Notes on the morphometry and anatomy of some Pisidium and Sphaerium species (Bivalvia, Sphaeriidae)

The intraspecific and interspecific variation in the morphometry of Pisidium (25 recent and 11 fossil populations of 17 species) and Sphaerium (2 fossil populations of 2 species) was studied. Two simple indices, height index (100 height/length) and roundness index (100 diameter/height) were calculat...

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Bibliographic Details
Published in:Annales zoologici fennici 1982-01, Vol.19 (2), p.93-107
Main Authors: Holopainen, Ismo J., Kuiper, Johannes G. J.
Format: Article
Language:English
Subjects:
Anatomy
Biological taxonomies
Bodies of water
Bogs
Boycotts
Fauna
Fossils
Freshwater
Lakes
Pisidium
Population ecology
Population growth
Sphaerium
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Summary:The intraspecific and interspecific variation in the morphometry of Pisidium (25 recent and 11 fossil populations of 17 species) and Sphaerium (2 fossil populations of 2 species) was studied. Two simple indices, height index (100 height/length) and roundness index (100 diameter/height) were calculated and plotted against shell length. Both indices show a linear correlation with shell length: in the case of the roundness index the correlation is almost always positive but in the height index the correlation coefficient is lower and the correlation again usually positive but negative in 5 species. These kinds of morphometric index give an additional quantitative character which could be more widely used in identification. The effect of environment on shell shape and the possible relation between fecundity and shell shape are discussed. The length of the pre-siphonal suture in P. casertanum and P. subtruncatum were measured and shown to be c. 10 % and 20—25 % of shell length, respectively. The tissue around the foot slit was clearly thickened in P. subtruncatum and could be used in species identification in case of material in which the hard shells are totally corroded e.g. after preservation in formalin.
ISSN:0003-455X
1797-2450