Phylogenetic Position of the Barnacle Chelonibia testudinaria Linnaeus, 1758 from the Persian Gulf

Abstract

Chelonibia testudinaria is a globally widespread epibiont barnacle. Previous phylogenetic studies have shown that specimens of this species positioned in three separate clades. One clade contains specimens of the Eastern Pacific, one clade contains specimens of the West and East Atlantic, and one clade contains specimens of the Western Pacific and Southeast Asia. In the present study, we addressed the phylogenetic position of specimens of C. testudinaria from the Persian Gulf using the mitochondrial COX1gene. The results show that specimens of the Persian Gulf cluster with specimens of Southeast Asia from Taiwan, Malaysia, Singapore as well as Japan in a supported clade. The widespread distribution of this species in the Indo-West Pacific seems to have been facilitated by sea turtles. Key words: Bandar Abbas, Molecular Phylogeny, COX1, Chelonibia testudinaria, Portunus segnis. Introduction Indo-West Pacific region is known for its high marine biodiversity (Roberts et al., 2002; Wafar et al., 2011). Land masses like the Malay Peninsula and Sumatra Island separated this oceanic region into two areas, east and west. Phylogenetic studies of species complexes (e.g., Ragionieri et al., 2009; Lai et al., 2010; Bowen et al., 2016) have confirmed genetic isolation between the two sides of these land barriers in the Indo-West Pacific. Chelonibia testudinaria Linnaeus, 1758 is a globally widespread epibiont barnacle, attached to the carapace of crabs and sea turtles (Rawson et al., 2003). Previous phylogenetic studies have shown that specimens of this species positioned in three separate clades. One clade contains specimens of the Eastern Pacific, one clade contains specimens of the West and East Atlantic, and one clade contains specimens of the Western Pacific and Southeast Asia (Cheang et al., 2013). This species is also a common barnacle in the Persian Gulf and the Gulf of Oman (Shahdadi et al., 2014). In this regard, the present study aims to address the phylogenetic position of C. testudinaria from the Persian Gulf using a mitochondrial marker. Materials and Methods Specimens of the Swimming crab, Portunus segnis were collected by a local fisherman from the coastal area of Bandar Abbas, Persian Gulf, Iran. The specimens of C. testudinaria were removed from the carapace of two crabs and preserved in 96% ethanol. Genomic DNA was isolated using the Puregene method. A fragment of the mitochondrial protein-coding gene cytochrome c oxidase subunit 1 (COX1) was amplified by polymerase chain reactions (PCRs). To amplify a segment of 670 bp of the COX1 gene, corresponding to the generally used barcoding region, the Folmer primers LCO1490 and HCO2198 (Folmer, 1994) were used. In addition to the sequences of the Persian Gulf material, we recovered homologous sequences of this species from GenBank (NCBI) and used them for phylogenetic analyses. Chelonibia Caretta was used as an outgroup for this analysis. For phylogenetic tree reconstruction, we applied a Maximum Likelihood (ML) algorithm using the software raxmlGUI (Silvestro & Michalak, 2012). Results and Conclusion In total, 58 sequences of C. testudinaria were collected to be used in the present phylogenetic analysis. Nine sequences were obtained from the Persian Gulf and the rest were recovered from GenBank from different areas. Corresponding to previous studies (Rawson et al., 2009; Cheang et al., 2013), the present ML tree recovered three distinct clades for C. testudinaria from around the world. These include the Eastern Pacific clade, the Atlantic clade including western specimens along with Mediterranean sequences, and the West Pacific clade including sequences from Southeast Asia. The results of the study show that the specimens of the Persian Gulf cluster with specimens of Southeast Asia from Taiwan, Malaysia, Singapore as well as Japan in a supported clade. The widespread distribution of this species in the Indo-West Pacific seems to have been facilitated by sea turtles.

Keywords

• bandar abbas
• molecular phylogeny
• cox1
• chelonibia testudinaria
• portunus segnis