Seasonal effects on testes size and sustained semen quality in captive golden-headed lion tamarins, Leontopithecus chrysomelas.

The golden-headed lion tamarin (Leontopithecus chrysomelas) is an endangered primate that, according to timing of births, there seems to have seasonal reproductive patterns in captive populations inhabiting the Southern Hemisphere. The extent to which male tamarins have circannual cyclic fluctuations in testicular functions, however, remains unknown. Changes in testis size and seminal variables, therefore, were evaluated during the rainy and dry seasons of the year in seven males. There was estimation of mating and birth seasons from the breeding colony using a 27 year database (229 birth records). Births were distributed throughout the year with peaks occurring in August-October and January-March (39.7 % and 30.5 % of all births, respectively). Semen collection using penile vibrostimulation was successfully induced in more than 96 % of the attempts regardless of the season (total of 75 ejaculates). Body mass did not vary significantly between seasons, but relative testes size was larger during the dry season. Values for none of the seminal variables (total sperm count, total and progressive motility, plasma membrane and acrosome integrity, and total sperm defects), however, were different during the rainy and dry seasons. These results indicate that testicular function in golden-headed lion tamarins may not be affected by daylength changes, and that seasonal patterns of female reproduction is perhaps more relevant for the reproductive timing of the species. Furthermore, the possibility of year-round production of ejaculates containing viable sperm broadens our perspective of preserving genetic diversity within the species because there is a greater opportunity for semen collection and freezing.

Pelage Variation and Distribution of the Black Lion Tamarin, Leontopithecus chrysopygus.

The black lion tamarin, Leontopithecus chrysopygus, is endemic to the Atlantic Forest of the interior of the state of São Paulo in Brazil. Since the discovery of the species, authors have described variations in the pelage of L. chrysopygus, but the nature of this variation has remained unknown. We examined museum specimens and living animals to see if the pelage of L. chrysopygus varies individually, geographically or ontogenetically. We reviewed all known locality records of the species, and concluded that the pelage of L. chrysopygus varies individually and ontogenetically, but not geographically. The extent of the golden chromogenetic fields is larger in younger individuals, and the pelage becomes darker after successive moults. We examined 2 juveniles that presented a pelage similar to adult L. caissara. Geographically, there is a clear break in the phenotypes attributed to L. caissara and L. chrysopygus, precluding clinal variation and corroborating the specific status of the former. The separation between these 2 species is coincident with a tectonic fault known as the 'Guapiara lineament', and may have been caused by a recent activation of this geological formation. We also suggest a historical contact zone between L. chrysopygus and the marmoset Callithrix aurita in the upper Rio Tietê region.

Finite element analysis of performance in the skulls of marmosets and tamarins.

Reliance on plant exudates is a relatively rare dietary specialization among mammals. One well-studied example of closely related exudate feeders is the New World marmosets and tamarins. Whereas marmosets actively gouge tree bark with their incisors to stimulate the flow of sap, tamarins are opportunistic exudate feeders that do not gouge bark. Several studies of the dentaries and jaw adductors indicate that marmosets exhibit specializations for increased gape at the expense of bite force. Few studies, however, have looked to the cranium of marmosets for evidence of functional specializations. Using 3D finite element models of the marmoset Callithrix jacchus and the tamarin Saguinus fuscicollis, we investigated the performance of the cranium under loading regimes that mimicked unilateral molar biting and bark-gouging. We investigated three measures of performance: the efficiency with which muscle force is transferred to bite force, the extent to which the models are stressed (a predictor of failure), and the work expended by muscles as they deform the skull (total strain energy). We found that during molar biting the two models exhibited similar levels of performance, though the Saguinus model had slightly higher mechanical efficiency, a slightly lower state of stress, and expended more energy on deformation. In contrast, under the bark-gouging load, Callithrix exhibited much higher mechanical efficiency than Saguinas, but did so at the expense of more work and higher levels of von Mises stress. This analysis illustrates that differences in the shapes of the skulls of Callithrix and Saguinus confer differences in performance. Whether these aspects of performance are targets of selection awaits broader comparative analyses.

