BIOLOGIYA MORYA, 2016, Vol. 42, No. 2, pp. 104-114 |
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Original description of larval stages of Phoronis australis Haswell, 1883 and analysis of World fauna of phoronid larvae 1Department of Invertebrate Zoology, Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow 119899; E-mail: Phoronida is a phylum of marine invertebrates; they have a worldwide distribution and form huge benthic aggregations in some areas. The taxonomy of Phoronida remains very poorly developed: with only 13 species of phoronids described all over the world, about 40 varieties of competent larvae are known. Morphological description of larval Phoronida and the search for correspondence between the larval and adult forms make an important contribution to the taxonomy of this mysterious group. We present here an original description of larval forms of Phoronis australis Haswell, 1883. The larvae and adults of P. australis were collected in the plankton of Nhatrang Bay, South China Sea. For the first time, the external morphology of larval forms of P. australis is presented at the stages of 4, 8, and 20 tentacles. The basic species-specific traits of Phoronis australis larvae have been distinguished: opaque integuments, the presence of a characteristic dark pigmentation of the oral field epidermis, of the unpaired ventral hepatic outgrowth of the stomach, and more than 20 tentacles in the competent larvae. A molecular genetic analysis based on comparison of DNA sequences of nuclear genes 18S rDNA and 28S rDNA has confirmed the identity of the phoronid larvae found in the planktonic samples from Nhatrang Bay and adult P. australis collected in the same area. The problems of Phoronida taxonomy and correspondence of larval and adult forms can be solved only with a complex approach involving both morphological and molecular-genetic information. Key words: Phoronida, taxonomy, 18S, 28S, morphology, larvae. |
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