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Marstonia
''Marstonia'' is a genus of freshwater snails with a gill and an operculum (gastropod), operculum, aquatic animal, aquatic gastropod mollusks in the family Hydrobiidae. Distribution Species in the genus ''Marstonia'' are distributed in springs, streams and lakes in eastern North America. Most of these species have extremely narrow geographic ranges and consequently have become a focus of conservation activities; two are federally listed as endangered and others are variously listed by state wildlife agencies. Description The freshwater gastropod genus ''Marstonia'' is composed of 15 small (shell height < 5.0 mm), ovate- to elongate-shelled species. ''Marstonia'' differs from the other eight North American nymphophiline genera in that the (female) oviduct and bursal duct join well in front of (instead of behind) the posterior wall of the pallial cavity. It has also been resolved as a well supported sub-clade within its ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marstonia Comalensis
''Marstonia comalensis'' is a species of minute freshwater snail with a gill and an operculum, an aquatic gastropod mollusk or micromollusk in the family Hydrobiidae. It is found in south central Texas, United States. ''Marstonia comalensis'' is large for this genus. It has an ovate-conic, openly umbilicate shell. The penis has a short filament and oblique, squarish lobe bearing a narrow gland along its distal edge. It is well differentiated morphologically from other congeners that have similar shells and penes, and is also genetically divergent relative to those congeners that have been sequenced ( mt COI divergence 3.0–8.5%). This species has often been confused with ''Cincinnatia integra''. Taxonomy In 1906, Henry Augustus Pilsbry and James Ferriss described this species under the name ''Amnicola comalensis'' based on six shells from Comal Creek and the Guadalupe River near New Braunfels, south-central Texas. Pilsbry and Ferriss differentiated this species from '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
