Testicular volume, semen traits, and pituitary-gonadal hormones were measured in populations of Felis concolor from Florida, Texas, Colorado, Latin America, and North American zoos. More Florida panthers (F. concolor coryi) were unilaterally cryptorchid (one testicle not descended into the scrotum) than other populations (43.8 versus 3.9%, respectively). Florida panthers also had lower testicular and semen volumes, poorer sperm progressive motility, and more morphologically abnormal sperm, including a higher incidence of acrosomal defects and abnormal mitochondrial sheaths. Transmission electron microscopy revealed discontinuities in the acrosome, extraneous acrosomal material under the plasma membrane, and remnants of the golgi complex under the acrosome. No differences were detected in mean-circulating follicle-stimulating hormone, luteinizing hormone, or testosterone between Florida panthers and other populations of mountain lions. Seminal traits and concentrations of follicle-stimulating hormone, luteinizing hormone, and testosterone were similar between cryptorchid and noncryptorchid Florida panthers. Animals with F. concolor coryi ancestry were categorized on the basis of amount of genetic variation (low = type A; medium = type B; high = captive Piper stock). Compared to counterparts, type A Florida panthers had the lowest testicular volume and sperm-motility ratings and were the only animals exhibiting unilateral cryptorchidism. These results demonstrate the existence of major morphological and physiological differences among populations of F. concolor, a finding potentially related to differences in genetic diversity.

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