Saccostrea Dollfus & Dautzenberg, 1920

Genus Saccostrea Dollfus & Dautzenberg, 1920 View in CoL

Saccostrea View in CoL is a widespread genus in the Indo-Pacific, with a number of species described largely on the basis of shell morphology, but Saccostrea View in CoL taxonomy remains very confusing. Lam & Morton (2006) used genetic techniques in an attempt to differentiate the species. They proposed a ‘superspecies’ of S. cuccullata View in CoL and a separate clade based on S. mordax ( Gould, 1850) View in CoL (= S. scyphophilla View in CoL ; see Snow et al., 2023) to include all the different ecotypes and/or forms. Recent studies indicate that 10 distinct lineages are present within Saccostrea View in CoL (non- mordax View in CoL ); these are all probably valid species. Sekino & Yamashita (2016) argued that they should not be included in S. cuccullata View in CoL , but referred to them as Saccostrea View in CoL A–J. This terminology was used by Snow et al. (2023) and we have followed their recommendations. Tan et al. (in press) have recently demonstrated that S. cuccullata View in CoL was described from Ascension Island in the South Atlantic Ocean and does not occur in the Indo-West Pacific.

Visootiviseth et al. (1998) pointed out the confused taxonomy of small oysters in the genus Saccostrea View in CoL in Thailand and used a combination of electrophoretic and morphometric techniques to distinguish three species: A, B, and C. All three occurred in the Gulf of Thailand but were not named. Klinbunga et al. (2005) also recognised three groups (1–3) of Saccostrea View in CoL in Thailand, with groups 1 and 3 occurring in the Gulf of Thailand. These results cannot be compared with the present study as Visootiviseth et al. (1998) used allozyme analysis and Klinbunga et al. (2005) used Polymerase Chain Reaction-Restriction Fragment Length Polymerase (PCR RFLP), vastly different molecular techniques from those used here.

Saccostrea species present in the upper Gulf of Thailand: