Distribution and biology of Lightiella magdalenina (Crustacea, Cephalocarida)

Lightiella magdalenina is the more recently cephalocarid species described (La Maddalena Archipelago, Sardinia). This first important finding in the Mediterranean sea fills a gap in the distribution of the genus and of the entire class. The aim of the present study is to report some information about distribution and biology of this cephalocarid species. L. magdalenina, like most cephalocarid species, shows a pronounced anamorphic mode of development with a gradual and sequential addition of segment and limbs throughout more of 17 stages of development. It is currently known from a single locality where 55 specimens have been found during more than nine years of sampling. The Type locality is characterised by muddy sand bottom, very rich in organic matter with leaf fragments of Posidonia oceanica; grain size analysis, has underlined that sand is a very fine sand with an organic component of 95%. Zoobenthos was composed of 11 different taxa; Cletopsyllidae and Normanellidae Copepoda are unknown for Italy. A new species of family Cletopsyllidae, Isocletopsyllus sp. nov. has been identified. Up to present, only one species Hutchinsoniella macracantha, have been studied at molecular level. We report the partial sequences of two mitochondrial genes of relevant importance for phylogenetic analysis (cytochrome c oxidase I and cytochrome b) from Lightiella magdalenina. A reduced median network analysis clarified the genetic relationships between the two cephalocarid species.