Skip to main content Skip to main navigation menu Skip to site footer
Type: Article
Published: 2021-05-11
Page range: 255–279
Abstract views: 516
PDF downloaded: 16

Worming its way in—Polydora websteri (Annelida: Spionidae) increases the number of non-indigenous shell-boring polydorin pests of cultured molluscs in South Africa

Department of Marine Science and Conservation, Cape Peninsula University of Technology, PO Box 652, Cape Town, South Africa.
Department of Marine Science and Conservation, Cape Peninsula University of Technology, PO Box 652, Cape Town, South Africa.
Department Botany and Zoology, Stellenbosch University, Matieland Private Bag X1, Stellenbosch, South Africa.
Annelida aquaculture COI Cyt b 18S rRNA non-indigenous species shell-boring pest polydorin


Polychaete worms of the Polydora-complex (commonly referred to as polydorins) include some of the most common pests of cultured molluscs. Modern culture of molluscs, particularly oysters, is associated with large-scale movement of stock which facilitates movement of polydorins either as “hitchhikers” on the transported molluscs or in the packaging. In 2009, a species identified as Polydora cf. ciliata Johnston, 1838 was reported from oysters in a culture facility in Port Elizabeth, South Africa. Since then, more specimens of this species were recorded on farmed oysters from Namibia, Kleinzee and Paternoster on the west coast of South Africa, but tentatively reidentified as Polydora cf. websteri Hartman in Loosanoff and Engle, 1943 based on morphology and limited genetic evidence. The main aim of this study is therefore to clarify the identity of these specimens by integrating morphological and genetic (mitochondrial COI, Cyt b and nuclear 18S rRNA) evidence. Specimens from South Africa match the morphology of the lectotype of P. websteri and are morphologically and genetically very similar to P. websteri from Australia, China, Japan, and the east, gulf and west coasts of the USA. This confirms the presence of P. websteri in South Africa, making this the second most widespread polydorin pest of aquaculture known. Understanding the full distribution range of the species will help to better understand its global route of invasion and consequently assist with preventing or at least minimising further spread. Polydora websteri increases the number of polydorin pests in South Africa to seven.



  1. Abd-Elnaby, F.A. (2019) New recorded alien polydorid species (Polychaeta: Spionidae) from the Egyptian waters. Egyptian Journal of Aquatic Biology and Fisheries, 23, 409–420.

    Amaral, A.C.Z., Nallin, S.A.H., Steiner, T.M., Forroni, T.O. & Gomes Filho, D. (2013) Catálogo das Espécies de Annelida Polychaeta do Brasil. University of Campinas, São Paulo, Brazil, 141 pp. Available from: (accessed 3 August 2020)

    Bailey-Brock, J.H. (1990) Polydora nuchalis (Polychaeta: Spionidae), a new Hawaiian record from aquaculture ponds. Pacific Science, 44, 81–87.

    Bailey-Brock, J.H. & Ringwood, A. (1982) Methods for control of the mud blister worm, Polydora websteri, in Hawaiian oyster culture. Sea Grant Quarterly, 4, 1–6.

    Barros, T.L., Gomes Santos, C.S., De Assis, J.E. & de Souza, J.R.B. (2017) Morphology and larval development of Polydora cf. websteri (Polychaeta: Spionidae) in a tropical region of north-eastern Brazil. Journal of Natural History, 51, 1169–1181.

    Basilio, C.D., Cañete, J.I. & Rozbaczylo, N. (1995) Polydora sp. (Spionidae), un poliqueto perforador de las valvas del ostión Argopecten purpuratus (Bivalvia: Pectinidae) en Bahía Tongoy, Chile. Revista de Biología Marina, 30, 71–77.

    Bergman, K.M., Elner, R.W. & Risk, M.J. (1982) The influence of Polydora websteri borings on the strength of the shell of the Sea scallop, Placopecten magellanicus. Canadian Journal of Zoology, 60, 2551–2556.

    Bernatzeder, B. (2017) Feasibility study of oyster and mussels aquaculture in South Africa: PO 4013628. South Africa: Department of Agriculture, Forestry and Fisheries, 003, 1–125.

    Blake, J.A. (1969) Systematics and ecology of shell-boring polychaetes from New England. American Zoologist, 9, 813–820.

