Iguana_11.2_text.ps 78 IGUANA • VOLUME 11, NUMBER 2 • JUNE 2004 HOLLINGSWORTH Distribution of Chuckwallas. Illustration by John Binns. Sauromalus ater, Rancho Los Tepetates, Sierra La Libertad, Baja California. Sauromalus ater, Mountain Springs, San Diego County, California. This population and all of those in the United States were previously assigned to S. obesus. Chuckwallas typically inhabit arid regions with moderate low-lying shrub cover and usually are found on or near rocky outcrops with plenty of crevices for use as retreats. Among iguanid lizards, members in the genus Sauromalus rep- resent some of the most divergent forms in the family. Among the 45 species in the family Iguanidae, Chuckwallas rep- resent a modest radiation of five currently recognized species (Hollingsworth 2004, Pregill 2004). Sauromalus ater is found in the southwestern United States, adjacent regions in México, much of the Baja California peninsula, and on islas Willard, Tiburón, San Marcos, El Coyote, Danzante, San Cosme, Santa Cruz, San Diego, San José, San Francisco, Ballena, Gallo, Partida Sur, and Espíritu Santo in the Gulf of California. The other four species are restricted to islands in the Gulf of California. Sauromalus hispidus occurs on islas Ángel de La Guarda, Granito, Mejía, Pond, San Lorenzo Norte, San Lorenzo Sur, Cabeza de Caballo, La Ventana, Piojo, Flecha, Mitlán, and Smith; S. varius on islas San Esteban and Roca Lobos; S. klauberi only on Isla Santa Catalina; and S. slevini on islas Carmen, Los Coronados, and Monserrate. Over the past few years, a sometimes heated nomenclatural debate has raged regarding the best way in which to represent the species-level diversity within the genus (Montanucci et al. 2001, McDiarmid et al. 2002; see also Iguana Times 9(1–2):18–26, Understanding the Diversity of Chuckwallas (Genus Sauromalus) and a Debate Over Names Bradford D. Hollingsworth Department of Herpetology, San Diego Natural History Museum San Diego, CA 92112 All photographs by the author. IGUANA • VOLUME 11, NUMBER 2 • JUNE 2004 79UNDERSTANDING THE DIVERSITY OF CHUCKWALLAS � Sauromalus varius, Isla San Esteban, Sonora. This large species is commonly found in both the arroyo bottoms and on the rocky hillsides. which includes the text of the Montanucci et al. petition). The debate has focused on the choice of names for the widespread populations that inhabit the deserts of the southwestern United States, northwestern México, peninsular Baja California, and numerous islands in the Gulf of California. The root cause of this controversy was the synonymy of three species found to inter- grade with one another and which lacked diagnosable characters (Hollingsworth 1998). The recent ruling by the International Commission of Zoological Nomenclature (ICZN) brought this specific matter to a close (ICZN 2004; see also p. 10) — but for 80 IGUANA • VOLUME 11, NUMBER 2 • JUNE 2004 HOLLINGSWORTH Sauromalus ater, Sierra Vizcaíno, Baja California Sur. This population was previously assigned to S. australis. A speckled juvenile Sauromalus hispidus, Isla La Ventana, Baja California. Note the faint cross-barring remnant of the juvenile pattern. Sauromalus klauberi, Isla Santa Catalina, Baja California Sur. Adult male Sauromalus slevini, Isla Monserrate, Baja California Sur. Sauromalus varius, Isla San Esteban, Sonora. IGUANA • VOLUME 11, NUMBER 2 • JUNE 2004 81UNDERSTANDING THE DIVERSITY OF CHUCKWALLAS biologists studying these lizards, understanding this nomenclat- ural debate, the process of nomenclatural decision-making, and the species diversity within Sauromalus is important. As many as ten different species of Chuckwallas have been recognized since Duméril (1856) first described Sauromalus ater, but today, only half are considered valid. Evaluating how best to represent biodiversity is the primary motivation of systematic biologists. Since species are regarded as hypotheses to be contin- ually tested, taxonomies inevitably and naturally will change as new information is evaluated. Unfortunately, when systematists modify taxonomies, confusion often develops. Among the users of these taxonomies, the first concern usually centers on the adoption of the new naming system and how to recover infor- mation from previously published works that may have used one or more different names. Secondary to these immediate responses is how the new naming system changes previous ideas on diver- sity, distributional limits, and levels of variance in ecological pref- erences. Prior to the synonymy of the three formerly recognized species of Chuckwallas, the name Sauromalus obesus was used to describe populations from Arizona, California, Nevada, and Utah. Sauromalus obesus also was applied to populations found in western Sonora, northern Baja California, and some islands in the Gulf of California. In the more remote regions of Baja California, the name S. australis was used to describe populations inhabiting the southern portion of the peninsula, and the name S. ater described populations on islands off its southern peninsu- lar coastline in the Gulf of California. Each of these names had Sauromalus ater, Sierra Vizcaíno, Baja California Sur. This population was previously assigned to S. australis. Adult male Sauromalus ater, South Mountain, Maricopa County, Arizona. Some isolated populations of S. ater may yet reveal species- level diversity within the genus. 