Leostyletus misakiensis

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 unpublished data); and the Golden Gate in 2003 (California Academy of Sciences 2014).

---

Description

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).

---

Taxonomy

Ecology

General:

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.

Food:

Obelia spp. Hydroids

Trophic Status:

Carnivore

Carn

---

Habitats

General Habitat	Rocky	None
General Habitat	Marinas & Docks	None
General Habitat	Unstructured Bottom	None
Salinity Range	Polyhaline	18-30 PSU
Salinity Range	Euhaline	30-40 PSU
Tidal Range	Subtidal	None
Vertical Habitat	Epibenthic	None

---

---

Tolerances and Life History Parameters

Broad Temperature Range	None	Cold temperate-Warm temperate
Broad Salinity Range	None	Polyhaline-Euhaline

General Impacts

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

---

References

Agarwal, Robin Gwen 2023 After the algal bloom cleared out of Lake Merritt, the nudibranchs came to party in droves. https://baynature.org/2023/05/30/after-the-algal-bloom-cleared-out-of-lake-merritt-the-nudibranchs-came-to-party-in-droves/



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



Baba, Kikutaro (1960a) Two new species of the genus Eubranchus from Japan (Nudibrancida-Eolidacea), Publications of the Seto Marine Biological Laboratory 8(2): 299-302

Barnes, Robert D. (1983) Invertebrate Zoology, Saunders, Philadelphia. Pp. 883

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

Behrens, David W; Tuel, Merritt (1977) Notes on the opisthobranch fauna of South San Francisco Bay, Veliger 20(1): 33-36

Behrens, David W. (1971) Eubranchia misakiensis Baba 1960 (Nudibranchia: Eolidiacea) in San Francisco Bay, Veliger 14(2): 214-215

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

California Academy of Sciences 2002 <i>Eubranchus misakiensis</i>. <missing URL>



California Academy of Sciences 2005-2015 Invertebrate Zoology Collection Database. <missing URL>



Carlton, James T. (1979) History, biogeography, and ecology of the introduced marine and estuarine invertebrates of the Pacific Coast of North America., Ph.D. dissertation, University of California, Davis. Pp. 1-904

Cohen, Andrew N.; Carlton, James T. (1995) Nonindigenous aquatic species in a United States estuary: a case study of the biological invasions of the San Francisco Bay and Delta, U.S. Fish and Wildlife Service and National Sea Grant College Program (Connecticut Sea Grant), Washington DC, Silver Spring MD.. Pp. <missing location>

Foss, Stephen (2011) <missing title>, California Department of Fish and Game, Office of Spill Prevention and Response, Sacramento. Pp. 54

Goddard, Jeffrey H. R. (2007) The Light and Smith Manual: Intertidal Invertebrates from Central California to Oregon, University of California Press, Berkeley CA. Pp. 781-782

Kim, Daemin; Taylor, Andrew T.; Near, Thomas J. (2022) Phylogenomics and species delimitation of the economically important Black Basses (Micropterus), Scientific Reports 12(9113): Published online
https://doi.org/10.1038/s41598-022-11743-2

McDonald, Gary R. (2007) The Light and Smith Manual: Intertidal Invertebrates from Central California to Oregon, University of California Press, Berkeley CA. Pp. 788-807

Miller, Michael D. 2004-2014 Slug Site. <missing URL>



Rudman, W. B. 1997-2016 Sea Slug Forum. http://www.seaslugforum.net/

---