medullar type

Patrones cuticulares y medulares de pelos de mamíferos del noroeste argentino (Carnivora y Artiodactyla)

Daniela E. Vázquez, Pablo G. Perovic, Ana A. de Olsen

Se analizaron características estructurales a nivel microscópico de pelos de 167 especímenes con el objeto de identificar 18 especies de Carnívoros y 8 especies de Artiodáctilos del noroeste argentino. La variación en tales características se midió considerando el tipo de escamas y médula, ancho de pelo y médula, porcentaje de medulación, ancho y número de escamas. Se encontraron escamas en mosaico y lanceoladas romboidales; los tipos de médula observados fueron retículo tabicada, esponjosa no fragmentada, esponjosa fragmentada y nido de abeja. Sobre la base de estos caracteres se pudo aproximar la distinción de taxa a niveles jerárquicos superiores (Orden y Familia). La variabilidad intrafamiliar mostró también diferencias significativas que permitieron caracterizar taxa a nivel genérico. Se discute el valor de las características de los pelos como una herramienta indirecta para la identificación de especies de mamíferos y se propone una clave para el reconocimiento de 23 especies de Carnívoros y Artiodáctilos del noroeste argentino.

Structural patterns in hairs of mammals from northwestern Argentina (Carnivora and Artiodactyla). Several studies analyzing hair characteristics to identify mammals were undertaken. We analyzed microscopical features of the hairs in 167 specimens of 18 species of Carnivora and 8 species of Artiodactyla from northwestern Argentina. The objective of this study is to provide a guide to species identification through morphological characteristics of hairs. In this report we describe qualitative characters as: types of cuticular scales and medulla, and quantitative characters as: hair width, medulla width, width of cuticular scales, medullar percentage and number of scales. Our results show six different patterns from which it is possible to distinguish taxa at the levels of order and family. Cuticular scales are mosaic or lanceolate rhomboidal, and medullas of four types: reticulate common, unbroken lattice, fragmental lattice, and honeycomb. Furthermore, there are significant differences at genus level. We discuss the value of these traits as indirect tools for identification of mammal species, and propose an identification key for 23 species from northwestern Argentina.

Medullar type and cuticular scale patterns of hairs of rodents and small marsupials from the Monte scrubland (San Luis Province, Argentina)

Gustavo J. Fernández, Silvia M. Rossi

Hair characteristics are often used to identify mammalian prey in guts, feces or pellets of predators when other more easily identifiable remains, such as bone fragments or teeth, are not available. Indeed, hair can provide qualitative data about prey species. By using guard hair cuticular scale patterns and medullar types, we built a key which enabled us to accurately identify nine of thirteen rodents and small marsupials found in San Luis Province (Argentina). Our results support the use of hairs to identify mammalian prey but emphasize that at least two criteria must be examined to accurately distinguish among species.