From the abstract:
"A critical issue with species names derived from Linnaeus’ 10th edition of the Systema Naturae is the lack of holotypes, which in many instances has led to taxonomic confusion and uncertainty, as well as an unstable taxonomy. In the particular case of the South American cottontail, currently known as Sylvilagus brasiliensis, Linnaeus listed the type locality as “America Meridionali,” or South America. As a result, S. brasiliensis was ascribed a widespread distribution in North and South America, over an area estimated as approximately 1.09 × 107 km2, and containing upwards of 37 named subspecies.
In order to stabilize the taxonomy and initiate the process of illumination of evolutionary and biogeographic relationships among the South American cottontails, we designate herein a neotype for S. brasiliensis. Because the original description by Linnaeus was based on the posthumously published 1648 work of Georg Marcgraff, we restrict the type locality of S. brasiliensis to coastal Pernambuco State, near Recife, where Marcgraff largely was based. We select and describe a neotype from that area, specifcally from a forest fragment in the Pernambuco Endemism Center of the Atlantic Forest Biome, collected at ca. 7º50′38.4″S, 35º6′7.3″W, elevation: ca. 137 m. Niche modeling suggests that S. brasiliensis as thus defned may have a much more restricted range of 500–700 km2, in a narrow distributional band along northern Atlantic coastal Brazil.
We compare the neotype of S. brasiliensis to holotype material of S. andinus and S. tapetillus and find suffcient distinction in characters and measurements between S. brasiliensis, S. andinus, and S. tapetillus, to retain the latter two as valid species level taxa. Molecular phylogenetic analyses based on a limited number of sequences from the mitochondrial 12S rRNA and cytochrome–b genes support the distinction between S. andinus and S. brasiliensis. Genetic distances also support the lack of close relationship between the two taxa, with cytochrome–b showing a patristic distance between the two of ca. 15%, the largest interspecifc distance among Sylvilagus species previously examined for that locus.
Our analysis of Lineages Through Time suggests that the vast unreported taxonomic diversity among Tropical Sylvilagus is based on high speciation rates in the genus, combined with unusually low extinction rates. Episodes of explosive speciation in Sylvilagus, hypothesized to be ecologically driven, have been coeval with cooling events at the Miocene–Pliocene transition and following the Piacenzan Warm Period (Late Pliocene) into the Pleistocene; warm periods have in contrast slowed down speciation rates. The status of all described subspecies of S. brasiliensis will require careful scrutiny and comparison with the neotype to ascertain and establish species limits.
Because of a lack of specimens of Neotropical Sylvilagus in collections, our study suffers from a typological schema, however, our approach from first principles – examination of holotypes – not only serves to establish a more stable taxonomic framework for Neotropical Sylvilagus, but also further suggests that many of the existing taxa currently subsumed as subspecies within Sylvilagus brasiliensis likely are valid species in their own right."