers because of exportation laws, the authors were fortunate to acquire representatives of the remaining two genera: Callicebus (titi monkeys) and Pithecia (sakiwinkis). Besides defining cutaneous characteristics common to specific taxa, two earlier works by Hanson and Montagna ('62) and Perkins et al, ('68) also suggested that members of the cebid subfamilies Aotinae and Pitheciinae possess cutaneous traits that bridge an interesting gap with the callithricids. Therefore, the acquisition of these two additional aotine and pithecine genera provided the opportunity to test this hypothesis. The following, therefore, is not just another detailed manuscript regarding the skin of primates. Rather, it is an effort to define the integumental characteristics of the last obtainable New World monkey genera, and to assess those cutaneous signatures which are interfamilially common to both the callithricids and more primitive cebids. Primary emphasis is placed on the genus Pithecia; pertinent findings concerning Callicebus will be incorporated into the forthcoming and final summarization of the phylogenetic significance of the skin of New World monkeys (Perkins, '75).

The skin primates. XLIV. Numerical taxonomy of primate skin

Data on 84 characteristics of the skin of 36 species of primates were extracted from a series of articles describing the histological and histochemical properties of the skin of primates. The data were subjected to a cluster analysis. The results were in reasonably good agreement with orthodox primate taxonomies although some exceptions were apparent. The species clustered into four main groups approximately comparable to Prosimii, Cercopithecoidea, pithecoidea, and Hominoidea are commensurate with standard taxonomic practice. Within the Ceboidea, however, the Atelinae and Alouattinae tend to group with the Hominoidea, Aotus and Saimiri show variable placements, and Callimico groups with the Callithricidae.