2011 Volume 69 Issue 3-4 Pages 177-194
In Yamaguchi Prefecture, there are found Trishoplita eumenes eumenes and Trishoplita eumenes cretacea, which both belong to the "Trishoplita eumenes" complex. These two subspecies have four forms that were described by the differences in shell coloration. There are some opinions concerning the classification of this complex. In this study, the taxonomic relationship of these two subspecies is investigated based on various morphological characters of the hard parts and on habitat preference. As a result, the distribution areas of the two subspecies have been clearly separated. Both subspecies are arboreal, but Trishoplita eumenes eumenes lives on parts of trees that are up to 1 m in height from the ground, and in meadows. On the other hand, Trishoplita eumenes cretacea lives on trees at from 1 to 3 m from the ground, and in forests. It was revealed that significant differences were found in the t-test for the diameter of the shell, the height of the shell, the angle of the apex, and the thickness of the shell. Significant differences were also found in the Mann-Whitney test for height/diameter and diameter of the umbilicus/shell diameter. In addition, these two subspecies were distinguishable in coloration and the surface quality of the shells. These results strongly suggest that these two subspecies are distinct species. So we think Trishoplita eumenes eumenes and Trishoplita eumenes cretacea are two independent species.