BIOLOGIYA MORYA, 2015, Vol. 41, No. 3, pp. 188-195

Spermatozoon structure of Coptothyris adamsi (Davidson, 1871) (Brachiopoda: Rhynchonelliformea) and analysis of 18S and 28S rRNA sequences

© 2015 A. L. Drozdov^1,3, I. P. Vladychenskaya², A. A. Lomov², S. A. Tyurin¹, N. B. Petrov²

¹A.V. Zhirmunsky Institute of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok 690041;
²Lomonosov Moscow State University, Moscow 119991;
³Far Eastern Federal University, Vladivostok 690091

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The position of brachiopods in the animal system remains controversial, with morphological data being often inconsistent with the results of molecular phylogenetic analysis. In this study, we investigated the structure of the spermatozoa and determined the combined sequences of the genes 18S and 28S rRNA of the articulate brachiopod Coptothyris adamsi (Davidson, 1871). Spermatozoa of C. adamsi are similar to those of other articulate brachiopods. Two types of sperm structure can be distinguished within Brachiopoda: the first type is characteristic of the articulate brachiopods (Rhynchonelliformea), the second type - for the inarticulate brachiopods (Linguliformea and Craniaformea). Rhynchonelliformea spermatozoa are similar to those of the deuterostome animals, in particular to the sperm of the Echinodermata, whereas Linguliformea and Craniaformea spermatozoa are similar to the typical sperm of the Trochozoa animals, such as annelids and mollusks. Molecular phylogenetic analysis has shown that the brachiopods and phoronids form two monophyletic groups within the group Brachiozoa, in which phoronids are united in a separate clade, while brachiopods are divided into two clades.

Key words: Brachiopoda, Rhynchonelliformea, Linguliformea, Craniiformea, spermatozoon ultrastructure, 18S and 28S rRNA, phylogeny, Coptothyris adamsi.