82 IGUANA • VOLUME 11, NUMBER 2 • JUNE 2004 HOLLINGSWORTH Sauromalus hispidus, Isla San Lorenzo Norte, Baja California. A gravid adult female excavating a burrow. An adult Sauromalus hispidus basking outside a burrow on Isla Ángel de La Guardia, Baja California. IGUANA • VOLUME 11, NUMBER 2 • JUNE 2004 83UNDERSTANDING THE DIVERSITY OF CHUCKWALLAS been in use since Charles Shaw revised the genus in 1945, and his taxonomy had provided stability for nearly a half century. The synonymy of Sauromalus obesus and S. australis with S. ater was based on an analysis of additional specimens and previ- ously used diagnostic characters, as well as a search for new char- acters that could help delimit the species boundaries within the genus (Hollingsworth 1998). With evidence of intergrades and the overlap of diagnostic characters, the species limits between the three could not be determined. Consequently, the familiar name of S. obesus was subsumed into S. ater, because the former now was considered a junior synonym of the latter. Decisions regarding the application of zoological names are governed by the ICZN and the rules established in the Code (ICZN 1999). Here, the decision to select Sauromalus ater to rep- resent the combined species was based on the Principle of Priority (Article 23). Since S. ater was the oldest of the three names, the Principle of Priority gives it precedence over the others. Without the overseeing body of the ICZN and the Code, the authority of researchers who first describe taxa could be undermined at the will of subsequent authors. In extreme cases, a new name could be applied to the same population every year, which would result in taxonomic instability. Petitions to the ICZN can be submitted when clarification is needed on the validity of names or exceptions to the Code are requested. Montanucci et al. (2001) petitioned the ICZN and requested that the long-used and well-known name, Sauromalus obesus, be given precedence over the little-used and older name, S. ater. For two years, the ICZN received and published com- ments on the petition. One of the greatest concerns was the tax- onomic stability of Sauromalus obesus and its abundant use in the scientific literature. In opposition to the petition, McDiarmid et al. (2002) commented that the discrepancy in usage between S. obesus and S. ater reflected the large number of papers published on S. obesus in the United States, which could not have been expected to mention S. ater. In addition, the name S. ater has been used regularly for the last 145 years and should not be regarded as a name infrequently used. In its recent decision (Opinion 2072), the ICZN ruled that the priority of the name Sauromalus ater should be maintained (ICZN 2004). In their comments, commissioners stated that publication capacity should not be given precedence over the Principle of Priority and reversing priority does not achieve stability. During the intervening period, when petitions, comments, and opinions are published, confusion often develops as to which nomenclature to follow. Many invoke a section of the Code (Article 82.1) that requires that the prevailing usage of names be maintained while a case is under consideration. In this instance, authors have chosen to use either Sauromalus obesus or S. ater. Because different interpretations of prevailing usage can result, Sauromalus ater, Isla Espirítu Santo, Baja California Sur. This popu- lation served as the type locality for many years. Sauromalus ater, Bahía Kino, Sonora. This population and all of those in mainland Sonora were previously assigned to S. obesus. Adult male Sauromalus hispidus, Isla San Lorenzo Sur, Baja California. 