Meeting Abstract

24.4  Wednesday, Jan. 5  Molgula pugetiensis is a Pacific tailless ascidian within the Roscovita clade of molgulids MALISKA, ME*; SWALLA, BJ; University of Washington, Department of Biology and Friday Harbor Laboratories; University of Washington, Department of Biology and Friday Harbor Laboratories mem24@uw.edu

The molgulid ascidians are a monophyletic group of tunicates that share specific morphological features, including a heart/kidney complex and hermaphroditic gonads found on both sides of the adult. The larval body plan, however, is quite plastic, with tailless species evolving at least four times independently within the molgulids. The Roscovita clade of molgulid ascidians includes three species that are found sympatrically in Roscoff, France, and includes both tailed and tailless species. Molgula pacifica is a direct developing tailless molgulid ascidian within the Roscovita clade found on the outer coast of Vancouver Island. The “larvae” never hatch, and the adult juveniles undergo metamorphosis within the chorion. Molgula pugetiensis is a molgulid ascidian found in the San Juan Islands, but the development of it has not been reported. Here, we show that this species is a tailless ascidian species that hatches from the chorion, similar to the well-described tailless Molgula occulta, from Roscoff, France. Immediately after hatching, the tailless larva develops ampullae and proceeds with metamorphosis, completely lacking a tadpole larval stage These results also predict that there are tailed molgulid ascidians within the Roscovita clade in the Pacific.