Cambarus (Tubericambarus) thomai Jezerinac, 1993

Loughman, Zachary J. & Simon, Thomas P., 2011, Zoogeography, taxonomy, and conservation of West Virginia's Ohio River floodplain crayfishes (Decapoda, Cambaridae), ZooKeys 74, pp. 1-78 : 18-25

Cambarus (Tubericambarus) thomai Jezerinac, 1993

Cambarus diogenes Girard 1852:88 [in part]. Williamson 1899:48 [in part]. Ortmann 1905:398 [in part]. Newcombe 1929:286. Rhoades 1944a:146 [in part]; 1944b:98 [in part].

Cambarus diogenes diogenes Hay 1899:959 [in part]. Marlow 1960:233.

Cambarus (Bartonius) diogenes Ortmann 1906:402. Turner 1926:168 [in part].

Cambarus (Lacunicambarus) diogenes diogenes Hobbs 1969: 110 [in part]. Bouchard 1972:56 [in part], 1975:595 [in part]. Lawton 1979:47. Thoma and Jezerinac 1982:136. Jezerinac and Thoma 1984:123. Jezerinac 1985:7.

Cambarus (Lacunicambarus) diogenes Jezerinac 1985:7. Hobbs 1989: 24, fig. 88.

Cambarus (Tubericambarus) thomai Jezerinac 1993:532, fig. 4. Jezerinac et al. 1995:172-179, fig. 84 a– 84h. Taylor and Schuster 2004:121-123, figs. 92, 93 A– 93H. Loughman 2010:46-50, fig. 12.

Cambarus thomai Taylor et al. 1996:29. Taylor et al. 2007:383.

Diagnosis.

Rostrum slightly broad, margins converging to form acumen terminating in single reduced, upturned tubercle; postorbital ridges reduced, rarely terminating in small tubercle; cephalothorax dorsolaterally compressed in profile and vaulted; areola obliterated; branchiostegal region devoid of tubercles; chelae robust and diamond shaped; mesial surface of palm with disorganized prominent tubercles, mesialmost tubercles serrate; basiodactyl row consisting of 5-9 reduced rounded tubercles; first form male gonopods contiguous, with 2 terminal elements bent 90° to the shaft; central projection truncated distally and lacking sub-apical notch; total length of central projection equal to mesial process length; mesial process short, truncating distally; second form gonopod non-corneous and blunt; annulus ventralis rhomboid in shape with deep “S” shaped sinus, embedded shallowly in sternum, and movable.

Color in life.

Carapace dorsally brown, light green, olive, light blue, or blue grey; rostrum margins orange or red; chelae body light green, light brown, or blue; propodus light blue or light green; dactyl and propodus denticles cream or yellow; pereiopods tan, light green, cream, or gray; abdomen body light green, light blue gray or brown; tubercles covering chelae light yellow, cream, or orange; two light dorsal stripes present on dorsal surface of abdomen; ventral surface cream or white.

Specimens examined.

Cambarus thomai were collected from eight counties at 26 localities, listed below.

