Brachyanodon kennerlyi

Brachyanodon, formerly a subgenus of Anodonta, is now recognized as a distinct genus following Campbell and Lydeard (2025). Brachyanodon needs review to determine what are species-level clades.

There remains taxonomic confusion surrounding this species complex. Williams et al. (2017) retain A. californiensis, A. kennerlyi, A. nuttalliana, and A. oregonensis based on their phylogenetic affinity to Eurasian Anodonta (Mock et al. 2004, Zanatta et al. 2007, Chong et al. 2008). Zanatta et al. (2007) supported the monophyly of both Pyganodon and Utterbackia using mutation coding of allozyme data, but also resolved the Eurasian Anodonta cygnea to Pyganodon, Utterbackia, and North American Anodonta; indicating further phylogenetic analysis of the Anodontinae is required including both North American and Eurasian species.

This species has a fairly wide northern range in northwestern North America and despite taxonomic uncertaintly with the genus Anodonta, remains little affected by threats due to its isolation from typical southerly threats of habitat loss, pollution, and introduced species. It is often quite common when found.

In Canada, it is common and often abundant in British Columbia, particularly Vancouver Island and other coastal islands (including Queen Charlotte Islands) and on the mainland from the Columbia to the Fraser and Skeena River systems (Clarke, 1981). It also occurs in Alberta with little precise information (two lakes) (Metcalfe-Smith and Cudmore-Vokey, 2004). Clarke (1981) also cites a few mountain lakes in the uppermost North Saskatchewan (questionable) and Athabasca River systems of Alberta and extends in the Pacific drainage to Oregon. Nedeau et al. (2005) list distribution as the watersheds of Oregon, Washington, British Columbia, Alberta, and northern Saskatchewan. The species also occurs in the southeast panhandle of Alaska (AK NHP, pers. comm., 2007).

Clarke (1981) depicts specimens from Aberdeen, Washington; Queen Charlotte Islands, British Columbia; and Lillouet District, British Columbia. Nedeau et al. (2005) list the Peace River in British Columbia, part of the Arctic watershed as well as coastal islands in British Columbia; and include a photo of Kachess Lake in Washington. In Oregon, several populations of Anodonta were recently confirmed in the Middle Fork John Day River and the lower main stem of the Umatilla River, but due to the taxonomic confusion surrounding the western Anodonta, identification to species level was not attempted (Brim Box et al., 2003; 2006), although preliminary evidence indicates the John Day River population includes A. californiensis/nuttalliana clade and the Umatilla River population include both A. oregonensis/kennerlyi and A. californiensis/nuttalliana clades in sympatry (K. Mock, Utah State University, pers. comm., 2007). In Canada, it is common and often abundant in British Columbia as far north as Prince George and Kootenay Lake in the south, particularly Vancouver Island and other coastal islands (including Queen Charlotte Islands) and also occurs in Alberta with little precise information (two lakes) (Metcalfe-Smith and Cudmore-Vokey, 2004). Clarke (1981) also cites a few mountain lakes in the uppermost North Saskatchewan and Athabasca River systems of Alberta and extends in the Pacific drainage to Oregon). It is sparingly documented in southeast Alaska (AK NHP, pers. comm., 2006). Historically, it has been seen in Quiniault and Sammamish Lakes in western Washington, at Spokane and Yakima on the Columbia River, and in Eugene and just north of Coos Bay, Oregon (Henderson, 1929, 1936; Ingram, 1948; Clarke, 1981). Chong et al. (2007) used specimens from Chilliwack Lake, British Columbia. Museum specimens (UMMZ) exist for Alaska (Heckman Lake in southeast Alaska), Washington (King Green Lake in King Co., Black Lake in Thurston Co., Quiniault Lake in Grays Harbor, Skookumchuck River in Lewis Co., Sammamish Lake in Whatcom, Latah Creek in Spokane, Beaver Lake in Skagit), Oregon (Ten Mile Lake in Coos, Fern Ridge Lake in Lane Co.), Nevada (Humboldt River in Elko), and British Columbia (Fraser River, Nicole Lake; including Texada Island).

Since the western floater is distributed in less-disturbed northern areas, it has not experienced the full range of stressors experienced by more southern and coastal Anodonta species. Land use, water diversion, pollution, and dams may affect populations in the Columbia River in Washington (Nedeau et al., 2005).