Note Rediscovery of the Headwater Catfish Ictalurus Lupus (ictaluridae) in a Western Gulf-slope Drainage

Stream flow modifications, such as reduced spring flow and construction of low-head dams, have led to declines in the headwater catfish (Ictalurus lupus) across much of its range, as has competition with channel catfish (I. punctatus). Hybridization between headwater catfish and channel catfish also poses a threat to the headwater catfish. Our analyses of cytochrome-b sequences of headwater catfish from the Frio River, Devils River, and Independence Creek indicated that a population of headwater catfish occurs in the Frio River of the Nueces Drainage, where it was considered extirpated since 1967, and that hybridization is occurring in populations that inhabit the Frio River and Independence Creek. No obvious sign of hybridization was present in the population of headwater catfish in the Devils River. RESUMEN—La modificación de flujo de arroyos como reducida alimentación por manantiales y la construcción a pequeña escala de diques ha provocado la disminución del bagre lobo (Ictalurus lupus) a lo largo de mucha de su distribución geográfica, ası́ como la competencia con el bagre de canal (I. punctatus). Hibridación entre el bagre lobo y el bagre de canal también amenaza al bagre lobo. Nuestro análisis de secuencias de citocromo-b del bagre lobo de los rı́os Frı́o y Devils y del arroyo Independence demostraron que una población del bagre lobo habita el rı́o Frı́o donde fue considera extirpada desde 1967, y que la hibridación está ocurriendo en las poblaciones del rı́o Frı́o y del arroyo Independence. No hubo ninguna indicación de la hibridación en la población del bagre lobo del rı́o Devils. The headwater catfish Ictalurus lupus is a medium-sized member of the channel catfish complex (maximum total length 5 431 mm; Sublette et al., 1990) that occurs in riffles, runs, and pools of spring-fed streams (Thomas et al., 2007) and is most abundant in deep, run habitats (Bonner et al., 2005). Historical distribution of the headwater catfish includes the Colorado, Guadalupe, and Nueces drainages in Texas, the Rio Grande drainage in Texas, New Mexico, and Mexico, as well as the Rı́o San Fernando, Rı́o Soto la Marina, Rı́o Conchos, and the endorheic Cuatro Ciénegas Basin in Mexico (Conner and Suttkus, 1986; Kelsch and Hendricks, 1986; Edwards et al., 2003). Ranges of the headwater catfish and channel catfish Ictalurus punctatus historically overlapped in the Colorado, Guadalupe, and Nueces drainages (Kelsch and Hendricks, 1990; McClure-Baker et al., 2010) where the headwater catfish occurred primarily in heavily spring-influenced streams and channel catfish occurred primarily in larger streams and rivers. However, the headwater catfish presently is considered to be extirpated from western gulf-slope drainages north of the Rio Grande (i.e., Colorado, Guadalupe, and Nueces drainages), presumably as a result of degradation of habitat, as well as competition and hybridization with the channel catfish (Kelsch and Hendricks, 1990; McClure-Baker et al., 2010). Because of declines throughout much of its range, the headwater catfish is considered to be The Southwestern Naturalist swna-56-02-24.3d 1/4/11 23:26:22 287 Cust # N10-RJE-08 THE SOUTHWESTERN NATURALIST 56(2):287–291 JUNE 2011 THE SOUTHWESTERN NATURALIST 56(2):287–291 threatened by Jelks et al. (2008), a species of special concern by C. Hubbs et al. (http://www. utexas.edu/tmm/tnhc/fish/hubbs/HIS/Hubbs_ et_al_2008_checklist.pdf) and Texas Parks and Wildlife Department (2005), and critically imperiled by the New Mexico Department of Game and Fish (Propst, 1999). We report herein a recent collection of the headwater catfish from the Frio River in the Nueces drainage of southern Texas. This represents the first collection of the headwater catfish in the Frio River and the rediscovery of the species in the Nueces drainage, where it was last collected in 1967 (Kelsch and Hendricks, 1990). The Frio River arises in Real County and flows southeastward through Uvalde, Medina, Frio, La Salle, McMullen, and Live Oak counties before