Spurwinkia: Morphology, Systematics, and Ecology of a New Genus of North American Marshland Hydrobiidae (Mollusca: Gastropoda)

Abstract

-Spurwinkia is described as a new genus of Hydrobiidae (Gastropoda: Prosobranchia: Rissoacea). The type species, S. salsa (Pilsbry), inhabits high marsh pools from Maine to Connecticut and possibly to the DELMARVA Peninsula with salinities of 0-29%o and is frequently sympatric with Hydrobia truncata Vanatta. The definition of the Hydrobiidae was expanded to include this genus. New character-states are: (1) an anterior lobe of the digestive gland; (2) a prostate posterior to the posterior end of the mantle cavity; (3) a spermathecal duct separated from the closed pallial oviduct; (4) an oviduct that opens into the albumen gland; and (5) a connection of the oviduct to the bursa complex by a sperm duct opening into the duct of the seminal receptacle. Spurwinkia is placed in the subfamily Littoridininae because of close morphological resemblance to South American taxa here considered Heleobia but known in the literature as Littoridina. Cladistic relationships are presented but tentative due to lack of data for Heleobia and related taxa. [anatomy, cladistics, ecology, Hydrobia, Hydrobiidae, Hydrobiinae, Littoridininae, North America, Spurwinkia, systematics] The Hydrobiidae comprise a major group of deposit feeding invertebrates of estuaries and salt marshes along the east coast of the United States (Hershler and Davis 1980). There is considerable current interest in hydrobiid snails by ecologists interested in population biology, reproduction, resource use, sympatric interactions, character displacement, behavior, and niche partitioning (Russell-Hunter and Russell-Hunter 1962; Newell 1964, 1965; Fenchel 1975; Anderson 1971; Hylleberg 1975; Fenchel, Kofoed, and Lappolainen 1975; Fenchel and Kofoed 1976; Levinton and Lopez 1977; Lopez and Levinton 1978; Wells 1978; Barnes and Greenwood 1978; Lassen 1979; Levinton 1979; Barnes 1981a, b). Ecological studies depend upon reliable species identifications and reliable systematic analyses. A reliable systematic foundation for North American hydrobioid saltmarsh snails has yet to be established. Only Hydrobia truncata Vanatta has had the indepth morphological analysis (Hershler and Davis 1980) necessary for systematic comparisons with other regional North American hydrobioid taxa. Only a partial analysis has been provided for H. totteni Morrison (Davis 1966). There are, as far as is known, three spe-