CABELL COUNTY: Green Bottom Swamp at Hoeft Marsh Wildlife Management Area, 38.58616 N / 82.24878 W; 2 April 2009 - (WLU 09040201), 2 I♂. HANCOCK COUNTY: Tomlinson Run backwater at RT 2 crossing, 40.54026 -80.628075; 30 March 2006 - (WLU 06033001), 3 I♂. JACKSON COUNTY: Flooded field adjacent to RT 33 S, 9.72 air km (6.04 mi) N of Ravenswood, 39.04274 -81.7827; 18 March 2005 - (WLU 05031803), 7 I♂, 3 O♀. Vernal pool complex adjacent to railroad tracks 3.56 km (2.21 mi) N of Ravenswood, 39.09015 -81.79469; 3 April 2005 - (WLU 05040302), 3 I♂, 1 II♂. MASON COUNTY: Ditch adjacent to RT 2 N, 1.77 km (1.10 mi) N of Rt 2 railroad crossing in Ashton, 38.63165 -82.16464; 18 March 2005 - (WLU 05031805), 3 I♂, 1 II♂. Krodel Park marsh adjacent to Fort Randolph reproduction, 38.785404 -82.12209; 5 March 2005 - (WLU 05030502), 4 I♂. Maple swamp adjacent to RT 2 railroad crossing in Ashton, 38.622005 -82.16758; 26 March 2004 - (WLU 04032601), 18 I♂, 2 ♀; 30 March 2004 - (WLU 04033001), 6 I♂, 3 O♀, 1 ♀; 28 April 2004 - (WLU 04042801), 4 I♂,1 O♀, 2 ♀; 18 March 2005 - (WLU 05031805), 2 I♂. Pin oak swamp adjacent to Point Pleasant Moose Lodge in Wagner, 38.833603 -82.12227; 26 March 2004 - (WLU 04032601), 3 I♂; 12 April 2004 - (WLU 04041205), 3 I♂, 2 O♀. Red-Osier Dogwood swamp adjacent to RT 33 S in Hartford, 39.008915 -81.99847; 5 March 2005 - (WLU 05030504), 1 I♂. Roadside ditch adjacent to RT 2 N, 2.91 km (1.81 mi) N of Clover, 38.589428 -82.19548; 4 March 2005 - (WLU 05030402), 3 I♂. Roadside ditch adjacent to RT 2, 9.17 km (5.7 mi) S of Point Pleasant, 38.80469 -82.18821; 12 April 2004 - (WLU 04041206), 6 I♂. Roadside ditch adjacent to RT 2 N, 0.22 air km (0.14 mi) N of Hogsett, 38.694496 -82.1765; 17 March 2005 - (WLU 05031707), 5 I♂. Roadside ditch adjacent to RT 2 N 0.90 air km (0.56 mi.) N of Hogsett, 38.70056 -82.17708; 17 March 2005 - (WLU 05031707), 4 I♂, 1 II♂. Roadside ditch adjacent to RT 2 N 1.93 km (1.2 mi) N of Glenwood, 38.58816 -82.201004; 3 April 2005 - (WLU 05040305), 1 I♂. Roadside ditch adjacent to RT 62 N, 0.34 km (0.21 mi) N of Hallwood, 38.97562 -82.081314; 17 March 2005 - (WLU 05031706), 1 I♂. Roadside ditch adjacent to RT 62 S at Mountaineer Power Plant, 38.974934 -81.94418; 5 March 2009 - (WLU 05030509), 2 I♂. Slough adjacent to RT 33 N in Mason, 39.00983 -82.03899; 5 March 2005 - (WLU 05030505), 1 I♂; 17 March 2005 - (WLU 05031704), 6 I♂, 4 ♀. Vernal pool complex at RT 2/Lighthouse Gospel Church Road intersection, 38.82201 -82.13136; 17 March 2005 - (WLU 05031707), 2 I♂, 2 O♀. PLEASANTS COUNTY: Ohio River embayment 4.03 air km (2.52 mi) S of St. Mary’s, 39.397575 -81.202415; 12 April 2004 - (WLU 05030506), 1 II♂, 1 OF. Vernal pool adjacent to RT 2 N across from Cytec Community Fishing Area, 39.347824 -81.32024; 5 March 2005 - (WLU 04041203), 2 I♂. TYLER COUNTY: Maple swamp adjacent to RT 2 S in Friendly, 39.50822 -81.06736; 20 March 2004 - (WLU 04032001), 2 I♂. WETZEL COUNTY: Maple Swamp adjacent to RT 2 S in New Martinsville, 39.32582 -80.866234; 2 April 2004 - (WLU 04040201), 8 I♂, 2 ♀; 21 March 2006 - (WLU 06032104), 3 I♂, 1 II♂. (23.) Ohio River backwater at Marshall/Wetzel County line, 39.717846 -80.514959; 2 April 2004 - (WLU 04040203), 2 I♂; 21 March 2006 - (WLU 06032101), 3 I♂. WOOD COUNTY: Bellville Wildlife Management Area 4.03 km (2.50 mi) S of Bellville, 39.132915 -81.730865; 5 March 2005 - (WLU 05030507), 6 I♂. Boaz Swamp Wildlife Management Area, 39.462868 -81.10855; 25 March 2004 - (WLU 04032501), 1 I♂; 12 April 2004 - (WLU 04041203), 2 I♂, 1 O♀; 5 March 2005 - (WLU 05030509), 1 I♂. Lee Creek at CR 11 crossing, 39.153275 -81.73507; 2 April 2004 - (WLU 04040203), 2 I♂.

Morphometrics.

Cambarus thomai is the largest burrowing crayfish occurring in West Virginia, and the most frequently collected species in this study. The largest individual collected was a form I male, 53.6 mm TCL from Bellville, Wood County. The largest female measured 38.6 mm TCL and was collected from a flooded field 1.1 km north of Ravenswood, Jackson County. Mean Cambarus thomai carapace length was 37.0 mm (n = 148, SE = 5.41). Morphometric data for Cambarus thomai are presented in Table 6.

Distribution.

Cambarus thomai distribution includes western Pennsylvania, central and eastern Ohio, central and western West Virginia and eastern Kentucky ( Taylor and Schuster 2004). ( Ortmann (1905a, 1906) was the first to mention the presence of Cambarus thomai (= Cambarus diogenes Girard, 1852) in Brooke and Hancock counties, stating that populations persisting in both counties were stable. Newcombe (1929) documented the species in Hancock and Brooke counties, and like Ortmann, identified the species as Cambarus diogenes . Jezerinac described Cambarus thomai in 1993 based on material from West Virginia in his description ( Jezerinac 1993), but. questioned the validity of Newcombe’s records. Jezerinac (1993) found northern Cambarus thomai populations problematic, specifically those occurring in Brooke County. This study did not collect any specimens from Brooke County, but specimens were collected in Tomlinson Run Backwater, validating previous records for Hancock County. Cambarus thomai was not taken in Brooke County during this study, but has been collected recently from portions of the county not associated with the floodplain.

