External morphology of barnacle cypris larvae in the family Poecilasmatidae (Cirripedia: Thoracica: Pedunculata): Toward a template for scoring cypris characters

The morphology of the cypris larvae of four genera of pedunculate lepadomorph barnacles of the family Poecilasmatidae (Megalasma, Octolasmis, Poecilasma and Temnaspis) was studied with SEM, focusing on the carapace with lattice organs, thoracopods and abdomen with furcal rami. The morphology of adult poecilasmatid barnacles presents few if any convincing autapomorphies for the family. Cypris characters provide additional data to help confirm the monophyly or paraphyly of the Poecilasmatidae. The form and distribution of the lattice organs and the morphology of the telson with its furcal rami, as well as adult morphology, suggest paraphyly, but we refrain from implementing any cladistic analysis of the Poecilasmatidae based on this limited dataset. Instead, we take the first critical step by formalizing our observations into a preliminary matrix of 10 cypris characters that may be considered as a base for further studies. Several cyprids of Megalasma minus were infested with parasitic benthimermithid nematode larvae.