Morfologia macroscópica do aparelho reprodutor feminino de Leontopithecus cativos (Lesson, 1840) Primates-Callitrichidae / Gross morphology of the female genital tract of captive Leontopithecus (Lesson, 1840) Primates-Callitrichidae

Descreveu-se o sistema reprodutor feminino em três espécies de mico-leão Leontopithecus (Lesson 1840), cativos: L. rosalia, L. chrysopygus e L. chrysomelas. A vulva está delimitada pelos lábios vulvares menores e com clitóris conspícuo. A superfície do períneo urogenital apresenta elevações papilares mais concentradas nos lábios vulvares, conferindo-lhe aspecto rugoso. O vestíbulo vaginal constitui um tubo muscular de parede espessa que se estende da rima da vulva até o óstio da vagina. A vagina é um tubo muscular alongado e achatado dorsoventralmente, que comunica o vestíbulo vaginal ao colo uterino. O útero piriforme está localizado na porção caudal da cavidade abdominal. Craniolateralmente abrem-se tubas uterinas convolutas e ovários grosseiramente fusiformes de superfície lisa.

It is described the female genital tract of three species of lion tamarin: Leontopithecus rosalia, L. chrysopygus, and L. chrysomelas. Fifteen animals were selected from the Museum of the Center of Primatology of Rio de Janeiro - CPRJ/FEEMA. The vulva is delimited by the labia and has a conspicuous clitoris. The surface of the urogenital perineum has papillary elevations more concentrated in the labia, which results in a rough aspect. The vestibule is a thick-walled muscular tube, extending from the pudendal cleft to the vaginal orifice. The vagina is an elongated and flat muscular tube, which communicates dorsoventrally the vestibulum and the cervix of uterus. The pyriform uterus is located in the caudal portion of the abdominal cavity. Craniolaterally, the convolute uterine tubes open, enveloping the ovaries, which are roughly fusiform with a smooth surface.

Secondary pneumatization of the maxillary sinus in callitrichid primates: insights from immunohistochemistry and bone cell distribution.

The paranasal sinuses remain elusive both in terms of function and in the proximate mechanism of their development. The present study sought to describe the maxillary sinuses (MSs) in three species of callitrichid primates at birth, a time when secondary pneumatization occurs rapidly in humans. The MSs were examined in serially sectioned and stained slides from the heads of two Callithrix jacchus, one Leontopithecus rosalia, and two Saguinus geoffroyi. Specimens were examined microscopically regarding the distribution of osteoclasts and osteoblasts along the osseous boundaries of the MS and other parts of the maxillary bone. Selected sections were immunohistochemically evaluated for the distribution of osteopontin (OPN), which facilitates osteoclast binding. Taken together, OPN immunoreactivity and bone cell distribution suggested trends of bone resorption/deposition that were consistent among species for the superior (roof) and inferior (floor) boundaries of the MS. Expansion at the roof and floor of the MS appeared to correspond to overall vertical midfacial growth in callitrichids. Much more variability was noted for the lateral (alveolar) and medial (nasal walls) of the MS. Unlike the other species, the nasal wall of Saguinus was static and mostly composed of inferior portions of the nasal capsule that were undergoing endochondral ossification. The variation seen in the alveolar walls may relate to the presence or absence of adjacent structures, although it was noted that adjacency of deciduous molars influenced medial drift of the alveolar wall in Saguinus but not Leontopithecus. The results of this study are largely consistent with the "structural" or "architectural" hypothesis of sinus formation with respect to vertical MS enlargement, and the variable cellular/OPN distribution found along the nasal and alveolar walls was evocative of Witmer's (J Vert Paleontol 1997;17:1-73) epithelial hypothesis in revealing that most expansion occurred in regions unopposed by adjacent structures.