Invasion History

First Non-native North American Tidal Record: 1962
First Non-native West Coast Tidal Record: 1962
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Leostyletus misakiensis was described from Mukaishima, Honshu, Japan. It occurs on both coasts of Japan from the Seto Inland Sea to the Sea of Okhotsk (Rudman 2003; Behrens 2004). This nudibranch has been reported from Hong Kong, but the identity of these specimens is uncertain (Rudman 2001). In 1962, L. misakiensis was first collected in San Francisco Bay, and was later found to be abundant (Behrens 1971; Carlton 1979; Cohen and Carlton 1995). It has been reported from British Columbia, but those reports appear to be misidentifications (Jeffrey Goddard, in Rudman 2003).

North American Invasion History:

Invasion History on the West Coast:

Leostyletus misakiensis was first collected in California at San Francisco Municipal Marina in 1962, where it was very abundant on hydroids of the genus Obelia, which is cryptogenic in the Northeast Pacific (Behrens 1971). It was subsequently found in trawls and on marina floats near Redwood City in South San Francisco Bay (Behrens and Tuel 1977). It appears to be established and abundant in the South and Central Bays. Records include collections from Richardson Bay in 1991 (California Academy of Sciences 2014); Pete's Harbor, Redwood City in 2000 (California Academy of Sciences 2002); the Port of Oakland and Treasure Island in 2000 (Ruiz e al. unpublished data); and the Golden Gate in 2003 (California Academy of Sciences 2014).


The body of Leostyletus misakiensis is long and narrow, with a maximum width of about a twelfth to a sixth of the length. The front corners of the foot form short horns. The rhinophores are simple and prolonged, longer than the oral tentacles. The cerata are spindle-shaped and somewhat inflated, with a yellow ring below the tip. The cerata are arranged in six oblique rows, with bunches of cerata not paired symmetrically, but at an angle from the opposite bunch. Japanese specimens reached about 5 mm (Baba 1960), but San Francisco Bay animals were up to 20 mm (Behrens 1971) in size. The background color is yellowish white, marked with numerous chocolate-brown spots. The oral tentacles are marked with a brown ring, while the rhinophores have 2-3 rings of the same color. This description is based on Baba (1960) and Behrens (1971).

Leostyletus misakiensis lays its eggs in ribbon-shaped masses about 7-11 mm long and 2-14 mm wide (Behrens 1971).


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Mollusca
Class:   Gastropoda
Subclass:   Opisthobranchia
Order:   Nudibranchia
Family:   Eubranchidae
Genus:   Leostyletus
Species:   misakiensis


Eubranchus misakiensis (None, None)
Leostyletus misakiensis (Martynov, 1998)

Potentially Misidentified Species

Eubranchus rustyus
Baja California to British Columbia (McDonald in Carlton 2007)

Eubranchus sanjuanensis
Alaska to Washington (McDonald in Carlton 2007)

Nudibranchus rupium
Found from central California to Alaska, Greenland, Norway (McDonald in Carlton 2007), synonymous with E. olivaceus (Behrens 2004). Reports of L. misakiensis from British Columbia probably refer to N. rupium (Goddard, in Rudman 2003).



Leostyletus misakiensis is a nudibranch found in soft-substrate habitats and harbors. Nudibranchs are simultaneous hermaphrodites and copulate reciprocally or unilaterally. Leostyletus misakiensis lays its eggs in ribbon-shaped masses attached to hard substrates and the stalks of Obelia spp. hydroids. Most Northeast Pacific nudibranchs hatch out as planktotrophic larvae, but some have lecithotrophic larvae (Barnes 1983; Behrens 1984; Goddard 2007).

Leostyletus misakiensis inhabits warm-temperate to cold-temperate regions, on habitats including piers, jetties, and floating structures. In San Francisco Bay, it is widespread in the south and central bays in waters of polyhaline and euhaline salinities (Behrens 1971; Behrens and Tuel 1977; Ruiz et al., unpublished data). It has been found repeatedly on cryptogenic hydroids (Obelia spp.) (Behrens 1984; Behrens 2004, in Miller 2014), but the range of its diet is not known. In many nudibranchs which feed on cnidarians, the nematocysts (stinging cells) are ingested, and are then incorporated into the cerata, as a defensive mechanism (Barnes 1983). This is probably the case in Leostyletus misakiensis.


Obelia spp. Hydroids

Trophic Status:




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

Tolerances and Life History Parameters

Broad Temperature RangeNoneCold temperate-Warm temperate
Broad Salinity RangeNonePolyhaline-Euhaline

General Impacts

No impacts have been reported for Leostyletus misakiensis in North American waters.

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NWP-3b None 0 Native Estab
NEP-V Northern California to Mid Channel Islands 1962 Def Estab
NWP-5 None 0 Native Estab
NWP-4a None 0 Native Estab
P090 San Francisco Bay 1962 Def Estab
P093 _CDA_P093 (San Pablo Bay) 1962 Def Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude
2911 Behrens and Tule 1977, cited by Carlton 1979 1974 1974-01-01 Redwood City Def 37.5250 -122.2000
2912 California Academy of Sciences 2002 None 2002-03-29 None Def 37.5044 -122.2139
2913 Ruiz et al., unpublished data None 2000-09-12 None Def 37.8102 -122.3230
2914 Ruiz et al., unpublished data None 2000-09-11 None Def 37.8203 -122.3626
27984 Foss 2011 2010 2010-06-28 Santa Fe Channel - Front Def 37.9101 -122.3644
30799 Foss 2011 2010 2010-06-28 Santa Fe Channel - Back Def 37.9207 -122.3684
32363 Behrens 1971; Carlton 1979 1962 1962-01-01 San Francisco Municpal Marina Def 37.8061 -122.4462
767879 Ruiz et al., 2015 2011 2012-09-15 Berkeley Marina, San Francisco Bay, CA, California, USA Def 37.8758 -122.3181


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Behrens, D.W. (1991) Pacific Coast Nudibranchs, In: (Eds.) . , Monterey, California. Pp. <missing location>

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Behrens, David W. (2004) Pacific coastal nudibranchs, supplement II: new species to the information on the oldies., Proceedings of the California Academy of Sciences, Third Series 55(2): 11-54

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