First record of endoparasitism of Pycnogonida in Hydrozoan polyps (Cnidaria) from the Brazilian coast

Abstract

Abstract:Despite the relatively high number of recent studies on Cnidaria off the Brazilian coast, we have observed only two records of parasitism on macromedusae and none on polyps. Endoparasitic associations between Pycnogonida larvae and hydroids have been well known since the early 20 th century. Protonymph larvae develop inside the gastrovascular cavity of polyps, typically gastrozooids, which are then called gallzooids. This short communication is an unprecedented record of parasitism on the polyps of Brazilian cnidarian fauna. The parasitic association between Pycnogonida Anoplodactylus stictus and a new hydroid species of Podocoryna has been casually detected on the encrusting communities of experimental polyethylene plates installed at the Paranaguá Yacht Club, Paranaguá, south of Brazil from February 2007 to February 2008. This hydrozoan host is most likely an exotic species because it had not been observed in previous studies of Paranaguá Bay or beaches along the southern coast of Brazil in the previous 20 years. Eighty-eight hydroid colonies were analyzed, of which 19 were parasitized mainly from June to August 2007. Protonymphs were pink-red colored, similar to gallzooids and all other polyps of the colony, thus indicating that they had eaten the hosts' tissues. Up to six protonymphs were observed inside the gallzooids. The gallzooid column was elongated, and the tentacles were atrophied or even absent because of the development of the larvae. Some observations of endoparasitism in two live colonies that were maintained in aquaria until their complete disappearance (one month) are also described in this note. Resumo: Apesar do número relativamente elevado de estudos recentes sobre Cnidaria da costa brasileira, encontramos dois casos de parasitismo, ambos em macromedusas, e nenhum em pólipos. Associações endoparasíticas entre larvas de picnogônidas e hidroides são bem conhecidas desde início do século 20. A larva protoninfa desenvolve-se no interior da cavidade gastrovascular dos pólipos, geralmente dos gastrozoóides, que são então chamados "gallzooids". Esta nota é um registro inédito de parasitismo em pólipos de cnidários da fauna brasileira. A associação parasitária entre o picnogônida Anoplodactylus stictus e uma espécie nova de hidroide do gênero Podocoryna foi detectada casualmente sobre a comunidade incrustante de placas experimentais, instaladas no Iate Clube de Paranaguá, Paranaguá, sul do Brasil, de fevereiro/2007 a fevereiro/2008. O hospedeiro hidrozoário provavelmente é uma espécie exótica, pois não havia sido observado em estudos anteriores da Baía de Paranaguá ou praias ao longo da costa sul do Brasil nos últimos 20 anos. Foram analisadas 88 colônias do hidroide das quais 19 estavam parasitadas, principalmente nos meses de junho a agosto/2007. As protoninfas eram rosa-avermelhadas, a mesma coloração dos "gallzooids" e dos demais pólipos da colônia, indicando que elas ingeriram tecidos do hospedeiro. Até seis protoninfas foram observados no interior dos "gallzooids". O comprimento da col...

Feeding ecology in sea spiders (Arthropoda: Pycnogonida): what do we know?

“…Dogiel [ 30 ] also found a similar mode of development in Endeis spinosa , whose larva develops attached to the hydranth of Obelia sp. Since then, such a relationship has also been found in many other species (see overview in [ 31 ]). In most Ammotheidae and Pycnogonidae as well as in Nymphon gracile [ 32 ], the larvae are ectoparasites of hydroids, although in the Pycnogonidae the adults feed mostly on actinians [ 30 , 33 ].…”

Anoplodactylus (Pycnogonida: Phoxichilidiidae)from Brazil, new records and two new species

“…An association of A. stictus with the hydrozoan Tubularia crocea (Agassiz, 1862) was recorded (Genzano, 2002), probably representing a predator (Varoli, 1994). However, they were also recorded as parasites of a new hydrozoan species of the genus Podocorina Sars, 1846, an association established by chance in an incrusting community of experimental plates in Paranaguá, Paraná (Bettim and Haddad, 2013). According to Marcus (1940), A. stictus is the closest to A. californicus but may be distinguished mainly by the larger size, by the presence of a remnant of the propodus in A. californicus, by the presence of a cutting lamina in the propodal sole in A. stictus, and by a small protuberance on the movable finger of the chela (Stock, 1992).…”