Quantitative Evaluation of Mantle Attachment Scarson the Shell of Margaritifera dahurica
A characteristic feature shared by all Margaritiferidae mussels consists in the presence of scars on the internal surface of their shells. These scars mark places of mantle attachment by specific epithelial cells. According to some authors, such parameters of mantle attachment scars as the density and degree of their manifestation can be used for the purposes of species identification. Quality indicators (numerous or few, pronounced or poorly visible scars) are typically used. However, the use of quantitative criteria is preferable. This work was aimed at developing quantitative indicators of mantle attachment scars in the freshwater pearl mussels Margaritifera dahurica for the populations of the rivers of the Amur basin (Transbaikal territory). It is shown that the density of mantle attachment scars is approximately the same for all the investigated shell samples regardless of their age. The average density of mantle attachment scars is 0.72 scars/cm<sup>2</sup>. According to a two-factor ANOVA test, the distribution of mantle attachment scars appears to be irregular across the shell surface. The highest value of the density of mantle attachment scars occurs on the caudal and anterior edges. The average diameter of mantle attachment scars for a particular individual depends on the length of the shell. This dependence can be described by the linear regression equation with a regression coefficient of 0.0012 ± 0.0001. Issues associated with the application of the investigated parameters for the purposes of mollusk species and/or genera identification are discussed.