Orconectes causeyi Jester, 1967

Morehouse, Reid L. & Tobler, Michael, 2013, Crayfishes (Decapoda: Cambaridae) of Oklahoma: identification, distributions, and natural history, Zootaxa 3717 (2), pp. 101-157 : 126-127

Orconectes causeyi Jester, 1967 : Western Plains Crayfish

General charateristics. Adults rarely exceed 100 mm in total length. The carapace is stocky, subovate, depressed, and the areola is open. The abdomen is slightly shorter than the carapace. The rostrum is long, excavate, and margins converge with weak lateral spines. Chelae are large with tubercles along mesial margin of palm and dactyl. In form I males, gonopods reach the base of second pereiopods and terminate in two processes. The central projection of gonopods is corneous, long, and slightly recurved caudally, while the mesial processes are noncorneous, slender, and shorter than the central projection. In females, the annulus ventralis is immovable and spindle-shaped (Jester, 1967).

Life coloration. The background color is reddish-brown to olive brown ( Figure 45 ). The abdomen has two rows of black blotches running longitudinally. Chelae have a bluish-green tint, with yellow to off-white tubercles along the inner margin of the palm and fingers. Fingers are tipped with orange. The ventral side is white.

Similar species. In Oklahoma, O. causeyi closely resembles O. nais and O. virilis . Orconectes virilis is virtually indistinguishable from O. causeyi (Hobbs, 1989) . Orconectes nais differs from O. causeyi by exhibiting a light tan stripe along the side of the carapace in live specimens. The gonopods differ in the degree of curvature of the tips, although some individuals are difficult to discern based on this trait (Hobbs, 1989).

Distribution and habitat. Orconectes causeyi occurs in western Missouri, eastern Kansas, Oklahoma's Arkansas River drainage, and into northeastern New Mexico. This species has also been translocated into the Rio Grande River drainage and drainages north into Colorado (Jester, 1967). In Oklahoma, O. causeyi species has been collected in the upper section of the South Canadian River and surrounding reservoirs. We were unable to confirm reports of this species further east in Oklahoma, and likely they represent misidentifications of O. nais or O. virilis . Our ecological niche model shows that the northeastern and northwestern portions of the state have suitable environmental conditions ( Figure 46 ). Due to potential confusion with O. virilis and O. nais further examination of the species and range are highly warranted.

Life history. Orconectes causeyi is a tertiary burrower and is likely a species from cool headwater systems of the South Canadian River and from there has colonized the cool, deep waters of surrounding reservoirs (Jester, 1967). Form I males have been collected from August through October, while form II males and females have been collected year round, and no ovigerous females or females with young have been reported. Juveniles were collected in New Mexico in July (Jester, 1967).

Syntopic species. Orconectes deanae .

Conservation status. AFS: Currently Stable; Heritage Rank: Widespread (G5); IUCN: Least Concern; ODWC: Not Listed.

Additional resources. Dean (1969).

Figures

FIGURES 45 – 52. 45. Orconectes causeyi 46. Potential distribution of Orconectes causeyi 47. Orconectes deanae 48. Potential distribution of Orconectes deanae 49. Orconectes difficilis 50. Potential distribution of Orconectes difficilis 51. Orconectes lancifer 52. Potential distribution of Orconectes lancifer.