Orconectes (Crockerinus) sanbornii (Faxon, 1884)

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 : 34-37

Orconectes (Crockerinus) sanbornii (Faxon, 1884)

Cambarus Sanbornii Faxon 1884:128.

Cambarus propinquus sanbornii Faxon 1885:91, figs. 3, 10.

Cambarus propinquus var. sanbornii Underwood 1886:372.

Cambarus propinquus var. sanbornii Osborn and Williamson 1898:21

Cambarus propinquus sanbornii Faxon 1898:660.

Cambarus propinquus sanborni Ortmann 1905b:128.

Cambarus (Faxonius) propinquus sanbornii Ortmann 1906:365.

Cambarus obscurus sanbornii Ortmann 1906:437.

Faxonius sanbornii Creaser 1933a:3.

Faxonius (Faxonius) sanbornii Creaser 1933b:21.

Orconectes propinquus sanbornii Hobbs 1942a: 352. Fitzpatrick 1963:61.

Orconectes (Orconectes) propinquus sanbornii Hobbs 1942b:154.

Faxonius sanborni sanborni Creaser 1962:2.

Orconectes sanbornii sanbornii Fitzpatrick 1967:157, figs. 2-18, 23.

Orconectes sanbornii Stevenson 1967:208. Taylor et al. 1996:31. Taylor et al. 2007:385.

Orconectes sanbornii sanbornii Hobbs 1974: 40, fig. 121.

Orconectes (Crockerinus) sanbornii sanbornii Fitzpatrick 1987:50, fig 3. Hobbs 1989:37, fig.159.

Orconectes (Crockerinus) sanbornii Jezerinac et al. 1995:35-43, figs. 15 a– 15h. Taylor and Schuster 2004:196-198, figs. 166, 167 A– 167G.

Diagnosis.

Rostrum with slghtly converging margins, not thickened, with marginal spines or tubercles; median carina absent. Cephalothorax ovoid, slightly, dorsoventrally compressed, without setae. Areola 3.4-9.3 times longer than wide, comprising 31-37% of TCL, with 2-3 rows of punctations across narrowest region; cervical groove interrupted just above cervical spine; lacking hepatic spines; suborbital angle obsolete. Antennal scale about 1.5 times as long as wide; basiopodite spine of antenna well developed; ischiopodite of antenna without spine. Chelae smooth, broad and robust, length 85% of TCL; mesial surface of palm with two well developed rows of tubercles; mesialmost row consisting of 7-11 tubercles; dorsolateral row with 7-11; lateral margin of propodus smooth, dorsal surfaces of both dactyl and fixed finger of propodus with weak dorsolateral ridges; some elongate setae at base of fixed finger. First form male gonopods short, comprising 30% of TCL, with two terminal elements about subequal length; corneous central projection comprising 16% of pleopod length, tapering distally to point; mesial process non-corneous, spatulate, partially surrounding central projection; cephalic base of central projection sloping, without right angle shoulder. Form two male gonopod non-corneous, blunt, shoulder not prominent or absent. Female annulus ventralis deeply embedded in sternum, moveable, wider than long, cephalolateral prominences flattened; fossa and sulcus shallow; sinus straight.

Color in life.

Carapace, abdomen and dorsal surface of chelae brown; rostral margins, caudal edge of carapace, and central surface of terga dark brown; tips of chelae and tubercles at dactyl base orange; tubercles on mesial and lateral margins of dactyl, mesial margin of palm, and mesial margin of fixed finger of propodus, and two spines or tubercles on anterodorsal surface of carpus, yellow; reddish stripe on lateral margin of chelae; ventral margins beige.

Specimens examined.

Orconectes sanbornii were collected from four counties at seven locations in the current study, as listed below.

JACKSON COUNTY: Little Mill Creek at crossing of RT 33 N 9.43 air km (5.86 mi) N of Ravenswood, 38.86171 -81.85407; 20 July 2006 - (WLU 06072001), 1 II♂, 2 ♀. Little Sandy Creek at intersection of RT 68/CR 8, 38.991497 -81.761765; 21 July 2006 - (WLU 06072103), 1 I♂, 1 II♂, 11 ♀, 4 Juv. MASON COUNTY: Sliding Creek at intersection of CR 4/RT 33, 38.999382 -81.987686; 20 July 2006 - (WLU 06072002), 2 I♂, 1 ♀. PLEASANTS COUNTY: Middle Island Creek at RT 2 crossing, 39.40328 -81.197624; 21 July 2006 - (WLU 06072104), 1 II♂, 2 ♀. WOOD COUNTY: Big Run at CR 21-1 crossing, 39.364048 -81.45656; 21 July 2006 - (WLU 06072106), 3 II♂, 5 ♀, 1 Juv. Lee Creek at CR 11 crossing, 39.153275 -81.73507; 21 July 2006 - (WLU 06072102), 1 II♂, 2 ♀. Nameless tributary crossing 3.54 km (2.2 mi) S of Parkersburg, 39.05142 -81.742836; 21 July 2006 - (WLU 05072105), 1 II♂, 1 ♀.

Distribution.

Orconectes sanbornii occurs throughout the Middle Ohio river drainage in Ohio, West Virginia and Kentucky ( Taylor and Schuster 2004). Sites harboring Orconectes sanbornii are shown in Figure 19. The most northern historic populations of the species on the floodplain occurred in Fishing Creek, Wetzel County were recently replaced by southward expanding Orconectes obscurus populations. Orconectes sanbornii is absent from lower reaches of Fishing Creek associated with the confluence of the Ohio River, and still is present in mid- and headwater sections of Fishing Creek (Loughman, unpublished data). Currently, Orconectes sanbornii inhabits the Middle Ohio North, Middle Ohio South, and Lower Ohio basins (Figure 19). Within these basins, Orconectes sanbornii is the only native orconectid.

Morphometrics.

The largest individual was a female with a 35.5 mm TCL from West Creek, Jackson County. The largest male was a form I with a TCL of 34.3 from West Creek. The mean TCL for Orconectes sanbornii was 24.15 mm (n = 35, SE = 8.91). Morphometric data for Orconectes sanbornii is presented in Table 9.

Habitat and natural history.

Orconectes sanbornii (Figure 21) habitat requirements were similar to those of Orconectes obscurus . Orconectes sanbornii is typical of tertiary burrowing crayfish, and inhabited small-to large-sized streams. Slab boulders, leaf packs, and depositional environments were all habitats used by the species. Based on this study, the life cycle of Orconectes sanbornii mirrors that of Orconectes obscurus (Table 9).

Orconectes sanbornii demonstrated the same gregarious behavior observed in Orconectes obscurus . Behavioral differences observed between Orconectes obscurus and Orconectes sanbornii specifically differed in the use of stream cover.In West Creek, Jackson County, Orconectes sanbornii were observed exposed in the stream channel. Orconectes sanbornii used interstitial spaces between boulder margins, and the majority of individuals were collected from exposed areas. Orconectes sanbornii were exposed mid-channel resting on the stream bottom with their antennae held posteriorly over their cephalothorax, and would not seek cover until prodded. Orconectes were noted for using cover less than cambarids in this study, but the extreme level of behavior observed in Orconectes sanbornii warrants special mention. Crayfish associates collected with Orconectes sanbornii include Cambarus bartonii cavatus and Cambarus thomai .

Conservation status within study area.

The ramifications of Orconectes obscurus expansion southward into historic ranges of Orconectes sanbornii remains to be seen. This interaction needs to be monitored to determine the true relationship between these sibling species.