Invasion History

First Non-native North American Tidal Record: 1975
First Non-native West Coast Tidal Record: 1975
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Amblyosyllis 'speciosa' was first described from Japan by Izuka (1912). Imajima (1966d) described and illustrated five color phases, which probably represent distinct species. Southern California specimens, seen by Leslie Harris, resemble Imajima's form 4 (Fig. 27d) (Leslie Harris, 2014, personal communication). Amblyosyllis speciosa form 4 was collected from the northern and southern Pacific coasts of Japan, the Seto Inland Sea, and the Sea of Japan (Imajima 1966d), which is considered its native geographical distribution. Dorsey (1978) collected polychaetes identified as A. speciosa from Southern California, somewhat resembling Imajima's form 4, but with some color differences. Amblyosyllis speciosa appears to be established in Long Beach Harbor and Mission Bay (Cohen et al. 2002). Records from Panama (Capa et al. 2001) include no descriptions, while Pernet's (1998) specimens from the San Juan Islands, Washington resembled Dorsey's in coloration but differed in having a benthic reproductive mode.

North American Invasion History:

Invasion History on the West Coast:

Amblyosyllis speciosa was first reported from the West Coast by Dorsey (1978), based on worms collected in 1975 from Wilson Cove, on San Clemente Island, California. During a field survey of estuaries in southern California in 2000, A. speciosa (Fig. 27d of Imajima 1966d, identified by Leslie Harris) was found in Mission Bay and Los Angeles-Long Beach Harbor (Cohen et al. 2002; Cohen et al. 2005). A syllid, identified as A. speciosa was collected in 1995 from Friday Harbor, on San Juan Island, Washington. However, females of this polychaete lacked swimming setae and laid benthic egg masses, unlike Dorsey's worms from southern California (Pernet 1998). The Friday Harbor worms may represent a different species, and are omitted from our maps.

Invasion History Elsewhere in the World:

Amblyosyllis speciosa has been reported from the Pacific coast of Panama, from Coiba National Park (Capa et al. 2001). No morphological details were given, so it is unclear whether these records refer to one of the Japanese members of the A. speciosa complex.


Amblyosyllis 'speciosa' was a species complex of epibenthic polychaetes.(Augado et al. (2019) have revised the genus and described a number of species that were subsumed under 'A. speciosa'. A. nigrolineata, described by Okada in 1934, was treated by Imajima (1966c) as a synonym of A. speciosa). This genus belongs to the Syllidae, a family that is extremely diverse and taxonomically difficult, including more than 700 described species (San Martin et al. 2014). Imajima (1966c) described five different color phases, which represented distinct species (Leslie Harris, personal communication 2014; Aguado et al. 2019). Specimens introduced to US West Coast waters resemble Imajima's (1966c) form 4 (fig. 27d), widely distributed on Japanese coasts.

Family characteristics of the Syllidae include: a prostomium with two pairs of eyes, and sometimes a couple of eyespots; three antennae and paired palps; an eversible pharynx and proventricle; the anterior-most segment (peristomium) lacking chaetae, but bearing 1-2 pairs of tentacles; uniramous parapodia (biramous in reproductive individuals); dorsal and ventral cirri on each chaetiger (except in the Autolitinae subfamily); and a pygidium (anal segment) with 2-3 anal cirri (Pettibone 1963; Blake and Ruff 2007). Members of the genus Amblyosyllis have short flattened bodies with ~10-16 segments and a pair of nuchal epaulettes extending posteriorly from the prostomium (Pettibone 1963; Imajima 1966c).

Amblyosyllis 'speciosa' has 16 segments, all but three of which, the first and the last two, bear chaetae. The prostomium is a flattened globe, with two pairs of reddish eyes and a median antenna rising between them. On each side of the prostomium is a lateral antenna, about half the length of the median antenna. A pair of lozenge-shaped nuchal epaulettes extends backward from the prostomium, reaching the 2nd segment - they are attached only to the prostomium. The prostomium has a pair of conical palps, located ventrally. The pharynx bears six pentacuspid teeth, arranged in a hexagon, each with a taller central cusp, and two smaller lateral cusps. The proventriculus extends back to segments 5 or 6 (Imajima 1966c; Dorsey 1978; Aguado et al. 2008).

