Three New Species of Minute Salamanders (Thorius: Plethodontidae) from Guerrero, México, Including the Report of a Novel Dental Polymorphism in Urodeles Author(s): James Hanken, David B. Wake and Howard L. Freeman Source: Copeia, Vol. 1999, No. 4 (Dec. 17, 1999), pp. 917-931 Published by: American Society of Ichthyologists and Herpetologists (ASIH) Stable URL: https://www.jstor.org/stable/1447967 Accessed: 01-06-2020 21:19 UTC JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at https://about.jstor.org/terms American Society of Ichthyologists and Herpetologists (ASIH) is collaborating with JSTOR to digitize, preserve and extend access to Copeia This content downloaded from 128.32.10.230 on Mon, 01 Jun 2020 21:19:52 UTC All use subject to https://about.jstor.org/terms Copeia, 1999(4), pp. 917-931 Three New Species of Minute Salamanders (Thorius Plethodontidae) from Guerrero, Mexico, Including the Report of a Novel Dental Polymorphism in Urodeles JAMES HANKEN, DAVID B. WAKE, AND HOWARD L. FREEMAN Three new species of minute lungless salamanders of the Mexican genus Thorius (Plethodontidae) are described from montane forests in the Sierra Madre del Sur of Guerrero. Each species is distinguished from congeners by a combination of body size, external morphology, osteology, dental traits, and proteins. Thorius omiltemi and T. grandis are among the largest species within the genus; standard length (SL) approaches or exceeds 30 mm in many adults. Thorius infernalis is much smaller (SL < 19 mm). Adult T. grandis display an extreme, unique sexual dimorphism involving the presence/absence of maxillary teeth and several related features of cranial os- teology. Protein (allozyme) data for T. omiltemi and T. grandis reveal substantial levels of genetic differentiation relative to species in Veracruz, Puebla, and Oaxaca. Com- parable genetic data are unavailable for T. infernalis. The three species collectively define a broad elevational range, from high elevation T. omiltemi and T. grandis (2200-2700 m and 2495-3360 m, respectively) to lower montane T infernalis (1140 m). Description of several additional species of plethodontid salamanders from cen- tral montane Guerrero underscores the region's rich herpetological diversity, which includes many endemic species of both amphibians and reptiles. Se describen tres especies nuevas de salamandras mexicanas del genero Thorius, las cuales habitan el bosque de montaila de la Sierra Madre del Sur en el estado de Guerrero, Mexico. Cada especie se distingue de sus congeneres por una combina- ci6n de caracteres que incluyen: tamafio total del cuerpo, morfologia externa, os- teologia, caracteres dentales y proteinas. Thorius omiltemi y T. grandis alcanzan lon- gitudes mayores a 30 mm, lo cual las sitfia dentro de las especies mis grandes dentro del genero. En contraste, Thorius infernalis alcanza una longitud maxima de s61o 19 mm. Los adultos de T. grandis poseen un dimorfismo sexual extremo, incluyendo la presencia o ausencia de dientes maxilares, asi como varios aspectos relacionados con la osteologia del craineo. Los datos de proteinas de T. omiltemi y T. grandis revelan una diferenciaci6n genetica substancial con aquellas especies de Veracruz, Puebla y Oaxaca. Se carece de informacion genetica para T. infernalis. Las tres especies en conjunto presentan una amplia distribuci6n altitudinal, desde eleva- ciones de 2200-2700 msnm y 2495-3360 msnm para T. omiltemi y T. grandis, respec- tivamente, a elevaciones de 1140 msnm para T. infernalis. La descripci6n de varias especies de salamandras pletod6ntidas, para la zona montafiosa del estado de Guer- rero, enfatiza la diversidad herpetol6gica de la zona, la cual incluye muchos taxa endemicos tanto de anfibios como de reptiles. crease in numbers of species can be traced to THE ismstotal formallynumber recognizedof species representsof living organ-only a changing definitions of species and species con- small fraction of existing biological diversity cepts (de Queiroz and Gauthier, 1994; Frost and (Hammond, 1992). Ongoing description of new Hillis, 1990; Ghiselin, 1997) and to more fre- species is common even in many groups that are quent use of sophisticated molecular tools for seemingly well known taxonomically, including defining species boundaries (Hillis et al., 1996). vertebrates. In amphibians alone, the total num- Both methodological refinements have led to ber of formally described, valid species in- finer subdivision of what earlier-based on creased by 13% in the seven-year period be- more traditional methods-were regarded as tween 1985 and 1992 (Frost, 1985; Duellman, single species (Highton et al., 1989; Good and 1993), and many more new species continue to Wake, 1992). Yet, many other new species follow be described in all three Recent orders (e.g., the discovery of previously unknown forms, es- Nussbaum and Hinkel, 1994; Mendelson, 1997; pecially in biogeographic provinces that have Campbell and Smith, 1998). Some of the in- never been inventoried adequately. ? 