Cambarus dubius, Faxon, 1884

Allison, Patrick F., Lieb, David A. & Loughman, Zachary J., 2022, Distribution, natural history, and conservation of Cambarus dubius in Pennsylvania, Journal of Natural History 56 (13 - 16), pp. 829-848 : 838

Cambarus dubius ecology and life history notes

Cambarus dubius was collected at elevations ranging from 372 m to 955 m, primarily in the valleys between mountain ridges. The species was collected from burrows in wet, clay-bottomed roadside ditches, wetlands, forested seeps, wet grassland and agricultural habitat, and stream floodplains . Burrow portals often had fresh mud piled around their entrances in the shape of chimneys, especially after rain events ( Figure 4 (b)) . Deciduous forest was the most common macrohabitat associated with collections of C . dubius. This species was often found with skunk cabbage, constructing shallow yet complex tunnel systems intertwining horizontally amongst their root systems ( Figure 4 (c)) . Cambarus dubius burrows were generally 0.3–1.5 m in depth and complex, often containing 3–4 ancillary tunnels. Burrows would occasionally travel deeper than 1.5 m, but this was uncommon, especially in skunk cabbage wetlands . While free-living juveniles were collected alongside singular females from burrows, no collections yielded two adults from the same burrow .

Cambarus dubius was occasionally collected from under boulders in roadside ditches or along the banks of ditches. Tunnels were visible under these boulders, and often had multiple burrow portals directly associated with the boulder. The species was also collected from a flooded ditch during the late morning in late August. At this site, three small C. dubius (16.2–20.4 mm TCL) that were actively moving in the pooled water of the ditch were captured. These individuals were seen close to their burrow portals, and attempted to escape to their burrows when collected. At another site in mid-May, a single C. dubius was found outside of its burrow in a ditch around 21.30–22.00 h.

A total of 141 C. dubius were collected during this survey, including 33 juveniles that were measured and returned to their burrows after collection. Mean TCL for C. dubius was 25.9 mm. The largest individual collected was a 39.8 mm TCL female ( Table 1 ). The largest form I male collected was 34.7 mm TCL, and the smallest form I male was 27.7 mm TCL. The largest form II male collected was 34.0 mm TCL. The largest ovigerous female collected was 38.0 mm TCL, and the smallest ovigerous female was 32.3 mm TCL. Form I males were collected in May and October . Form II males were collected in May, June, July , August and October . Two ovigerous females were collected from burrows on 28 and 30 May , respectively . The mean egg count was 22.5 eggs per female, with a range of 5– 40 eggs. No females carrying live young were collected. Females were collected alongside free-living juveniles in the same burrow complex during mid-late June .

Figures

Figure 4. (a.) Cambarus dubius. (b.) Cambarus dubius burrow with a distinct mud chimney. (c.) Skunk cabbage wetland with Cambarus dubius burrows.(d.) Juvenile Cambarus dubius aggressively attacking baited line used to lure crayfish out of the burrow as described by Loughman et al. (2013).