Study of the Taxonomy and the Inter and Intra Specific Variability of Phacopidae from the Lower Devonian of Algeria: Morphometric Approach and Meaning.

Sammanfattning: An Algerian Phacopid fauna, described by Lemaître in 1952, is reexamined here. Species arereevaluated in order to be in agreement with modern taxonomy. To characterize the size and shape of our specimens, as well as inter- and intraspecific variations, a morphometric analysis was performed. Only holaspids were analyzed. Results of our analysis show that genera can be be well differentiated thanks to quantitative methods. However, at a specific level, only Austerops lemaitrii nov. sp. is well- defined. Other species can be defined, however, thanks to quantitative methods. Shape variations during growth were also defined in order to understand the evolution of our specimens. Three species show a correlation between shape and size variations for cephala, and two species for the pygidia, which show an ontogenic control of the shape. A covariate analysis was made between the shape of the cephala and the shape of the pygidia, and all of the specimens analyzed show a covariance betweencephalic and pygidial shape.