Nerocila sp . ( Isopoda : Cymothoidae ) parasitizing Mugil liza ( Teleostei : Mugilidae ) in São Francisco do Sul , Santa Catarina , Brazil

Isopods from the family Cymothoidae are fish ectoparasites displaying low host specificity found commonly attached to the gills, mouth, opercular cavity, nostrils and body surface of several host species. Damage can vary according to the degree of parasitism and the infestation site and may provoke respiratory discomfort in hosts. The aim of this study was to report the occurrence of a Nerocila sp. Leach, 1818 isopod parasitizing Mugil liza Valenciennes, 1836 captured in the Babitonga Bay, Santa Catarina State, Brazil. The female parasite specimen was recovered from the pectoral fin of M. liza and was 24 mm in length and 11 mm in width, and the mean egg size was 1.18 ± 0.08 x 1.03 ± 0.06 mm.

Nerocila spp.can be highlighted as one of the species from Cymothoidae (Leach, 1818) and is among the parasitic isopods (BRUSCA et al., 2001).They possess prehensile pereopods through their powerful curved claws and highly modified buccal parts that help them to remain attached to their hosts (THATCHER, 2006).They are also temporary and obligatory parasites and display low host specificity (ESPINOSA-PÉREZ;HENDRICKX, 2001;SMIT et al., 2014).The Cymothoidae life cycle is protandric and monoxenic (involving just one host) with direct transmission and sexual dimorphism (LEONARDOS;TRILLES, 2003;HIRANO et al., 2006); they are bloodfeeding organisms, but can also feed on body surface mucus as well as epithelial and subcutaneous host tissues (RAMDANE et al., 2007).
Host damage can vary according to the degree of parasitism and infestation site and ranges from light to severe damage with hemorrhage and tissue destruction.In general, severe damage can result in secondary infections.One of the main problems associated with parasitism is the repugnant appearance of infested fish, because parasites can be seen by the naked eye; this can cause significant economic losses to fisheries (EIRAS, 2004;LIMA et al., 2013;EIRAS;CASTRO, 2016).
The mullet Mugil liza is a widely distributed species and an important fisheries resource.They are traditionally exploited by inshore fishing and have been incorporated into various cultural events.Their bodies are elongated and fusiform, and notable morphological characteristics include the display of dark longitudinal striae alternating with white striae.They are detritivorous, pelagic and catadromous fish that form large schools during reproductive migrations (SECKENDORFF; AZEVEDO, 2007;MENEZES et al., 2010).Bruce (1987), Ramdane et al. (2007Ramdane et al. ( ), Öktener et al. (2010)), Kayiş and Ceylan (2011), Al-Zubaidy and Mhaisen (2013), Mahmoud et al. (2016), describe the occurrence of Nerocila in mugilids, but they do not mention M. liza as hosts.In this study we report the occurrence of the isopod Nerocila sp.parasitizing specimen of M. liza captured in Babitonga Bay, Santa Catarina, Brazil.
One male mullet specimen measuring 41 cm in total length, 38.4 cm standard length and with a weight of 983 g was captured in March 2016 by a fisherman using a net in Babitonga Bay (26°12'50.0"S,48°39'00.2"W) in the São Francisco do Sul municipality, Santa Catarina State, Brazil.The parasite was found attached to the right pectoral fin of the fish (Figure 1) and was removed and placed in alcohol 70 for posterior identification according to Bruce (1987), Trilles (1975) and Brusca (1981).The host was identified according to Menezes et al. (2010;2015).
The female isopod measured 24 mm long and 11 mm wide and was identified as Nerocila sp.(Figure 2) harboring 1.18 ± 0.08 x 1.03 ± 0.06 mm sized eggs.
Using subaquatic pictures, Öktener et al. (2010) studied Nerocila parasites in mugilid fi sh from the Aegean and Black Seas.According to Bruce (1987), Al-Zubaidy and Mhaisen (2013) and Ramdane et al. (2007), Nerocila occurs mostly in Mugilidae fi sh, which corroborates results from the current study on the mullet M. liza.This is the fi rst report of Nerocila sp. on a mullet from southern Brazil.Additional studies are needed to elucidate the patterns of parasitism by these isopods on M. liza and other mullets, mainly for evaluating their potential to cause economic damage.