Two new species of umagillid flatworms from the 20-rayed antarctic crinoid Promachocrinus kerguelensis

• Published in: Canadian Journal of Zoology
• Main Author: Shinn, George L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1987
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Antarctic; The Antarctic; Antarctic Peninsula; Antarc*; antarcticus
• Online Access: http://dx.doi.org/10.1139/z87-159; http://www.nrcresearchpress.com/doi/pdf/10.1139/z87-159

Two new endosymbiotic turbellarians from the 20-rayed crinoid Promachocrinus kerguelensis are described from specimens collected off the western coast of the Antarctic Peninsula. Desmote antarcticus sp.n. differs from previously described members of the genus in the shape of the penis stylet, orientation of the terminal branches of the ovaries, and connections of the genital ducts to the exterior. Parafallacohospes bransfieldensis gen. et sp.n. is distinctive among known umagillids in having a pair of broad lobes projecting from each side of the body. The anatomy of the reproductive system is similar to that of Fallacohospes inchoatus Kozloff except that P. bransfieldensis lacks a secondary uterus. In addition, P. bransfieldensis has a functional digestive tract with small intestinal ceca, whereas F. inchoatus, the only species in the genus Fallacohospes, lacks a digestive tract. In this respect, Parafallacohospes appears to be intermediate between Desmote, which has large intestinal ceca, and Fallacohospes. Both new species belong to the subfamily Bicladinae, which includes all other crinoid-inhabiting umagillid flatworms.