Studies of Serrasentis sagittifer (Linton, 1889) Van Cleave, 1923 from cobia Rachycentron canadum (Linn.) in the Arabian Gulf; with Molecular Analysis and Optical Microscopy

Authors: Omar M Amin*, Anshu Chaudhary, Milad Badri, Aida Vafae Eslahi and Hirdaya S Singh

DOI: 10.23880/izab-16000602

Volume 7, Issue 4

Abstract

The finding of a population of Serrasentis sagittifer (Linton, 1889) Van Cleave, 1923 in Cobia Rachycentron canadum (Linn.) in the Arabian Gulf off Iranian waters prompted the study of its molecular parameters known previously only from a population of adults from the same host species, and of immatures from northern Australian waters and from other hosts in the Red Sea. We have previously described S. sagittifer from Cobia and from paratenic hosts in the same Gulf waters off Kuwait and Qatar and detailed its worldwide morphological variability and geographical distribution. We have processed and sampled a few specimens from the Arabian Gulf off Iran for morphological verification of their diagnosis and offered a few light microscopical images that accentuate their identity in Iranian waters for the first time. We document additional diagnostic features of S. sagittifer using optical microscopy. We determine that the distribution of S. sagittifer runs parallel that of its primary adult host, R. canadum, worldwide. We have used the 18S and 28S gene regions of ribosomal RNA, including the mitochondrial cox1 gene, for molecular analysis of an Arabian Gulf population for the first time. Maximum likelihood and Bayesian inference methods were used for phylogenetic reconstructions, the sequences of S. sagittifer from Iran were grouped within the genus Serrasentis and placed as a sister group to S. nadakali George and Nadakal, 1978. Due to the lack of molecular data for other species of this group of Rhadinorhynchidae, the present phylogenetic inferences are required to continue exploring the genetic diversity of this group of species to infer their phylogeny. The cox 1 haplotype network inferred with 14 sequences of S. sagittifer revealed 13 haplotypes separated from each other by a few substitutions. Our ocular microscopy accentuated morphological details of S. Sagittifer and the haplotype network genealogy produced in this study based on mt cox1 sequences from S. sagitiffer show a phylogeographic structure for the first time; therefore, the haplotypes grouped into their own geographic clusters.

Keywords: Serrasentis sagittifer; Acanthocephala; Arabian Gulf; Optical Microscopy; Genealogy; Cox 1 Sequence

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