Portal de Periódicos da CAPES

Phylogenetic relations and the early evolution of the class Bivalvia

1978; Royal Society; Volume: 284; Issue: 1001 Linguagem: Inglês

10.1098/rstb.1978.0064

2054-0280

O. A. Scarlato, Ya. I. Starobogatov,

Aquatic Invertebrate Ecology and Behavior

By virtue of the structure of the shell, the morphology of the heart and gills and the characteristics of the larval form, the Bivalvia are sharply distinct from other Conchifera. The closest allies of the Bivalvia are the Polyplacophora and Aplacophora, and these three should be united in the subphylum Peltophora, the remaining molluscan classes being contained in the Cochleophora. After the first phylogenetic appearance of the Bivalvia (close to the most primitive Polyplacophora), the following stages ensued: (1) formation of a hypothetical monomyarian form with a straight dorsal margin; (2) formation of the Protobranchia; (3) formation of the Autobranchia, with ciliary water-transport and suspension-filtering gills; (4) formation of the Septibranchia, with a pallial septum forming a membrane pump; (5) adaptive radiation of the three above mentioned superorders. Arguments are considered in favour of the opinion that the Rostroconchia constitute an order of the Septibranchia rather than a separate class. A proposed scheme of the phylogeny and systematics of the Bivalvia is presented.