Molecular and morphological evidence for the widespread distribution of Laticola paralatesi infecting wild and farmed Lates calcarifer in Australia

Abstract

Infections with monogeneans of the Diplectanidae can limit productivity of and cause considerable health issues for fish in aquaculture. To date, 9 species of diplectanids have been reported from the Asian sea bass or barramundi Lates calcarifer (Perciformes: Latidae) in the AsiaPacific region. This study characterised the diplectanid parasite fauna found infecting wild and farmed barramundi from 5 localities in tropical Australia, including north Queensland and Western Australia. A combination of morphometric and comparative genetic analyses of partial 28S ribosomal RNA (28S rRNA) from specimens recovered were used to confirm their identity and to explore relationships with other diplectanids. These data revealed that a single, dominant species of diplectanid, Laticola paralatesi, infects wild and farmed Lates calcarifer in tropical Australia. Dis Aquat Org 113: 195-205, 2015 connective tissue of gill lamellae (Dezfuli et al. 2007). The feeding activity of diplectanids can destroy epithelial cell layers, reduce the number of chloride cells on gills, cause over-production of mucus and ultimately reduce respiratory performance of host fish (Thoney & Hargis 1991, Buchmann & Lindenstrøm 2002, Whittington 2005. Laticola lingaoensisLosses or reduced productivity of commercially important fish stocks due to diplectanid infection have been well documented. Dezfuli et al. (2007) estimated that Diplectanum aequans induced up to 10% of the annual mortality (worth US$700 000) of juvenile European sea bass Dicentrarchus labrax cultured in the Mediterranean. In Asia, Pseudorhabdosynochus species plague grouper (Epinephelus spp.) culture in the South China Sea (Yang et al. 2005, Luo & Yang 2010. Nine diplectanid species, representing 3 genera, have been reported from barramundi, Lates calcarifer (including Diplectanum narimeen, D. penangi, D. setosum, Laticola latesi, L. lingaoensis, L. paralatesi, L. seabassi, Pseudorhabdosynochus epinepheli, and P. lantauensis), some which develop high prevalences and intensities on cultured fish (Leong & Wong, 1990).Barramundi farming is a rapidly expanding, high value aquaculture industry in tropical Australia (production was 4352 tonnes, valued at AUD$35.7 million in 2011; Skirtun et al. 2013). There is a surprising paucity of research on the identification of diplectanids infecting Lates calcarifer in Australia, considering that the industry is plagued with persistent infections in many aquaculture facilities. The only diplectanid that has been previously reported from Australia is Laticola paralatesi, obtained from wild L. calcarifer off Bathurst Island, Northern Territory (Yang et al. 2006). The aim of this study was to conduct a survey of the diplectanid fauna infecting wild and farmed L. calcarifer from a wide range of loca lities around Australia. A combination of morpho logical and molecular analyses were used to diagnose the putative taxa present in the region.Knowledge of the species present will assist further investigations of species-specific pathological effe...

Morphological and molecular characterization of the monogenean gill parasite, Acleotrema maculatus, infecting Argyrops filamentosus fish in the Red Sea, Saudi Arabia

“…The family Diplectanidae is unambiguous and located in a distinct clade, as demonstrated by the sequence alignment and phylogenetic trees in the current study. Similar findings have been reported by Chotnipat et al (2015), Tambireddy et al (2016), Villar-Torres et al (2019), and Nitta (2021. The recorded parasite cannot be assigned to any of the aligned sequences since the percentage of sequence identities between the present parasite and the aligned sequences exhibited a maximum identity of 98.92% with Acleotrema sp.…”

An integrative study of morphological and molecular characterization of Diplectanum aequans (Diplectanidae: Monogenea) infecting European sea bass Dicentrarchus labrax (Linnaeus, 1758) from Turkish coasts

“…Because the end of cirrus of our diplectanids tapering characteristically slightly end as the curve and typically comprise 24-25 rows of sclerotized pieces in a squamodisc, we did not hesitate to identify it as D. aequans in the present study (Figure 1). Most morphometric measurements of the same diplectanids which were preserved using the different fixation techniques may be insufficient for identifying the same species because different measurements could be obtained (5,14).…”

“…The molecular methods combined with morphological identifications have been commonly used to identify species of diplectanids and estimate their phylogenetic relationships (4,5,25,32) (34).…”

“…The ITS region, 18S, and 28S rRNA have been proven to be particularly useful for molecular characterization and the accurate identification of Diplectanidae species (4,5,25,32). Although D. aequens has a wide geographic distribution, there has been limited information on its genetic diversity with only one publication from the Balearic Sea (Western Mediterranean Sea, 80 FAO area 37.1.1) (32).…”