1999 by the American Society of Ichthyologists and Herpetologists This content downloaded from 128.32.10.230 on Mon, 01 Jun 2020 21:19:52 UTC All use subject to https://about.jstor.org/terms 918 COPEIA, 1999, NO. 4 *kMexio City A Thorius scribed species omiltemi of Thorius known throughout its .. ..... ...A '..,".type locality"I. .(-O(X)m . S UERRER ..O ....... Thorius grandis 1000 200Gm range in southern Mexico. This, in turn, rep- MAP OAXACA O type locality resents a more than doubling of the number of AREA Thorius infernalis species in the genus recognized as recently as ..a..es .ail i ..ii..;;i.;!i .. de . J............i:i:.:iTT Oro de Or . i six years ago (Duellman, 1993). ST: ..r.]: . .. __tChilponcingo... ...".."... ......., MATERIALS AND METHODS te / 1730'N I ---( Measurements were made using digital or dial dacatepec $ . '"i " ' ' ,'/il~li:l;:I i 99::.............. calipers or a dissecting microscope fitted with .Veladera an ocular micrometer; standard length (SL) was measured from the anterior tip of the snout to the posterior angle of the vent. Limb interval equals the number of costal interspaces be- C. Prieto IW 10km - 37___ tween the tips of appressed fore- and hind limbs, measured in one-half increments (e.g., 3, Fig. 1. Map of central Guerrero, Mexico, showing known distributions of 4.5).three Whole-mount new speciesskeletal preparations of Thorius. were Thorius infernalis is known stained only for bone from and cartilage the usingtype alizarin locality, red which lies within lower Smontane and Alcian blue forest 8GX, respectively (elev. (Klymkows- 1140 m). Ranges of T grandis and ky andT omiltemiHanken, 1991). Osteological are somewhat descrip- more extensive, but each is centered around Cerro tions use the cranial character states and me- Teotepec/Cerro Toro Muerto and Cerro Cacho de sopodial patterns described and illustrated by Oro/Omiltemi, respectively. Neither species has been Hanken (1982, 1984, 1985) and Hanken and taken at elevations below 2200 m. The irregular line Wake (1994, 1998); see Wake and Elias (1983) around the village of Omiltemi is the state park for comparisons with other tropical genera. boundary. Cerro Cacho de Oro is named Cerro Yo- hualatzco on some earlier maps. Adapted with per- Counts of presacral (trunk) vertebrae do not in- mission from Adler (1996). clude the first, or atlas, vertebra. Tooth counts are based on cleared-and-stained specimens when available; all alcoholic specimens were ex- In this paper, we describe three new species amined for the presence of maxillary teeth. of minute lungless salamanders of the Mexican Numbers of maxillary and vomerine teeth in genus Thorius (Plethodontidae) from montane each holotype are provided for right and left forests in the Sierra Madre del Sur of Guerrero sides; these counts are summed for other indi- (Fig. 1). This is a region of high diversity viduals. for Institutional abbreviations are as listed herpetological fauna; many endemic species in Levitonof et al. (1985) except for MZFC (Mu- both amphibians (Adler, 1965; Adler and seo Den- de Zoologia, Facultad de Ciencias, Univer- nis, 1972; Savage, 1984) and reptiles (Smith, sidad Nacional Autonoma de Mexico, Mexico, 1972; Smith and Savitzky, 1974; Myers DF). and Campbell, 1981) have been described over the last 35 years. Although the existence of Thorius DESCRIPTIONS OF NEW SPECIES in Guerrero has been known to herpetologists for decades (Adler 1965; Freeman, 1977; Sal- Thorius omiltemi n. sp. dafia de la Riva and Perez Ramos, 1987), iden- Omiltemi Minute Salamander tification of these salamanders to the species level has been hampered by the generally poor Figure 2A-B understanding of the taxonomy and systematics Holotype.-MVZ 110916, an adult female from of the group overall (Wake and Lynch, 1976; 3.2 km SW of Carrizal de Bravos, Guerrero, Hanken, 1983a). Recently, two of us completed Mexico, elevation 2400 m, collected by T. J. Pa- systematic revisions of Thorius from two centers penfuss, 31 August 1973. of species diversity in the states of Veracruz, Puebla, and northern Oaxaca (Hanken and Paratypes.-All from Guerrero, Mexico: MVZ Wake, 1994, 1998).