Post-larval development of the microcotylid monogenean Sparicotyle chrysophrii (Van Beneden and Hesse, 1863): Comparison with species of Microcotylidae and Heteraxinidae Aigües Repullés-Albelda a, ⁎, Juan A. Raga a , Francisco E. Montero a, b a Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, PO Box 22085, Valencia, Spain b Departament de Biologia Animal, Biologia Vegetal i d'Ecologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain abstract article info Article history: Received 24 November 2010 Received in revised form 27 September 2011 Accepted 29 September 2011 Available online 12 October 2011 Keywords: Microcotylidae Sparicotyle chrysophrii Growth development Haptor Attachment The chronology of post-larval development in S. chrysophrii, a polyopisthocotylean monogenean parasite of the gilthead seabream (Sparus aurata L.), was experimentally studied. It is compared with other species within the Microcotylidae and the Heteraxinidae, including an analysis of the changes in attachment and the growth rate. Gilthead seabreams infected by larvae of S. chrysophrii were killed periodically in order to collect the different developmental stages. Parasite total body length, haptor length, largest clamp width, and total number of clamps were recorded. Specimens of S. chrysophrii in culture conditions at 20 °C became gravid after 26–30 days, with 37 pairs of clamps. The S. chrysophrii growth curve appears to be sigmoid with 3 growth periods (slow–fast–slow). The haptor of S. chrysophrii grows linearly with total body length, but the main contribution to total body length growth is that of the non-haptoral body. The relationship between number of clamps and total body length during development can be fitted to an exponential curve for all the reviewed species, i.e.: Microcotyle spinicirrus, Microcotyle donavini, Microcotyle gotoi, Microcotyle sebastis, Microcotyle hiatulae, Polylabroides multispinosus, Bivagina tai, Heteraxinoides xanthophilis, Heteraxine heterocerca, and Zeuxapta seriolae. The sequence of events was common for all of the species compared: terminal lappet is lost when about 15% of clamps were developed; primordia of testes at approximately 30% of clamps developed, and maturity (as first egg appearance) at about 65% of clamps developed. © 2011 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Sparicotyle chrysophrii Van Beneden & Hesse, 1863 is a microcoty- lid (Monogenea, Polyopisthocotylea) infecting the gills of the gilthead seabream Sparus aurata (Linnaeus, 1758) in the Mediterranean region [1]. This species causes severe epizootics in high density cultures of gilthead seabreams mostly due to host re-infection. Epizootic episodes have been mainly reported in Spain and Greece [2–4]. Outbreaks occur more frequently during spring and summer [4–6] al- though recent studies reported the highest prevalences and abun- dances during winter [7]. These apparently ambiguous observations can be explained by the effects of the environmental conditions on hosts and parasites. During summer, monogenean life-cycles are usually faster and favour transmission and re-infection [8]. However, during winter, although parasite life-cycles are presumably slower, the gilthead seabreams are particularly immunosuppressed making them especially susceptible to parasites (see [9]). Currently, no effective treatment exists to eradicate these parasites and the disease recurs. Knowledge of life cycle chronology of S. chrysophrii is of major importance in order to un- derstand the parasite dynamics in culture. Furthermore experimental treatments have been observed to be differently effective against adults, juveniles and eggs, [10] consequently it is important to know the duration of each parasite developmental stage. Pathological effects provoked by polyopisthocotyleans are mainly related with blood loss due to attachment and feeding and with a reduction of gill breathing surface due to the parasite presence [8]. Polyopisthocotyleans change their morphology drastically during development, especially increasing the complexity of the haptor. As a consequence, damage provoked by these changing haptors also must vary during development. Furthermore, as parasites grow they consume more blood and, at the same time, their haptors affect a higher gill surface. In this way, the study of parasite developmental stages can provide information about severity of effects on fish in each moment. The first detailed studies on development of Microco- tylidae species date from the 1940s (Microcotyle spinicirrus [11] Microcotyle donavini [12]) and the 1950s (Microcotyle gotoi [13]). Euzet [14] reported descriptions of the first post-larval stages of S. chrysophrii (therein named as Microcotyle chrysophrii) after describ- ing the morphology of the oncomiracidum [15]. Later, several studies Parasitology International 60 (2011) 512–520 ⁎ Corresponding author at: Unitat de zoología marina, Cavanilles Institute of Biodi- versity and Evolutionary Biology, University of Valencia, PO Box 22085, Valencia, Spain. Tel.: +34 963543685; fax: +34 963543733. E-mail address: aigues.repulles@uv.es (A. Repullés-Albelda). 1383-5769/$ – see front matter © 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.parint.2011.09.008 Contents lists available at SciVerse ScienceDirect Parasitology International journal homepage: www.elsevier.com/locate/parint