Three New Species of Minute (: ) 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

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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 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

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*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 tification of these salamanders to the species level has been hampered by the generally poor Figure 2A-B understanding of the 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). These studies resolve much 57116-17, 57119, 4.8 km W of Omiltemi, ele- of the previous taxonomic uncertainty, thereby vation 2500 m; MVZ 110624, 110656, 110664, allowing us to confidently formulate descrip- 110673, 110694, 110697-98, 110700, 110703-4, tions of the Guerreran Thorius as comprising 110706, 110913-15, 110919, 110921-22, three new species based on both morphological 187014-31, 187070, same locality as the holo- and molecular criteria. These new species bring type, although some elevations are listed as to 22 the total number of valid, formally de- 2520 m; MVZ 110902, 110906, 110908, 0.7 km

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A

B

'C C

D

Fig. 2. Photographs of three new species of Thorius from Guerrero. (A) Holotype of T omiltemi, MVZ 110916, an adult female. (B) Live T omiltemi, collected at the type locality byJ. Hanken, 31 July 1976 (museum number unavailable). (C) Holotype of T grandis, MVZ 183384, an adult female. (D) Holotype of T infernalis, MVZ 183426, a subadult male. Constrictions along the trunk in C and D are artifacts of museum tags, which were removed temporarily to photograph the specimens. Scale bars = 1 cm. southwest of Carrizal de Bravos, elevation 2200 crete toes and broadly rounded digital tips, rel- m; UMMZ 222368-69, logging road between atively short tail, and maxillary teeth absent in Puerto Chico and Asoleadero, elevation 2500- most adults. Compared to T grandis, T omiltemi 2580 m; MZFC 2954, 2954-2, and 2954-6, 5 km is stouter and more robust across the shoulders north Zona Trincheras, Parque Ecol6gico Esta- and has a relatively broader and longer (in tal Omiltemi, Chilpancingo, elevation 2800 m. males) head, somewhat shorter limbs, and more Some specimens are cleared and stained or elongate nostrils. It also lacks the extreme sex- have had tissue removed for protein compari- ual dimorphism that is characteristic of T gran- sons. dis.

Diagnosis.-This is a large, dark, Description.-Thisand robust spe- is a large species; adult SL av- cies of Thorius, which differs from most other erages 24.9 mm in 10 males (range 24.2-26.5) members of the genus by the following combi- and 27.3 mm in 10 females (26.5-29.6). The nation of traits: large body size, dark dorsolat- head is relatively broad; SL averages 7.2 times eral coloration, moderately large feet with dis- head width in both sexes (range 6.4-8.0 in

