Аннотация:The combined sequences of 18 and 28S rRNA genes in Pacific brachiopod Coptothyris adamsi (Davidson, 1871) were studied. On the phylogenetic trees combined gene sequences of 18 and 28S rRNA, brachiopods with phoronid positioned as statistically well-supported monophyletic group within Lophotrochozoa, occupying a position on the tree between the molluscs and annelids, i.e. within the group protostomes animals. In this phoronid take basal position, in the clade called Brachiozoa, and brachiopods are divided into two groups corresponding to the castle (Rhynchonelliformea) and inarticulate (Linguliformea and Craniaformea). Thus, the similarity of sperm in semen brachiopods and echinoderms should be regarded as homoplasy. The similarity of the structure of gametes of lingulyat and kraniat supports the view that the inarticulate brachiopods as a class-wide taxon rank should be saved when compared with other Lophotrochozoa, in particular phoronid, bryozoans, and molluscs.
Ancestors of brachiopods quite early split from the trunk of bilaterally symmetrical animals. Therefore, brachiopods are so different from each other in a number of important characteristics such as sperm morphology, type of cell division, the way of gastrulation, the chemical composition and structure of the shell. All these features are reflected in the diagnoses of classes, united in a phylum and superphylum taxons Brachiozoa.