its confluence with the Nueces River. Flows in the Frio River are primarily from groundwater discharge from the Edwards-Trinity Aquifer. Dominant substrates in the upper Frio River are cobble and gravel derived from the Cretaceous limestone that forms the Edwards-Trinity Aquifer. Ictalurid catfishes, identified in the field as the headwater catfish, were collected and preserved as vouchers on 30 June 2007 from the Frio River at the Ranch Road 1120 (Real County, Texas) and Ranch to Market Road 1050 (Uvalde County, Texas) crossings near the city of Leakey. For comparative purposes in genetic analyses, we also collected the headwater catfish from the Devils River and Dolan Creek (at the confluence with the Devils River) above Dolan Falls (Val Verde County, Texas; n 5 9) and Independence Creek (Terrell County, Texas; n 5 5), and the channel catfish from the Rio Grande (Brewster County, Texas; n 5 3), Pedernales (Gillespie County, Texas; n 5 2), Concho (Concho County, Texas; n 5 1), and Brazos rivers (Waller County, Texas; n 5 2). A subset was retained as vouchers from the Devils River (n 5 2), Independence Creek (n 5 1), and Brazos River (n 5 2). All vouchers were deposited in the Texas Cooperative Wildlife Collection at Texas A&M University (TCWC 13605–13609). Each individual was measured for total length (mm) and field identifications were based on counts of anal fin rays (C. Hubbs et al., http://www.utexas.edu/tmm/tnhc/fish/hubbs/ HIS/Hubbs_et_al_2008_checklist.pdf) and coloration pattern. The headwater catfish has many small black spots, whereas the channel catfish has a few large black spots or no spots (Thomas et al., 2007). A sample of tissue from fins of each specimen was preserved in 70% ethanol and subsequently stored at 280uC in the Michael R. J. Forstner Frozen Tissue Collection at Texas State University-San Marcos. DNA was isolated using a DNeasy Tissue Kit (QIAGEN, Inc., Valencia, California). Amplification of a 1,000-bp fragment of the cytochrome-b mitochondrial gene was performed using primers MT11 and MT29 (Waldbieser et al., 2003) in reactions with 0.3 M TRIS, 0.075 M (NH4)2SO4, 0.0175 M MgCl2, 0.1 mM dNTPs, 0.01 mM each primer, 2.5 U Taq polymerase, and pH 5 8.5. PCR was performed in the GeneAmp PCR System 9700 (Perkin Elmer, Boston, Massachusetts) for 35 cycles, each consisting of denaturing at 95uC for 30 s, annealing at 50uC for 1 min, and extension at 72uC for 1 min, and with a final extension period of 72uC for 5 min. PCR products were purified with AMPure PCR Purification System (Agencourt Bioscience Corporation, Beverly, Massachusetts) and cycle sequenced with the above primers, using a CEQ DTCS Quick Start Kit (Beckman Coulter, Inc., Fullerton, California). Thermal cycling was 30 cycles of 96uC for 20 s, 55uC for 20 s, and 60uC for 4 min. Three internal primers were used to achieve bidirectional sequencing: MT30, MT31 (Waldbieser et al., 2003), and MT30DJM (59– GCA ACA CTA ACC CGA TTC TTT–39). Products were cleaned with CleanSEQ Dye Terminator Removal (Agencourt Bioscience Corporation, Beverly, Massachusetts) and analyzed on a CEQ 8800 Genetic Analysis System (Beckman Coulter, Inc., Fullerton, California). Sequences were edited and aligned in Sequencher Version 4.5 (Gene Codes Corporation, Ann Arbor, Michigan). The flathead catfish Pylodictis olivaris was used as an outgroup. All sequences were deposited at GenBank (accessions GQ396767–GQ396797). Maximum-parsimony analysis was conducted using PAUP* (Swofford, 2002). The most-parsimonious tree was found using a full-heuristic search with simple stepwise addition and tree bisection-reconnection. A non-parametric bootstrap analysis was implemented for 1,000 replications with 10 random stepwise-addition sequences each, and the resulting 50% consensus topology was retained. Additional model-based phylogenetic evaluations under alternative reconstruction criteria also were conducted. Voucher specimens were further identified using the canonical-discriminant analysis of The Southwestern Naturalist swna-56-02-24.3d 1/4/11 23:26:22 288 Cust # N10-RJE-08 288 The Southwestern Naturalist vol. 56, no. 2