Morphological variability and molecular characterisation of Dichelyne (Cucullanellus) pleuronectidis (Yamaguti, 1935) (Ascaridida: Cucullanidae) from the flatfish Pleuronichthys cornutus (Temminck & Schlegel) (Pleuronectiformes: Pleuronectidae) in the East China Sea

Abstract

Cucullanid nematodes identified morphologically as Dichelyne (Cucullanellus) pleuronectidis (Yamaguti, 1935) were collected from the ridged-eye flounder Pleuronichthys cornutus (Temminck & Schlegel) (Pleuronectiformes: Pleuronectidae) in the East China Sea. Their examination using light microscopy and, for the first time, scanning electron microscopy, revealed several important, but previously unreported morphological features and the presence of remarkable morphological differences in the intestinal caecum and deirids among some individuals. Consequently, specimens of D. pleuronectidis were characterised using molecular methods by sequencing and analysing the internal transcribed spacer (ITS) of the ribosomal DNA to test whether the present material with broad range of morphological variability, represents a complex of sibling species or a single species. The results of molecular analyses proved that the differences in the intestinal ceacum and deirids should be considered as intraspecific variation and that the nematode material collected from P. cornutus in the East China Sea represented a single species, D. pleuronectidis. These new morphological and genetic data contributed to an accurate diagnosis of this hitherto insufficiently known nematode and also indicated that a more rigorous study based on morphological and genetic data with broader representation of the Cucullanidae is required to assess whether the traditionally used diagnostic character of absence or presence of intestinal ceacum is of generic importance in distinguishing Dichelyne and Cucullanus.

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

“…In recent years, high prevalence and intensity of infections with nematode parasites in the marine fishes in the Chinese waters were reported (Shih ; Li, Liu & Zhang ; Li et al . , ; Zhang et al . ; Guo et al .…”

“…The ITS region was amplified by PCR using the primers and cycling conditions described previously (Li et al . ). PCR products were checked on GoldView‐stained 1.5% agarose gel and purified by the Column PCR Product Purification Kit (Shanghai Sangon).…”

Morphological and molecular characterization of Cucullanus hainanensis sp. nov. (Ascaridida: Cucullanidae) from Muraenichthys gymnopterus (Bleeker) (Anguilliformes: Ophichthidae) in the South China Sea

“…nov. and C. dodsworthi). Li et al (2014) investigated the genetic diversity of Dichelyne pleuronectidis (Yamaguti, 1935) and found there is very low level of intraspecific nucleotide variability in the ITS region (0-0.58% nucleotide differences) among different individuals. However, there has been no record of the level of the intraspecific nucleotide variation in the partial 18S rDNA in cucullanids so far.…”

“…The ITS-2 region was amplified by PCR using the primers XZ1 (forward: 5'-ATTGCGCCATCGGGTTC ATTCC-3') and NC2 (reverse: 5'-TTAGTTTCTTTTCCTC-CGCT-3') (Zhu et al 2002). The cycling conditions were described previously (Li et al 2014). PCR products were checked on GoldView-stained 1.5% agarose gel and purified by the Column PCR Product Purification Kit (Shanghai Sangon, China).…”

Ophidascaris wangi sp. n. and O. najae (Gedoelst, 1916) (Ascaridida: Ascaridoidea) from snakes in China

“…(see Sprent 1988;present study). This situation also occurs in Dichelyne pleuronectidis (Yamaguti, 1935) (Ascaridida: Cucullanidae) (see Li et al 2014).…”