STYELIDAE, Herdman, 1881

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 : 2505-2506

Family STYELIDAE

Botryllus schlosseri (Pallas, 1766) Introduced

This colonial ascidian forms characteristic star-shaped zooid systems and although it has been considered to be native from Europe ( López-Legentil et al. 2006), a confirmation of the native range remains. Therefore we have considered this species for now as being of unknown origin. It was first recorded by Millar (1955) based on specimens collected in 1946 from Durban harbour on the east coast. It is now found in many South African harbours as a fouling organism, from Alexander Bay (west coast) to Port Elizabeth on the southeast coast (M. Rius, unpublished results). As Botryllus schlosseri often colonizes other species when they are present in harbours, there is some concern as to possible impacts on indigenous kelp species; Griffiths et al. (2009) also recognize the potentially negative impact of Botryllus schlosseri on the eelgrass Zostera capensis (mistakenly referred to as Spartina maritima therein).

Symplegma brakenhielmi (Michaelsen, 1904) Cryptogenic (= Symplegma viride of authors, not of Herdman 1886)

This species is common in many harbours of the Atlantic and Pacific Oceans, as well as in Australia ( Monniot et al. 2001). First recorded by Millar (1955) as Symplegma viride, Monniot et al. (2001) recognized that the specimens collected from Durban Harbour (east coast) in 1952 were Symplegma brakenhielmi . Its distribution remains

on the east coast (M. Rius, unpublished results), concurring with Millar (1962) who attributed it as a warm-water component of the South African ascidian fauna.

Polycarpa insulsa ( Sluiter, 1898) Cryptogenic

One specimen of this species was collected and reported by Monniot et al. (2001) from KwaZulu-Natal (Isipingo) on the east coast. Of unknown origin, it is widespread throughout the western tropical Atlantic Ocean and New Caledonia ( Monniot et al. 2001).

Cnemidocarpa humilis (Heller, 1878) Introduced

This solitary ascidian has a leathery tunic and adults can be found attached to floating pontoons and harbour ropes ( Monniot et al. 2001; M. Rius, unpublished results). Its origin remains unknown. It is a common species in New Zealand, Australia and the southern part of South America ( Primo and Vázquez 2004). The fact that it is such a large, conspicuous species that had not been reported previously led Monniot et al. (2001) to regard it as an introduction into South Africa. Cnemidocarpa humilis is found along the west coast all the way down to False Bay on the southwest coast (M. Rius, unpublished results).

Styela canopus (Savigny, 1816) Cryptogenic (= Styela stephensoni Michaelsen 1934 ; = Styela marquesana Michaelsen, 1918 )

This small and inconspicuous solitary ascidian originally from the Western Indo- Pacific can be found in sheltered areas (mainly harbours) as a fouling organism, although it can occur in natural habitats such as mangrove swamps ( Monniot et al. 2001). According to Monniot et al. (2001), Michaelsen (1934) first recorded Steyla canopus as Styela stephensoni (a South African endemic) and Millar (1955) subsequently recorded it as Styela marquesana . This species is found on the east coast (M. Rius, unpublished results).

Styela plicata (Lesueur, 1823) Introduced

This solitary western Pacific ascidian has a characteristic thick, tough tunic and it is commonly found attached to floating pontoons and harbour ropes. It can compete and displace native species ( Rius et al. 2009b). It is one of the most common harbour ascidian species worldwide ( Lambert and Lambert 2003; Rocha and Kremer 2005; Wyatt et al. 2005). Styela plicata was first detected in South Africa by Millar (1955) based on specimens from Durban collected in 1951 and 1952. It is surprising that a species of such large size was not identified by Monniot et al. (2001), as later samplings by M. Rius (unpublished results) found this species to be very abundant in several locations along the South African coast. It ranges from Mossel Bay (southeast coast) to Durban on the east coast (M. Rius, unpublished results).