Common name: a New Zealand amphipod

Synonyms and Other Names: Chaetocorophium lucasi (Hurley, 1954)

Identification: Paracorophium lucasi is an amphipod with a compressed body and head with lateral lobes. Eyes are small, black, and round. The rostrum and ocular lobes are short. The 1st antenna is slender without flagellum (thin threadlike structure), and the 2nd antenna is robust with small flagellum. The defining characteristics of the species include the outer plate of maxilliped (appendage modified for feeding) with a fringe of many fine setae (hair or a bristle) along the inner margin. The 1st through 3rd epimeral plates along the body are all with marginal fringes of long slender setae. The 3rd through 5th paraeopods (four pairs of appendages) have long fine setae (Hurley 1954, Fenwick 2001). 

Size: Adults are about 4 mm long (Chapman 2007)

Native Range: New Zealand, on the North Island (Lake Rotorua, Lake Waikare, Lake Rotoiti, at Whakatane, Raglan, Waitara, and Wanganui) and in lakes and intertidal mudflats across South Island (Fenwick 2001, Chapman et al. 2002, Stevens and Hogg 2004).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Mainly a sedentary species (epigean) of tube-building amphipods occurring in estuaries of highly variable salinity. Most often found living in fine organic sediments in the tidal regions of sand or mudflats of harbors and inlets or in slow-flowing brackish regions of streams and rivers (Hurley 1954, Fenwick 2001). Paracorophium lucasi feed on phytoplankton, detritus, and benthic microalgae or filamentous epiphytic algae (Bousfield 1973).

Means of Introduction: Paracorophium lucasi was most likely introduced on logs from New Zealand imported in the 1970s, or lumber used for dry ballast (Boyd et al. 2002).

Status: Established in Humboldt County, California. 

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

Remarks: Australasian species of Paracorophium is very closely related to Chaetocorophium, and some researchers propose synonymising the two genera (Chapman et al. 2002).

References: (click for full references)

Bousfield, E.L. 1973. Shallow-water gammaridean Amphipoda of New England., Comstock Publishing Associates, Ithaca, NY.  

Boyd, M.J., Mulligan, T.J., and F.J. Shaughnessy. 2002. Non-indigenous marine species of Humboldt Bay, California., California Department of Fish and Game, Sacramento. PP: 1-118 

Chapman, M.A., Hogg, I.D., Schnabel, K.E.,  and M.I. Stevens. 2002. Synonymy of the New Zealand corophiid amphipod genus, Chaetocorophium Karaman, 1979, with Paracorophium Stebbing, 1899: morphological and genetic evidence. Journal of the Royal Society of New Zealand 32(2): 229-241.

Chapman, J.W. 2007. Gammaridea, University of California Press, Berkeley CA. PP: 545-611 

Fenwick, G.D. 2001. The freshwater Amphipoda (Crustacea) of New Zealand: A review. Journal of the Royal Society of New Zealand 31(2):341-363. 

Hurley, D.E. 1954. Studies on the New Zealand Amphipodan Fauna No. 7. The Family Corophiidae, including a new species of Paracorophiumtran. Transactions of the Royal Society of New Zealand 82(2):431-460. 

Stevens, M.I., and I.D. Hogg. 2004. Population genetic structure of New Zealand’s endemic corophiid amphipods: evidence for allopatric speciation. Biological Journal of the Linnean Society 81: 119–133.

Author: Daniel, W.M.

Peer Review Date: 9/20/2019

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.