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 920 COPEIA, 1999, NO. 4 males, 6.8-8.3 in females). Measurements ofSL the holotypeis 5.2 (in millimeters) times and head length in males (range tooth counts.-Head 4.8-5.6) width 3.6;and snout 5.8to gular in fe- males (4.9-6.3). Snouts fold (head arelength) 4.9;bluntly head depth at posterior pointed. Nostrils are elongate, angle especially of jaw 2.4; eyelid width in 0.6; females, eyelid length and of moderate size for 1.5; the anterior genus;rim of orbit to the snout 1.0; mean horizon- ratio of major to minor tal axesorbit diameter equals 1.3; interorbital 1.63 distance 2.2; in males (range 1.3-2.0) and distance 2.25 separating in externalfemales nares 0.7; major(1.7-3.0). Eyes are relatively axis small of nostril 0.6; andminor axis protrude of nostril 0.2; only slightly beyond the snoutmargin projection beyondof the mandible jaw 0.7; SL in29.6; dorsal view. A suborbital groove snout to anterior intersects angle of vent 26.7; thesnout to lip on each side of the head. forelimb There 7.1; axilla to groinare 17.2; 1-2 limb interval premax- illary teeth in adult 6.0; malesshoulder width (mean 2.6, tail length 1.8) 31.1; andtail 0-6 teeth in females (mean width at3.3). base 2.1; Maxillarytail depth at base 2.5; forelimbteeth are absent in all males and length present(to tip of longest in toe) only4.0; hind limbtwo of 20 females (mean 0.9); length the 4.0; hand latter width 1.0; foot two width 1.2.specimens Num- have three and 15 teeth, bers of teeth: respectively. premaxillary 3; maxillary Vomerine4-11; vo- teeth average 6.1 in merine males 4-6. (range 4-8) and 7.1 in females (range 3-10). Limbs are relatively short; limb interval Colorationaverages of the 5.5 holotype in (inmales alcohol).-The (range 4.0-5.5) and 5.8 in females (range 5.0-6.5). ground color is a dark blackish brown. It is dark- Hands and feet are narrow. Digits are fused for est dorsolaterally and becomes progressively much of their length but are free at their tips, lighter onto the medium-brown venter. The which are broadly rounded and even expanded. dorsum of the head becomes increasingly dark Fingers, in order of decreasing length, are 3-2- toward the snout, which is essentially black, as 4-1; toes are 3-4-2-5-1. The tail is stout near the are dorsal surfaces of the eyelids. Tips of the base and tapers posteriorly. It is rounded in nasolabial protuberances and the upper lip are cross-section and about as long as SL; mean SL unpigmented. A narrow, irregularly bordered, divided by tail length equals 1.02 in males dark-tan band extends from the nape to the (range 0.85-1.33) and 1.12 in females (range base of the tail. Ventrally, there are scattered 0.89-1.15). The mental gland is present in large white flecks in the gular region and a very few adult males and is round to moderately ellipti- on the trunk. Flecks become more numerous cal (maximum dimensions: 1.0 mm wide, 1.0 on the ventral surface of the tail but are still mm long). The postiliac gland is prominent ex- widely scattered. The iris is black. ternally. Many specimens have dermal glands with enlarged external openings distributed Coloration in life.-Based on field notes by J. over the back of the head and other dorsal body Hanken (2 Aug. 1976) for MVZ 183360-63, surfaces, including the trunk and the tail. 187014-31, and 187070 (Carrizal de Bravos): Coloration is dark blackish-brown dorsolater- Most specimens have a dorsal stripe that ranges ally but becomes progressively lighter ventrally. from brick red to brown, sometimes tan. The A somewhat paler, golden-brown dorsal stripestripe is faint in at least one specimen, which in extends from the nape to the base of the thistail respectin resembles T spilogaster (Veracruz). many specimens. In some specimens, the There stripe is abundant whitish flecking on the ven- is a lively golden tan, whereas in others it ter is ob-and flanks. The specimen illustrated (Fig. scure and may have a fine, middorsal dark 2B) line. has a distinct dorsal stripe that is separated A few specimens have a herring-bone pattern from the lighter flanks by a well demarcated, within the stripe. Lateral borders between straight the border. The stripe becomes diffuse on stripe and either flank are irregular, but the occa- tail and develops an irregular border. The sionally there is a nearly straight line along head the bears a Y-shaped, dorsal groove that is trunk separating the stripe from the darker than surrounding areas. According to flank. There are numerous white spots ventro- Freeman (1977), specimens from the Asolead- laterally and ventrally, especially in the erogular region have a light brown-bronze dorsal and pectoral regions, to a lesser extent on stripe the with thin tan-cream margins and a dark tail, and rarely on the belly. Limb insertions brown to black middorsal groove. The stripe ex- tend to be lighter than the rest of the limbs.tends from the occiput to the tail. The head is About half the specimens have a bright nuchalflecked with silvery white and has a blackish spot, and in some the nuchal gland is lightlybrown, Y-shaped mark. Flanks are blackish- pigmented. Snouts typically are black, and brown the grading to grey-brown ventrolaterally, iris is dark. with flecks of white. The venter is greyish-brown

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 HANKEN ET AL.-THORIUS OF GUERRERO 921 with scattered flecks and small Thorius whitish omiltemi spots. Ad- ditional color notes are provided in field notes by W. Riemer for MVZ 57116-19 (Omiltemi): The dorsal stripe is golden brown in two larger , red brown in a smaller one. Sides have a heavy suffusion of very pale blue specks de- creasing in number ventromedially.

Osteology.--This description is based on 20 cleared-and-stained specimens (MVZ 110624, 187014-31, and 187070). The skull is relatively well developed. Ascending processes of the pre- maxillary bone usually arise separately and re- main apart for their entire lengths (character 1, state a), but each of the other character states (b-d) appears in at least one specimen. Facial processes of the premaxilla and maxilla overlap in ventral view and articulate directly in most females (character 2, state d), but they overlap broadly and do not articulate Thorius in grandistwo females (state c), and overlap only slightly in another (state b). This character is sexually dimorphic, and the two elements fail to overlap (state a) in all males but one, in which they slightly overlap (state b). The premaxilla bears teeth in all adults (character 8, state b) but one (state a). The nasal bone is relatively well developed and broad in most individuals (character 3, state c), extending somewhat over the posterior portion of the cartilaginous nasal capsule. It is frag- mented in a few individuals. The nasal and the maxilla articulate to some degree in all individ- uals (character 4, state b). The prefrontal bone is relatively well developed and articulates with the nasal in all females and most males (char- acter 5, state c). The bones do not articulate in two males (state b). The prefrontal and maxilla are separated and do not overlap in most spec- Imm imens (character 6, state a), but the bones ar- ticulate in a few of the males (state b). Septo- Fig. 3. Sexual dimorphism in cranial osteology maxillary bones are absent in all specimens and dentition in Thorius grandis, compared to T om- (character 7, state a) except one female iltemi. in Maxillary bones are depicted in left lateral view; anterior is to the left. Maxillary bones lack teeth in which the bone is present on one side only most adult T omiltemi and in all male T grandis, but (state c). The maxilla is relatively well devel- all female T grandis possess large numbers of maxil- oped anteriorly but becomes extremely attenu- lary teeth. The maxillary bone also is generally more ate posteriorly (Fig. 3). It lacks teeth (character robust and has a straighter ventral margin when teeth 9, state a) in all specimens but one female, are present. Specimens depicted: T omiltemi--MVZ which has just two teeth on one side and 187022 one (male), MVZ 187016 (female, and the only on the other (state b; Fig. 3). The vomer is specimen well with maxillary teeth among 20 cleared-and- developed and bears a small but distinct stained pre- adults of this species); T grandis-MVZ 187032 (male), MVZ 187038 (female). orbital process. There are moderate numbers of vomerine teeth, which occur in a short, curved row. They extend onto the preorbital process in four females and six males. The frontal fonta- crests are lacking, and there is no columellar nelle is relatively narrow for Thorius; the parietal process on the operculum. The postsquamosal fontanelle is moderately wide (its breadth process is well developed. Hyobranchial carti- equals 0.40-0.66, mean 0.50, times the maxi- lages are unmineralized. mum skull width across the parietals). Otic All specimens have 14 presacral vertebrae.

