DIDEMNIDAE, Giard, 1872

Mead, A., Carlton, J. T., Griffiths, C. L. & Rius, M., 2011, Introduced and cryptogenic marine and estuarine species of South Africa, Journal of Natural History 45 (39 - 40), pp. 2463-2524 : 2503-2504

Family DIDEMNIDAE

Didemnum granulatum Tokioka, 1954 Cryptogenic

This species was first found in South Africa by Monniot et al. (2001) from samples collected off Port Elizabeth on the southeast coast and KwaZulu-Natal on the east coast. Although the origin of this species is unclear, it is present in the Atlantic, Pacific and Indian oceans, as well as the Red Sea. This widespread global distribution leads us to suspect it as cryptogenic.

Didemnum psammathodes (Sluiter, 1895) Cryptogenic

Monniot et al. (2001) first reported this species based on specimens collected from Thompson’s Pool in KwaZulu-Natal (east coast). As with Didemnum granulatum , the origin of this species is unknown; however it is widely distributed around the world, and so thought to be cryptogenic.

Didemnum rodriguesi Rocha and Monniot, 1993 Cryptogenic

This species represents another ascidian of unknown origin, but becuase of a global distribution throughout tropical seas and it is thought to be cryptogenic. This species was first detected in South Africa by Monniot et al. (2001), based on specimens collected from Sodwana Bay on the east coast.

Trididemnum cerebriforme Hartmeyer, 1913 Cryptogenic

This species was first described by Hartmeyer (1913) from South African samples. Subsequently, it has been recorded in several regions around the world, including the western Indian Ocean, Australia, Japan and the western tropical Pacific Ocean ( Monniot et al. 2001); we therefore suspect it to be cryptogenic. It is widespread along South African coasts, ranging from Saldahna Bay (west coast) to Sodwana (east coast). Both Millar (1955) and Monniot et al. (2001) noticed a large morphological variability between the South African specimens, although no distinct characteristic exists that would justify splitting them in different species.

Diplosoma listerianum (Milne-Edwards, 1841) Introduced

This species forms transparent colonies (although they can also appear grey and opaque yellow) that, despite the small size of its zooids, can colonize very large areas. Diplosoma listerianum is common in harbours, where it overgrows other sessile organisms such as mussels, algae and other ascidians. The origin is Europe ( Monniot et al. 2001), but this species now occurs globally ( Lambert and Lambert 1998). The first South African record is by Millar (1955) based on specimens collected from Langebaan on the west coast in 1949. It is found from Alexander Bay on the west coast to Durban on the east coast (M. Rius unpublished results).