MORPHOLOGICAL CHARACTERIZATION OF 3 PHENOTYPES OF THE ISOPOD ARMADILLIDIUM-VULGARE

The morphological characteristics and ommochrome quantity in the integ ument of red, white, and wild type (black-grey) Armadillidium vulgare were studied. The red phenotype was found to possess two kinds of imma ture ommochrome pigment granules within its pigment cells, in addition to mature pigment granules. The immature granules seemed to contain u niformly distributed fibrilles, or to have an electron-dense central r egion surrounded by an electron-lucent outer edge. Since these immatur e pigment granules were typically observed to be distributed along wit h the mature ones, and were also more easily extractable than the wild type's, it is hypothesized that ommochrome granule maturation in the red phenotype may occur slowly due to a defect in the pigment granule internal process which combines pigments with matrix proteins. Regardi ng the white phenotype, although its pigment cells were undeveloped, s everal large-sized vesicles containing a small amount of electron-dens e material appeared in the pigment cell cytoplasm. The wild and red ty pe males of A. vulgare were found to have an ommochrome content twice as large as that of the corresponding females, with no ommochrome pigm ent being detected in the white phenotype. The genetic relationship be tween the white and red phenotypes was discussed using as a basis the observed pigment granule structure.