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T. omiltemi T. grandis in many species of Thorius. However, pattern V (like I, but with fused intermedium and fibu- IX XII IX lare) is also common (37%). Three additional tarsal patterns, each with additional fusions rel- ative to pattern I, are present at low frequencies: VII (fused distal tarsal 4-5 and centrale; 5%), IX VII , \ /V (fused distal tarsals 3 and 4-5 plus centrale; 3%), and XII (fused intermedium and fibulare plus centrale; 3%). Tarsal pattern XII is known only V I VII in T omiltemi and is reported here for the first time. Asymmetry is common; at least three- fourths of the specimens have a different carpal or tarsal pattern between right and left sides. iciN The digital skeleton also is highly variable, in- cluding many instances of phalangeal loss. The predominant phalangeal formula in the hand is 1-2-3-2 (60% of adult carpi). 1-2-3-1 is a com- mon variant (32%); 1-2-2-1 is rare (8%). The modal formula in the foot is 1-2-3-3-1 (65% of adult tarsi); 1-2-3-2-1 and 1-2-3-3-2, the typical formula in Thorius, are rare variants (24% and Fig. 4. Interspecific variation 10%, in respectively). limb-skeletal Limb bone mor- epiphyses and phology between Thorius omiltemi mesopodial and elements T grandis. are mineralized Pie in many diagrams depict frequencies adults.of alternate tarsal pat- terns (roman numerals, described in text), based on 20 specimens (equals 40 tarsi) Comparisons per species. to other taxa.-Thorius The pre- grandis, a sec- dominant tarsal pattern in eachond large-bodied species species is depicted from high-montane below its corresponding pie diagram. The two pat- forests of central Guerrero, differs from T om- terns differ solely regarding the condition of the in- iltemi in several respects. Most T grandis have a grandistermedium but separate(i) and fibulare in T omiltemi. (f), V- to which Y-shaped Carpal aremark pattern fused on the dorsumfre-in T. of the quencies are similar between head, the which two is absentspecies, or at bestwhich weakly devel- differ principally in the presence oped in of most rare T omiltemi. variants. They also generally lack the conspicuous dorsal glands with relative- ly large openings that are characteristic of many Typically, all trunk vertebrae T omiltemi. but Also, the T grandis last has bear extreme sexual ribs, but in a few specimens dimorphism the lastof adult trunk cranial morphology ver- (hy- tebra has a partial rib. The perossification limbs are and maxillary relatively teeth present in robust. The tibial spur ranges females only)from that isfree less conspicuous to at- in T om- tached in approximately equal iltemi. Finally, frequencies. the two species differ in several Mesopodial morphology proteins. is variable. Thorius infernalis, Carpal the only other con- pattern I predominates in generic the speciesforelimb from Guerrero, (76% is much of smaller adult carpi examined). This and patternis found at much contains lower elevation six than ei- separate elements, with two ther derived T grandis orstates T omiltemi. in re- See account of T lation to outgroup genera: grandis fused for intermediumcomparison with species that have plus ulnare, and fused distal maxillary carpal teeth, 4 whichplus arecen- rarely present in trale. It is the most generalized adult T omiltemi. pattern ob- served in Thorius and is the likely ancestral state for the genus. Two other Habitatcarpal and patterns,range.-Thorius omiltemi each is a terres- with additional fusions relative trial species to of pattern montane forests I, arein the Sierra Ma- also present in adults: II (fused dre del Sur distalof central Guerrerocarpals west 1- of Chil- 2 and 3; 21%) and IV (fused intermedium-ul- pancingo (Fig. 1). Recorded localities are from nare plus centrale; 3%). Carpal pattern IV is Cerro Cacho de Oro (elev. 2200-2673 m) and known only in T omiltemi. The modal tarsal pat- from near the village of Omiltemi, within the tern is I (52%; Fig. 4). This pattern contains Omiltemi State Ecological Park (elev. 2200- eight separate elements, with one derived state 2700 m). Localities on Cerro Cacho de Oro are in relation to outgroup genera: fused distal tar- between Carrizal de Bravos and Asoleadero (an sals 4 and 5. As with carpal pattern I, it is the abandoned lumber camp and sawmill) along presumed ancestral pattern and predominates the original road between Atoyac de Alvarez

