Three new Echinoderes (Kinorhyncha, Cyclorhagida) from North Spain, with new evolutionary aspects in the genus

Abstract

Three new species of the kinorhynch genus Echinoderes from the north coast of Spain are described through light microscopy and scanning electron microscopy (SEM): Echinoderes isabelae n. sp., Echinoderes neospinosus n. sp., and Echinoderes parrai n. sp. Diagnostic characters of E. isabelae n. sp., E. neospinosus n. sp. and E. parrai n. sp. are given. Examination of body proportions in the genus Echinoderes has revealed that two different trunk shapes can be distinguished: the fusiform shape and the bulbous shape. These trunk shapes mostly depend on differences in width of anteriormost trunk segments. In the fusiform shape, the anterior margin of segment 3 is narrower than the posterior margin, while in the bulbous shape the anterior and the posterior margins of the same segment are more or less of similar width. The study of middorsal spine patterns in the genus, together with sensory spot types and trunk shapes allow us to suggest an initial hypothesis for two evolutionary lines within the genus Echinoderes in accordence with two proposed patterns for alternative middorsal spine loss. Such hypothesis needs to be evaluated and completed along with future descriptions of new species.