New distributional record of Chelonibia testudinaria (Linnaeus, 1758) from the island of Gökçeada, northern Aegean Sea, Turkey

Abstract

* Correspondence: ogonulal@istanbul.edu.tr Chelonibia testudinaria (Linnaeus, 1758) is a cosmopolitan species of barnacle common in warm seas and all over the Mediterranean as an epibiont of marine turtles and other hosts (Newman and Abbott, 1980; Koukouras and Matsa, 1998; Zardus et al., 2014). C. testudinaria is the most often reported sea turtle barnacle and it has been commonly found on Caretta caretta (Linnaeus, 1758) (loggerhead) and Chelonia mydas (Linnaeus, 1758) (green turtle) dating as far back as the Miocene epoch (Blick et al., 2011). The barnacle is considered an obligate commensal with narrow host specialization and is reported from all species of sea turtles (Zardus et al., 2013). Relini (1980) has noted that this species is also rarely found on inanimate objects. The effects of epibionts on marine turtles are poorly known. Zardus et al. (2013) conducted a worldwide molecular phylogenetic survey of Chelonibia. They found four species (C. testudinaria, C. patula, C. manati, and C. caretta); apart from C. caretta these are genetically indistinguishable. The three taxa are morphotypes of the same species and synonymized under C. testudinaria. The only record known to date from Turkish seas is from the eastern Mediterranean coast (Geldiay et al., 1982). C. testudinaria has been reported from C. caretta from the Strymonikos Gulf (Aegean Sea, Greece) (Koukouras and Matsa, 1998). The geographical distributions recorded for C. testudinaria in the Mediterranean Sea are given in Table 1. In the present study, C. testudinaria is reported for the first time from the Turkish coast of the Aegean Sea. Description: C. caretta, five pairs of lateral scutes, anterior pair touching the precentral scute, two claws on each flipper (Fischer et al., 1987). C. testudinaria, the aperture is oval, exceeding in length one third of the longer basal diameter. The mandibles have five teeth. The shell is strong, conical, and depressed, with more or less deep notches on it (Gruvel, 1965). In September 2014, two dead loggerhead turtles (C. caretta) washed ashore on the island of Gokceada in the northern Aegean Sea, Turkey (Figure 1). I carefully analyzed the body of the turtles completely. It was not clear how long the turtles’ carcasses had stayed in the sea before becoming stranded. Firstly the weights were measured with handheld luggage scales. The turtles were measured according to Bolten (1999). Measurements were taken either with calipers (straight-line measurements) or with a flexible tape measure (curved measurements). Straight carapace length (SCL) is measured from the anterior edge of the carapace to the posterior tip of the supracaudals. Also anterior and posterior locations are on the same side of the carapace. Straight carapace width (SCW) is measured at the widest point; there are no anatomical reference points. Chelonibia barnacles were photographed and counted and their diameters were measured with calipers to the nearest 0.1 mm. Chelonibia barnacles are usually oval rather than round and so measurements are taken of the longest axis, called the rostro-carinal length. The number of Chelonibia individuals and morphological analysis of both turtles are given in Table 2. Abstract: A total of 420 specimens of Chelonibia testudinaria (Linnaeus, 1758) were found on two dead loggerhead turtles (Caretta caretta) washed ashore on the island of Gokceada (northern Aegean Sea). The species is reported for the first time from the Turkish coast of the Aegean Sea and is the second record since 1982 for the Turkish Seas.