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Remarks.-Freeman (1977) identified specimens from Cerro Cacho de Oro as an undescribed species. Saldafia de la Riva and Perez Ramos (1987) discuss T omiltemi as T narisovalis (part). Adler (1996; Fig. 5) depicts the geographic and elevational distribution of T omiltemi from Cer- ro Cacho de Oro and Omiltemi (identified as Thorius undescribed species) vis-i-vis other plethodontid salamanders recorded from cen- tral and western Guerrero. Genetic variation in T omiltemi and the spe- cies' relationships to congeners were examined using protein electrophoresis by Hanken [1980, 1983a; population 58, listed as T. sp. F (part)] and M. J. Mahoney (unpubl.). Evolutionary con- sequences of miniaturization of adult body size for appendicular morphology were examined by Hanken (1982, 1985; listed as T. sp. F). Large numbers of additional specimens reside at MVZ and MZFC, with others at KU and UMMZ.

Thorius grandis n. sp.

Grand Minute Salamander Fig. 5. Type locality of Thorius omiltemi, Figure 3.22C km southwest of Carrizal de Bravos, Holotype.-MVZ Guerrero, 183384, an inadult June female from 1964. The site is known locally as Asoleadero, an aban- Puerto del Gallo, Guerrero, Mexico, elevation doned lumber camp and sawmill, and is also the type locality for Hyla chryses, Sceloporus 2500 m, adleri, collected andby T. Pseudoeu-J. Papenfuss, 22 Decem- ber 1976. rycea mixcoatL Specimens of Thorius were collected be- neath bark on fallen logs and under loose bark on the forest floor. Since this photograph Paratypes.-All was from taken, Guerrero, the Mexico: MVZ forest has been largely cleared 183366-68, (Adler, 183381-83, 1996:18). 183386-87, Pho- 183389-90, to courtesy of K. Adler. 183392-93, 183401, 183404-5, 183408-9, 187032-51, same data as the holotype; MVZ 183417-18, Cerro Teotepec, 9 km (road) north- and Milpillas (now Mexican east highway of Puerto del Gallo,196). elevation They 3109 m; UTA include oak-pine-fir cloud A-4107,forest 1.6 kmand north pine-oak of Puerto del Gallo, ele- forest (Adler, 1965, 1996; vation Fig. 2743 5), m; UMMZwhere 222366-67, sala- 11.3 km manders may be locally abundant (road) east of Cerro(field Teotepec, notes elevation 2850 of J. Hanken, 31 July 1976; m; KU 182519,Freeman, 182521-22, 1977).9.5 km (road) north- Specimens have been collected east of fromPuerto del inside, Gallo, elevation un- 3296 m. derneath, and beneath the Somebark specimens of fallen are cleared logs. and stained or Recent collections near Omiltemi are from have had tissue removed for protein compari- pine-alder forest (Flores-Villela and sons. Mufioz Alonso, 1993). According to field notes by W. Riemer for MVZ 57116-19 (4.8 km west Diagnosis.-This of Om- is among the largest and most iltemi), specimens were taken in fallen, sexually rotting dimorphic species of Thorius. It differs logs in "semi-open mixed pine-oak from forest most on other members of the genus by the steep slope" and in a canyon bottom following within a combination of traits: very large body "dense broadleaf forest." size, moderately long limbs, oval nostrils, and maxillary teeth that are present (and numer- Etymology.-The species name recognizes ous)Omil- in adult females but typically absent in temi State Ecological Park, which includes males. the It differs from its geographically closest earliest known collecting locality for Thorius congener, in T omiltemi, in having somewhat lon- the state of Guerrero (four specimens collected ger limbs; different coloration, including a 28 April and 1 May 1950 by W. Riemer andbroader F. and more prominent dorsal stripe; a Pitelka, MVZ 57116-19). narrower and shorter (in males) head, larger

