First record of the Saccostrea oyster in Bertioga, São Paulo, Brazil

Abstract

This study presents the first record of an alien species of oyster in Bertioga, São Paulo State (Southeastern Brazilian coast). Alien oysters were found attached to mangrove roots, rock shores, stones and gravel in the riverbed, forming clusters of 10í 20 individuals and cohabiting with native oyster species (Crassostrea mangle, C. brasiliana and Ostrea sp.). Results are presented based on molecular analysis of specimens collected in the Itaguaré River in June 2014. We used partial sequences of 16S and COI genes to assess the taxonomic identity. The Neighbor-joining method was used to analyze phenetic relationships among samples and the genetic diversity was calculated from the Kimura two-parameter (K2P) distances. The sequences in this work clustered with a sequence of "Saccostrea cucullata†from Madagascar for both genes (COI and 16S) and presented a genetic distance of 1.7í 2.2% and 3.5í 5.3% from other sequences of "S. cucullata group†for 16S and COI fragments respectively. The genetic distances from others Saccostrea species (S. palmula, S. glomerata and S. mordax) ranged from 4.7 to 9.1% for 16S and from 13.8 to 19.0% for COI. The genetic distances from other oysters’ species sequences (genera Ostrea and Crassostrea) are over than 14.0% and 25.0% for 16S and COI respectively. The record is discussed in the context of possible consequences on the environment and probable pathways of introduction. This is the first published record of a Saccostrea species in the southwestern Atlantic Ocean.