The Chittenango ovate amber snail (Novisuccinea chittenangoensis) is a species of small air-breathing land snail in the family Succineidae, the amber snails. This species was discovered in 1905, and was reported three years later as a subspecies of the oval ambersnail, Succinea ovalis. Several taxonomic reviews took place in the subsequent decades until the end of the 1980s, when the Chittenango ovate amber snail was finally judged to be a distinct species based on chemical and morphological data.
The Chittenango ovate amber snail is endemic to the Chittenango area of Madison County, New York, United States. There is only one population, located at Chittenango Falls State Park in central New York, even though it was believed to have a broader range previously; based on fossil records, some authors argue that the distribution of this species may have been much wider in the past. In opposition to this, other authors argue that it is impossible to identify this species based on fossil records, because they only allow for examination of shell features. Shell features of species in this particular family of snails are usually not very distinctive.
Novisuccinea chittenangoensis has a small (an average of 20.9 mm in length in adult individuals), delicate, ovate shell of 3¼ whorls, with deep sutures. The shell is almost translucent, and varies in color from a chalky pale yellow to white, with a glossy surface. Several internal organs of the animal can be distinguished through the shell's outer surface. The visible soft parts of the animal are of a pale subtranslucent yellow color, with different markings during distinct stages of development.
Studies on the ecology of the Chittenango ovate amber snail are fairly recent. It is an herbivorous species which lives in the fresh spray zone of the Chittenango Falls, in partially sunlit areas with lush herbaceous growth. Several parameters appear to be influential in its habitat selection, namely humidity, substrate, temperature, vegetation, and water quality. Novisuccinea chittenangoensis is a hermaphroditic species, and its mating season is from May through July. It lays egg clusters, each one containing an average of 8 to 14 eggs, at the base of plants, under matted vegetation, or in loose, wet soil. Maturity is reached in five to eight months, and its life span is roughly 2.5 years. Some of its predators include insects, amphibians, mammals, birds, and occasionally other snails.
Since the time of its discovery in 1905, there have been many attempts to estimate the population size of this species. Results varied greatly, but the more recent ones suggest a very reduced number of individuals. This coupled with a very restricted distribution have led to the listing of Novisuccinea chittenangoensis as an endangered or threatened species. Humans frequently invade its habitat, though such disturbances have been greatly reduced by preventive measures. Recent efforts in conservation include perpetuating the extant population at a baseline size as well as maintaining captive populations.
Taxonomy
The snail was first discovered at Chittenango Falls in August 1905 by a field party from the Academy of Natural Sciences of Philadelphia. In 1908, Henry Augustus Pilsbry reported the discovery, describing the snail as a subspecies of the widely distributed Succinea ovalis. Because of this, the Chittenango ovate amber snail is referred to in many publications as Succinea ovalis chittenangoensis.Solem A. (1976). "Status of Succinea ovalis chittenangoensis Pilsbry, 1908". The Nautilus 90(3): 107-114.
Pilsbry placed Succinea ovalis in the subgenus Novisuccinea in 1948.Pilsbry H. A. (1948). Land mollusca of North America (north of Mexico). Vol. 2., Part 2. The Academy of Natural Sciences of Philadelphia. Monograph 3. 2(2): 771-790; 801-808. Alan Solem (1976) considered this snail to be merely a form of Succinea ovalis, citing similarities in genitalia and radula, and attributing shell differences to, possibly, a marked genetic mutation. Grimm (1981) considered it to be a distinct species due to external morphological differences (color and shell shape).Grimm F. W. (1981). "A review of the Chittenango ovate amber snail, Succinea chittenangoensis, Pilsbry, 1908 - a Pleistocene relict now greatly restricted in distribution". Contract report to the New York State Department of Environmental Conservation Endangered Species Unit. 30 pp. By 1981, Succinea ovalis could not be found at the Falls; however, during sampling for Hoagland's electrophoretic analyses, Succinea ovalis was found at two locations within approximately 16 kilometers of Chittenango Falls. Individuals assigned to Novisuccinea chittenangoensis appeared to be divided into two color morphs, a "gray morph" that was relatively common and widespread at the Falls, and a "red morph" that was restricted to the ledges at the base of the Falls. A preliminary analysis by Hoagland (1984)Hoagland K. E. (1984). "The succineid snail fauna of Chittenango Falls, New York: Taxonomic Status and Population Genetics". Final contract report to New York State Dept. of Environmental Conservation under Federal Aid to Endangered Species Project E-1-7. 36 pp. stated unequivocally that the red and the gray morphs were two distinct species, possibly in separate genera. Solem examined specimens of the gray morph and assigned it to Succinea putris, an introduced snail possibly from Europe which appears to crowd out all other species.Solem A. (8 May 1985). Field Museum of Natural History, Chicago. Personal communication. In: U.S. Fish and Wildlife Service. (2006).