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 924 COPEIA, 1999, NO. 4 and less elongate nostrils;Measurements of the holotype indistinct (in millimeters) and dorsal glands; and many maxillary tooth counts.-Head teethwidth 3.2; snoutin tofemales. gular fold (head length) 4.6; head depth at posterior angle of jaw 2.2; eyelid width 0.7; eyelid length Description.-This is a very large species; adult 1.2; anterior rim of orbit to snout 1.2; horizon- SL averages 27.0 mm tal orbit indiameter 10 1.1; interorbitalmales distance (range 1.7; 22.3- 28.6) and 27.6 mm in 10 females (24.4-30.6). distance separating external nares 0.7; major The head is moderately axis of nostril wide0.5; minor axis in of nostril both 0.4; sexes-SL averages 7.8 times head width in males (range snout projection beyond mandible 0.4; SL 26.0; 7.2-8.2) and 7.5 in females (7.4-8.7). SL aver- snout to anterior angle of vent 23.6; snout to ages 5.5 times head forelimblength 6.4; axilla in to groin males 15.4; limb (rangeinterval 5.1- 6.4) and 5.8 in females (5.4-6.3). Snouts are 5.0; shoulder width 2.4, tail length 25.0; tail bluntly pointed. Nostrils are oval and of mod- width at base 2.3; tail depth at base 3.0; forelimb erate size for the genus; the mean ratio of major length (to tip of longest toe) 3.6; hind limb to minor axes equals 1.40 in both males and length 4.0; hand width 0.9; foot width 0.9. Num- females (range 1.3-1.7). Eyes are of moderate bers of teeth: premaxillary 5; maxillary 10-13; size and protrude slightly beyond the margin ofvomerine 4-6. the jaw in dorsal view. A suborbital groove in- tersects the lip on each side of the head. There Coloration of the holotype (in alcohol).-The are 2-3 premaxillary teeth in adult males (mean ground color is medium brown. A moderately 2.2) and 3-8 teeth in females (mean 5.5). Max- broad, golden-tan dorsal band extends from be- illary teeth are present in all females (mean hind the eyes to the tip of the tail. It broadens 27.8, range 19-37) but in only 1 of 10 males at the back of the head to include the weakly (mean 0.2, range 0-2). Vomerine teeth average developed parotoid glands but narrows over the 7.1 in males (range 4-9) and 8.5 in females (7-shoulders. It broadens again at the level of the 10). Limbs are moderately long; limb interval second costal interspace (behind the arm), re- averages 4.8 in males (range 3.5-5.5) and 5.3 in tracts to the standard width at the third inter- females (4.0-6.0). Hands and feet are moder- space, and is broader again posteriorly. The ately broad. Digits are joined at the base but band is bordered dorsolaterally by medium free distally; the longest finger and toe are ex- brown pigment of the flanks, which is darkest panded distally and have bluntly rounded tips. alongside the band. The ground color of the Fingers, in order of decreasing length, are 3-2- flanks becomes progressively lighter onto the venter, which is light brown with abundant, ir- 4-1; toes are 3-(2%-4)-5-1. The tail is stout and tapers posteriorly. It is rounded in cross-section regularly shaped, small white flecks. These and only rarely exceeds SL; mean SL divided by flecks are organized into more discrete spots, tail length equals 1.01 in males (range 0.97- about 20 in number, in the gular region. White 1.13) and 1.11 in females (1.0-1.34). The men- flecking extends to the tip of the tail on the ventral surface and onto the ventrolateral tal gland is present in large adult males and is round to moderately elliptical (maximum di- flanks. Limb insertions are light tan; the rest of each limb is medium brown with some white mensions: 1.3 mm wide, 1.2 mm long). The pos- flecking. A distinctive, dark Y-shaped mark ex- tiliac gland is prominent externally. Dorsolateral coloration is medium brown. All tends from the eyes to the midline near the nape; it ends at a slight nuchal pit. The tip of specimens have a prominent dorsal stripe the(Fig. snout is darker than the rest of the head 2C), which is slightly broader than in T omiltemi; and is the same color as the cheeks. There is about half the specimens have a distinctive ven- some white flecking on the upper lips. Eyelids trolateral excursion from the stripe immediately are dark brown; the iris is black. behind the shoulder. Tiny white spots are scat- tered over the head and dorsal surfaces. The Osteology.-This description is based on 20 spots become dense ventrolaterally, forming cleared-and-stained a specimens (MVZ 187032- kind of "frosting," and then give way to 51). sparser, The skull, and especially the jaws, shows larger spots ventrally, especially in the gularextreme re- sexual dimorphism; individual bones gion. Most specimens have a dark V- areor Y-more fully developed and adjacent bones shaped mark on the top of the head, which are more ex- completely articulated in females. As- tends posteriorly as a thin median line. Thiscending dis- processes of the premaxillary bone are tinctive color pattern is only weakly developed relatively stout; they may be separate (character or absent in the remaining specimens. The1, state iris a) or partly fused (states c and d). Pre- is dark. maxillae are well separated from the maxillary

