Comparison of shell morphology and DNA sequences of COI and ITS1 in the ectosymbiotic bivalves (Galeommatoidea) attached to the inarticulate brachiopods: Lingula anatina and L. adamsi

초록

Lützen et al. (2009) described the shell, soft anatomy, and reproduction of the montacutid bivalve, Koreamya arcuata (A. Adams, 1856) gen. nov. (Figure 1) from several South Korean tidal-flats along the Yellow Sea. This species is very unique to live commensally with inarticulate brachiopods Lingula anatina from South Korea (Hong et al. 2007) and Philippines (Savazzi, 2001), Lingula translucida from Southeastern India (Fernando and Fernando, 1983) and Lingula sp. from Western Australia. However, there are no studies to compare the shell morphology and DNA sequence among these bivalves attached to Lingula spp. In May 2003, we found another population of genus Koreamya attached to Lingula adamsi (Figure 1) from the Woldoo tidal flat, Muan-gun, South Korea (Sato et al., 2004). These individuals are very similar to K. arcuata attached to Lingula anatina from South Korea, but their size is generally smaller, the shell thinner and its shape more rounded than in K. arcuata (Lützen et al., 2009). In the present study, therefore, we collected more samples of Lingula adamsi and L. anatina from South Korean tidal-flats, and compared shell morphology and DNA sequences of COI and ITS1 between these ectosymbiotic bivalves attached to two different brachiopod species. Koreamya arcuata attached to Lingula anatina was collected from the following local tidal-flats in the middle intertidal level, sandy mud bottom; Seondo-ri, Biin-myeon, Seocheon-gun on Apr. 28, 2007 and Apr. 3, 2008, Okbong-ri, Okseo-myeon, Gunsan City on Mar. 25, 2009, Simpo-ri, Jinbong-myeon, Gimje City on Aug. 16, 2002 and Yubudo Is., Seocheon-gun on Sep. 9, 2006. Koreamya sp. attached to Lingula adamsi was also collected from the mud tidal-flats in the middle intertidal level at Woldoo, Yongjeong-ri, Hyeongyeong-myeon, Muan-gun on May 2 and Sep. 28-29, 2003 and Apr. 8, 2008. Comparison of shell morphology suggested that there are some differences between the two populations of Koreamya attached to