Occurrence of Hysterothylacium Species (Nematoda: Raphidascarididae) from Some Marine Fishes from Iraqi Waters

Abstract

Parasitological investigation of 22 species of marine fishes in territorial Iraqi waters, during the period from October 2019 till September 2020, revealed recording of six different species of Hysterothylacium Ward & Magath, 1917 in different developmental stages. These nematodes including two species in adult stage of Hysterothylacium viz, H. reliquens (Norris & Overstreet, 1975) and Hysterothylacium sp. (females only), two species of fourth larval stages (Hysterothylacium sp. type BH and Hysterothylacium sp. type BI) and two species of third larval stages (Hysterothylacium sp. type BA and Hysterothylacium sp. type BC). Identification of Hysterothylacium sp. was based on female only isolated from Blackfin stonefish Pseudosynanceia melanostigma Day, 1875; Hysterothylacium sp. type BH 4th larval stage isolated from Arabian backspot threadfin Polydactylus mullani (Hora, 1926) and Hysterothylacium sp. type BI 4th larval stage from purple-spotted bigeye Priacanthus tayenus Richardson, 1846; all these parasitic nematodes recorded for the first time in the Arabian Gulf. In addition, 14 fish species are considered as new hosts for Hysterothylacium sp. type BC 3rd larval stage. Description of female Hysterothylacium sp., Hysterothylacium sp. type BH and BI both 4th larval stages are given. The interest record of inverse intestinal caecum in some specimens of 3rd larval stage of Hysterothylacium type BC in some marine fishes of the current study is given.