Molecular identification of intertidal rock oyster species in north-eastern Australia reveals new candidates for aquaculture

The development of multiplex PCR assays for the rapid identification of multiple Saccostrea species, and their practical applications in restoration and aquaculture

“…The species chosen for primer development were S. glomerata , lineage B, lineage F, lineage G and S. spathulata . Lineage I was not selected as this species has several distinctive characteristics including broad but delicate purple lobe-like squamae (lamellae) on the lower/bottom (left) valve, internal shell iridescence, and preferred settlement on the roots of mangroves, enabling straightforward identification [ 12 , 16 ]. S. scyphophilla and S. mordoides were also excluded as these oysters are not part of the S. cuccullata complex and can be distinguished morphologically by their distinctive shape, deep longitudinal ridges, and purple colouration [ 12 ].…”

“…Misidentification is especially prevalent within the genus Saccostrea , where multiple species occur across Australia and the Indo-Pacific. Multiple species within this genus have been collectively lumped into two “superspecies”; Saccostrea scyphophilla (previously Saccostrea mordax ) which is comprised of at least three genetically distinct lineages, designated A – C, and Saccostrea cuccullata which contains at least ten genetically distinct lineages (designated A – J), with most lineages likely representing a separate species [ 7 , 9 – 12 ]. For example, Saccostrea scyphophilla lineage C has now been described as a new species Saccostrea mordoides [ 13 ], Saccostrea cuccullata lineage J has recently been assigned to the species Saccostrea spathulata [ 12 ], Saccostrea cuccullata lineage F may correspond to the species Saccostrea malabonensis [ 10 ], and accidental sampling of Saccostrea cuccullata lineage B and G during a Saccostrea glomerata population study showed that these three lineages are likely separate species through nuclear DNA markers [ 14 ].…”

“…Tropical Australia has been identified as having high potential for the establishment and expansion of oyster aquaculture and oyster reef restoration, however the high diversity of species and taxonomic uncertainties pose a challenge [ 6 , 12 , 15 ]. For example, Saccostrea echinata is a small spiky oyster endemic to the Indo-Pacific and likely Australia [ 7 , 11 , 16 ], however, the name continues to be incorrectly applied to the tropical blacklip oyster (now known to be S. spathulata [ 12 ]), a promising species for aquaculture in the Australian tropics [ 17 – 20 ]. The use of “superspecies” names in scientific literature, especially S. cuccullata , is also problematic as it is unclear which specific lineage research is reporting on [ 21 – 24 ].…”

“…The past use of what we now know to be incorrect or “superspecies” names has trickled through to government and industry, causing difficulty for summarising species-specific biological information necessary for advancing restoration and aquaculture [ 6 ]. There is a need for all stakeholders to adopt the lineage naming system proposed by Lam and Morton, 2006 to delineate species and species-specific information until species boundaries have been ascertained and scientific names can be assigned [ 9 , 10 , 12 , 15 ].…”

“…While most lineages within the S. cucullata complex are yet to be assigned to a new or existing species, molecular work has enabled a better understanding of habitat preferences and geographic ranges which will aid in species identification and understanding aquaculture and restoration potential in localised regions [ 7 , 9 , 15 , 28 ]. Five species belonging to the S. cuccullata complex have recently been documented in the Queensland tropics: lineage B, lineage F, lineage G, lineage I and Saccostrea spathulata (lineage J) [ 12 ]. Most of these species are sympatric with one another as well as with S. glomerata (in subtropical locations), and in most cases are unable to be distinguished from one another morphologically.…”