From Chile to the South African west coast: first reports of the Chilean stone crab Homalaspis plana (H.Milne Edwards, 1834) and the South American sunstar Heliaster helianthus (Lamarck, 1816) outside their natural ranges
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The South American multiradiate sunstar Heliaster helianthus (Lamarck, 1816) and the Chilean stone crab Homalaspis plana (H. Milne Edwards, 1834) are marine predators that, previous to this report, have no invasion history. However, during subtidal maintenance of a pier within Saldanha Bay along the South African west coast during 2015–2017, a single individual of each species was detected on the seafloor. Following this, intertidal and subtidal surveys were undertaken in surrounding natural habitats, but no further individuals were recorded. Both species are native to Chile, a region with very similar environmental conditions to the west coast of South Africa and from which other South African marine alien species originate, highlighting the connectedness between these regions and the risk for future transfers and establishment. The presence of two pathways from Chile to South Africa (shipping and aquaculture imports) and closely matching environmental conditions are likely to play a role in future successful introductions of Chilean species to the South African west coast. It is, therefore, recommended that particular attention be paid to monitoring aquaculture imports from the west coast of South America and that incoming vessels from that region be inspected upon arrival. Additionally, both H. heliaster and H. plana should be added to alien species watchlists in South Africa and other regions connected to Chile via marine vectors and which experience similar environmental conditions.