Procambarus tenuis (Hobbs)

AR Map [dots indicate Arkansas Ouachita National Forest collection sites]

OK Map [dots indicate Oklahoma Ouachita National Forest collection sites]

Recognition Characters: Rostrum without lateral spines; branchiostegal spines absent; areola narrow with only two punctations in narrowest part; cephalothorax strongly compressed and bearing prominent setiferous punctations between which are crowded numerous smaller ones; antennal scale widest anterior to midlength; males with hooks on ischiopodites on third and fourth periopods; palm of chela of first form male not bearded but bearing a row of seven to nine tubercles along inner margin; first pleopod terminates in three processes; noncorneous mesial process thin, triangular and directed caudally at nearly a 90 degree angle with axis of shaft; cephalic process plate-like; corneous central projection most prominent of the three terminal elements.

Coloration: Basic body coloration light tan with blackish speckles.

Size: Adults are approximately 3 to 5 inches (76-127 mm) in total length.

Habitat: This burrowing species has been collected from under rocks in clear cold streams, where it is apparently quite active even in very cold water (Williams, 1954). In this study P. tenuis was taken from simple burrows beneath rocks in a spring-fed runoff area in Arkansas and in spring-outflows under rocks in the Oklahoma portion of the ONF.

General Range: The range of Procambarus tenuis is the Arkansas, Ouachita, and Red River basins of eastern Oklahoma and western Arkansas (Hobbs, 1989).

Range Within Arkansas: Within the state, this Ouachita Mountains endemic species inhabits limited areas of the upper Ouachita, upper Little River tributaries (Red River drainage), and Arkansas River basins of western Arkansas.

Comments: The type locality of this species is six miles (9.6 km) east of Page and just west of the Oklahoma state line, LeFlore County, Oklahoma (Hobbs, 1950).

Procambarus tenuis was collected four times during the study, twice in the Arkansas portion of the ONF and twice on the Oklahoma side. In Arkansas, one specimen was collected at the spring behind the Wonder House in Queen Wilhelmina State Park (Station 214) while a second specimen was taken from a roadside seepage area, 9.5 miles (15.3 km) northwest of Mena, Polk County (Station 213). In Oklahoma, two specimens of O. tenuis were found at the Billy Creek Recreation Area in the spring outflow there (Station 154) and four specimens were taken at Pipe Spring located north of Big Cedar (Station 155). These mark totally new known localities for this rarely seen Ouachita Mountain endemic crayfish. It is a very rare crayfish within the entire ONF as only eight specimens were taken in the four-year study.

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