Acanthocephala

McDermott, John J., 2011, Parasites of shore crabs in the genus Hemigrapsus (Decapoda: Brachyura: Varunidae) and their status in crabs geographically displaced: a review, Journal of Natural History 45 (39 - 40), pp. 2419-2441 : 2426-2427

Phylum ACANTHOCEPHALA

Cystacanth larvae of three species of Profilicollis (Polymorphidae) parasitize three species of Hemigrapsus ( Table 2). Profilicolis antarcticus employs H. crenulatus from Chile ( Pulgar et al. 1995) as an intermediate host, and in New Zealand the same crab plus H. sexdentatus are hosts for Profilicollis antarcticus and Profilicollis novaezelandensis ( Brockerhoff and Smales 2002; Latham and Poulin 2003; Poulin et al. 2003). In Chile H. crenulatus is the only known intermediate host for Profilicollis antarcticus , whereas in New Zealand Profilicollis antarcticus and Profilicollis novaezelandensis infect another varunid, Austrohelice crassa (Dana, 1851) as well as the ocypodid crab Macrophthalmus hirtipes . Balboa et al. (2009) had difficulty identifying cystacanths taken from 297 specimens of H. crenulatus collected in Chile because these cystacanths had morphological characteristics similar to those of Profilicollis antarcticus as well as Profilicollis chasmagnathi Holcman-Spector, Mañé-Garzón and Dei-Cas, 1977 parasitic in Chasmagnathus granulata Dana, 1851 (Varunidae) from Uruguay.

Koehler and Poulin (2010) conducted a survey of infections with Profilicolis spp. in Hemigrapsus spp. and Macrophthalmus hirtipes from Otago Harbour, New Zealand. They found prevalences of 40–94% and intensities from 68 to 150. The more distant relative Halicarcinus varius was only lightly infected (5% prevalence, 0.1 mean intensity). Cystacanths were probably a combination of the two species but because of difficulty in identification they were not distinguished.

In the northeast Pacific Profilicollis botulus parasitizes H. oregonensis but not the sympatric H. nudus ( Ching 1989) . Cystacanths of this worm, however, are also wellknown parasites of other brachyurans, particularly Carcinus maenas and Hyas araneus (Linnaeus, 1758) in Europe ( Uspenskaja 1960; Rayski and Garden 1961; Liat and Pike 1980; Ching 1989; Torchin et al. 2001; McDermott et al. 2010). The anomurans Paralithodes camtschaticus (Tilesius, 1815) and Pagurus pubescens Krøyer, 1838 ) are also intermediate hosts for Profilicollis botulus ( Uspenskaja 1960; McDermott et al. 2010). Suggesting that brachyurans may be preferred hosts for Profilicollis botulus, Uspenskaja (1960) observed ∼ 100% versus 12% prevalence of the parasite in Hyas araneus and Pagurus pubescens , respectively, in the Barents Sea.

Birds are definitive hosts of the aforementioned Profilicollis species. Profilicollis antarcticus infects the Pale-faced sheathbill, Chionis alba (Gmelin, 1789) , Variable oystercatcher, Haematopus unicolor Forster, 1844 and the South Island pied oystercatcher, Haematopus ostralegus Linnaeus, 1758 among others, whereas Profilicollis novaezelandensis parasitizes the South Island pied oystercatcher and the Bar-tailed godwit, Limosa lapponica (Linnaeus, 1758) ( Pulgar et al. 1995; Brockerhoff and Smales 2002; Latham and Poulin 2003). Ching (1989) provided a long list of definitive bird hosts for Profilicollis botulus from British Columbia as follows: Common goldeneye, Bucephala clangula (Linnaeus, 1758) , Greater scaup, Aythya marila (Linnaeus, 1761) , Whitewinged scoter, Melanitta fusca (Linnaeus, 1758) , among others. He also indicated that Profilicollis botulus infects Oldsquaw, Clangula hyemalis (Linnaeus, 1758) in New Brunswick, Canada and the Common eider, Somateria mollissima (Linnaeus, 1758) in Scotland.

Latham and Poulin (2002a) showed that in New Zealand mortality in H. crenulatus and H. sexdentatus through bird predation is greater in crabs infected with Profilicollis antarctica and Profilicollis novaezelandensis than in uninfected specimens. They suggested that parasitization might interfere with the tendency of crabs to seek shelter during periods of low tide. Latham and Poulin (2002b), however, failed to detect such a behavioural tendency in infected H. crenulatus , but in the shore crab Macrophthalmus hirtipes the prevalence and intensity of cystacanths were greater in exposed than hidden crabs. In Chile Haye and Ojeda (1998) showed a correlation between an increased oxygen consumption (metabolic rate) and greater activity in H. crenulatus infected with cystacanths of Profilicollis antarctica . Poulin et al. (2003) found that the neurotransmitter serotonin in crabs from New Zealand was negatively correlated with the number of Profilicollis antarcticus cystacanths in H. crenulatus , suggesting a neurobiological basis for the behavioural changes caused by parasitism.