Hoagland and Davis (1987) subsequently completed a thorough analysis, based on electrophoresis, shell morphology, and internal anatomy, of the succineids at Chittenango Falls. They divided Succinea into two genera, keeping the Old World Succinea in the genus and elevating the New World Succinea, of the Section Novisuccinea including ovalis and chittenangoensis, to the genus level.Hoagland K. E. & Davis G. M. (1987). "The succineid snail fauna of Chittenango Falls, New York: taxonomic status with comparisons to other relevant taxa". Proceedings of the Academy of Natural Sciences of Philadelphia 139: 465-526. They also determined that the Old World Succinea putris is probably a species complex and that the gray morph, although closely related to Succinea putris sensu lato, is a distinct species, which they designated Succinea sp. B. Based on these factors, the species designation Novisuccinea chittenangoensis is considered valid. Both species have been observed with red and gray morphs, bringing into question whether the earlier separation truly represented taxonomic distinctiveness. Currently, Novisuccinea chittenangoensis, Succinea sp. B, and 3–4 Oxyloma spp. are considered to be the only succineid species present at Chittenango Falls. In 2003, the U.S. Geological Survey (T. King, unpublished data) amplified and sequenced the cytochrome oxidase I region of mitochondrial DNA and the ITS-1 region of nuclear DNA in Novisuccinea chittenangoensis and Succinea sp. B. The results (sequence divergence of 10–15 percent) suggest large differences between the two species. No hybridization was observed.
Distribution
The only verified extant colony of Novisuccinea chittenangoensis is the type population, which is at Chittenango Falls, in Chittenango Falls State Park, 3.6 miles north of Cazenovia, between the towns of Cazenovia and Chittenango, in Madison County, New York. At various times in the past, the species has been thought to have a broader range. To date, although many potentially suitable colony sites have been searched, no colony has been conclusively identified as Novisuccinea chittenangoensis outside of the Chittenango Falls area.
During the summer of 1982, "sub-fossil" shells of what appeared to be Novisuccinea chittenangoensis were found in the banks on the west side of Chittenango Creek near the Falls. Grimm (1981) postulated that Pleistocene deposits of what was originally described as Novisuccinea ovalis pleistocenica (Baker, 1927)Baker F. C. (1927). "Descriptions of new forms of pleistocene land mollusks from Illinois with remarks on other species". The Nautilus 40(4): 114-120. are in fact shells of Novisuccinea chittenangoensis, and that this species was widely distributed during the Pleistocene epoch. Shell specimens have been recorded from Yarmouthian Interglacial, Sangamonian Stage, and Wisconsinan Stage deposits in the states of Arkansas, Illinois, Iowa, Michigan, Missouri, and Nebraska, and in Ontario. Alan Solem, however, questioned the assignment of the fossil succineid shell deposits to any species group. Although Hubricht (1985)Hubricht L. (1985). "The distribution of the native land mollusks of the eastern United States". Fieldiana, Zoology, New Series 24: 191 pp. page 14, map on page 96. mapped the location of extant populations of Novisuccinea chittenangoensis to include New York, West Virginia, Virginia, Tennessee, and North Carolina, with fossil records from Iowa, Illinois, Missouri, and Arkansas, Hoagland and Davis (1987) concluded that there is only one verified extant population of Novisuccinea chittenangoensis and that it is impossible to verify fossil records as being Novisuccinea chittenangoensis based on shell characteristics alone.
Description
The shell of Novisuccinea chittenangoensis is ovate, slender, acute, and of moderate thickness. The shell suture is deep. The spire is gently convex, laterally compressed, with 3¼ whorls. The spire is long, slightly less than half the shell length, and the aperture is very oblique. The shell color is subtranslucent, calcareous pale yellow to white. The surface is somewhat glossy and marked with growth wrinkles and lines. The size varies somewhat, but adult specimens of the type lot averaged 20.9 millimeters (mm) in shell length. Various adult specimens measured during the summer of 1981 and 1982 ranged from 19 to 24 mm.Aloi M. A. & Ringler N. H. (1982). "Population biology and density of Succinea chittenangoensis". Final Contract Report to New York State Dept. Environmental Conservation under Federal Aid to Endangered Species Project E-1-7. 27 pp.
Hatchlings measure 1 to 2 mm in shell length,Molloy A. W. & Norton R. A. (1993). "Establishment of a captive colony of Chittenango ovate amber snails (Novisuccinea chittenangoensis)". Interim Technical Report - DEC Contract #C002743. and yearlings average around 10 mm.Aloi M. A. (1985). "Population dynamics of a pulmonate snail adjacent to a central New York stream". Unpublished MS thesis. State University of New York, College of Environmental Science and Forestry. 116 pp. Measurements of all Novisuccinea chittenangoensis in 2002Arrigoni J. E. Jr. (2002). "Mark-release-recapture study of the Chittenango ovate amber snail (Novisuccinea chittenangoensis Pilsbry), July–October, 2002". Final Report to New York State Department of Environmental Conservation Endangered Species Unit. ranged from 7 to 23 mm.
The base color of the living animal is very pale subtranslucent yellow. The mantle, kidney, and hepatopancreas are visible through the shell but are often slightly obscured by the thickness of the shell. The dorsal surface of the mantle is pale yellow, tinted with olive, often marked with black streaks and blotches. Over the hepatopancreas is a golden yellow tessellation that is marked with gray or black spots and streaks. A dark marking on the posterior surface of the foot is distinctive.Thomee E. T. (1986). "Behavioral ecology of the endangered Chittenango ovate amber snail Succinea chittenangoensis and a sympatric introduced succineid". Unpublished MS thesis. State University of New York, College of Environmental Science and Forestry. 227 pp. However, the mark is not present on the hatchlings, making them impossible to identify in the field. The mark becomes obvious once the snail reaches approximately 6 to 9 mm in length.
Ecology