    Blake, J.A. (1971) Revision of the genus Polydora from the east coast of North America (Polychaeta: Spionidae). Smithsonian Contributions to Zoology, 1971, 1–32.

    Blake, J.A. (1983) Polychaetes of the family Spionidae from South America, Antarctica and adjacent seas and islands. L. S. Kornicker (Ed). Antarctic Research Series, 39, 205–287.

    Blake, J.A. & Evans, J.W. (1973) Polydora and related genera Polychaeta Spionidae as borers in mollusk shells and other calcareous substrates. The Veliger, 15, 235–249.

    Blake, J.A. & Kudenov, J.D. (1978) The Spionidae (Polychaeta) from southeastern Australia and adjacent areas with a revision of the genera. Memoirs of the National Museum of Victoria, 39, 171–280.

    Bonifácio, P.H.O. (2009) Polidorideos (Polychaeta: Spionidae) em Crassostrea rhizophorae (Mollusca : Bivalvia) de cinco rios da costa pernambucana. Master’s thesis, Universidade Federal de Pernambuco, Recife. Available from: (accessed 12 April 2021)

    Boonzaaier, M.K., Neethling, S., Mouton, A. & Simon, C.A. (2014) Polydorid polychaetes (Spionidae) on farmed and wild abalone (Haliotis midae) in South Africa: an epidemiological survey. African Journal of Marine Science, 36, 369–376.

    Boore, J.L. & Brown, W.M. (2000) Mitochondrial genomes of Galathealinum, Helobdella, and Platynereis: sequence and gene arrangement comparisons indicate that Pogonophora is not a phylum and Annelida and Arthropoda are not sister taxa. Molecular Biology and Evolution, 17, 87–106.

    Bower, S.M., Blackbourn, J., Meyer, G.R. & Nishimura, D.J.H. (1992) Diseases of cultured Japanese scallops (Patinopecten yessoensis) in British Columbia, Canada. Aquaculture, 107, 201–210.

    Breves-Ramos, A., Lavrado, H.P., Junqueira, A.O.R. & da Silva, S.H.G. (2005) Succession in rocky intertidal benthic communities in areas with different pollution levels at Guanabara Bay (RJ-Brazil). Brazilian Archives of Biology and Technology, 48, 951–965.

    Çinar, M.E. (2013) Alien polychaete species worldwide: current status and their impacts. Journal of the Marine Biological Association of the United Kingdom, 93, 1257–1278.

    Clement, M., Snell, Q., Walke, P., Posada, D. & Crandall, K. (2002) TCS: estimating gene genealogies. In: Proceedings 16th International Parallel and Distributed Processing Symposium. IEEE, Ft. Lauderdale, Florida, 184 pp.

    Clements, J.C., Bourque, D., McLaughlin, J., Stephenson, M. & Comeau, L.A. (2017) Siltation increases the susceptibility of surface-cultured eastern oysters (Crassostrea virginica) to parasitism by the mudworm Polydora websteri. Aquaculture Research, 48, 4707–4717.

    Darling, J.A. & Carlton, J.T. (2018) A Framework for understanding marine cosmopolitanism in the Anthropocene. Frontiers in Marine Science, 5, 293.

    David, A.A., Matthee, C.A., Loveday, B.R. & Simon, C.A. (2016) Predicting the dispersal potential of an invasive polychaete pest along a complex coastal biome. Integrative and Comparative Biology, 56, 600–610.

    Day, J.H. (1967) A monograph on the Polychaeta of southern Africa. Part 2 Sedentaria. Publication from the Trustees of the British Museum Natural History, London, pp. 656–878.

    Díaz-Díaz, O. & Liñero-Arana, I. (2003) Poliquestos epibiontes de Pinctada imbricata Röding, 1798 (Bivalvia: Pteriidae) en el golfo de Cariaco, Venezuela. Interciencia, 28, 298–301.

    Díaz-Díaz, O. & Liñero-Arana, I. (2009) Porcentaje del grado de infestación de Polydora cf. websteri Hartman, 1943 (Polychaeta: Spionidae) por clase de talla de Crassostrea rhizhophorae (Guilding, 1828) de la Laguna la Restinga (Isla Margarita, Venezuela). Revista Científica, 19, 113–118.

