Morphological and genetic characterization of Hysterothylacium Ward & Magath, 1917 (Nematoda: Raphidascarididae) larvae in horse mackerel, blue whiting and anchovy from Spanish Atlantic and Mediterranean waters

Abstract

The presence of zoonotic Hysterothylacium larvae in fish from Spanish Atlantic and Mediterranean waters, which can cause economic losses for commercial fisheries, has been reported in several studies; however, little is known about species identity in this region. The aim of this study was to identify at species level the Hysterothylacium morphotypes detected in three commonly consumed fish: horse mackerel (Trachurus trachurus), blue whiting (Micromesistius poutassou) and anchovy (Engraulis encrasicolus). Third- and fourth-stage Hysterothylacium larvae, as well as adults obtained from larval in vitro culture, were morphologically and molecularly identified by ITS1/ITS2 rDNA sequencing. Four Hysterothylacium morphotypes were detected. Genetic analysis showed that morphotypes VIII and IX were different larval stages of Hysterothylacium aduncum, which was supported by cultured adult species identification. Morphotypes III and IV were found to correspond to different developmental stages of another species of Hysterothylacium. As all larval types detected were morphologically indistinguishable from others previously reported yet showed clear genetic differences, they are referred here as new genotypes. This is the first time that ITS-sequence data of various developmental stages of the same species, including adults, have been studied and compared, providing crucial knowledge for future studies on Hysterothylacium identification and biology.

In situevidence of the role ofCrangon crangonin infection of codGadus morhuawith nematode parasiteHysterothylacium aduncumin the Baltic Sea

“…The nematode Hysterothylacium sp. (mainly H. aduncum), a member of the Raphidascarididae family, is a common parasite of marine fish throughout the world (Andersen, 1993;Rello et al, 2008;Knoff et al, 2012;Moravec et al, 2012;Kong et al, 2015;Morsy et al, 2015;Shamsi et al, 2015;Shamsi et al, 2016;Shamsi, 2017;Ghadam et al, 2018;Roca-Geronès et al, 2018) and is the most frequently occurring parasite in invertebrates acting as intermediate hosts: it has been reported in 70 different invertebrate species (Lick, 1991). Hysterothylacium aduncum (Rudolphi 1802) has a circumpolar distribution in the Northern hemisphere (Deardorff and Overstreet, 1981) and has been found in the north-west Atlantic (Marcogliese, 1996), the North Sea and the Baltic Sea (Lick, 1991;Klimpel and Ruckert, 2005), but also in the Mediterranean Sea (Dural et al, 2011;Abdel-Ghaffar et al, 2015), the Black Sea (Pekmezci et al, 2013) and the waters around Japan (Moravec and Nagasawa, 1986;Kong et al, 2015).…”

Effectiveness of Gutting Blue Whiting (Micromesistius poutassou, Risso, 1827), in Spanish Supermarkets as an Anisakidosis Safety Measure

“…The higher incidence in Spain can be chiefly attributed to the country's culinary traditions, with most infections deriving from the popular consumption of European anchovies (Engraulis encrasicolus) and European pilchard (Sardina pilchardus), marinated in vinegar [2,22]. Other fish which are widely consumed in Spain include blue whiting (Micromesistius poutassou), horse mackerel (Trachurus trachurus), European hake (Merluccius merluccius), and Atlantic bonito (Sarda sarda), and these present high infection rates for ascaridoid larvae [25][26][27][28][29][30][31].…”

Anisakid and Raphidascaridid parasites in Trachurus trachurus: infection drivers and possible effects on the host’s condition

“…Species of the genus Hysterothylacium Ward and Magath, 1917, formerly belonging to the Anisakidae and currently assigned to the family Raphidascarididae, are common parasites in different marine and freshwater fish species (Bezerra et al 2020 ). H. aduncum Rudolphi, 1802 and H. fabri Rudolphi, 1819 are the most frequently reported species in teleost fish from the Mediterranean region (Roca‐Geronès et al 2018 ; Tedesco et al 2018 ). Evidence of the direct consequences of Hysterothylacium infection on fish health is limited: parasites of this genus are considered only mildly pathogenic for adult fish (Ishikura et al 1993 ; Yagi et al 1996 ; Valero et al 2003 ; Cavallero et al 2012 ); however, mortality episodes in larval and juvenile fish have been reported (Bristow 1990 ; Balbuena et al 2000 ).…”