Magallana bilineata ( Röding, 1798 )

Magallana bilineata ( Röding, 1798) View in CoL

( Figs. 4A–C, 6A, B)

Ostrea bilineata Röding, 1798: 170 View in CoL ( type locality: not stated).

Ostrea lugubris Sowerby II, 1871 (in 1870–1871): pl. 26, fig. 63 ( type locality: “North America?”).

Ostrea iredalei Faustino, 1932: 546 View in CoL , 547, pl. 1, figs. 1–4 ( type locality: “ Navotas, Malabon, Parañaque, and other places on Manila Bay ”, Philippines).

Ostrea madrasensis Preston, 1916: 33–35 View in CoL , figs. 11, 11a ( type locality: “ Ennur backwater, Madras ”, India).

Habitat. Recorded on rocky shores and aquaculture ropes.

Material examined. Site 1, Sriracha; Site 6, mouth of Kungkraben Bay; Site 7, south Kungkraben Bay; Site 9, Pattaya. Magallana bilineata was also identified from the aquaculture farms in Chonburi.

Published Gulf of Thailand records. Crassostrea bilineata ( Röding, 1798) : Nabhitabhata (2009); Bussarawit & Cedhagen (2010, 2012). Crassostrea lugubris (Sowerby II, 1871) : Aungtonya et al. (1999); Murugan et al. (1999);

Day et al. (2000); Trivej & Kesjinda (2018). Crassostrea iredalei Faustino, 1932 : Aungtonya et al. (1999); Yoosukh & Duangdee (1999); Klinbunga et al. (2000, 2001, 2002, 2003, 2005); Yoosukh (2000); Lam & Morton (2004); Bussarawit et al. (2006); Bussarawit & Simonsen (2006a).

Geographic range. Native to Southeast Asia, with sequenced records from: India, Thailand, Malaysia, Singapore, southern Japan, and Vietnam. Unsequenced records are from Pakistan and the Philippines ( Tan et al., 2024). Introduced to Queensland, Australia ( Willan et al., 2021).

Remarks. Magallana bilineata is known as the black scar oyster because its black adductor muscle scar differentiates it from M. belcheri , the white scar oyster, with its white adductor muscle scar. Magallana bilineata is well known in Thailand where it has been variously identified as Crassostrea bilineata , C. lugubris , and C. iredalei . Torigoe and Bussarawit (2010) clarified that there is a single species present in Thailand ( C. bilineata ), and C. lugubris and C. iredalei are synonyms. Identified in the field as Crassostrea sp. ( Table 2). The species was introduced to aquaculture farms in the Sriracha area about 20 years ago from Kungkraben Bay and has now become naturalised in the region (Attawut Kuntavong, pers. comm.).