Faxonius propinquus

Based on Crandall and De Grave (2017), the representatives of Orconectes form at least two distinct groups. The nominal group (the "cave Orconectes") form a monophyletic group that is more closely related to members of Cambarus, while the remaining "Orconectes" are more closely related to Barbicambarus, Creaserinus, and other species of Cambarus (Crandall and Fitzpatrick 1996, Fetzner 1996). As the type species of Orconectes, Orconectes inermis Cope, 1872, belongs to the cave-dwelling group, the genus is herein restricted to just those taxa. The surface-dwelling taxa now excluded from Orconectes sensu stricto are herein placed in the resurrected genus Faxonius Ortmann, 1905a, the oldest available name previously considered to be a synonym of Orconectes Cope, 1872.

This species is wide ranging and common. It has historically been abundant and widespread. It is however being outcompeted and replaced by the invasive crayfish species Orconectes rusticus in certain parts of its range, including Ohio, Illinois, Wisconsin, Massachusettes, Vermont, Ontario, Quebec and Iowa. While these displacements and declines are not sufficient to warrent a regionally more threatened category listing, and perhaps will not unless the population numbers fall to very low levels, they are of concern.

It occurs in glaciated areas from Hudson Bay south through Ontario to west Massachusetts, south Wisconsin, and east Iowa (Hobbs, 1989). Fitzpatrick (1967) lists range as the Great Lakes Drainage of the U.S. and Canada, northern Hudson River drainage, Rock River drainage in Illinois and Wisconsin. Also Minnesota in Saint Louis River basin (Kutka et al., 1996).

In New York's Hudson River drainage, Smith (1979) added Rensselaer and Washington Cos. It is found in the Hoosic River basin in Massachusetts where it is possibly native, and outside this system in southern New England it has been introduced into the Housatonic River drainage system with several established disjunct populations plus two small populations from the Connecticut River drainage system (Mill Brook in Plainfield and Swift River in Ashfield, both Westfield River basin in Massachusetts) (Smith, 2000). In Ohio it is confined to the Lake Erie basin where it can be found in the lake proper and its tributaries, but has been reduced in abundance (Thoma and Jezerinac, 2000). Jezerinac (1986) lists Ashtabula, Cuyahoga, Erie, Geauga, Lake, Lorain, Lucas, Ottawa, Portage, Sandusky, Trumball, and Wood Cos., Ohio. It occurs in surface streams in southern Indiana but also in Pless Cave 100 feet from the entrance (Hobbs, 1976). Simon et al. (2005) cites Jordan River, Jackson Creek, Bean Blossom Creek, all in Monroe Co., for Indiana. Introduced populations were discovered in 2010 in Monument Reservoir and nearby North Lake, Las Animas Co., Colorado (C. Taylor, pers. comm., August 2010).

Many populations threatened by introduced Orconectes rusticus (Fitzpatrick, 1989). Kuhlmann (2008) found that although there were some reproductive differences between sympatric and allopatric areas in the Susquehanna River watershed where Orconectes rusticus is invading native Orconectes propinquus habitat, they are not strongly indicative of reproductive interference, but instead are more likely the result of the size differences among females collected from allopatric and sympatric areas. Although ruling out reproductive interference, Kuhlmann (2008) did note the apparent success of O. rusticus as an invader in the upper Susquehanna River watershed, often at the apparent expense of O. propinquus (see Kuhlmann and Hazelton, 2007). Various studies have shown that introduced O. rusticus has a higher growth rate than its congeners contributing to its dominance over other crayfish species (Hill et al., 1993; Mather and Stein, 1993); however studies by Pintor and Sih (2009) indicate higher growth rates is a characteristic of introduced but not native populations of O. rusticus (higer foraging activity and exploitation of bait of introduced versus native populations; as well as bait piracy).