A description of the baculum of the bobcat (Felis rufus), with comments on its development and taxonomic implications

Abstract

Examination of the genitalia of male bobcats collected in Arkansas revealed the common occurrence of bacula. The preformed architecture of dense connective tissue and cartilage was evident in juveniles (<1 year). Observed morphological variation in adults was partially ascribed to ontogeny. Maximum dimensions observed were 7.6 mm (length) and 3.1 mm (width). The distal portion of the baculum is a narrow shaft, while the proximal region is expanded and bifurcated ventrally. A vertical septum separates two vacuities in the base of the baculum. These vacuities house the primarily adipose ends of the corpora cavernosa. Morphology of the baculum of the bobcat is similar to that of the European lynx, and, while different from other felids, it indicates validity of the genus Lynx.

Postcopulatory sexual selection and the evolution of shape complexity in the carnivoran baculum

“…Alpha shapes also successfully highlight more subtle taxonomic trends, such as the comparatively complex baculum of otariids versus phocids and the walrus, and the notably simple baculum of otters when compared to other mustelids. Felids are a notable exception; however, their baculum having previously been described as 'rudimentary' or 'residual' [44] and often analysed separately or excluded entirely [28,45]. While undoubtedly diminutive in length relative to body size, our scale-invariant alpha complexity approach identifies felid baculum as highly complex.…”

“…This may be attributable to the unusual structure of the proximal baculum region. Although simple and 'rod-like' distally, the proximal portion of the cat baculum is often characterized by paired, deep depressions, divided by a dorsoventrally aligned septum corresponding to the terminal ends of the corpora cavernosa [44]. These depressions can be extensively developed and probably contribute to the seemingly 'complex' structure of the felid baculum.…”

“…Felids are a notable exception; however, their baculum having previously been described as ‘rudimentary’ or ‘residual' [ 44 ] and often analysed separately or excluded entirely [ 28 , 45 ]. While undoubtedly diminutive in length relative to body size, our scale-invariant alpha complexity approach identifies felid baculum as highly complex.…”

Baculum shape complexity correlates to metrics of post‐copulatory sexual selection in Musteloidea

“…A potential explanation for this is our present focus on the Musteloidea. While Musteloidea possess relatively well developed bacula, the wider order, Carnivora, can vary between extremely large and robust bones in groups such as Ursidae and Canidae (Dixson, 1995 ) to fragments of bone considered ‘rudimentary’ in the family Felidae (Tumlison & McDaniel, 1984 ) making regional complexity difficult to quantify and compare.…”