A new genus of the ‘Pitar’ group (Bivalvia: Veneridae) from the Western Atlantic Ocean revealed by geometric morphometric analysis

Abstract

Understanding shell morphology is central to taxonomic and evolutionarystudies of bivalves. When traditional systematic studies find limitations in therecognition and classification of taxa, geometric morphometrics methods become a toolto tackle these uncertainties. Taxonomic difficulties are frequently found in systematicsstudies of the generally homoplastic Pitarinae (Venereidae). Recent contributions haveproposed that Neogene-Recent South American species traditionally assigned to Pitarsensu stricto showed a distinguishable morphology that allowed separating themfrom that genus, including them in Proteopitar. In this contribution, we perform twomorphometric analyses: elliptic Fourier analysis (EFA) and 2D landmark analysis with theaim of evaluating the intra- and interspecific variation of these taxa from the WesternAtlantic Ocean included in Pitar s.s. to evaluate its doubtful generic assignments. EFAresults show a highly variable outline in Proteopitar patagonicus, superimposed in themorphospace of all other taxa. The three analyzed groups, Pitar, Proteopitar, and extantWestern Atlantic Ocean species, are statistically differentiable in hinge morphologies(landmark analysis), as corroborated by the Discriminant Function Analysis. The lattertaxa are also distributed in a restricted portion of morphospace in EFA and along withthe recognition of additional morphological differences allow us to define the newgenus Jasypitar.