The segments are trapezoidal in shape, with the joints deeply incised. The tentacular and dorsal cirri of the first segment (peristomium) and the dorsal cirri of the rest of the chaetigers are much longer than the median antenna, and are distinctly annulated. The parapodia are elongated laterally, each with a dorsal triangular prechaetal lobe (a lobe bearing a cluster of about 20 chaetae, with the dorsal-most being longest), and a large paddle-like ventral cirrus bearing two rows of dark granular material. The chaetae in these bundles have a secondary tooth near the tip (bidentate compound falcigers). The anterior portion of the 5th chaeta-bearing segment is roughly rectangular. The pygidium (anal segment) bears 2-3 anal cirri. This worm is 10-15 mm in length (Imajima 1966c; Aguado et al. 2008).

Worms in southern California, found by Leslie Harris, resembled form 4 (Fig. 27d) of Imajima (1966c), and match descriptions of A. nigrolineata (Okada 1934, cited by Aguado et al. 2019). They were brownish purple, with a white transverse band between the dorsal cirri, and the posterior part of the white band was darker than the anterior. Aquado et al. (2019) describe this worm has having rhomboid segments, each having brown patch in the center, with a dark line below.

The mode of reproduction in the Amblyosyllis 'speciosa' species complex is not clear, and may vary across species. Dorsey (1978), Aguado et al. (2008), and Aguado et al. (2019) found females with epigamic (reproductive) modifications, including elongated swimming chaetae, carrying eggs in the water column. Pernet (1998) found a worm then identified as A. speciosa which brooded benthic egg masses. This worm has been described as A. anae sp. nov. (Aguado et al. 2019).


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Annelida
Class:   Polychaeta
Subclass:   Palpata
Order:   Aciculata
Suborder:   Phyllodocida
Family:   Syllidae
SubFamily:   Eusyllinae
Genus:   Amblyosyllis
Species:   nigrolineata


Amblyosyllis speciosa form 4 (d) (Imajima, 1966)

Potentially Misidentified Species

Amblyosyllis ana
Described as Amblyosyllis speciosa by Pernet (1999) from Friday Harbor, San Juan Island, Washington (Aguado et al. 2019).

Amblyosyllis formosa
Amblyosyllis formosa Clarapede 1863 (synonym A. lineata Grube 1863). This species has a wide range in the Northeast Atlantic, from Norway to the Mediterranean (Appeltans et al. 2014). It resembles A. speciosa Izuzu 1966 (form 4) in coloration but has six tricuspid teeth in the pharnyx, as opposed to the pentacuspid teeth of A. speciosa.

Amblyosyllis hectori
Described as Amblyosyllis hectori from San Diego, by Dorsey (1978)., and is presumably native to the Northeast Pacifi (Aguado et al. 2019).



Amblyosyllis nigrolineata is a one of a species complex of marine syllid polychaetes. Sexes are separate, but the mode of reproduction is unclear, and may vary among species in the complex. I Populations of the A. speciosa  group in Japan (Aguado et al. 2008) and San Clemente Island, California (A. hectori, Aguado et al. 2019) show epigamic (reproductive) modifications, including enlarged eyes and swimming chaetae (Dorsey 1978). Similar modifications are known in other members of the genus, such as A. finmarchicus (Pettibone 1963). However, Pernet (1998) found that polychaetes from Friday Harbor, Washington, then identified as A. speciosa (now A. anae, Aguado et al. 2019)/ lacked swimming chaetae and laid gelatinous benthic egg masses. These larvae were benthic and lecithotrophic, and left the egg mass after 3-4 weeks, with a body consisting of the prostomium and four segments, 300-400 µm long (Pernet 1998). The life history and mode of reproduction of A. speciosa in California harbors is unknown.

'Amblyosyllis speciosa' has been collected from the interidal zone to 140 m in Japan (Imajima 1966c). Specimens from San Clemente Island, California, were collected in coralline algal debris at 1-4 m (Dorsey 1978). In Southern California harbors, they were found among pilings and dock floats (Cohen et al. 2002). Amblyosyllis anae from Friday Harbor, Washington, were collected from bivalve shells, infested with the boring sponge Cliona, on a harbor breakwater (Pernet 1998). Amblyosyllis nigrolineata belongs to the subfamily Eusyllinae. Most members of this family feed on colonial benthic invertebrates (e.g., hydroids, bryozoans, etc.), but some feed on diatoms and other algae (Fauchald and Jumars 1979).

