Physalia megalista

Physalia megalista is a species of colonial siphonophore in the genus Physalia. As with other Physalia, it is composed of multiple specialised zooids that function together as a single floating colony, including a gas-filled pneumatophore (float) and trailing tentacles bearing nematocysts.

The species name was introduced by Charles Alexandre Lesueur and Nicolas-Martin Petit in 1807, based on an illustrated plate published in the atlas of the Baudin expedition. For much of the 19th and 20th centuries, many Physalia records were assigned to Physalia physalis, and P. megalista was widely treated as a synonym, contributing to nomenclatural and identification uncertainty.

Recent morphological reassessment, together with global genomic and population-genomic analyses, supports recognition of P. megalista as a distinct lineage within Physalia and links modern specimens to the 1807 illustration. Species-specific ecological, reproductive and distribution data remain limited in the available literature.