Crayfishes (Decapoda: Cambaridae) of Oklahoma: identification, distributions, and natural history Author Morehouse, Reid L. Author Tobler, Michael text Zootaxa 2013 3717 2 101 157 journal article 10.11646/zootaxa.3717.2.1 fad4163f-156b-4f1a-a5e9-c9f48df52e0a 1175-5326 248539 C8CDC011-974C-48B4-9E03-88F570EEDE13 Orconectes virilis Hagen, 1870 : Virile Crayfish General charateristics. Adults rarely exceed 130 mm in total length. The carapace is slightly longer than the abdomen and the areola is open. The rostrum is moderately broad with a trough-like depression, and lateral margins are thick and set off by spines from the acumen. Chelae have prominent tubercles along the inner margins. In form I males, gonopods terminate in two long slender processes and the central projection is longer and gently curved, while the mesial process is shorter and curved in same direction as central projection with a distinct space between the two. In females, the annulus ventralis is rounded on the posterior margin, without any triangular posterior extensions (Pflieger, 1996). Life coloration. The background color is reddish-brown to olive brown. The abdomen has two rows of black blotches running longitudinally ( Figure 71 ). Chelae have a bluish-green tint with yellow to off-white tubercles along the inner margin of the palm and fingers. Fingers are usually tipped with orange. The ventral side is white in color. Similar species. In Oklahoma, O . virilis closely resembles O . nais and O . causeyi (see O . causeyi and O . nais sections for differences). Distribution and habitat. Orconectes virilis has a broad distribution and occurs from the southern tip of the Hudson Bay, southward from New England to western Montana and through the Missouri, Mississippi, and Ohio River basins to northern Arkansas and Oklahoma. In Oklahoma, O . virilis is found in the Cimarron and Arkansas River drainages in the northern two thirds of the state. Our ecological niche model indicates that the north-central and northeastern portions of the state provide suitable environmental conditions for Orconectes virilis ( Figure 72 ). In general, O . virilis is most often collected in open water or around logs, rocks, and other debris. It is a tertiary burrower, but rarely burrows into the sediment or surrounding landscape. As fall leads into winter, O . virilis has been noted to move to deeper pools and become relatively inactive (Aiken, 1968). This pattern has also been noted in Missouri (Pflieger, 1996) and in Oklahoma (personal observation). Life history. Orconectes virilis is the most northern ranging crayfish species reaching into Oklahoma. Throughout its range, breeding occurs over an extended period of time from July to late November and early December (Taylor & Schuster, 2004). Eggs are laid in late spring, and females with young have been collected in mid-May and into June. In Oklahoma, we have collected ovigerous females in March and April. Form I and II males have been collected in the fall and spring. Syntopic species. Orconectes nais and Procambarus acutus . Conservation status. AFS: Currently Stable; Heritage Rank: Widespread (G5); IUCN: Least Concern; ODWC: Not Listed. Additional resources. Bovbjerg (1953); Dorn & Wojdak (2004); Keller & Hazlett (2010); Martinez (2012); Perry et al. (2000).