Trichodina centrostrigeata Basson, Van As et Paperna, 1983 from Oreochromis mossambicus (Peters) and O. niloticus (Linnaeus) from different host populations from Argentina, Mexico and South Africa was reviewed. Although T. centrostrigeata has a distinct denticle structure that makes morphological taxonomic inferences uncomplicated, variation of the denticles within and among individuals and populations were still observed. While traditional taxonomy of mobilines is heavily reliant on morphometrics, and recently even more so on molecular analysis, this paper proposes the use of geometric morphometry, specifically elliptical Fourier analysis, to address morphological conflicts that arise when comparing different populations. By applying this technique, combined with traditional taxonomy, it was found that T. centrostrigeata in this study can be grouped into two separate morphotypes, the first (type a) from aquaculture farms in Argentina and Mexico and the second (type b) from a natural habitat in Glen Alpine Dam, South Africa. This study supports the validity of geometric morphometry as an additional technique to distinguish not only between species but also evolutionary plasticity of the same species from different localities and habitats.
We studied phenotypic relationships among six European Apodemus species (A. agrarius, A. epimelas, A. flavicollis, A. sylvaticus, A. uralensis, and A. alpicola) using landmark based morphometrics. Cartesian coordinates of 14 landmarks were recorded on the occlusal projection of upper molars from 175 specimens. Results revealed A. agrarius as the most distinct, having long and slender molars. Since primitive members of the genus (A. atavus, A. orientalis, A. dominans) are characterised by broad and robust molars, we conclude that A. agrarius is the most derived in this respect. Within the Sylvaemus subgenus/species group A. epimelas differed from the remaining four species in having more robust molars and a relatively longer second molar. Within the remaining four species two clusters emerged, although differences between them were slight. The flavicollis-sylvaticus tandem exhibited a relatively shorter second molar and more robust first molar. In five Sylvaemus, the robustness of molars correlated negatively with molar size, suggesting that between-species differences in molar shape result from allometric relations.