    Diez, M.E., Radashevsky, V.I., Orensanz, J.M. & Cremonte, F. (2011) Spionid polychaetes (Annelida: Spionidae) boring into shells of molluscs of commercial interest in northern Patagonia, Argentina. Italian Journal of Zoology, 78, 497–504.

    Edgar, R.C. (2004) MUSCLE: A multiple sequence alignment method with reduced time and space complexity. BMC Bioinformatics, 5, 1–19.

    Foster, N.M. (1971) Spionidae (Polychaeta) of the Gulf of Mexico and the Caribbean Sea. Studies on the Fauna of Curacao and other Caribbean Islands 129, 1–183.

    Handley, S.J. (1995) Spionid polychaetes in Pacific oysters, Crassostrea gigas (Thunberg) from Admiralty Bay, Marlborough Sounds, New Zealand. New Zealand Journal of Marine and Freshwater Research, 29, 305–309.

    Handley, S.J. & Bergquist, P.R. (1997) Spionid polychaete infestations of intertidal Pacific oysters Crassostrea gigas (Thunberg), Mahurangi Harbour, northern New Zealand. Aquaculture, 153, 191–205.

    Haupt, T.M., Griffiths, C.L. & Robinson, T.B. (2012) Intra-regional translocations of epifaunal and infaunal species associated with cultured Pacific oysters Crassostrea gigas. African Journal of Marine Science, 34, 187–194.

    Haupt, T.M., Griffiths, C.L., Robinson, T.B. & Tonin, A.F.G. (2010a) Oysters as vectors of marine aliens, with notes on four introduced species associated with oyster farming in South Africa. African Zoology, 45, 52–62.

    Haupt, T.M., Griffiths, C.L., Robinson, T.B., Tonin, A.F.G. & De Bruyn, P.A. (2010b) The history and status of oyster exploitation and culture in South Africa. Journal of Shellfish Research, 29, 151–159.

    Hopkins, S.H. (1958) The planktonic larvae of Polydora websteri (Annelida, Polychaeta) and their settling and on oysters. Bulletin of Marine Science, 8, 268–277.

    Keppel, E., Keith, I., Ruiz, G.M. & Carlton, J.T. (2019) New records of native and non-indigenous polychaetes (Annelida: Polychaeta) in the Galapagos Islands. Aquatic Invasions, 14, 59–84.

    Kumar, S., Stecher, G. & Tamura, K. (2016) MEGA7: Molecular Evolutionary Genetics Analysis Version 7.0 for bigger datasets. Molecular biology and evolution, 33, 1870–4.

    Lauckner, G. (1983) Diseases of Mollusca: Bivalvia. In: Kinne, O. (Ed.), Diseases of marine animals. Biologische Anstalt Helgoland, Hamburg, pp. 477–961.

    Lleonart, M., Handlinger, J. & Powell, M. (2003) Spionid mudworm infestation of farmed abalone (Haliotis spp.). Aquaculture, 221, 85–96.

    Loosanoff, V.L. & Engle, J.B. (1943) Polydora in oysters suspended in the water. Biological Bulletin, 85, 69–78.

    Lunz, G.R. (1941) Polydora, a pest in South Carolina oysters. Journal of the Elisha Mitchell Scientific Society 57, 273–283.

    Malan, A., Williams, J.D., Abe, H., Sato-Okoshi, W., Matthee, C.A. & Simon, C.A. (2020) A worm by any other name—shell-boring Polydora haswelli and Polydora neocaeca (Spionidae, Annelida) are a single species. Marine Biodiversity, 50, 51.

    Martinelli, J.C., Lopes, H.M., Hauser, L., Jimenez-Hidalgo, I., King, T.L., Padilla-Gamino, J.L., Rawson, P., Spencer, L.H., Williams, J.D. & Wood, C.L. (2020) Confirmation of the shell-boring oyster parasite Polydora websteri (Polychaeta: Spionidae) in Washington State, USA. Scientific Reports, 10, 3961.

    Moreno, R.A., Neill, P.E. & Rozbaczylo, N. (2006) Poliquetos perforadores nativos y no indígenas en Chile: una amenaza para moluscos nativos y comerciales. Revista Chilena de Historia Natural, 79, 263–278.

