Morphologic and genetic relationships among four species of Armadilloniscus Uljanin, 1875 (Isopoda: Oniscidea: Scyphacidae)

Three morphologically similar species of the isopod genus Armadilloniscus Uljanin 1875 (Armadilloniscus litoralis Budde-Lund, 1885; A. ellipticus (Harger, 1878); and A. holmesi Arcangeli, 1933) have been described, respectively, from Europe, and the east and west coasts of North America. Although these three taxa are geographically separated, the morphological criteria by which they can be distinguished have never been adequately delineated. We have compared these three taxa both morphologically and biochemically. We have found that A. litoralis is virtually identical to A. ellipticus both morphologically and biochemically, but that both are clearly morphologically and biochemically distinct from A. holmesi. The results of this study demonstrate conclusively that A. litoralis should be considered a junior synonym of A. ellipticus but that A. holmesi is a valid and well-defined species. The relationships among A. ellipticus and the three native American members of the genus (A. holmesi; A. lindahli (Richardson, 1905); and A. coronacapitalis Menzies, 1950) are discussed.