Аннотация:Organization of the lophophore is an important point in frame of the problem of
the lophophorates monophyly. Although the lophophorates monophyly was supported by
anatomical and embryological data and by few results of molecular phylogeny, most of
molecular data reject the unity of the lophophorates because of specific phylogenetic position
of bryozoans. The detailed investigation of the lophophore, which is the morphological
peculiarity of the lophophorates, may help to clarify question of the lophophorates
monophyly. Neuro-muscular system of the lophophore was investigated in four phoronid
species with different types of the lophophore organization: Phoronis ovalis, Phoronis
ijimai, Phoronis australis, Phoronopsis harmeri. Comparative analysis of new data
revealed that the simplest lophophore of tiny P. ovalis is innervated by more numerous
nerves than complex lophophores of other studied phoronid species. Nervous system of
P. ovalis lophophore consists of the dorsal ganglion, the tentacular nerve ring, the inner
nerve center, and the inner nerve ring, which gives rise to the frontal and laterofrontal
tentacular nerves. Serotonin-like immunoreactive flask-like cells are located on inner
nerve ring between tentacles at their base. The presence of these cells, peculiarities of
innervation of tentacles, and the presence of the inner nerve ring make the nervous system
of the lophophore of P. ovalis different from the nervous system of the lophophore of
other adult phoronids and similar to the nervous system of the lophophore of bryozoans.
This similarity allows to regard P. ovalis as a connecting link between phoronids and
bryozoans. Project is supported by RFBR (17-04-00586).