Two new species of Syndesmis (Platyhelminthes, Rhabdocoela, Umagillidae) from the sea urchin Pseudechinus magellanicus (Echinodermata, Echinoidea) in the Southwestern Atlantic Ocean

• Published in: International Journal for Parasitology: Parasites and Wildlife
• Main Authors: Francisco Brusa, Martin M. Montes, Paula Marcotegui, Sergio R. Martorelli
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2017
• Subjects: Turbellaria; Parasites; South Atlantic Ocean; Zoology; QL1-991
• Online Access: https://doi.org/10.1016/j.ijppaw.2017.03.002; https://doaj.org/article/499ff3f5bf614c409195f745b4d6afbb

In this paper, we describe two new species of Syndesmis living in Pseudechinus magellanicus in the Southwest Atlantic Ocean. The new species have a long stylet in the male reproductive system, which is different from that of the known species of the genus. Specimens of Syndesmis selknami n. sp. have a ∼220-μm-long stylet (∼1/3 of the body length, 0.69 mm). This ratio is unique because only four species (Syndesmis echinorum, Syndesmis rubida, Syndesmis inconspicua and Syndesmis echiniacuti) have similar stylet lengths but are larger in body sizes (3–5 mm). Specimens of Syndesmis aonikenki n. sp. have a ∼148-μm-long stylet (∼1/10 of the body length, 1.11 mm). Syndesmis pallida has a similar ratio but the uterus is located posteriorly, and the filament glands are very small and located in the posterior region of the body. These are the first flatworms reported parasitizing Pseudechinus magellanicus.