The shallow water marine Brachyura (Crustacea, Decapoda) in the eastern Pacific and Atlantic Oceans: Approaches to understanding species richness and biodiversity

Three approaches to the study of biodiversity are presented. The first approach uses a large dataset of species' ranges from which patterns of biodiversity are discussed in relation to latitude and coastal features. Additionally, statistical analyses and null models are used to test hypotheses about these patterns. The second approach is a traditional taxonomic review of a set of species found in a given location and includes the description of new species. The third approach shows how digital photography of live animals can be a viable and important source of taxonomic information and how it can be incorporated into modern collecting expeditions.; The known ranges of species of shallow water coastal marine brachyuran crabs in the eastern Pacific, western Atlantic, and eastern Atlantic were analyzed. The observed curves of biodiversity vs. latitude for the three coastlines did not fit curves predicted by null models. The Rapoport effect was rarely found when range length data for the six low to high latitude coastal regions was analyzed using Stevens' method, the Midpoint method, or a Man-Whitney U method developed for this study. However, there was statistical evidence that at some faunal boundaries species ranges centered at high latitudes are less affected than are the opposing species whose ranges are centered at lower latitudes.; Review of specimens of the species in the families Leucosiidae, Calappidae, and Parthenopidae in the waters of Cocos Island, eastern Pacific, resulted in the description of Thyrolambrus verrucibrachium and Osachila kaiserae. In addition, the split of Cryptosoma garthi from Cryptosoma bairdii, was deemed not warranted, and linear regression analysis supported the separation of the eastern Pacific Aethra scruposa from the western Pacific Aethra scutata.; A three year biodiversity survey of Guana Island, British Virgin Islands, resulted in over one thousand color photographs of the marine animals that were collected. A representative collection of these digital images, the images of the brachyuran crabs, can be found at [http://www.nhm.org/guana/home.html]. An estimation of the number of different species represented in the images indicates that nearly half of the brachyuran biodiversity of the Caribbean can be found at this one small island.