    Morgulis, A., Coulouris, G., Raytselis, Y., Madden, T.L., Agarwala, R. & Schäffer, A.A. (2008) Database indexing for production MegaBLAST searches. Bioinformatics, Oxford, England, 24, 1757–1764.

    Mustaquim, J. (1988) Electrophoretic variation of isozymes in Polydora ciliata complex (Polychaeta: Spionidae). Comparative Biochemistry and Physiology Part B: Comparative Biochemistry, 91, 197–205.

    Nel, R., Coetzee, P.S. & Van Niekerk, G. (1996) The evaluation of two treatments to reduce mud worm (Polydora hoplura Claparéde) infestation in commercially reared oysters (Crassostrea gigas Thunberg). Aquaculture, 141, 31–39.

    Nell, J.A. (2001) The history of oyster farming in Australia. Marine Fisheries Review, 63, 14–25.

    Netto, S.A. & Gallucci, F. (2003) Meiofauna and macrofauna communities in a mangrove from the Island of Santa Catarina, South Brazil. Hydrobiologia, 505, 159–170.

    Nishitani, G., Nagai, S., Hayakawa, S., Kosaka, Y., Sakurada, K., Kamiyama, T. & Gojobori, T. (2012) Multiple plastids collected by the dinoflagellate Dinophysis mitra through kleptoplastidy. Applied and Environmental Microbiology, 78, 813–821.

    Nylander, J.A.A. (2004) MrModeltest. Version 2. Distributed by author, Evolutionary Biology Centre, Uppsala University. Available from: (accessed 3 August 2020)

    Oyarzun, F.X., Mahon, A.R., Swalla, B.J. & Halanych, K.M. (2011) Phylogeography and reproductive variation of the poecilogonous polychaete Boccardia proboscidea (Annelida: Spionidae) along the west coast of North America. Evolution and Development, 13, 489–503.

    Pearson, W.R. (2013) An introduction to sequence similarity (“Homology”) searching. Current Protocols in Bioinformatics, 42, 3.1.1–3.1.8.

    Radashevsky, V.I. (1999) Description of the proposed lectotype for Polydora websteri Hartman in Loosanoff & Engle, 1943 (Polychaeta: Spionidae). Ophelia 2, 107–113.

    Radashevsky, V.I., Choi, J. & Gambi, M.C. (2017) Morphology and biology of Polydora hoplura Claparède, 1868 (Annelida: Spionidae). Zootaxa, 4282 (3), 543–555.

    Radashevsky, V.I. & Migotto, A.E. (2017) First report of the polychaete Polydora hoplura (Annelida: Spionidae) from North and South America and Asian Pacific. Marine Biodiversity, 47, 859–868.

    Radashevsky, V.I. & Williams, J.D. (1998) Polydora websteri Hartman in Loosanoff & Engle, 1943 (Annelida, Polychaeta): proposed conservation of the specific name by a ruling that it is not to be treated as a replacement for P. caeca Webster, 1879, and designation of a lectotype for. Bulletin of Zoological Nomenclature, 55, 212–216.

    Rambaut, A. (2016) FigTree. Version 1.4.3. Distributed by the author, Institute of Evolutionary Biology, University of Edinburgh. Available from: (accessed 3 August 2020)

    Rambaut, A., Drummond, A.J., Xie, D., Baele, G. & Suchard, M.A. (2018) Posterior summarization in Bayesian phylogenetics using Tracer 1.7. Systematic Biology, 67, 901–904.

    Read, G.B. (2010) Comparison and history of Polydora websteri and P. haswelli (Polychaeta: Spionidae) as mud-blister worms in New Zealand shellfish. New Zealand Journal of Marine and Freshwater Research, 44, 83–100.

    Rice, L.N., Lindsay, S. & Rawson, P. (2018) Genetic homogeneity among geographically distant populations of the blister worm Polydora websteri. Aquaculture Environment Interactions, 10, 437–446.

