Molecules clarify a cnidarian life cycle--the "hydrozoan" Microhydrula limopsicola is an early life stage of the staurozoan Haliclystus antarcticus.
BACKGROUND
Life cycles of medusozoan cnidarians vary widely, and have been difficult to document, especially in the most recently proposed class Staurozoa. However, molecular data can be a useful tool to elucidate medusozoan life cycles by tying together different life history stages.


RESULTS
Genetic data from fast-evolving molecular markers (mitochondrial 16S, nuclear ITS1, and nuclear ITS2) show that animals that were presumed to be a hydrozoan, Microhydrula limopsicola (Limnomedusae, Microhydrulidae), are actually an early stage of the life cycle of the staurozoan Haliclystus antarcticus (Stauromedusae, Lucernariidae).


CONCLUSIONS
Similarity between the haplotypes of three markers of Microhydrula limopsicola and Haliclystus antarcticus settles the identity of these taxa, expanding our understanding of the staurozoan life cycle, which was thought to be more straightforward and simple. A synthetic discussion of prior observations makes sense of the morphological, histological and behavioral similarities/congruence between Microhydrula and Haliclystus. The consequences are likely to be replicated in other medusozoan groups. For instance we hypothesize that other species of Microhydrulidae are likely to represent life stages of other species of Staurozoa.
Miranda
Lucília S
LS
Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil. mirandals@ib.usp.br
Collins
Allen G
AG
Marques
Antonio C
AC
D000818:Animals; D002965:Classification; D003063:Cnidaria / Q000145:classification / Q000502:physiology*; D005819:Genetic Markers; D037402:Hydrozoa / Q000145:classification / Q000502:physiology*; D008018:Life Cycle Stages
D005819:Genetic Markers