Exploration of morphospace using Procrustes analysis in statoliths of cuttlefish and squid (Cephalopoda : Decabrachia) - Evolutionary aspects of formdisparity

This paper reports on a pilot study using, for the first time, a Procrustes type analysis of shape in exploring the morphospace of cephalopod statolit hs. A total of 12 species of cuttlefish and squid (Decabrachia) from the Me diterranean were analyzed, based on 18 homologous points (landmarks) chosen on the anterior statolith surface. For two species (one cuttlefish, one lo liginid squid) size ranges were sufficiently large to reveal ontogenetic tr ends in statolith. Comparisons between species resulted in four well-define d sets of statolith morphology corresponding, respectively, to (1) sepiid c uttlefish, (2) Rossia (a large sepiolid squid), (3) myopsid squids, (4) oeg opsid squids and small sepiolids. The morphological ''dissociation" of larg e and small sepiolids suggests a relation between statolith size and shape " distinctness." and draws attention to the possibly paedomorphic shapes at the lower end of the size scale.