DAO 106:163-172 (2013)  -  DOI: https://doi.org/10.3354/dao02650

Postmonorchis sp. inq. (Digenea: Monorchiidae) metacercariae infecting natural beds of wedge clam Donax trunculus in Italy

F. Carella1,*, J. Culurgioni2, S. Aceto1, G. Fichi3, T. Pretto4, D. Luise1, A. Gustinelli5, G. De Vico

1Department of Biology, University of Naples Federico II, 80134 Napoli, Italy
2Department of Life and Environmental Sciences, University of Cagliari, 09126 Cagliari, Italy
3Laboratory of Ichthyopathology, Experimental Zooprophylactic Institute of Lazio and Tuscany, 56123 Pisa, Italy
4Experimental Zooprophylactic Institute of Venice, 35020 Legnaro, Padua, Italy
5Department of Veterinary Public Health and Animal Pathology, University of Bologna, 40064 Ozzano dell’ Emilia, Italy

ABSTRACT: The wedge clam Donax trunculus Linnaeus, 1758 is one of the most common bivalve molluscs inhabiting the sandy shores of the Mediterranean Sea and is considered an important commercial resource. In this study, we report the first molecular, morphological and histopathological descriptions of metacercariae from a trematode belonging to the genus Postmonorchis (Digenea: Monorchiidae) that infects D. trunculus in natural beds of the Italian Tyrrhenian coast (Campania, Lazio and Tuscany). Morphological analysis of the parasite revealed a combination of features that exist in the 3 previously identified species of Postmonorchis, viz. P. donacis, P. variabilis and P. orthopristis, with the addition of new, distinctive morphological characteristics. The pathogen exhibited a predilection for the gill; however, it was also present in the labial palp and mantle in addition to the gut, kidney epithelium and foot. The inflammatory response was characterised by either a focal or diffuse haemocyte infiltration followed by the formation of multiple, large multi-layered capsules associated with tissue destruction. The prevalence of the pathogen ranged from 75 to 100%, while the infection intensity fluctuated among the study areas. Further studies regarding the life cycle of this parasite and the identification of other larval and adult stages and their respective hosts may confirm the identification of a new species of Postmonorchis that infects wedge clams in Mediterranean waters. The study of the parasite is completed by molecular analysis of the ITS1 and ITS2 rDNA sequences.


KEY WORDS: Donacidae · Bivalvia · Metacercariae · Monorchiidae · Postmonorchis · Trematoda · Parasite · Mediterranean · ITS


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Cite this article as: Carella F, Culurgioni J, Aceto S, Fichi G and others (2013) Postmonorchis sp. inq. (Digenea: Monorchiidae) metacercariae infecting natural beds of wedge clam Donax trunculus in Italy. Dis Aquat Org 106:163-172. https://doi.org/10.3354/dao02650

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