27 Additional Distributional Records of the Ouachita Mountain Crayfish,Procambarus tenuis (Decapoda: Cambaridae), in Arkansas and Oklahoma, with Notes on Ecology and Natural History Henry W. Robison Department of Biological Sciences, Southern Arkansas University, Magnolia, Arkansas 71754-9354 Chris T. McAllister RapidWrite, 102 Brown Street, Hot Springs National Park, Arkansas 71913-7063 The Ouachita Mountain crayfish Procambarus( tenuis) is an uncommon endemic spe- cies known from several localities in the Ouachita Mountain Province of four counties (Howard, Montgomery, Polk, and Scott) of western Arkansas and three counties (LeFlore, Pittsburg, and Pushmataha) of eastern Oklahoma. Populations of P. tenuis are typically small. They inhabit small first and second order clear streams and springs where they hide and burrow under rocks. Forty-eight P. tenuis were collected during our 1.5 year study period from 19 of 93 (20.4%) localities. First form males were captured in May and June. We document several new localities for P. tenuis as well as providing a summa- tion of all known localities for the species. Additional aspects of the biology of P. tenuis are discussed. We recommend a conservation status of vulnerable for P. tenuis. © 2008 Oklahoma Academy of Science. INTRODUCTION that specimens from Polk County, Arkan- sas, were examined and noted additional The Ouachita Mountain crayfish (Procam- specimens from Montgomery County in barus tenuis) was originally described by Arkansas. In addition, Reimer (1968) cited Hobbs (1950) from specimens collected in P. tenuis only briefly and noted its distribu- 1934 by Charles E. Burt at two localities in tion was the “Ouachita Mountain Province the headwaters of the Little River system in of Oklahoma and Arkansas.” Jones and Oklahoma and Arkansas (Ouachita Moun- Bergey (2007) reported collections of 28 P. tains). Voucher specimens were deposited in tenuis from tributaries of the upper Kiamichi the collection of the United States National River, all sites within the known range. Museum, Smithsonian Institution (USNM). Unfortunately, we know little about the Since the description, few collections of this distributional limits of P. tenuis and even species have been made and the species is less about natural history and ecological apparently rare and its current distribution aspects including its reproductive biology, is poorly known (Jones and Bergey 2007). habitat requirements, and general biology. Indeed, populations of P. tenuis are consid- Our study is a compilation of information ered by the Natural Heritage Inventory to on the geographic distribution, life history be imperiled (S2 rank) in Arkansas, endan- aspects, and conservation status of Procam- gered (S1 rank) in Oklahoma, and imper- barus tenuis. iled/vulnerable (G2-G3 rank) in rounded Specific objectives of the study were (1) global status (NatureServe 2008; E. A. to determine the relative abundance and Bergey “personal communication”). In his precise distributional limits of the range unpublished thesis, Reimer (1963) reported of Procambarus tenuis; (2) to gather data on Proc. Okla. Acad. Sci. 88: pp 27-34 (2008) 28 H. W. ROBISON and C. T. McALLISTER life history aspects of this crayfish species several localities in the Ouachita Mountains. including information on habitat, reproduc- Often, P. tenuis was the only crayfish spe- tive period, and any other biological data cies living in the smaller spring-fed, first available; (3) to provide data on ecological order and second order streams. However, requirements of P. tenuis; and (4) to assess other crayfishes collected where P. tenuis the current status of this crayfish species was found included the redspotted stream based on distributional data collected. crayfish (Orconectes acares), the Little River creek crayfish (O. leptogonopodus), the Mena MATERIALS and METHODS crayfish (O. menae), and the western painted crayfish (O. palmeri longimanus). Field work was conducted from October 2006 through June 2008. Much of it occurred DISCUSSION during the fall, spring, and summer to utilize optimal field environmental condi- Overview of crayfishes tions. A total of 93 collections were made Freshwater crayfish are a highly diverse in Montgomery, Polk, and Scott counties, group of decapod crustaceans with over 540 Arkansas, and LeFlore County, Oklahoma. species currently described (Crandall and A variety of collecting methods were used Buhay 2008). In North America alone, 363 including the use of aquatic dipnets, baited native crayfish or nearly two-thirds of the and unbaited crayfish traps, and seines. One world’s crayfish fauna inhabit the continent to two specimens from each collecting site (Butler et al 2003; Taylor et al 2007). Crayfish were preserved in 60% isopropyl alcohol for play important roles in ecosystems as preda- later study. Voucher specimens were depos- tors, bioprocessors of vegetation and carrion, ited in the Southern Arkansas University and serve as an important food resource for (SAU) Invertebrate Collection, Magnolia, fishes and numerous other terrestrial and Arkansas, and the Brigham