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 HANKEN ET AL.- THORIUS OF GUERRERO 925 bones in all males (character 2, state a), but 4 plus centrale. It is the most generalized pat- these bones are firmly articulated in all females tern observed in Thorius and is the likely ances- (state d). The premaxilla bears teeth in all tral state for the genus. Two other carpal pat- adults (character 8, state b). The nasal bone is terns, each with additional fusions relative to relatively well developed (character 3, state c) pattern I, are also present in adults: II (fused and extends anteriorly over at least the poste- distal carpals 1-2 and 3; 27%) and III (fused dis- rior edge of the cartilaginous nasal capsule. The tal carpals 3 and 4 plus centrale; 3%). In the prefrontal bone is always a separate ossification, tarsus, pattern I (eight elements, with one de- but it usually articulates with the nasal (charac- rived state in relation to outgroup genera: fused ter 5, state c). It is well separated from the max- distal tarsals 4 and 5), the presumed ancestral illa in males (character 6, state a), but these el- pattern which predominates in many species of ements articulate in most females (state b). The Thorius, is absent. Instead, the modal pattern is foramen for the nasolacrimal duct is incised in V (fused intermedium and fibulare; 50%), but the posterior border of the nasal and patternsis fre- VI (like V, but with fused distal tarsals quently bordered posteriorly by the prefrontal 1-2 and 3; 10%), VII (like V, but with fused dis- in females. In males, there usually is no talbony tarsal 4-5 and centrale; 20%), and VIII (like posterior border to this foramen. Septomaxil- VII, but with fused distal tarsals 1-2 and 3; 17%) lary bones are absent in most specimens occur(char- at moderate frequencies (Fig. 4). Tarsal acter 7, state a) but present in a few males pattern and IX (like VII, but with fused distal tarsals females (state b). The maxilla in females is a 3 and 4-5 plus centrale) occurs at a very low robust bone that bears many teeth (character 9, frequency (3%). Asymmetry is common; ap- state b), but it is slender, irregularly shaped, and proximately one-third of the specimens have a toothless in nearly all males (state a; Fig. 3). The different carpal or tarsal pattern between right vomer is well developed and bears a preorbital and left sides. The predominant phalangeal for- process that varies from small to relatively well mula in the hand is 1-2-3-2; 1-2-3-1 is the only developed, but this process never extends to the variant, found in 15% of adult carpi. The modal posterior border of the internal nares. There formula in the foot is 1-2-3-3-1, although it is are moderate numbers of vomerine teeth, found in fewer than half of adult tarsi. 1-2-3-2- which are typically arranged in a short row. 1, The 1-2-3-2-2, and 1-2-3-3-2, the typical formula in frontal fontanelle is very narrow; the bones Thorius, may are common variants. contact one another at the midline. The parie- tal fontanelle, while wider than the frontal fon- Comparisons to other taxa.-Maxillary teeth are tanelle, is still relatively narrow for Thorius plesiomorphous (its for Thorius and are found in breadth equals 0.29-0.59, mean 0.38, times seventhe species: T spilogaster T schmidti, T aureus, maximum skull width across the parietals). TOtic smithi, T grandis, T omiltemi, and T minydemus crests are lacking, and there is a short columel- (some adults only of the last three). The ex- lar process on the operculum in many speci- treme sexual dimorphism in dentition immedi- mens. The postsquamosal process is present ately differentiates T grandis from all species ex- and well developed. The nasal capsule and cept T omiltemi and T minydemus. The latter is some hyobranchial cartilages (basibranchial a much smaller and little known species from and second ceratobranchial) are partly miner- Veracruz. Thorius aureus resembles T grandis in alized in a few specimens, and even the procor- possessing several additional plesiomorphic acoid cartilages are mineralized in one speci- character states that are lacking in most other men. species, such as a small frontoparietal fontanelle All specimens have 14 presacral and large vertebrae. adult body size. However, in addition Typically, all trunk vertebrae tobut having the maxillary last bear teeth in adult males, T au- ribs, but in some specimens the reus last has trunka unique colorver- pattern and a small, cir- tebra has a partial rib. Limbs are cular relatively nostril (vs elongate well in T grandis). See ac- developed, with ossified condyles. count for TheT omiltemi tibial for additional comparisons spur ranges from free in a few between specimens T grandis to and at- its two congeners from tached in most. Mesopodial elements Guerrero. are min- eralized in many adults. Mesopodial morphology is variable.Habitat and range.-ThoriusCarpal grandis is a terrestri- pattern I predominates in the alforelimb species of montane(70% of forests in the Sierra Ma- adult carpi examined). This pattern dre del Surcontains of central Guerrerosix northeast of separate elements, with two derived character Atoyac de Alvarez (Fig. 1). Most recorded local- states in relation to outgroup genera:ities are fromfused the in- flanks of Cerro Teotepec termedium plus ulnare, and fused (2500-3360 distal m). The carpal easternmost of these lo-

