This catalog lists all published species-group and genus-group names that have been applied to the nonmarine gastropod fauna of the Samoan Islands. Politically, the archipelago is composed of Samoa (known until recently as Western Samoa) and American Samoa (see map). In this catalog, to avoid confusion, the use of "Western Samoa" is retained, with "Samoa" and "Samoan" referring to the entire group of islands. In overall format the catalog follows the Hawaiian catalog of Cowie et al. (1995). Full citations are given for the original proposal of each name. The current status of each name, according to the most recent authoritative revision, is indicated. The type locality and location of type material, if known, is given for all available species-group names. The island(s) within the Samoan Archipelago on which each valid taxon is known to occur is (are) indicated. Background information on each major group (family, genus) is provided, with an introduction to other relevant literature, making the catalog a basic source of reference for studies on the Samoan fauna. Following the main body of the catalog, a checklist of all the names is provided for ease of reference. Extralimital junior synonyms of Samoan taxa, i.e., names that have been applied to these taxa only outside Samoa, are excluded from the catalog, although sometimes they may be noted in Remarks sections for clarity.

Many of the early descriptions were published by Augustus Addison Gould, Constant Récluz (predominantly Neritidae), and Albert Mousson, between 1840 and 1871. Gould’s material derived from the United States Exploring Expedition. All the names proposed by Gould have been listed by Johnson (1964), with details of type localities and type material. Récluz worked on material from a wide range of sources (see Kabat & Finet, 1992). Mousson’s species were largely based on material from the Museum Godeffroy in Hamburg and due mostly to the collecting efforts of Édouard Graeffe. Catalogs of the Museum Godeffroy were published by J.D.E. Schmeltz around the same time as Mousson was publishing his descriptions. Dates of publication of the Schmeltz catalogs and of Mousson’s publications (see Bibliography) reveal that in a large number of cases, names, although attributed to Mousson by Schmeltz, appeared first as nomina nuda in the catalogs. All these names are listed herein if Schmeltz gave a Samoan locality. Other authors of note who described significant numbers of Samoan taxa include Lovell Reeve in the Conchologia Iconica, Louis Pfeiffer, William Harper Pease (see Kay & Clench, 1975), and more recently for specific groups, William Clench and Elizabeth-Louise Girardi (Cyclophoroidea) and Alan Solem (Endodontoidea). Unfortunately, a number of groups have not been treated recently and it is likely that some taxa listed here will ultimately prove to be junior synonyms or misidentifications of other, extralimital or widely distributed taxa. Others, especially small species, await discovery or description.

The native Samoan land snail fauna includes 94 nomenclaturally valid species, including the supralittoral Ellobiidae (18 species), but excluding the Siphonariidae, which although pulmonates are intertidal and subtidal, and excluding those species that are recorded from Samoa with doubt (14 species). Of these 94 species, 59 are endemic to Samoa, with 34 of these 59 recorded only from single islands. A number of species of land snails and slugs have been introduced to the Samoan Archipelago through human activities, both inadvertently and deliberately. Those that have been reported in the literature (18 species) are listed. There is no recent treatment of the terrestrial fauna as a whole.

The fresh- and brackish-water snail fauna of Samoa has most recently been reviewed by Starmühlner (1992b, 1993, see also 1976). However, the major work (Starmühlner, 1993) focused almost entirely on his own material collected on Tutuila and ‘Upolu, and a number of taxa known to occur on those islands were not included, although some were listed in the shorter paper (Starmühlner, 1992a). Taxa known only from other islands were generally not dealt with. He included a number of littoral taxa that are treated here as marine and therefore excluded from this catalog. The only other major recent survey of the freshwater fauna is that of Haynes (1990), from whose paper additional records of taxa and distributions have been obtained. Her study is also based only on her own collecting activities on Savai‘i, ‘Upolu, and Tutuila and thus, from an archipelago-wide perspective, suffers from the same limitations as that of Starmühlner. This catalog lists 46 nomenclaturally valid species of fresh- and brackish-water snails. Only a very small proportion of this fauna is endemic to Samoa (3 species of Thiaridae), and even these taxa may ultimately prove to be junior synonyms or misidentifications of other extralimital or widely distributed taxa. For many of the species it is not at all clear whether they have been artificially introduced or whether they occur naturally in Samoa, although Haynes (1990) favored the latter for most species.

It must be stressed that this catalog is derived from the literature and incorporates no revisionary treatment of the fauna. It is a nomenclatural not a taxonomic work. Many groups have not been treated recently, and modern revisionary study would certainly change the status of many included taxa, especially in the freshwater fauna.

As is the case in much of the Pacific, the diverse and highly endemic terrestrial snail fauna of Samoa, and perhaps to a lesser extent the fresh- and brackish-water fauna, is severely threatened with extinction. Many species are no doubt already gone. Habitat destruction, due both to urban and agricultural development and to inadvertent but extensive replacement of native vegetation with introduced plant species, is of major significance. Introduced predators, including rats and ants, have also no doubt had an impact, but the recent introduction of the carnivorous snail Euglandina rosea in attempts to control the giant African snail, Achatina fulica, has had drastic consequences. At the time of writing, E. rosea has only been introduced to Tutuila and Ta‘u. It is important that it is kept out of the other islands. This catalog is intended as a basic reference not only for systematists but also for evolutionary biologists, ecologists, conservation biologists, and resource managers, all of whom can contribute to saving this unique fauna.