The species assigned to the genus Leitoscoloplos are re-examined. With the inclusion of five new taxa (L. geminus sp. nov., L. geminus provincialis subsp. nov., L. banzareae sp. nov., L. mammosus sp. nov., L. obovatus sp. nov.), seventeen species and two subspecies are now recognized. A further four species are newly referred to the genus Scoloplos: S. armiger alaskensis (HARTMAN, 1948), S. normalis (DAY, 1977), S. intermedius (HARTMAN, 1965), and S. similis sp. nov. (for Haploscoloplos cf. fragilis DAY, 1963).
The status of the genus Leitoscoloplos and its relationship to Scoloplos are discussed. Identification of species is shown to require the combined consideration of several characters, some of which vary with size and age. A tabular guide to the species of Leitoscoloplos is given. Using a combination of features, five morphological groupings can be discerned. Of these, the L. kerguelensis group is the most morphologically and geographically cohesive. This observation suggests some degree of vicariance within the genus or, further, may be indicative of polyphyletic origins.