APPLICATION OF GEOMETRIC MORPHOMETRICS TO THE GENUS LENTICULINA (LAMARCK)

The Foraminiferal genus Lenticulina (Lamarck) has a long and complex history. Over 650 species names have been assigned to the genus and various subgenera. In addition, to the confusion generated by numerous species names, multiple species have reported ranges greater than 20 million years. In part the taxonomic confusion arises from the relatively simple morphology of the genus. Lenticulina has a planisprial generally involute form with varying degrees of ornamentation. As a result most species descriptions have emphasized the number of chambers in last whorl, apertural characters and ornamentation. All of these characters vary within and between populations resulting in unstable diagnosis of species.

Geometric Morphomterics shows promise in clarifying the definition and variation of species within Lenticluina. The identification of a set of landmarks or pseudo-landmarks that can be located on all specimens allows for consistent quantification of variation within and between taxa. In addition, the use of landmark data allows reproduction and testing of taxonomic ideas without reliance on subjective descriptors. In this study 12 landmarks and pseudo-landmarks were identified in the lateral view of the holotypes of 27 species assigned to Lenticulina. Pseudo-landmarks were used to capture the test shape due to a lack of homologues points in test after posterior to the ultimate chamber. Preliminary analysis of this data indicates quantifiable differences between species and groups of species which will lead to a stable taxonomic structure and allow revision of the genus.