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Remarks.-Freeman (1977) recognized speci- mens from Cerro Teotepec as a distinct species. Saldafia de la Riva and Perez Ramos (1987) dis- cuss T grandis as T narisovalis (part). Adler (1996, Fig. 5) depicts the geographic and ele- vational distribution of T grandis on Cerro Teo- tepec and Cerro Toro Muerto (identified as Thorius undescribed species) vis-af-vis other plethodontid salamanders recorded from cen- tral and western Guerrero. Genetic variation in T grandis and the spe- cies' relationships to congeners were examined using protein electrophoresis by Hanken [1980, 1983a; populations 59-60, listed as T. sp. F Fig. 6. Collecting locality (part)] and M.for J. Mahoney Thorius (unpubl.). Largegrandis, 3.2 km east of the type locality numbers of additional at Puerto specimens of delthis species Gallo, Guer- rero, in December 1969. reside at TheMVZ, with site others atis KU, knownUMMZ, and locally as La Victoria in honor UTA.of Thean paratype important specimen of Rhadinophanes Mexican revo- lutionary battle. Thorius monticola, were a small colubrid common snake from 1.6 here, km especial- ly in the forest and deep north ofinside Puerto del Gallo,moist contained pine two or logs. Other species taken include Sceloporusthree specimens of T grandisadleri in its and stomach Eleuthero- (My- dactylus saltator (K. Adler, ers and Campbell, pers. 1981). comm.). Photo cour- tesy of K. Adler.

Thorius infernalis n. sp. calities is near Jiguero, 29.5 km (by road) west of Cruz Ocote; the westernmost is from the vi- Atoyac Minute Salamander cinity of Puerto del Gallo, an abandoned lum- Figure 2D ber camp (Fig. 6). An additional locality is from Cerro Toro Muerto, about 10 km (by air) to the Holotype.-MVZ 183426, an adult male from northwest of Cerro Teotepec. Adler (1996, Fig. 13.7 km northeast (road from Atoyac to Puerto 5) and Saldafia de la Riva and Perez Ramos del Gallo) of El Paraiso, Guerrero, Mexico, el- (1987) note the elevation of this locality as lying evation 1140 m, collected byJ. E. Cadle, 18 No- vember 1977. between 2000 and 2500 m, but collection data associated with the three known specimens (IBH 06463, 06463-2, and 06463-3) list the ele- Paratype.-MVZ 183425, an adult female. Same vation simply as 2495 m. Habitats for T grandis data as the holotype. include pine-fir and pine-oak-fir forests at high elevations, and bamboo-tree fern cloud forest atDiagnosis.-This is a small species of Thorius, less lower elevations (Adler, 1996; Myers and Camp- than 20 mm SL, which differs from most other bell, 1981). According to field notes by J. A.members of the genus by the following combi- Campbell (1.6 km north of Puerto del Gallo; 21nation of traits: small body size with a relatively May 1974), UTA A-4107 was collected under long a tail; narrow head with a pointed snout and log in pine-oak forest. Additional specimens relatively small, elliptical nostrils; relatively short from several localities have been collected from limbs with narrow feet and pointed toe tips; inside and beneath the bark of fallen, rotting light dorsal stripe; and no maxillary teeth. It is logs (Adler, 1965; Saldafia de la Riva and Perez distinguished from T omiltemi and T grandis, the Ramos, 1987). Large numbers of specimens only other species of Thorius known from Guer- were taken from beneath bark on fallen and rero, by its much smaller adult body size, nar- dead standing trunks of fir trees, and others rower head, more pointed snout, shorter limbs, from under logs and in cracks and crevices and syndactylousin toes with pointed toe tips. well-rotted logs in fir and pine forest (Freeman, 1977). Description.-This is a small species; SL is 18.8 and 18.6 mm in the male and female, respec- Etymology.-The species name is derived tively.from Both specimens are maturing adults (see the Latin word, grandis (large, great, magnifi- below). The head is relatively broad in the cent), in reference to the very large adult male--SL body is 7.0 times head width-but only size (for Thorius), which frequently exceeds moderately 30 wide in the female (7.2). Snouts are mm SL. pointed. Nostrils are elliptical and of moderate

