Invasion History

First Non-native North American Tidal Record: 1966
First Non-native West Coast Tidal Record: 1966
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Spinileberis quadriaculeata was first described from specimens collected in the Inland Sea of Japan and 'off the reefs of Honolulu, Hawaii' during the 'Challenger' expedition of 1873-1876 (Brady 1880). The Hawaiian record is puzzling, since all further collections are from the coastal waters of Asia, often from shallow, estuarine waters (Tanaka et al. 2011). Living specimens of S. quadriaculeata are known from the East China Sea and the Okinawa Islands to Aomori Bay, at the northern tip of Honshu, Japan; while fossil specimens, from the Miocene to the Holocene occur from the Gulf of Tonkin, Vietnam to Hokkaido, Japan (Tanaka et al. 2011). In 1966, Les Watling collected specimens of an unfamiliar ostracod from Tomales Bay and described them as a new speces, S. hyalinus (Watling 1970), later corrected to S. hyalina (Cohen et al. 2007). He noted their similarity to S. quadriaculeata, and later noted that he found them identical to specimens from Japan (Watling, in Kornicker 1975; Carlton 1979).

North American Invasion History:

Invasion History on the West Coast:

Type specimens of 'Spinileberis hyalina’ were collected in Tomales Bay, California in October 1966 by Les Watling (U.S. National Museum of Natural History 2016). He noted their similarity to S. quadriaculeata in the initial description (Watling 1970). In a comment included in Kornicker's 1975 discussion of the introduction of Eursarsiella zostericola to San Francisco Bay, Watling indicated that S. hyalina appeared identical to specimens of S. quadriaculeata from Japan, and probably represented an introduction with Pacific oysters (Watling, in Kornicker 1975; Carlton 1979). To our knowledge, Spinileberis quadriaculeata (or 'S. hyalina') has not been reported from other West Coast estuaries (Carlton 1979; Cohen et al. 2007). Tomales Bay was a historically important location for culture of Crassostrea gigas (Pacific Oysters) and has been a site for many species introductions, including some known only from this bay (e.g., Gnorimosphaeroma rayi, Carlton 1979).


The body of an ostracod is enclosed by a bivalve carapace, with two calcified lateral shells connected by a dorsal band of un-calcified cuticle. The shell can be closed by bundles of transverse muscle fibers (central adductor muscles) near the center of each valve, or opened to permit the appendages to extend for crawling or feeding. The surface of the shell has numerous openings for pore canals, equipped with chemosensory and tactile sensilla, and may be ornamented with pits, tubercles, and irregular projections (Barnes 1983; Cohen et al. 2007).

In the order Podocopa, to which Spinileberis quadriaculeata belongs, there is no rostrum and no antennal notch in the anterior margin of the valves. Antenna 1 is uniramous. Antenna 2 has the exopodite reduced to a long, thin, 4-jointed rod. There are 7 pairs of limbs: Antenna 1, Antenna 2, Mandible, Maxilla, and 3 pairs of walking legs or pereiopods (Barnes 1983; Cohen et al. 2007). The body terminates in a greatly reduced furca, posterior to the anus, and ending in prominent claws (Barnes 1983; Cohen et al. 2007).

Spinileberis quadriaculeata has a subtriangular shaped carapace which is expanded anteriorly and tapers toward the posterior end. The greatest height is 2/3 of the length. A vertical, nearly median sulcus divides each valve into two inflated parts. The anterior end is broadly rounded and the posterior end is slightly pointed. Each valve has two posteriorly directed hollow spines, one dorsal and the other ventral. The surface is marked by many sub rectangular shallow pits. The two shells have a dorsal ridge and each shell has an oblique median ridge and two ventral dorsal ridges. Antenna 1 has 5 segments, with the terminal segment somewhat elongated, ending in 3 setae. Antenna 2 has the exopodite reduced to a 3-segmented flagellum, while the endopod has spines on the 2nd and 3rd segments and 3 stout claws at the tip. The 3 pairs of pereiopods are similar, with stout, curved claws at the tips. The male has a large, triangular penis. A furca is missing in the male and in the female it consists of a pair of single segments, ending in one bristle. The body length of the type specimen was 0.5 mm. This description is based on: Brady 1880, Watling 1970, and Tanaka et al. 2011.

