Revision of the genus Buccinanops (Mollusca: Neogastropoda: Nassariidae), an endemic group of gastropods from the Southwestern Atlantic, including a new genus and accounts on the Buccinanopsinae classification

The nominal species referred to the endemic southern South American genus Buccinanops are revised, clarifying the definition of Buccinanopsinae. All valid Recent species are redescribed based on type material and other specimens emphasizing anatomy and illustrated using SEM photographs of radulae, embryos, and shell ultrastructure. Only seven of 13 nominal species described are considered valid: Buccinanops cochlidium (Dillwyn, 1817) (type species); B. latus sp. nov. (formerly B. gradatus or B. lamarckii from Brazil only); B. monilifer (Kiener, 1834); B. deforme (King, 1832); B. paytense (Kiener, 1834); B. uruguayense (Pilsbry, 1897) and B. duartei Klappenbach, 1961. A phylogenetic analysis based on morphological characters of these species and 12 other buccinoideans is carried out in order to compare results with recent DNA sequence approaches. The ingroup cladogram is ((B. monilifer (B. latus‐B. cochlidium)) (B. duartei (B. uruguayense (B. deforme‐B. paytense))). The former genus Buccinanops, supported by 11 synapomorphies, can be divided, and Buccinastrum gen. nov. (3 synapomorphies of support) is introduced for the 4 latter species in the above cladogram; its type species is Buccinastrum deforme. Buccinanops (8 synapomorphies) is thus restricted to B. cochlidium, B. monilifer, and B. latus, which are large‐sized, living in relative deep waters (subtidal), while Buccinastrum includes small‐sized species mostly restricted to the intertidal zone. The analysis of morphological characters is suggestive of a traditional subfamily Dorsaninae, with 12 synapomorphies, including four genera—Dorsanum, Bullia, Buccinanops, and the new Buccinastrum, but this result is only informative, as it has been considered paraphyletic in a DNA sequence approach, being subdivided into Dorsaninae, Buccinanopsinae, and Buliinae. The genus Buccinanops is a popular group of neogastropods at the SE coast of South America. All seven extant valid species of the genus were analyzed including anatomic and phylogenetic inference. The result revealed a new species—B. latus—(previously known as “B. gradatus”) and that the genus was split into two genera: Buccinanops includes three large deep‐water species, while the new genus Buccinastrum includes four small and intertidal species.