    Ronquist, F., Teslenko, M., van der Mark, P., Ayres, D.L., Darling, A., Höhna, S., Larget, B., Liu, L., Suchard, M.A. & Huelsenbeck, J.P. (2012) MrBayes 3.2: efficient Bayesian phylogenetic inference and model choice across a large model space. Systematic biology, 61, 539–542.

    Royer, J., Ropert, M., Mathieu, M. & Costil, K. (2006) Presence of spionid worms and other epibionts in Pacific oysters (Crassostrea gigas) cultured in Normandy, France. Aquaculture, 253, 461–474.

    Rozas, J., Ferrer-Mata, A., Sanchez-DelBarrio, J.C., Guirao-Rico, S., Librado, P., Ramos-Onsins, S.E. & Sanchez-Gracia, A. (2017) DnaSP 6: DNA sequence polymorphism analysis of large data sets. Molecular Biology and Evolution, 34, 3299–3302.

    Ruesink, J.L., Lenihan, H.S., Trimble, A.C., Heiman, K.W., Micheli, F., Byers, J.E. & Kay, M.C. (2005) Introduction of non-native oysters: Ecosystem effects and restoration implications. Annual Review of Ecology, Evolution, and Systematics, 36, 643–689.

    Sabry, R.C. & Magalhães, A.R.M. (2005) Parasitas em ostras de cultivo (Crassostrea rhizophorae e Crassostrea gigas) da Ponta do Sambaqui, Florianópolis, SC. Arquivo Brasileiro de Medicina Veterinária e Zootecnia, 57, 194–203.

    Sato-Okoshi, W. (1999) Polydorid species (Polychaeta: Spionidae) in Japan, with descriptions of morphology, ecology and burrow structure. 1. Boring species. Journal of the Marine Biological Association of the United Kingdom, 79, 831–848.

    Sato-Okoshi, W. & Abe, H. (2012) Morphological and molecular sequence analysis of the harmful shell boring species of Polydora (Polychaeta: Spionidae) from Japan and Australia. Aquaculture, 368–369, 40–47.

    Sato-Okoshi, W. & Abe, H. (2013) Morphology and molecular analysis of the 18S rRNA gene of oyster shell borers, Polydora species (Polychaeta: Spionidae), from Japan and Australia. Journal of the Marine Biological Association of the United Kingdom, 93, 1279–1286.

    Sato-Okoshi, W., Abe, H., Nishitani, G. & Simon, C.A. (2017) And then there was one: Polydora uncinata and Polydora hoplura (Annelida: Spionidae), the problematic polydorid pest species represent a single species. Journal of the Marine Biological Association of the United Kingdom, 97, 1675–1684.

    Sato-Okoshi, W., Okoshi, K., Abe, H. & Li, J.Y. (2013) Polydorid species (Polychaeta, Spionidae) associated with commercially important mollusk shells from eastern China. Aquaculture, 406–407, 153–159.

    Sato-Okoshi, W., Okoshi, K. & Shaw, J. (2008) Polydorid species (Polychaeta: Spionidae) in south-western Australian waters with special reference to Polydora uncinata and Boccardia knoxi. Journal of the Marine Biological Association of the United Kingdom, 88, 491–501.

    Sato-Okoshi, W. & Takatsuka, M. (2001) Polydora and related genera (Polychaeta, Spionidae) around Puerto Montt and Chiloé Island (Chile), with description of a new species of Dipolydora. Bulletin of Marine Science, 68, 485–503.

    Schleyer, M.H. (1991) Shell-borers in oysters, Striostrea margaritacea: pest or symbionts? Symbiosis, 10, 135–144.

    Shinn, A.P., Pratoomyot, J., Bron, J.E., Paladini, G., Brooker, E.E. & Brooker, A.J. (2015) Economic costs of protistan and metazoan parasites to global mariculture. Parasitology, 142, 196–270.

    Simon, C.A. (2011) Polydora and Dipolydora (Polychaeta: Spionidae) associated with on the south coast of South Africa, with descriptions of two new species. African Invertebrates 52, 39–50.

    Simon, C.A. (2015) Observations on the composition and larval developmental modes of polydorid pests of farmed oysters (Crassostrea gigas) and abalone (Haliotis midae) in South Africa. Invertebrate Reproduction and Development, 59, 124–130.