Trophic Status:




General HabitatUnstructured BottomNone
General HabitatMarinas & DocksNone
General HabitatRockyNone
General HabitatOyster ReefNone
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Tidal RangeSubtidalNone
Tidal RangeLow IntertidalNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Maximum Length (mm)15Imajima 1966c
Broad Temperature RangeNoneCold temperate-Warm temperate
Broad Salinity RangeNonePolyhaline-Euhaline

General Impacts

No impacts have been reported for introduced Amblyosyllis speciosa on the California coast.

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NEP-VI Pt. Conception to Southern Baja California 1975 Def Estab
P050 San Pedro Bay 2000 Def Estab
NWP-3b None 0 Native Estab
P030 Mission Bay 2000 Def Estab
P058 _CDA_P058 (San Pedro Channel Islands) 1975 Def Estab
P062 _CDA_P062 (Calleguas) 2015 Def Estab
P090 San Francisco Bay 2014 Def Estab
NEP-V Northern California to Mid Channel Islands 2014 Def Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude
767478 Ruiz et al., 2015 2013 2013-08-04 Bahia Resort Marina, Mission Bay, CA, California, USA Def 32.7731 -117.2478
767678 Ruiz et al., 2015 2013 2013-07-17 Naval Station San Diego, San Diego Bay, CA, California, USA Def 32.6867 -117.1333


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Aguado, María Teresa; San Martín, Guillermo; Nishi, Eijiroh (2008) Contribution to the knowledge of Syllidae (Annelida, Phyllodocida) from Japan with descriptions of three new species, Systematics and Biodiversity 6(4): 521-550

Appeltans, W. et al. 2011-2015 World Registry of Marine Species. <missing URL>

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Blake, James A.; Ruff, R. Eugene (2007) The Light and Smith Manual: Intertidal invertebrates from Central California to Oregon (4th edition), University of California, Berkeley CA. Pp. 309-410

Capa, María;  San Martín, Guillermo;  López, Eduardo (2001) Autolytinae, Eusyllinae and Exogoninae (Syllidae:  Polychaeta) in the Parque Nacional de Coiba, Panamá, Revista de Biología Tropical 49(2): Published online

Cohen, A. N. and 11 authors (2005) Rapid assessment survey for exotic organisms in southern California bays and harbors, and abundance in port and non-port areas., Biological Invasions 7: 995-1002

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Fauchald, Kristian; Jumars, Peter A. (1979) The diet of worms : A study of polychaete feeding guilds, Oceanography and Marine Biology, an Annual Review 17: 193-284

Imajima, Minoru (1966c) The Syllidae (polychaetous annelids from Japan (III) Eusyllidane., Publication of the Seto Marine Biological Laboratory 14(2): 85-116

Messerman, Nicole A.; Bowden, Timothy J. (2016) Survey of potential reservoir species for the oyster parasite Multinucleate Sphere X (Haplosporidium nelsoni) in and around oyster farms in the Damariscotta River Estuary, Maine, Journal of Shellfish Research 35: 851-856

Pernet, Bruno (1998) Benthic egg masses and larval development of Amblyosyllis speciosa (Polychaeta: Syllidae), Journal of the Marine Biological Association of the United Kingdom 78: 1369-1372

Rodrigues, Nathalia; Ribeiro, Danielle; Miyahira, Igor C. Samira; Portugal, Luciano N.; Santos, G. M.; Neves, Raquel A. F. (2023) Do feeding responses of a non-native bivalve outperform the native one in a coastal lagoon? A possible explanation for the invasion success of the dark false mussel Mytilopsis leucophaeata, PeerJ 13(15848): Published online
DOI 10.7717/peerj.15848

Ruiz, Gregory M.; Geller, Jonathan (2018) Spatial and temporal analysis of marine invasions in California, Part II: Humboldt Bay, Marina del Re, Port Hueneme, and San Francisco Bay, Smithsonian Environmental Research Center & Moss Landing Laboratories, Edgewater MD, Moss Landing CA. Pp. <missing location>

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