Fallicambarus fodiens (Cottle, 1863)

Morehouse, Reid L. & Tobler, Michael, 2013, Crayfishes (Decapoda: Cambaridae) of Oklahoma: identification, distributions, and natural history, Zootaxa 3717 (2), pp. 101-157 : 124-125

Fallicambarus fodiens (Cottle, 1863) : Digger Crayfish

General charateristics. A heavy-bodied crayfish with broad chelae that rarely exceeds 80 mm in total length. The rostrum is broad and moderately excavated with no rostral spines. The acumen is very short with thinner margins than found on the rostrum. The areola is closed. Chelae are nearly oval or egg-shaped in outline, dorsoventrally flattened at the base of the fingers, and with a distinct basal notch on dactyl and dense patch of setae at base of propodus. There is a gap at the area of the notch when fingers are closed. In form I males, gonopods have two terminal processes that are at right angles to the main gonopod axis, and the primary process is strongly curved and bladelike. In females, the annulus ventralis is subcircular in outline and slightly asymmetrical with a deep medial trough through cephalic half (Taylor & Schuster, 2004).

Life coloration. Chelae, carapace, and abdomen are reddish-tan to light and dark brown in color ( Figure 39 ). The ventral side may be lighter from light brown to pale yellow. The abdomen sometimes exhibits darker brown longitudinal stripes on each side of midline.

Similar species. Fallicambarus fodiens most closely resembles Cambarus diogenes and C. ludovicianus . All of these species have a closed areola and a notch in the base of the dactyl. However, this notch is deeper and lacks tubercles along its distal margin in F. fodiens . Fallicambarus fodiens can also be separated from the two Cambarus species by the lack of a suborbital angle, a trait that is even visible in smaller individuals (Taylor & Schuster, 2004).

Distribution and habitat. Fallicambarus fodiens has a large but disjunct distribution (Hobbs, 1989; Hobbs & Robison, 1989; Jezerinac et al., 1995). The species occurs in the southern Great Lakes in Ontario and Michigan, south in the lower Ohio and central Mississippi River valleys, and along the Gulf Coast from east Texas to Florida. It can also be found along the Atlantic Coast from Maryland to South Carolina. Jezerinac and Stocker (1987) reported a third disjunct population along the Ohio River in west-central West Virginia. In Oklahoma, F. fodiens is known from 3 localities in LeFlore and McCurtain Counties, and 1 location in the north central portion of the state. According to the ecological niche model, suitable environmental conditions may also be found west of the 3 known southeast southeastern locations and north into the Ouachita and Boston Mountain ranges ( Figure 40 ). Fallicambarus fodiens is a primary burrower in ephemeral wetlands, wooded flood plains, and low-lying fields (Jezerinac & Stocker, 1987; Page, 1985; Pflieger, 1996; Taylor & Schuster, 2004). Because this species is a primary burrower, it is often difficult to collect and easy to overlook. Hence, F. fodiens ’ distribution in Oklahoma may be broader than currently known.

Life history. Fallicambarus fodiens constructs one of the least complex burrows of any species in its genus (Hobbs & Robison, 1989). Burrows often consist of a single, nearly vertical shaft, and depth varies depending on the distance to the water table. Frequently, there are other side passages leading away from the main shaft to the surface or a nearby water source. Surface openings are identified by a mound or chimney of mud, which is usually capped during drier periods. During high humidity, especially after warm rains, the crayfish may sit at the entrance of their burrow or move around the entrance in search of food, mates, or a new location for a burrow. Their food consists of plant fragments, especially grass seeds, and animal material, including insect fragments, crayfish parts, and juvenile salamanders (Bovbjerg, 1952). Creaser (1931) reported copulations occurring in the fall and early spring. Other studies have corroborated this finding with the collection of form I males, ovigerous females, and females with young from February through May and August through November, depending on the latitude (Bovbjerg, 1952; Creaser, 1931; Jezerinac et al., 1995; Page, 1985; Pflieger, 1996; Taylor & Schuster, 2004). Furthermore, Ainscough et al. (2013) have stated that F. fodiens is a species complex so as more research is conducted certain life history attributes may change.

Syntopic species. Cambarellus puer , Cambarus diogenes , and Procambarus gracilis .

Conservation status. AFS: Currently Stable; Heritage Rank: Widespread (G5); IUCN: Least Concern; ODWC: Not Listed.

Additional resources. Ainscough et al. (2013); Bovbjerg (1952); Guiasu (2007); Guiasu & Dunham (2002); Jezerinac & Stocker (1987); Norrocky (1991); Taylor et al. (2010).

Figures

FIGURES 37 – 44. 37. Cambarus tartarus 38. Potential distribution of Cambarus tartarus (distribution map was not made for this species due to it subterranean lifestyle; climatic variables outside the cave systems do not accurately represent the climate within the cave) 39. Fallicambarus fodiens 40. Potential distribution of Fallicambarus fodiens 41. Faxonella blairi 42. Potential distribution of Faxonella blairi 43. Faxonella clypeata 44. Potential distribution of Faxonella clypeata.