ИСТИНА

Marine Enoplida constitute a group of free-living marine nematodes, which do not share any known morphological synapomorphy. On SSU rRNA phylogenies the group also lacks solid statistical support. In recent studies it was found that an enoplid nematode Trefusia zostericola possesses a rare nucleotide substitution within the region of hairpin 35 of the SSU rRNA secondary structure. The same substitution is common for all 17 Enoplida species studied to date, including Trefusia and Xenella (Trefusiidae), but is absent from other nematode lineages including Triplonchida and Dorylaimia. Thus, the substitution can be considered a molecular synapomorphy of Enoplida and Trefusiidae. Apart fromthis substitution, Enoplida are found to share a rare transversion in the loop of hairpin 48. This substitution is not strictly specific for Enoplida, as it is also known from Mesorhabditoidea and selected non-nematode taxa. These signatures may be used in designing specific primers and be considered as markers of the divergent sequences of marine Enoplida.