84 IGUANA • VOLUME 11, NUMBER 2 • JUNE 2004 HOLLINGSWORTH Adult male Sauromalus hispidus, Isla San Lorenzo Sur, Baja California. Sauromalus varius, Isla San Esteban, Sonora. IGUANA • VOLUME 11, NUMBER 2 • JUNE 2004 85UNDERSTANDING THE DIVERSITY OF CHUCKWALLAS both names have appeared in the literature. Deciding which name best reflected the populations under consideration was sub- jective, because the petition did not question the synonymy of the three species. However, now that Opinion 2072 has been issued, Sauromalus ater should be used. Before the time of formal taxonomies, the understanding of biodiversity was based on common names. The inherent insta- bility of common names provides insights into the importance of the ICZN and the Code. Stability is relative and our judgment on acceptable levels of change should be gauged against informal versus formal taxonomies. For example, the Indian origin for the name Chuckwalla appears to be derived from as many as four dif- ferent variants used by tribes in the southwestern United States. Merriam (1979) recorded Chah´ch wahl from the Cahuilla, Chah-kwar´-rah from the Southern Paiute, Chuk-war´-rah from the Mono Paiute, and Cha-gwar´-rah from the Kawaiisu. English-speaking peoples most likely adopted the word “Chuckwalla” from one or more of these variations. Other names for Chuckwallas recorded by Merriam (1979) include Hum- sooth´ (Kamia), Hum-sool´ (Yuma), Um thool´ya (Mohave), Tsah-wahr´ (Southern Paiute), Sow-wahr´(Chemehuevi), Sow- war´-rah (Panamint Shoshone), Sah-gwar´-rah (Southern Nevada Shoshone), Sahk-war´-rah (Shivwits), and Chakt´-tch (Serrano). Without the use of scientific names and the guidance of the ICZN rules, names describing the same animals could be as diverse as regional differences in dialects and languages. Now that this specific nomenclatural debate has come to a close, we can move on to evaluating the consequences of lump- ing the three species into one. Chuckwalla diversity and their overall biology should be reevaluated in light of our new inter- pretation of their relationships. The widespread Sauromalus ater is found across an extensive range of arid habitats with different plant communities and climatic cycles. Well-known populations should be compared to populations in more remote regions. Many populations are continuously distributed, whereas others are isolated in mountain ranges or on islands. Of the five recog- nized species of Chuckwallas, four are insular endemics in the Gulf of California. Sauromalus varius, S. hispidus, S. slevini, and S. klauberi were each described as a distinct insular species and little controversy has surrounded their recognition (see Grismer 2003 for a review). Since the greatest diversity of Chuckwallas occurs in relatively small, isolated islands or groups of islands, fur- ther diversity may be found in isolated populations of Sauromalus ater. This wide-ranging species will likely be the source of many more fascinating discoveries. Literature Cited Duméril, A. 1856. Descriptions des Reptiles Nouveaux et Imparfaitement Connus de la Collection du Museum d’Histoire Naturelle et Remarques sur la Classification et les Caracteres des Reptiles. Arch. Mus. Hist. Nat. 8:437–589. Grismer, L.L. 2003. Amphibians and Reptiles of Baja California, including its Pacific Islands and the Islands in the Sea of Cortés. University of California Press, Berkeley and Los Angeles, California. Hollingsworth, B.D. 1998. The systematics of Chuckwallas (Sauromalus) with a phylogenetic analysis of other iguanid lizards. Herpetol. Monogr. 12:38–191. Hollingsworth, B.D. 2004. The evolution of iguanas: An overview of rela- tionships and a checklist of species, pp. 19–44. In: A.C. Alberts et al. (eds.), Iguanas: Biology and Conservation. University of California Press, Berkeley and Los Angeles, California. International Commission of Zoological Nomenclature. 1999. International Code of Zoological Nomenclature. 4th ed. The International Trust for Zoological Nomenclature, London. International Commission of Zoological Nomenclature. 2004. Opinion 2072. Euphryne obesa Baird, 1858 (currently Sauromalus obesus Reptilia, Squamata): Proposal to give the specific name precedence over that of Sauromalus ater Duméril, 1856 not approved. Bull. Zool. Nomencl. 61:74–75. McDiarmid R.W., K. de Queiroz, K. Beaman, B. Crother, R. Etheridge, O. Flores-Villela, D. Frost, L.L. Grismer, B.D. Hollingsworth, M. Kearney, J.A. McGuire, J. Wright, G. Zug. 2002. Comment on the pro- posed precedence of the specific name of Euphryne obesus Baird 1859 over that of Sauromalus ater Duméril, 1856 (Reptilia, Squamata). Bull. Zool. Nomencl. 59:45–48. Merriam, C.H. 1979. Indian Names for Plants and Animals among Californian and other Western North American Tribes. Ballena Press, Socorro, New Mexico. Montanucci R.R., H.M. Smith, K. Adler, D.L. Auth, R.W. Axtell, T.J. Case, D. Chiszar, J.T. Collins, R. Conant, R. Murphy, K. Petren, R.C. Stebbins. 2001. Case 3143. Euphryne obesus Baird, 1858 (Reptilia, Squamata): Proposed precedence of the specific name over that of Sauromalus ater Duméril, 1856. Bull. Zool. Nomencl. 58:37–40. Pregill, G.K. and D.W. Steadman. 2004. South Pacific iguanas: Human impacts and a new species. J. Herpetol. 