    Simon, C.A. & Booth, A.J. (2007) Population structure and growth of polydorid polychaetes that infest cultured abalone Haliotis midae. African Journal of Marine Science, 29, 499–509.

    Simon, C.A., Ludford, A. & Wynne, S. (2006) Spionid polychaetes infesting cultured abalone Haliotis midae in South Africa. African Journal of Marine Science, 28, 167–171.

    Simon, C.A. & Sato-Okoshi, W. (2015) Polydorid polychaetes on farmed molluscs: Distribution, spread and factors contributing to their success. Aquaculture Environment Interactions, 7, 147–166.

    Simon, C.A., Thornhill, D.J., Oyarzun, F. & Halanych, K.M. (2009) Genetic similarity between Boccardia proboscidea from Western North America and cultured abalone, Haliotis midae, in South Africa. Aquaculture, 294, 18–24.

    Simon, C.A., Worsfold, T.M., Lange, L. & Sterley, J. (2010) The genus Boccardia (Polychaeta: Spionidae) associated with mollusc shells on the south coast of South Africa. Journal of the Marine Biological Association of the United Kingdom, 90, 585–598.

    Skeel, M.E. (1979) Shell-boring worms (Spionidae: Polychaeta) infecting cultivated bivalve molluscs in Australia. Proceedings of the World Mariculture Society, 10, 529–533.

    Surugiu, V. (2005) Inventory of inshore polychaetes from the Romanian coast (Black Sea). Mediterranean Marine Science, 6, 51–73.

    Surugiu, V. (2012) Systematics and ecology of species of the Polydora-complex (Polychaeta: Spionidae) of the Black Sea. Zootaxa, 3518, 45–65.

    Teske, P.R., Von Der Heyden, S., McQuaid, C.D. & Barker, N.P. (2011) A review of marine phylogeography in southern Africa. South African Journal of Science, 107, 43–53.

    Turner, H.J. & Hanks, J.E. (1959) Infestation of Pecten irradians by Polydora. Nautilus, 72, 109–111.

    Walker, L.M. (2011) A review of the current status of the Polydora-complex (Polychaeta: Spionidae) in Australia and a checklist of recorded species. Zootaxa, 2751, 40–62.

    Waser, A.M., Lackschewitz, D., Knol, J., Reise, K., Wegner, K.M. & Thieltges, D.W. (2020) Spread of the invasive shell-boring annelid Polydora websteri (Polychaeta, Spionidae) into naturalised oyster reefs in the European Wadden Sea. Marine Biodiversity, 50, 63.

    Williams, J.D. & Radashevsky, V.I. (1999) Morphology, ecology, and reproduction of a new Polydora species from the east coast of North America. Ophelia, 51, 115–127.

    Williams, L.G. (2015) Genetic structure of pest polydorids (Annelida: Spionidae) infesting Crassostrea gigas in southern Africa: Are pests being moved with oysters? Master’s thesis, Stellenbosch University, Stellenbosch, 75 pp.

    Williams, L.G., Karl, S.A., Rice, S.A. & Simon, C.A. (2017) Molecular identification of polydorid polychaetes (Annelida: Spionidae): Is there a quick way to identify pest and alien species? African Zoology, 52, 105–118.

    Williams, L.G., Matthee, C.A. & Simon, C.A. (2016) Dispersal and genetic structure of Boccardia polybranchia and Polydora hoplura (Annelida: Spionidae) in South Africa and their implications for aquaculture. Aquaculture, 465, 235–244.

    Wong, E., Kupriyanova, E., Hutchings, P., Capa, M., Radashevsky, V.I. & ten Hove, H. (2014) A graphically illustrated glossary of polychaete terminology: invasive species of Sabellidae, Serpulidae and Spionidae. Memoirs of Museum Victoria, 71, 327–342.

    Ye, L.T., Cao, C., Tang, B., Yao, T. & Wang, R. (2017) Morphological and molecular characterization of Polydora websteri (Annelida: Spionidae), and larvae using mitochondrial COI gene as a molecular marker. Pakistan Journal of Zoology, 49, 699–710.

    Zhang, Z., Schwartz, S., Wagner, L. & Miller, W. (2000) A greedy algorithm for aligning DNA sequences. Journal of Computational Biology, 7, 203–214.