Alien Freshwater Clams in the Hawaiian Islands 1 CARL C. CHRISTENSEN 2 Bishop Museum, 1525 Bernice Street, Honolulu, Hawai‘i 96817-2701; email: carl@bishopmuseum.org Cowie (1997) reviewed Hawaiian records of alien nonmarine snails and slugs but did not address alien nonmarine bivalves. This note summarizes the literature on alien freshwater clams of the Families Corbiculidae and Sphaeriidae that have been reported to occur in the Hawaiian Islands and presents evidence refuting the suggestion that sphaeriids were introduced to the Hawaiian Islands prehistorically; they are instead modern introductions. Corbiculidae Corbicula fluminea (Müller, 1774) Corbicula fluminea is a highly invasive freshwater clam of Asian origin (Counts 1986; Sousa et al. 2008) that first made its appearance in the Hawaiian Islands when living indi- viduals were found for sale in an O‘ahu market (Burch 1978). C. fluminea is now well established on that island (Devick 1991a; Eldredge 1994; Burch 1995; Englund & Filbert 1999; Englund & Godwin 2002; Englund et al. 2003; Brasher et al. 2004; Englund & Arakaki 2004) and has also been reported from the islands of Kaua‘i (Heacock 1991; Devick 1991a; Eldredge 1994; Englund et al. 2002), Lāna‘i (Staples & Cowie 2001), Maui (Hau 1991; Devick 1991a; Eldredge 1994; Higashi et al. 2008; Parham et al. 2008), and Hawai‘i (Devick 1991a; Eldredge 1994; Englund et al. 2001). Sphaeriidae Musculium lacustre (Müller, 1774) Musculium partumeium (Say, 1822) Pisidium casertanum (Poli, 1791) All three of these species are native to North America; Musculium lacustre has also been reported from Europe and Japan, while Pisidium casertanum also occurs in Eurasia, Central and South America, Africa, Australia, and New Zealand (Herrington 1962). In the Hawaiian Islands, Bryan (1915: 436-437, 440) reported unidentified species of Sphaerium and Pisidium to occur on “Oahu, Molokai, Kauai, and perhaps other islands of the group,” and Devick (1991b) and Eldredge (1994) reported the presence of an unidentified species of Musculium on O‘ahu and Maui. Musculium was formerly regarded as a subgenus of Sphaerium, and Bryan’s records may well refer to taxa now generally classified in Musculium. Herrington (1962) reported M. lacustre (as Sphaerium lacustre) to occur in the Hawaiian Islands but cited no authority or specimens to support that assertion; Miller (1966) included Hawai‘i within range of the species on Herrington’s authority. Its occur- rence in the Hawaiian Islands requires verification. Burky et al. (2000) reported M. par- tumeium and P. casertanum to be present in taro ponds at Ke‘anae, Maui, and subsequent- ly Higashi et al. (2008) and Parham et al. (2008) reported M. partumeium and an uniden- tified species of Pisidium from the same Maui watershed. Records of the Hawaii Biological Survey for 2015. Edited by Neal L. Evenhuis. Bishop Museum Occasional Papers 118: 1–4 (2016) Published online: 10 August 2016 ISSN (online): 2376-3191 1. Contribution No. 2016-007 the Hawaii Biological Survey. 2. Research Associate, Hawai Biological Survey, Bishop Museum, 1525 Bernice Street, Honolulu, Hawaii 96817- 2704, USA