Marrus claudanielis, a new species of deep-sea physonect siphonophore (Siphonophora, Physonectae)

Marrus claudanielis, a new species of deep-sea physonect siphonophore, is described from material collected by the ROV TIBURON, off California (eastern North Pacific), and the submersible JOHNSON-SEA-LINK II, off New Jersey (western North Atlantic). Marrus claudanielis is extremely fragile and all observed specimens autotomized some of their parts during observation or collection, due to the strong contraction of the stem. The siphosomal elements, the nectophoral and bracteal canals, and the pneumatophore were all deep red in life. This species is distinguished from other Marrus species by the undivided apico-lateral ridges on the nectophores, and the hook-shaped arc of enlarged ectodermal cells, including nematocysts, overlying the distal branches of the bracteal canals.