This species belongs to the Didemnidae, a family in which zooids form two morphologically distinctive buds--a thoracic bud producing the new branchial basket and brain, and an abdominal bud producing the new gastrointestinal tract and heart.
listerianum forms one thoracic bud containing the branchial basket including the ganglion, and an abdominal bud that includes the stomach region (Fig.
The branchial basket in adult Diplosoma listerianum zooids possesses several zones of active cell proliferation (Fig.
Swalla and Gretchen Lambert examined this adult specimen and found seven folds in the branchial basket; genomic DNA was then extracted and sequenced in the Swalla laboratory (4) (GenBank accession number AY903920.1 for 18S rDNA).
Although none of these species have yet been sequenced, the six folds in their branchial baskets would suggest that all of them may be more closely related to the Woods Hole Molgula clade.