THE SOUTHWESTERN NATURALIST 50(2):237–281 JUNE 2005 NOTES AQUATIC INVERTEBRATES OF CUATRO CIE ´ NEGAS, COAHUILA, ME ´ XICO: NATIVES AND EXOTICS ERIC C. DINGER,* ADAM E. COHEN,DEAN A. HENDRICKSON, AND JANE C. MARKS Merriam-Powell Center for Ecological Research, Department of Biology, Northern Arizona University, Box 5640, Flagstaff, AZ 86011 (ECD, JCM) Section of Integrative Biology, University of Texas, C0930, Patterson 521, UT, Austin, TX 78712 (AEC, DAH) *Correspondent: ecd2@dana.ucc.nau.edu ABSTRACT A recent survey of benthic macroinvertebrates of the Cuatro Cienegas basin found 118 species in the 21 sites collected. Four exotic macroinvertebrates that could threaten the native biota were found within or near the basin. RESUMEN Una inspeccio ´n reciente de macroinvertebrados be ´nticos del bolso ´n de Cuatro Cie ´- negas encontro ´ 118 especies en los 21 sitios que se muestrearon. Cuatro macroinvertebrados exo ´ticos que podrı ´an amenazar la biota nativa se encontraron dentro o cerca del bolso ´n. The Cuatro Cie ´negas basin is a small valley (about 1,500 km 2 ) in central Coahuila formed by the mountain ranges of the Sierra Madre Oriental. Although it is in one of the driest areas of the Chihuahuan Desert (200 mm of rainfall per year), it is estimated to contain more than 200 springs and other associated aquatic habitats with many endemic organisms and modern stromatolites. Six types of aquatic habitats occur in the basin: pozas (small spring- fed pools), lagunas (larger spring-fed lakes), playa lakes (large lakes fed by surface runoff, but without outlets), cie ´negas (shallow swamps), human-made canals (constructed be- tween the late 1800s and 1960s), and rivers (Minckley, 1969). The aquatic and terrestrial vegetation has been well described (Pinkava, 1984), as have fish and aquatic snail faunas (Minckley, 1984; Hershler, 1985). Largely due to its great biodiversity and high degree of en- demism, but also due to imminent threats of water extraction and exotic species, the Mexi- can government declared the basin a protect- ed area of flora and fauna in 1994 (Secretarı ´a de Desarrollo, 1994). Initial studies of the Cuatro Cie ´negas basin focused on endemic aquatic organisms and their habitats (e.g., Minckley, 1969). Despite the presence of large numbers of species of endemic snails and crustaceans (Taylor, 1966; Cole, 1984; Hershler, 1985), there have been no comprehensive surveys of aquatic insects and other non-gastropod and non-crustacean invertebrates (e.g., Annelida, Acarina), nor have regional surveys been published. The en- tire state of Coahuila lacks distributional re- cords of even some common aquatic insect or- ders, such as mayflies (Ephemeroptera) (McCafferty and Lugo-Ortiz, 1996). The order and suborders that are well studied in Coahui- la are dragonflies (Odonata: Anisoptera) and damselflies (Odonata: Zygoptera) (Needham and Westfall, 1954; Westfall and May, 1996). Within the basin, Crustacea, Gastropoda, and parasitic flukes have been studied (for respec- tive reviews see Cole, 1984; Hershler, 1984; and Guajardo-Martinez, 1984). The only published work on aquatic insects of the basin described a new widespread species of Rhagovelia (He- miptera: Veliidae), which occurs throughout the Sierra Madre Oriental (Polhemus, 1997). Anecdotal reports on aquatic insects in the val- ley usually describe them as depauperate. We conducted seasonal surveys of 21 sites in the basin during June and July 1999, October 1999, January 2000, and August 2000 (Table 1,