38:15–21. Shaw, C. E. 1945. The Chuckwallas, genus Sauromalus. Trans. San Diego Soc. Nat. Hist. 10:269–306. Chuckwallas from Isla Acatraz, Sonora represent hybrids among two or even three species, all or some of which are probably introduced. Euphryne obesa Baird, 1858 (currently Sauromalus obesus Reptilia, Squamata): proposal to give the specific name precedence over that of Sauromalus ater Duméril, 1856 not approved Abstract. The Commission has ruled that the priority of the name Sauromalus ater Duméril, 1856 should be maintained. Sauromalus ater is the senior name for the chuckwalla (family IGUANIDAE) from the southwest of North America. A proposal had been made to give precedence to a junior subjective syn- onym S. obesus (Baird, 1858). Keywords. Nomenclature; taxonomy; Reptilia; Squamata; IGUANIDAE; Sauromalus ater; Sauromalus obesus; chuckwal- las; southwestern North America. Ruling (1) The name obesa Baird, 1858 (specific name corrected under Article 34.2 of the Code), as published in the binomen Euphryne obesus, is not to be given priority over Sauromalus ater Duméril, 1856, as published in the binomen Sauromalus ater, whenever the two names are considered to be synonyms. The Principle of Priority is upheld and S. ater Duméril, 1856 has priority over Euphryne obesa Baird, 1858 whenever the two names are considered to be synonyms. (2) The name Sauromalus Duméril, 1856 (gender: masculine), type species by monotypy Sauromalus ater Duméril, 1856, is hereby placed on the Official List of Generic Names in Zoology. (3) The following names are hereby placed on the Official List of Specific Names in Zoology: (a) ater Duméril, 1856, as published in the binomen Sauromalus ater (specific name of the type species of Sauromalus Duméril, 1856); (b) obesa Baird, 1858, as published in the binomen Euphryne obesus. History of Case 3143 An application to conserve the specific name of Euphryne obesa Baird, 1858 (specific name corrected to agree in gender with the feminine generic name under Article 34.2 of the Code) for the chuckwalla (family IGUANIDAE) from the southwest of North America by giving it precedence over its junior subjec- tive synonym Sauromalus ater Duméril, 1856 was received from Richard R. Montanucci (Clemson University, South Carolina), Hobart M. Smith and David Chiszar (University of Colorado), Kraig Adler (Cornell University, Ithaca, New York), David L. Auth (University of Florida, Gainesville), Ralph W. Axtell (Southern Illinois University, Edwardsville), Ted J. Case (University of California at San Diego), Joseph T. Collins (The Center for North American Amphibians and Reptiles, Lawrence, Kansas), Roger Conant (Albuquerque, New Mexico), Robert Murphy (Royal Ontario Museum, Ontario, Canada), Kenneth Petren (University of Cincinnati, Ohio) & Robert C. Stebbins (Kensington, California) on 10 September 1999. After corre- spondence the case was published in BZN 58: 37-40 (March 2001). The title, abstract and keywords of the case were pub- lished on the Commission’s website. Comments opposing the application were published in BZN 58: 307-308; BZN 59: 45- 48 and 205. Comments in support of the application were published in BZN 58: 229; 307-308. Decision of the Commission On 1 December 2002 the members of the Commission were invited to vote on the proposals published in BZN 58: 39. At the close of the voting period on 1 March 2003 the votes were as follows: 12 Commissioners voted FOR the proposals, 12 Commissioners (Alonso-Zarazaga, Bouchet, Brothers, Calder, Halliday, Kraus, Lamas, Macpherson, Minelli, Patterson, Rosenberg and van Tol) voted AGAINST, no votes were received from Cogger, Dupuis and Mahnert. Ng was on leave of absence. Voting against, Alonso-Zarazaga commented that stability is not better achieved by reversing priority. A junior name should not be given precedence because of preference by a par- ticular school, or as a result of the publication capacity by a given set of researchers. Also voting against, Halliday com- mented that the case rests on two arguments. First, that there is uncertainty surrounding the type locality of S. ater. This is irrelevant to the nomenclatural issue. Second, it is argued that S. obesus should be preferred because it is used in a greater num- ber of papers than S. ater. There is no Article in the Code that invites the use of this argument, nor do the authors invoke any particular Article to support their case. The nearest relevant Article would be 23.9.3, however, both S. ater and S. obesus have been in continuous use for over 100 years. Therefore, the Principle of Priority should be upheld and the proposals should be rejected. Original References The following are the original references to the names placed on Official Lists by the ruling given in the present Opinion: ater, Sauromalus, Duméril, 1856, Archives du Muséum d’Histoire Naturelle, Paris, 8: 536. obesa, Euphryne, Baird, 1858, Proceedings of the Academy of Natural Sciences of Philadelphia, 10: 253. Sauromalus Duméril, 1856, Archives du Muséum d’Histoire Naturelle, Paris, 8: 536. 86 IGUANA • VOLUME 11, NUMBER 2 • JUNE 2004 OPINION 2072 (CASE 3143) OPINION 2072 (Case 3143)