APPLYING GEOMETRIC MORPHOMETRICS TO SIBLING SPECIES OF POLYSTIRA (GASTROPODA:TURRIDAE)
Morphometric methods have been developed to examine shape in a replicable mathematical manner, and are ideally suited for applying to the problem of distinguishing sibling species. Here, they were applied to Polystira, a hyper-diverse monophyletic clade of gastropods endemic to the tropical and subtropical Americas which molecular work has shown to contain sibling species. As Polystira has a character rich shell with a wide range of ornamentation, which can be homologised, it is ideal for carrying out morphological studies in conjunction with genetic data.
Two methods, relative warp analysis and extended eigenshape analysis, were applied to a traditional species in an attempt to distinguish and delimit its sibling members. The methods were able to distinguish three sibling species and produce easily interpretable and biologically meaningful results. Specimens representing unknowns could then be compared to the known species to aid identification.