Morphological and molecular characterization of Paraleptus chiloscyllii Yin & Zhang, 1983 (Nematoda: Physalopteridae) from the brownbanded bambooshark Chiloscyllium punctatum Müller & Henle (Elasmobranchii: Orectolobiformes).

Paraleptus (Spirurida: Physalopteridae) is a small genus of nematodes, parasitic in fishes, most species of which are inadequately described. Genetic data for these congeners have not been reported. The detailed morphology of P. chiloscyllii was studied using light and scanning electron microscopy, based on newly collected specimens from the brownbanded bambooshark C. punctatum Müller & Henle (Elasmobranchii: Orectolobiformes) in the Taiwan Strait. Some previously unreported morphological features of taxonomic significance were observed, i.e., pseudolabium with two sublateral rows of 6-7 small spines, 7-8 small spines on each lower rim between pseudolabia, deirids not distally bifurcated, vulva with remarkable protruding lip, presence of 1 pair medio-ventral precloacal papillae and 1 pair of discoid protrusions of postcloacal lip in male. The specimens described by González-Solís & Ali's (2015) as P. chiloscyllii from the Arabian carpetshark C. arabicum off Iraq are considered a new species, for which the name P. moraveci n. sp. is proposed. The genetic characterization of the partial small (18S) and large (28S) ribosomal DNA, and the partial mitochondrial cytochrome c oxidase subunit 1 (cox1) of P. chiloscyllii are provided for the first time. There was no intraspecific nucleotide divergence detected in the 18S and 28S regions among different individuals of P. chiloscyllii, but a low level of intraspecific genetic variation was found in the cox1 (0.62-0.92%). The present genetic data is very important for molecular identification, and will be valuable for further invertigantions on the population genetics and phylogeny of this group.