An enriched genomic library of M. squamiger resulted in a total of eight polymorphic loci that were genotyped in 20 individuals from a population within its introduced range, and 20 individuals more from a native population. The mean number of alleles per locus was 5.33 and mean observed heterozygosity was 0.432. No significant linkage disequilibrium was found among loci pairs. Significant genetic differentiation was observed between populations
: Ballast waters, Biofouling
: Not entered
Results of species assessment according to Target Species selection criteria
Known human health impact? No
Comments: Not available.
Known economic impact? Yes
Comments: Has been found in high abundance in oyster farms, where it poses an economic threat (Rodriguez and IbarraObando, 2008) (Rius et al., 2008).
References: Rius, M., Pineda, M. C., & Turon, X. (2008). Population dynamics and life cycle of the introduced ascidian Microcosmus squamiger in the Mediterranean Sea. Biological Invasions, 11(10), 2181–2194. doi:10.1007/s10530-008-9375-2
Mastrototaro, F., & Dappiano, M. (2008). New record of the non-indigenous species Microcosmus squamiger (Ascidiacea: Stolidobranchia) in the harbour of Salerno (Tyrrhenian Sea, Italy). Marine Biodiversity Records, 1. doi:10.1017/s1755267205001247
Known measurable environmental impact? Yes
Comments: Decline of other species, while M. squamiger has increased its abundance; can alter native biota (Rius et al, 2008).
References: Rius, M., Pineda, M. C., & Turon, X. (2008). Population dynamics and life cycle of the introduced ascidian Microcosmus squamiger in the Mediterranean Sea. Biological Invasions, 11(10), 2181–2194. doi:10.1007/s10530-008-9375-2
Mastrototaro, F., & Dappiano, M. (2008). New record of the non-indigenous species Microcosmus squamiger (Ascidiacea: Stolidobranchia) in the harbour of Salerno (Tyrrhenian Sea, Italy). Marine Biodiversity Records, 1. doi:10.1017/s1755267205001247
Included in the final TS list? - Yes
Comments: Assessed by the COMPLETE project experts (2021), included in target species list.