Reproductive system morphology of Lightiella magdalenina (Crustacea, Cephalocarida): functional and adaptive implications

Abstract

The reproductive systems of adults and larvae of Lightiella magdalenina were examined. Lightiella magdalenina, similar to the best-known cephalocarida species Hutchinsoniella macracantha, is a simultaneous hermaphrodite. Although the morphology of their reproductive system is similar, L. magdalenina differs from H. macracantha in exhibiting reduced fecundity: it lays one egg, not two, per reproductive event. This is due to asynchronous development of the oocytes inside the paired female reproductive structures, which determines the maturation of a single egg at a time. The reduced fecundity of L. magdalenina could be offset by the precocious release of oocytes from the germarium, which begins the vitellogenetic process during the last larval stages. Due to this process, after their last moult, reproductive adults can have a large number of advanced vitellogenic oocytes, reducing the time required for their maturation. A possible adaptive relationship between the halved fecundity with pre- and post-hatching parental care is discussed.

Keywords:

• egg
• oocyte development
• parental care
• simultaneous hermaphroditism
• testis

Acknowledgements

We thank La Maddalena Archipelago National Park and especially Mr Mirko Ugo for logistical and technical support during the collection of specimens. This work was financially supported by the Sardinia Autonomy Region with funds from Operative Program FSE 2007-2013 L.R.7/2007 ‘Promozione della ricerca scientifica e dell’innovazione tecnologica in Sardegna’.