We treat Spinileberis hyalina (S. hyalinus Watling 1970), known only from Tomales Bay, California, as a synonym, based on morphological similarity and biogeography (Watling 1970, Watling, in Kornicker 1975; Carlton 1979). Tomales Bay specimens of Spinileberis were initially described as a new species [S. hyalinus Watling 1970, later corrected to S. hyalina (Cohen et al. 2007; Appeltans et al. 2015)]. Watling noted the similarity of S. hyalina and S. quadriaculeata, with S. hyalina differing mainly in the lesser calcification of the shells, a wider anterior margin, and reduced development of the oblique central ridge (Watling 1970). However, in a comment included in Kornicker's 1975 discussion of the introduction of Eursarsiella zostericola to San Francisco Bay, Watling indicated that S. hyalina appeared identical to specimens of S. quadriaculeata from Japan and probably represented an introduction with Pacific oysters (Watling, in Kornicker 1975; Carlton 1979). This is supported by the biogeography of the genus, since five of the six living species occur in Japanese waters (Tanaka et al. 2011), while 'S. hyalina' is known only from Tomales Bay. However, S. hyalina has not been formally synonymized; morphological and genetic studies are desirable.


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Arthropoda
Subphylum:   Crustacea
Class:   Ostracoda
Subclass:   Podocopa
Order:   Podocopida
Suborder:   Cytherocopina
Superfamily:   Cytheroidea
Family:   Schizocytheridae
Genus:   Spinileberis
Species:   quadriaculeata


Spinileberis hyalinus (Watling, 1970)
Spinliberis hyalina (Watling, 1970)
Cythere quadriaculeata (Brady, 1880)
Cythereis quadriaculeata (Mueller, 1912)

Potentially Misidentified Species



Spinileberis quadriaculeata has separate sexes and internal fertilization. Eggs are released into the sediment, at a rate of about 5 per day, and hatching occurs after only a few days. In laboratory culture, females produced about 20 eggs per generation. Development is direct. There are eight molting stages until maturity Adults live 20-40 days (Ikeya et al. 1995).

Spinileberis quadriaculeata is known mostly from muddy, silty, or sandy coastal sediments and estuaries, from the intertidal zone to at least 79 m (Tanaka et al. 2011). In Japan, other species of Spinileberis (S. furyaensis, S. pulchra) are more tolerant of upper-intertidal conditions and low salinities, while S. quadriaculeata predominates in deeper water (Ikeya et al. 1995). In Tomales Bay, S. quadriaculeata was collected over a temperature range of 9-22C and salinities of 18-32 PSU (Watling 1970). Information on feeding is not available, but S. quadriaculeata probably feeds on detritus and microbes.


Detritus, microalgae

Trophic Status:

Deposit Feeder



General HabitatUnstructured BottomNone
General HabitatOyster ReefNone
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Tidal RangeSubtidalNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Minimum Temperature (ºC)9Field data, Tomales Bay CA (Watling 1970, cited by Carlton 1979).
Maximum Temperature (ºC)22.5Field data, Tomales Bay CA (Watling 1970, cited by Carlton 1979).
Minimum Salinity (‰)18Field data, Tomales Bay CA (Watling 1970, cited by Carlton 1979).
Maximum Salinity (‰)32Field data, Tomales Bay CA (Watling 1970, cited by Carlton 1979).
Maximum Length (mm)0.7Watling 1970; Ikeya et al. 1995
Broad Temperature RangeNoneWarm temperate-Cold temperate
Broad Salinity RangeNonePolyhaline-Euhaline

General Impacts

There are no known ecological and economic impacts of Spinileberis quadriaculeata.

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 1966 Def Estab
P110 Tomales Bay 1970 Def Estab
SP-XXI None 1880 Crypto Estab
NWP-3a None 0 Native Estab
NWP-4a None 0 Native Estab
NWP-2 None 0 Native Estab
NWP-4b None 0 Native Estab
P090 San Francisco Bay 2001 Def Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


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

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

Brady, G. Stewardson (1880) <missing title>, Her Majesty's Stationery Office, London. Pp. 1-185

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, Anne C.; Peterson, Dawn E.; Maddocks, Rosalie F. (2007) The Light and Smith Manual: Intertidal invertebrates from Central California to Oregon (4th edition), University of California Press, Berkeley CA. Pp. 417-446

Ikeya, N.; Shimura, K.; Iwasaki, Y (1995) Ostracoda and Biostatigraphy, A. A. Balkema, Rotterdam. Pp. 389-397

Kornicker, Louis S. (1975) Spread of ostracodes to exotic environs on transplanted oysters, Bulletins of American Paleontology 65: 129-139

Tanaka, Gengo; Kuroda, Sachiko, Noriyuki (2011) Taxonomy and microhabitats of the genus Spinileberis (Ostracoda, Crustacea) from Japan, Paleontological Research 15(4): 213-232

U.S. National Museum of Natural History 2002-2021 Invertebrate Zoology Collections Database.

Watling, Les (1970) Two new species of Cytherinae (Ostracoda) from central California, Crustaceana 19(3): 252-263

Yasuhara, Moriaki; Yamazaki, T, Hideo (2005) The impact of 150 years of anthropogenic pollution on the shallow marine ostracode fauna, Osaka Bay, Japan, Marine Micropaleontology 55: 63-74