Aspidoconcha limnoriae

Invasion History

First Non-native North American Tidal Record: 1953
First Non-native West Coast Tidal Record: 1953
First Non-native East/Gulf Coast Tidal Record:

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General Invasion History:

Aspidoconcha limnoriae was described from specimens of Limnoria lignorum, in wood cast ashore at Zandvoort, in the Netherlands in 1952 (de Vos 1953). Subsequently, in 1954 A. limnoriae was found on L. lignorum at Roscoff, in Brittany, France (de Vos and Stock 1956) and in 1984 in Strangford Lough, Northern Ireland, on the Irish Sea (Holmes and Jeal, 1987). Aspidoconcha limnoriae was also reported from the Northwest Atlantic, in Saguenay Fjord, Quebec, on L. lignorum and L. japonica, although these ostracods had some slight differences with de Vos' type (1953) specimens (Brunel 1963). Both L. lignorum and L. japonica are associated with cold, high-latitude waters. Limnoria lignorum is widespread in the North Atlantic and Pacific, while L. japonica is known only from Japan and Quebec (Menzies 1957). Both gribbles are considered cryptogenic, because of their potential transport both by ships and floating logs. Aspidoconcha limnoriae was also found on L. tripunctata, a gribble with a wide temperate-tropical distribution, in the Ligurian (Mediterranean) Sea in 2010 (Calcinai et al. 2013). In all of these Atlantic locations, we consider A. limnoriae cryptogenic, given the sparseness of the records, the wide distribution of the hosts, and the potential for natural or ship transport. However, the occurrence of A. limnoriae on L. tripunctata in San Diego Bay, California (de Vos 1953), is clearly an introduction, since L. tripunctata is introduced on the West Coast of North America (Carlton 1979; Cohen and Carlton 1956; Cohen et al. 2007).

North American Invasion History:

Invasion History on the West Coast:

Aspidoconcha limnoriae is known from the West Coast of North America from one collection of Limnoria tripunctata, taken from a U. S. Naval Repair base in San Diego Harbor in 1953 (de Vos and Stock 1956). The status of A. limnoriae as an introduced species in California reflects its commensal relationship with the introduced Limnoria tripunctata in San Diego Bay (Carlton 1979). There have been few studies of Limnoria in West Coast waters, and so, no further reports of A. limnoriae have been noted. However, we consider this species to be established on the West Coast.

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Description

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.

In the order Podocopa, to which Aspidoconcha limnoriae belongs, there is no rostrum and no antennal notch in the anterior margin of the valves. Antenna 1 is uniramous and 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 (pereiopods). The body terminates in a greatly reduced furca, posterior to the anus, and ending in prominent claws (Barnes 1983; Cohen et al. 2007).

The extent of sexual dimorphism in A. limnoriae is unclear, since de Vos (1953) gave a detailed description only of a male and Brunel (1963) provided only an illustration of the posterior region of a female. In males, the shell is thin and translucent with a seed-shaped ovoid. It is arched dorsally and flattened ventrally, with a length ~2.4 X the height. The valves are equal in size, marked with small pits, and have undivided pore canals with protruding sensillae. The hinge is simple, without teeth. Eyes are absent. Antenna 1 has 5 segments, with the subterminal segment partially subdivided. The joints between segments bear several spines, with finer setae on the outer-lateral edge of the 2nd segment from the base and at the distal end of the antenna. Antenna 2 has the exopodite reduced to a 4-segmented flagellum, while the endopod has spines on the 2nd and 3rd segments and two 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. The tip of the abdomen is blunt and rounded, with a cluster of setae, rather than claws. The body length of the male type specimen was 0.32 mm (de Vos 1953).

de Vos and Stock (1956) did not note any differences between specimens of A. limnoriae from the Netherlands, Brittany, or California. Brunel's (1963) ostracods from the Gulf of St. Lawrence, had some differences in setae on Antenna 1 and the tip of the abdomen, but considered these differences to be within the range of conspecific variation of A. limnoriae.

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Taxonomy

Ecology

General:

Aspidoconcha limnoriae has separate sexes and fertilization is internal. Eggs are brooded. Development is direct. Males and females mature through five instars to maturity (Barnes 1983).

Aspidoconcha limnoriae is known from cold-temperate to Mediterranean climates (Quebec, Italy and San Diego) and marine salinities (de Vos and Stock 1956; Brunel 1963; Calcinai et al. 2013). Habitats include marinas and piers, floating and submerged logs, and vessel hulls (de Vos and Stock 1956; Brunel 1963; Calcinai et al. 2013). The mouthparts of A. limnoriae do not appear specialized for parasitism (de Vos 1953), so it probably feeds on microbes associated with the carapace and excreta of Limnoria spp.

Food:

Commensal with Limnoria spp.

Trophic Status:

Parasite

Paras

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Habitats

General Habitat	Coarse Woody Debris	None
General Habitat	Marinas & Docks	None
General Habitat	Vessel Hull	None
Salinity Range	Polyhaline	18-30 PSU
Salinity Range	Euhaline	30-40 PSU
Tidal Range	Subtidal	None
Tidal Range	Low Intertidal	None
Vertical Habitat	Epibenthic	None

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Tolerances and Life History Parameters

Maximum Length (mm)	0.3	Length of male (de Vos 1953)
Broad Temperature Range	None	Cold temperate-Warm temperate
Broad Salinity Range	None	Polyhaline-Euhaline

General Impacts

No economic or ecological impacts have been reported for Aspidoconcha limnoriae.

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References

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

Brunel, Pierre (1963) [The wood-boring isopods Limnoria japonica and L. lignorum in the Gulf of St. Lawrence: Notes on their distribution and their commensal ciliates, ostracods, and copepods], Crustaceana %: 35-46

Calcinai, B.; Graziano, M.; Mori, M.; Cerrano, C. (2013) [Demographic structure of a population of Limnoria tripunctata Menzies 1951 (Crustacea, Limnoriidae) of the Ligurian Sea], Biologia Marina Mediterranea 20(1): 124-125

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

de Vos, A. P. C.; Stock, J. H. (1956) On commensal Ostracoda from the wood-infesting isopod Limnoria, Beaufortia 55(5): 133-139

de Vos, A.P.C. (1953) Three new commensal ostracods from Limnoria lignorum (Rathke), Beaufortia 34(4): 21-3`

de Vos, A.P.C. (1957) [Annotated list of the marine ostracods in the vicinity of Roscoff], Archives de Zoologie Experimental et Generale <missing volume>: 1-74

Holmes, J. M. C.; Jeal, F. (1987) Some crustaceans associated with the gribble Limnoria lignorum (Rathke) in Ireland., Irish Naturalists' Journal 22(7): 317-319

Karanovic, Ivana; Brandão, Simone Nunes (2014) Biogeography of deep-sea woodfall, cold seep and hydrothermal vent Ostracoda (Crustacea), with the description of a new family and a taxonomic key to living Cytheroidea, Deep-Sea Research II 111: 76-94

McKenzie, K. G. (1972) New data on the ostracode genera Laocoonella de Vos & Stock, Redekea de Vos, and Aspidoconcha de Vos; with a key to the family Xestoleberididae and a resume of symbiosis in Ostracoda, Beaufortia 19(254): 151-162

Menzies, Robert James (1957) The marine borer family Limnoriidae (Crustacea, Isopoda). Part I: Northern and Central America: Systematics, distribution, and ecology, Bulletin of Marine Science of the Gulf and Caribbean 7(2): 101-200

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