Orconectes saxatilis Bouchard and Bouchard, 1976

Morehouse, Reid L. & Tobler, Michael, 2013, Crayfishes (Decapoda: Cambaridae) of Oklahoma: identification, distributions, and natural history, Zootaxa 3717 (2), pp. 101-157 : 133-134

Orconectes saxatilis Bouchard and Bouchard, 1976 : Kiamichi Crayfish

General charateristics. Adults rarely exceed 60 mm in total length. The carapace has no cervical spines or tubercles and the areola is open. The rostrum has a central depression and marginal spines. Chelae have two subserrate rows of small tubercles along the mesial margin. In form I males, gonopods terminate in two processes which reach the base of the first pair of pereiopods when the abdomen is flexed. In females, the annulus ventralis is symmetrical with the cephalic half divided by a medial trough (Bouchard & Bouchard, 1976).

Life coloration. The background color is uniformly olive-brown to reddish brown. The posterior margin of the carapace has a prominent dark band ( Figure 69 ). The tail fan has a faint red margin, and the ventral side is mainly white.

Similar species. In its restricted range, O. saxatilis may be confused with similar sized individuals of O. palmeri longimanus and O. tenuis . It differs from these two species in the length of the gonopods of the form I males, which reach the base of the first pair of pereiopods when abdomen is flexed. Furthermore, O. saxatilis lacks cervical spines, which are present in the other two species.

Distribution and habitat. Orconectes saxatilis is only known from the upper 45 km of the Kiamichi River in Oklahoma. Our ecological niche model confirms the highly endemic nature of O. saxatilis ’ distribution. Suitable environmental conditions may be available just south of the Kiamichi River, but due to the mountainous terrain it is unlikely O. saxatilis can disperse to this area ( Figure 70 ). When adequate stream flow is present, the species is mainly found in riffle areas containing cobble and gravel substrates (Jones & Bergey, 2007). As water recedes, O. saxatilis will move to the nearest pool habitat or dig shallow burrows under large rocks as it is a tertiary burrower (Bouchard & Bouchard, 1976).

Life history. Form I males and females with glair (a white substance excreted before eggs are laid) were collected in September and October suggesting that reproduction occurs in the fall (Jones & Bergey, 2007). Ovigerous females were collected in March. We have collected form II males and females throughout the year.

Syntopic species. Orconectes palmeri longimanus and Procambarus tenuis .

Conservation status. AFS: Endangered; Heritage Rank: Critically Imperiled (G1); IUCN: Least Vulnerable; ODWC: Tier 1.

Additional resources. Taylor et al. (2007).

Figures

FIGURES 69 – 76. 69. Orconectes saxatilis 70. Potential distribution of Orconectes saxatilis 71. Orconectes virilis 72. Potential distribution of Orconectes virilis 73. Procambarus acutus 74. Potential distribution of Procambarus acutus 75. Procambarus clarkii 76. Potential distribution of Procambarus clarkii.