Marine gastrotrichs from Lanzarote, with a description of a phylogenetically relevant species of Urodasys (Gastrotricha, Macrodasyida)

Sampling campaign took place in October 2011 and included 7 locations and 16 stations along the eastern coast of the island of Lanzarote (Spain). Samples yielded 61 species for a total of 96 records. Thirty-six species (27 genera and 11 families) belong to Macrodasyida while 25 species (18 genera, 7 families) to Chaetonotida. Thirty-two are known species while 29 appear to be undescribed taxa or putatively so. The finding at Lanzarote of some of the known species bear particular significance: Oregodasys cirratus and Tetranchyroderma canariense are recorded for the second time ever, while Musellifer delamarei and Urodasys acanthostylis were previously known only from the Mediterranean, and Urodadys mirabilis was acknowledge only for northern Europe. Furthermore, the presence in the island of Chaetonotus apechochaetus, C. apolemmus, C. siciliensis, Heterolepidoderma loricatum, Lepidodasys unicarenatus, Musellifer delamarei, Thaumastoderma mediterraneum, and Urodasys acanthostylis, strongly suggest them to be part of the temperate/warm fauna that invaded the Mediterranean basin after the Missinian crisis during the different climate eras. Of the new species, one is described as its characteristics widen substantially our knowledge on the entire genus. Urodasys completus sp. nov. is unique in that it possesses, among others, two testes and a sclerotic stylet. Results of a phylogenetic analysis indicated that the sequence of the evolutionary transformation that have occurred in the reproductive system of the species of Urodasys are likely dissimilar from the ones proposed thus far. The overall results testify the need to continue the exploration in the Canary Islands.