Molgula manhattensis (De Kay, 1843)
This species is a simple, solitary ascidian, that sometimes grows in dense clusters. The body is globular in shape, measures 1-4 cm in diameter, and attaches to the substrate at its base. The oral and atrial siphons are positioned anteriorly, and prominent when extended. Overall, the tunic is translucent to greyish-green in colour; the surface is covered with numerous tiny hair-like fibrils, often fouled with pieces of shell, algae, or sediment. A bean-shaped kidney is located on the right side of the body, and along with the reproductive gonads, is often visible through the tunic.
In the Northeast Pacific, Molgula manhattensis is most similar to to other molgulid tunicates, including M. pacifica (Huntsman, 1912), M. pugetiensis Herdman, 1898, and M. verrucifera Ritter and Forsyth, 1917; another non-native species found in the region, M. ficus (Macdonald, 1859); and in Alaska, M. retortiformis Verrill, 1871 and the recently documented M. citrina Alder and Hancock, 1848.
Ecology and Distribution
Molgula manhattensis has been introduced to the Northeast Pacific, with confirmed records from British Columbia to California. In addition, this species has been introduced to several other locations around the world, including Australia, China, and Japan. In Great Britain and northern Europe, the species is considered cryptogenic. Its native geographical range includes the northeast United States from Maine to Louisiana.