title: Two new species ofSyndesmis(Platyhelminthes, Rhabdocoela, Umagillidae) from the sea urchinPseudechinus magellanicus(Echinodermata, Echinoidea) in the Southwestern Atlantic Ocean.
abstract: In this paper, we describe two new species ofSyndesmisliving inPseudechinus magellanicusin 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 ofSyndesmis selknamin. 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 inconspicuaandSyndesmis echiniacuti) have similar stylet lengths but are larger in body sizes (3-5 mm). Specimens ofSyndesmis aonikenkin. sp. have a ∼148-μm-long stylet (∼1/10 of the body length, 1.11 mm).Syndesmis pallidahas 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 parasitizingPseudechinus magellanicus.
authors.affiliation: División Zoología Invertebrados, Facultad de Ciencias Naturales y Museo (UNLP), Boulevard 120 & 61 (B1902CHX) La Plata, Buenos Aires, Argentina; CONICET - Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina.
authors.forename: Francisco
authors.initials: F
authors.lastname: Brusa
authors.affiliation: Centro de Estudios Parasitológicos y Vectores (CEPAVE), Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de La Plata (CCT-La Plata-CONICET -UNLP), Boulevard 120 S/N e/61 y 62 (B1902CHX) La Plata, Buenos Aires, Argentina.
authors.forename: Martin M
authors.initials: MM
authors.lastname: Montes
authors.affiliation: Centro de Estudios Parasitológicos y Vectores (CEPAVE), Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de La Plata (CCT-La Plata-CONICET -UNLP), Boulevard 120 S/N e/61 y 62 (B1902CHX) La Plata, Buenos Aires, Argentina.
authors.forename: Paula
authors.initials: P
authors.lastname: Marcotegui
authors.affiliation: Centro de Estudios Parasitológicos y Vectores (CEPAVE), Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de La Plata (CCT-La Plata-CONICET -UNLP), Boulevard 120 S/N e/61 y 62 (B1902CHX) La Plata, Buenos Aires, Argentina.
authors.forename: Sergio R
authors.initials: SR
authors.lastname: Martorelli
keywords: Parasites; South Atlantic Ocean; Turbellaria