Isolation and molecular identification of the scuticociliate Porpostoma notata Moebius, 1888 from moribund reared Hippocampus hippocampus (L.) seahorses, by amplification of the SSU rRNA gene sequences

The Scuticociliatia subclass includes hundreds of species with mostly uncertain phylogenetic relationships and classifications ( Alvarez-Pellitero et al. 2004). On the basis of morphological and morphogenetical data, Lynn (2008) recognized three Scuticociliatia orders: Philasterida, Thigmotrichida and Pleuronematida. They are endemic to worldwide coastal ecosystems where they thrive either as freeliving organisms or parasitic to aquatic animals. In fact, these facultative ciliated protists can occasionally become pathogenic for the hosts, leading to scuticociliatosis in some species of fish, crustaceans and molluscs (Iglesias et al. 2001). The scuticociliates Uronema marinum Dujardin, Miamiensis avidus Thompson & Moewus, and Philasterides dicentrarchi Dragesco have been recognized as causative agents of mass mortalities in some cultured marine fishes such as turbot Scophthalmus maximus (L.) (Iglesias et al. 2001), sea bass Dicentrarchus labrax L. (Dragesco et al. 1995) and olive flounder Paralichthys olivaceus (Temminck & Schlegel) (Kim et al. 2004), among others. In seahorses, ciliates have been reported to cause outbreaks of scuticociliatosis, with high mortality rates in Hippocampus erectus Perry (Cheung, Nigrelli & Ruggieri 1980), Hippocampus trimaculatus Leach (Meng & Yu 1985) and Hippocampus kuda Bleeker (Shin et al. 2011). Indeed, the ciliate P. dicentrarchi has been recognized as the main cause of mortality in captive reared seahorses H. kuda (Shin et al. 2011). P. dicentrarchi infections in syngnathids are usually accompanied by skin ulcerations, abdominal distension and central nervous anomalies. Lethargy, anorexia and rapid death have been also related to P. dicentarchi infections (Umehara, Kosuga & Hirose 2003). Seahorses have a ‘data deficient’ status on the IUCN Red List of Threatened Species (IUCN 2012), and all seahorse species are listed in CITES Appendix II. Due to this situation, seahorse research and rearing have substantially increased in the last decades (Planas et al. 2009). Consequently, a comprehensive identification of associated ectoor endoparasites can help to establish effective preventive treatments in reared seahorses. On this regard, the present work describes the isolation and molecular identification of the scuticociliate Porpostoma notata Moebius, 1888 in moribund Hippocampus hippocampus juveniles reared in captivity, from a batch with mass mortality. A pregnant male of H. hippocampus was captured by scuba diving in Toralla Island (Galicia, NW Spain) in 2011 and conveniently transferred to the facilities at the IIM-CSIC in Vigo. A batch of 784 newborn of 14.5 mm 2 in length and 3 mg 1.7 in weight was released and reared under controlled conditions, as reported by Planas et al. (2009). High survival rates were recorded Correspondence C Ofelio, Instituto de Investigaciones Marinas (IIM-CSIC), Eduardo Cabello 6, 36208 Vigo, Spain (email: claudiaofelio@gmail.com)