Cambarus thomai was collected from the Upper Ohio North, Middle Ohio North, Middle Ohio South, and Lower Ohio basins (Figure 12). Specimens from Jackson County, Middle Ohio South basin, represent county records. It is absent from the Upper Ohio South basin and occurs again in the Upper Ohio North basin (Figure 12). Within the Upper Ohio North, Cambarus thomai was collected, but not in large numbers. Cambarus thomai populations enter the Upper Ohio North basin from the Tuscarawas River in Eastern Ohio. Different soil types are found in the Upper Ohio North and South basins, which could explain the species’ distribution. Another possibility controlling Cambarus thomai distribution is the increased agricultural land use practices and declining riparian habitat that has sharply increased in the Upper Ohio South and North basins.

In the Middle Ohio North, Middle Ohio South, and Lower Ohio basins, Cambarus thomai is stable. Mason County contains substantial Cambarus thomai populations, with the species documented at every site (n = 18) sampled in the county. Populations decline north of these basins. The most substantial northern population occurs in New Martinsville, Wetzel County. Ortmann (1906) commented on this population based on surveys in the late 1800's, noting how numerous burrows were in “bottomlands” adjacent to the Ohio River.

Habitat and natural history.

Cambarus thomai (Figure 13) was the most frequently collected burrowing crayfish along the Ohio River floodplain. Marshes, swamps, embayments, wet fields, ephemeral pools, ponds, roadside ditches, and bottomland forests are habitats utilized by Cambarus thomai . Population density appears to be directly correlated with mature forest canopies, with a preference for ephemeral pool systems, bottomland forests, and marsh habitats.

Population densities decline in exposed agricultural fields. The species responds negatively to livestock even when adequate habitat is available. These pasture habitats exhibit soil compaction, excess nutrients, and low browse lines. A lack of vegetation possibly expedites drawdown conditions with increased levels of evapotranspiration. Exposed conditions and frequent manipulation of topsoil appear to limit Cambarus thomai density in agricultural settings.

Cambarus thomai uses surface waters during late-winter and early-spring. During all other seasons it was collected from burrows, which are complex, with a 0.3 m to 1.5 m deep central shaft ending in a resting chamber. Central shafts often have multiple ancillary tunnels prior to the resting chamber. Resting chambers also possess additional tunnels, particularly from their floors. Vegetation was frequently found in these auxiliary tunnels. In many instances a short 10-20 cm central shaft bifurcates into two complete central shafts, each ending in its own central chamber. Chimneys often were associated with these burrows (Figure 14).

Cambarus thomai were nocturnal, and displayed stylized behaviors while resting in their burrow portals. They rest with their antennae held laterally and their chelae barely breaching the burrow’s entrance. If pressure pulses are sent through the soil, they orient their antennae toward the pulse without shifting body position. If pulses continued, crayfish either retreated into their burrows or left their burrow’s to investigate the pulse source. The majority of Cambarus thomai observations at burrow portals occurred in June and July. During late winter and early spring, several form I males and ovigerous females were observed nocturnally cruising and feeding on periphyton in ephemeral pools.

As stated previously, February through April, Cambarus thomai uses surface waters extensively. Eighty-six percent of trap captures were form I males. Ovigerous females (n = 12) also used surface waters, with 50% of females captured at this time carrying eggs. Linear regression analysis of ovigerous females indicates there is not a strong relationship between carapace length and the number of pleopodal eggs (Figure 15). Egg counts ranged from 108-304 eggs per female. Pleopodal egg diameter ranged from 1.51-2.47 mm, with a mean diameter of 2.09 mm.

Given the high percentage of ovigerous females captured in late winter and early spring, mating likely occurs in the fall. Females carry sperm throughout the winter and extrude eggs in early spring when ephemeral pool hydroperiods are at their most active. Instars are carried by females throughout the spring, and released at the beginning of the summer season. This life history strategy enables neonates to mature throughout the summer and enter their first winter as juveniles. Jezerinac et al. (1995) collected ovigerous females in March, April, May, and June in West Virginia, and Taylor and Schuster (2004) collected a single ovigerous female in Kentucky in March. Our results validated previous seasonal data for Cambarus thomai as presented in Table 3.

Cambarus thomai neonates used surface waters throughout the summer season ( May–September) and were the only demographic observed at this time. Dip netting yielded large numbers of young-of-the-year in July and August; however, whether neonates remain in surface waters may depend on water availablility throughout the fall into winter. During drawdown in several sites in Mason County, juveniles were observed burrowing.

Neonate utilization of surface waters may be a dispersal mechanism to enable colonization and equally distribute individuals throughout wetlands or redistribute individuals into areas of high productivity. Nocturnal searches found Cambarus thomai utilizing surface waters rather than relying on burrows. On several occasions individuals would seek cover under substrate debris in surface waters although burrows were readily available.

Conservation status within study area.

Cambarus thomai populations are stable within the Middle Ohio North, Middle Ohio South and Lower Ohio basin. Additional survey efforts are needed in the Upper Ohio North and Upper Ohio South basins to determine the status of northern populations.