Morphological and genetic characterization of Syphabulea tjanschani ( ) (Nematoda: Oxyuridae), with phylogenetic position of Syphabulea in Oxyuridae

Abstract

Pinworms are important parasitic nematodes in animals and humans, and many species are of medical and veterinary importance. The genus Syphabulea is a poorly known group of pinworms. The systematic position of Syphabulea in Oxyuridae remains unclear. Moreover, there is still a paucity of detailed information on some morphological aspects of the type species S. tjanschani (Ablasov, 1962). In the present study, the detailed morphology of S. tjanschani was studied using light microscopy and, for the first time, scanning electron microscopy. The results revealed three traits useful for the characterization of the species including: cuticular depression around excretory pore, non-prominent labial teeth and number of adhesive ridges in three ventral mammelons. The ribosomal [small ribosomal DNA (18S), internal transcribed spacer (ITS) and large ribosomal DNA (28S)] and mitochondrial [cytochrome c oxidase subunit 1 (cox1)] target regions of S. tjanschani were also firstly amplified and sequenced for future use in the molecular identification of this poorly known species. In addition, in order to investigate the systematic position of Syphabulea in Oxyuridae, the phylogenetic analyses of representatives of the Oxyuridae were performed using maximum likelihood (ML) and maximum parsimony (MP) methods based on 18S, 28S and 18S + 28S + cox1 sequence data, respectively. The phylogenetic results based on different sequence data all supported the genus Syphabulea to be a member of the subfamily Syphaciinae. The phylogenetic analysis based on 28S sequence data also showed Syphabulea as sister to the genus Syphatineria. Our present study represents the first attempt to resolve the systematic position of the genus Syphabulea using phylogenetic analyses based on molecular data.