Young Univer- aquatic organisms (Hobbs 1993; Butler et sity (BYU) crayfish collection. In addition al 2003; DiStefano 2005). Crayfish are true to collections made during this survey, omnivores and occupy many trophic roles museum specimens of P. tenuis housed in (Adams 2006). the USNM and SAU were studied to docu- Crayfish exhibit four main habit types: ment the overall geographic distribution of primary burrowers (those crayfish who this species. All previous literature dealing spend their entire life cycle in burrows); with this crayfish species was also consulted stream-dwellers; pond/lake/large river and distributional information was utilized dwellers (including secondary burrowers when deemed accurate. who do require connectivity of burrows with freshwater); and stygobitic species RESULTS (obligate cave-dwellers) (Bouchard and Robison 1980; Crandall and Buhay 2008). Of these collections, 48 specimens from 19 Crayfish inhabiting each of these habitats of 93 (20.4%) localities were taken during occur in Arkansas and Oklahoma. this study (see Appendix). However, none of the P. tenuis were collected from Scott Recognition characters of P. tenuis County, Arkansas, sites re-visited where The name “tenuis” refers to the slender historical collections were previously or compressed carapace of this crayfish spe- known. First form males were collected in cies. When seen from above, the carapace May and June. This crayfish was found in of P. tenuis is noticeably more slender and small first and second order streams, living strongly compressed than other sympatric primarily beneath rocks. It was also found crayfish species. The rostrum of P. tenuis in springs and spring run-off streams in does not possess lateral spines nor bran- Proc. Okla. Acad. Sci. 88: pp 27-34 (2008) OUACHITA MOUNTAIN CRAYFISH IN ARKANSAS IN OKLAHOMA 29 chiostegal spines and the areola is narrow details were unknown to him. The only note with only two punctuations in the narrowest concerning habitat made in the description part. The antennal scale is widest anterior to was in the type locality description which the mid-length. The first pleopod terminates mentioned “in spring at base of mountains.” in three processes with the mesial process This shallow burrowing species has been projecting caudad at nearly a 90° angle with collected from under rocks in clear cold the axis of the shaft. The basic coloration of streams, where it is apparently quite active the body is light tan with blackish speck- even in very cold water (Williams, 1954). les. Robison (2000) collected P. tenuis from simple burrows beneath rocks in a spring- Taxonomic Remarks fed runoff area in Arkansas and in spring- Hobbs (1950) stated that P. tenuis was outflows under rocks in Oklahoma. This more closely allied to the White River cray- species was also taken from beneath rocks fish (Procambarus acutus) morphologically in shallow pool margins in first and second than to any other described species. Pend- order streams. Jones (2004: 35) noted that ing on-going DNA analyses of P. tenuis being “P. tenuis was not captured in any streams conducted by K. Crandall at BYU, no addi- that did not harbor O. saxatilis.” However, tional systematic work has been published other museum collections do not support on this species. this generalization. In addition, Jones and Bergey (2007) provided detailed descrip- Type Locality tions of streams with P. tenuis in the upper The type locality of P. tenuis was de- Kiamichi River in Oklahoma. scribed by Hobbs (1950) as “six miles east of Page and just west of the Oklahoma state Distribution line, LeFlore County, Oklahoma; in a spring The range of P. tenuis was given as the at base of mountains, a tributary of the Little Arkansas, Ouachita, and Red River basins River.” The holotype is USNM 90390 col- of eastern Oklahoma and western Arkansas lected on June 3, 1934 by Charles E. Burt. (Hobbs 1989). Prior to Hobbs (1989), the Ouachita Mountain crayfish was known Relative Abundance from only three localities in Montgom- Hobbs (1950) described P. tenuis from ery (Ouachita River drainage) and Polk 34 specimens taken from only two locali- (Ouachita River drainage) counties, Arkan- ties. Jones and Bergey (2007) found 29 P. sas, and one locality in LeFlore County (Red tenuis between July 2002 and May 2003, 13 River drainage), Oklahoma, the type local- from riffles and 15 from pools. During our ity. Reimer (1963) mentioned he examined field study, 48 specimens of P. tenuis were specimens from Polk County at a site in the collected from 19 different sites of 93 sites Ouachita River on US 71. He also reported (20.4%) sampled. Collections ranged from an additional record from Montgomery one to 19 specimens. The largest single col- County collected in 1948 (see Appendix; lection on record was 23 paratypes collected Hobbs 1950). Later, Robison (2000) found by C. E. Burt on 3 June 1934 (Hobbs 1950; see this crayfish at only four localities, two in Appendix). Typically, few (1-5) specimens Polk County, Arkansas, and two in LeFlore were collected because they were locally County, Oklahoma (Appendix).