Orconectes (Gremicambarus) virilis (Hagen, 1870)

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 : 37-39

Orconectes (Gremicambarus) virilis (Hagen, 1870)

Cambarus virilis Hagen 1870:63, fig. 23-28.

Cambarus wisonsinensis Bundy 1876:4.

Cambarus debilis Bundy 1876:24.

Cambarus cousii Streets 1877:803.

Cambarus Cousei Faxon 1885:97.

Cambarus wisconsiensis Harris 1900:271.

Cambarus cousei Harris 1903:134.

Cambarus viridis Moenkhaus 1904:111.

Cambarus (Faxonius) virilis Ortmann 1905b:113. Creaser 1932:326, fig. 1, 2, 8.

Faxonius virilis Creaser 1933a:3; 1962:2.

Faxonius (Faxonius) virilis Creaser 1933b:21

Orconectes virilis Hobbs 1942a:352; 1972:91, figs. 72h, 73e; 1974:42, fig. 162. Fitzpatrick 1963:61. Page 1985:417, fig. 151-154. Pflieger 1987:22. Pflieger 1996:122-126, fig. 28 A– 28I. Taylor et al. 1996:31. Taylor et al. 2007.

Orconectes (Orconectes) virilis Hobbs 1942b:154.

Orconectes (Gremicambarus) virilis Fitzpatrick 1987:54, fig. 5. Hobbs and Jass 1988:79-86, figs. 52 a– 52o. Hobbs 1989:42, fig. 199. Jezerinac et al. 1995:44-51, figs. 19 a– 19h. Loughman 2010:53-57, fig. 18.

Diagnosis.

Rostrum with straight margins, not thickened or possessing spines or tubercles; median carina absent; postorbital ridges terminating cephalically with spine or tubercle. Branchiostegal spine reduced; hepatic spine absent. Cephalothorax oval shaped and slightly dorsoventrally flattened in profile; without setae; suborbital angle obsolete. Areola 7.1-19.0 times longer than wide, comprising 34-39% of TCL, with 1-2 rows of punctations across narrowest region. Chelae smooth, broad and robust; mesial surface of palm with two rows of defined tubercles; first row with 6-8 rounded tubercles; second with 5-8 tubercles; lateral margin of propodus smooth; dorsal surfaces of both dactyl and fixed finger of propodus with prominent well developed longitudinal ridges; elongate plumose setae at base of fixed finger of propodus. First form male gonopods long, comprising 42% of TCL, with 2 terminal elements, both bent and curving at about 30° to the base; central projection corneous, comprising 24% of gonopod length, cephalic base without shoulder. Form two male gonopod noncorneus, gently curving caudally; mesial process subequal in length to central projection, blunt. Female annulus ventralis rhomboid, fossa large, sulcus wide, cephalolateral prominences weak, sinus only evident on caudal surface.

Color in life.

Carapace and abdomen dorsally olivaceus or brown; rostral margins darker brown to black; postorbital ridges and caudal margins of cephalic portion of carapace along cervical groove brown; two rows of blotches on dorsal surface of abdomen; dorsal surface of chelae emerald green; tips of propodus and dactyl darker green; all knobs on chelipeds beige or tan; ventral surfaces cream or white.

Specimens examined.

Orconectes virilis were collected in Mason and Pleasants counties at three locations in the current study, as listed below.

MASON COUNTY: Krodel Park marsh adjacent to Fort Randolph reproduction, 38.785404 -82.12209; 26 March 2004 - (WLU 04032601), 2 I♂, 1 ♀; 28 April 2004 - (WLU 04042801), 1 II♂, 1 ♀; 17 March 2005 - (WLU 05031703), 1 I♂; 28 March 2005 - (WLU 05032802), 7 I♂; 5 May 2005 - (WLU 05050501), 5 II♂, 1 ♀. Pin oak swamp adjacent to Point Pleasant Moose Lodge in Wagner, 38.833603 -82.12227; 27 February 2005 - (WLU 05022701), 1 I♂. PLEASANTS COUNTY: Ohio River embayment 4.03 air km (2.52 mi) S of St. Mary’s, 39.397575 -81.202415; 30 March 2004 - (WLU 04033002), 2 II♂.

Distribution.

Orconectes virilis native range includes Saskatchewan south through Montana and Utah east to Ontario, and throughout northern portions of the Mississippi River system. Several disjunct populations persist in Ohio and throughout the northeast.West Virginia Orconectes virilis populations are invasive ( Jezerinac et al. 1995). Orconectes virilis were limited to two sites in the Middle Ohio North and Middle Ohio South basins (Figure 10). The Middle Ohio South population is present in an Ohio River embayment at the northern city limit of Saint Mary’s, Pleasant County. The Lower Kanawha basin population occurs in Krodel Park lake, Point Pleasant, Mason County. The Saint Mary’s population does not appear to be abundant, with three individuals collected during seven collection events in 2004 and 2005. The Krodel Park population represents a potential source population for future invasions.

Morphometrics.

The largest observed individual was a 52.4 mm TCL form I male collected from Krodel Park Lake, Mason County. The largest female was 43.3 TCL, also from Krodel Park. The mean TCL for Orconectes virilis was 42.8 mm (n = 22, SE = 6.11). This species was the largest crayfish collected in this study. Morphometrics for Orconectes virilis are presented in Table 11.

Habitat and natural history.

Orconectes virilis (Figure 22) is an invasive floodplain species; the closest native populations are endemic to the upper Mississippi River valley ( Hobbs and Jass 1988; Page 1985). Two disjunct populations were discovered along the Ohio River floodplain, in Krodel Park, Mason County and near Saint Mary’s, Pleasant County, in an Ohio River embayment. Krodel Lake population stock undoubtedly came from bait-bucket introductions. Less than five km from Krodel Lake is an aquaculture facility that raises and sells Orconectes virilis for fish bait. Discussions with anglers informed the primary author that "soft craws" were purchased from local bait dealers and used in Krodel Park. Orconectes virilis has been collected from six wetlands surrounding Krodel Lake. All of these sites are within one km of the lake proper. Within the lake, Orconectes virilis uses riprap in the littoral zone for cover. Over one hundred adults were observed utilizing this habitat between 20:00-23:00 h on 5 May 2005.

In certain situations Orconectes virilis travels as far as one km from the lake to nearby wetlands. Its presence in a vernal pool system with zero fishing effort shows the propensity of this species to migrate. In one instance, Orconectes virilis had not been captured from an ephemeral pool system in spring and summer of 2004. After severe flooding in the fall of 2004, in which Krodel Lake spilled over into nearby bottomland forest, Orconectes virilis was captured in these wetlands. Life history information for invasive populations in West Virginia is unknown. Available life history information is presented in Table 9. Orconectes virilis are very large crayfish, and it is not hard to understand why they are capable of displacing native West Virginia species. The chelae on form I males in many instances were longer than the total body length of native Orconectes sanbornii .

Conservation status within study area.

Orconectes virilis populations require monitoring. This invasive species has proven to be successful in destroying several mid-Atlantic crayfish populations ( Jezerinac et al. 1995, Kilian et al. 2010, Loughman and Welsh 2010, Swecker et al. 2010). The Krodel Lake population represents an important potential source population for future introductions.