Morphological and molecular characterization of Raphidascaris (Ichthyascaris) lophii (Wu, 1949) (Nematoda, Anisakidae) from marine fishes from China, with a key to the species of the subgenus Ichthyascaris

Abstract

The little known ascaridoid nematode Raphidascaris (Ichthyascaris) lophii (Wu, 1949) is redescribed and illustrated based on newly collected specimens from the five different marine fishes: Lophius litulon (Jordan) (Lophiiformes: Lophiidae), Lophiomus setigerus (Vahl) (Lophiiformes: Lophiidae), Antennarius hispidus (Bloch et Schneider) (Lophiiformes: Antennaridae), Zeus faber Linnaeus (Zeiformes: Zeidae) and Ostichthys japonicus (Cuvier) (Beryciformes: Holocentridae) from the East and South China Sea. This species differs from all congeners in the subgenus Ichthyascaris by the length of the ventricular appendix (0.52-0.98 mm long), the number and arrangement of caudal papillae (26-32 pairs of precloacal, 3-4 pairs of paracloacal and 8-11 pairs of postcloacal) and the length of the spicules (0.49-0.88 mm long, representing 3.08-4.70% of body length). In addition, nematodes collected from these five different fishes have been characterized using molecular methods by sequencing and analysing the internal transcribed spacer (ITS) of ribosomal DNA. No variation in size and nucleotide polymorphisms is detected within the target sequence among all samples analysed. These data contribute to facilitate an accurate diagnosis of this poorly known nematode. An identification key to the species of the subgenus Ichthyascaris is also provided.

Nematode parasites infecting the starry batfish Halieutaea stellata (Vahl) (Lophiiformes: Ogcocephalidae) from the East and South China Sea

“…lophii in the present material, together with the lengths of oesophagus and tail, is smaller than the description by Xu et al . () and Wu (), and the relative length of spicules to body length is slightly larger than Xu et al . 's () material (see Table ).…”

“…Later, Xu et al . () reported R . lophii from five different fishes L. litulon , Lophiomus setigerus (Vahl) (Lophiiformes: Lophiidae), Antennarius hispidus (Bloch & Schneider) (Lophiiformes: Antennariidae), Zeus faber Linnaeus (Zeiformes: Zeidae) and Ostichthys japonicus (Cuvier) (Beryciformes: Holocentridae) in the East and South China Sea, and also provided the sequence of ITS of rDNA for molecular diagnosis of this species.…”

“…The morphology and measurements of the present adult specimens correspond, more or less, to the previous studies by Xu et al . () and Wu (), including morphology and length of lips, the lengths of ventricular appendix and spicules, the ratio of the oesophageal length to the body size, the number and arrangement of the caudal papillae, the position of vulva and the shape of tail tip. Consequently, we considered that the present adult specimens should belong to R .…”

“…Adult nematodes were identified to species level on the basis of diagnostic characters provided by Wu (), Yamaguti (), Moravec & Nagasawa () and Xu et al . (), including the body size, the morphology of the lips, the lengths of oesophagus, ventricular appendix, spicules, the number and arrangement of caudal papillae and the morphology of the tail tip. Larval specimens were identified to different morphotypes or generic level based on the morphological characters including the position of the excretory pore, the absence or presence of the intestinal caecum and ventricular appendix, the shape of the tail, the length and ratio of the intestinal caecum and ventricular appendix according to the descriptions by Hsü (), Li, Xu & Zhang () and Shamsi, Gasser & Beveridge (); and then, some adults and larval individuals of each morphotype were selected for molecular analysis (see Table ).…”

Ege Bölgesi Akarsularında Yakalanan Avrupa Yılan Balıklarında (Anguilla anguilla Linnaeus, 1758) Raphidascaris acus Bloch, 1779 (Nematoda: Anisakidae)’un İlk Moleküler Karakterizasyonu

“…There are three Raphidascaris species [R. lophii (Wu, 1949), R. trichiuri (Yin & Zhang, 1983), and R. longispicula ] belongs to the subgenus Ichthyascaris Wu, 1949 [22][23][24] and two species [R. acus (Bloch, 1779) Railliet [10,19] .…”