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 HANKEN ET AL.-THORIUS OF GUERRERO 927 size for the genus; the mean ratiobrown, itof is darkermajor along to the flanks and lighter minor axes equals 1.41 (1.5 in both male, dorsally 1.3 and ventrally.in fe- An obscure band ex- male). Eyes are of moderate size tends for from thethe head genus to the base of the tail. and protrude slightly beyond theThere margin are white of spots the in the gular region and a jaw in dorsal view. A suborbital few groove scattered, intersects irregular marks on other ventral the lip on each side of the head. surfaces. The Themale iris hasis gray. a single premaxillary tooth and five vomerine teeth. The female lacks premaxillary Comparisons teeth to other but taxa.-This is the smallest has seven vomerine teeth. Neither and least specimen known of has the three Guerreran species maxillary teeth. Limbs are relatively of Thorius. short; Both limbT omiltemi and T grandis are interval equals 5.5 in each specimen. larger species Handsrestricted to much higher eleva- and feet are narrow. Digits aretions syndactylous; in the Sierra Madre del Sur (approximate- only the two longest fingers lyand 2200 three m and longestabove, vs 1140 m for T infernalis). toes are free at their tips, which Maxillary are pointed.teeth are present in some adults of Fingers, in order of decreasing both length, species arebut are3-2- lacking in T infernalis. Sal- 4-1; toes are 3-4-2-5-1. The male's tail is stout amanders assigned to T minutissimus from near and tapers posteriorly. It is rounded in cross sec- Sola de Vega, in the Sierra Madre del Sur of tion and is slightly longer than the body; SL di- Oaxaca (Hanken, 1983a), are larger, have a vided by tail length equals 0.94. The tail is bro- more elongate nostril and have rounded, rather ken in the female. The postiliac gland is prom- than pointed, toe tips. Three species of Thorius inent externally. Lateral body surfaces are rela- occur at elevations as low as or lower than T tively dark. A pale dorsal stripe extends infernalis: T pennatulus, T narismagnus, and T anteriorly onto the nape but becomes obscure smithi, all from the Caribbean versant. All are on the tail. The venter is paler than the flanks small species like T infernalis, but all three have and is especially pale in the gular region. The rounded nostrils, and T smithi has maxillary iris is dark. teeth. All other congeneric species typically are The holotype is a sexually maturing (i.e., found at much higher elevations (> 2000 m). small adult) male based on both external and internal criteria. A mental gland is evident but Habitat and range.-Thorius infernalis is known obscure and cannot be measured, and the an- only from the type locality, which lies within the terior walls of the cloaca are papillate. Vasa de- Sierra Madre del Sur of central Guerrero along ferentia are relatively large. Testes are small, un-the original road between Atoyac de Alvarez pigmented, and unlobed, but they show lobules, and Milpillas (Adler, 1996; Fig. 1). According to which denote the onset of sexual maturation. field notes by J. E. Cadle (18 Nov. 1977), the The paratype is a maturing female. Ovaries locality con- is an area of steep slopes adjacent to a tain ovules of different sizes; some are modestly small stream. Hillsides are planted with coffee; enlarged with yolk. riparian vegetation grows along the stream. The hillsides had recently been cleared of under- Measurements of the holotype (in millimeters) growth, and leaving much fresh-cut vegetation on tooth counts.-Head width 2.7; snout to the gular ground, in addition to a few logs and rocks fold (head length) 3.3; head depth at posterior to turn. The two specimens were taken under angle of jaw 1.6; eyelid width 0.5; eyelid different length logs in the afternoon. Adler (1996) 1.1; anterior rim of orbit to snout 0.8; horizon- lists associated species of amphibians and rep- tal orbit diameter 1.0; interorbital distance tiles. 1.3; distance separating external nares 0.6; major axis of nostril 0.3; minor axis of nostril 0.2; Etymology.-The species name is derived from snout projection beyond mandible 0.4; SL 18.8; the Latin word, infernalis (of the lower world), snout to anterior angle of vent 17.5; snout to in reference to the low elevational occurrence forelimb 5.2; axilla to groin 10.3; limb interval of the species in comparison to most congeners. 5.5; shoulder width 1.9, tail length 20.1; tail The name also refers to the distinction of the width at base 1.5; tail depth at base 1.8; forelimb nearby city Atoyac de Alvarez as the hottest geo- length (to tip of longest toe) 2.9; hind limb graphical location in North America (average length 3.4; hand width 0.6; foot width 0.7. Num- annual maximum temperature 29.7 C; Anony- bers of teeth: premaxillary 1; maxillary 0; vo- mous, 1974). merine 2-3. Remarks.-This species is known from only two Coloration of the holotype (in alcohol).-This speci- specimens, and there are no allozyme data for men is clearly faded. Although generally golden use in assessing its genetic relationships to other

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TABLE 1. GENETIC DIFFERENTIATION AMONG Two SPECIES OF Thorius FROM GUERRERO (T omiltemi AND T grandis) AND TWO FROM SOUTHWESTERN OAXACA (T minutissimus, T SP. UNCERTAIN), MEXICO (BASED ON HANKEN, 1980 1983a). Above diagonal, mean pairwise Nei genetic distance between species (DN; range in parentheses), based on population samples of five or more specimens each.a Below diagonal, numbers of protein loci showing fixed differences between species (boldface) or nearly fixed differences (i.e., variant alleles are shared by two or more populations at frequencies of 0.25 or less). Numbers of populations sampled per species are listed in the left column. Data are not included for the pairwise comparison between the two Oaxacan species and are unavailable for T infernalis, a third species from Guerrero.

Species omiltemi grandis minutissimus Uncertain

omiltemi - 0.21 0.40 0.53 (1) (0.18-0.24) (0.38-0.44) (0.44-0.60) grandis 1, lb - 0.39 0.37 (2) (0.37-0.44) (0.24-0.51) minutissimus 3, 2c 3, 0d (3) uncertain 3, 2e 1, 1If (3)

a Populations are numbered according to Hanken (1980, 1983a): T omiltemi (58), T grandis (59-60), T minutissimus (64-66), T sp. Uncertain (61- 63). b LDH-1, MPI. Enzymes abbreviated according to Murphy et al. (1996). c GP-2, CAP, G3PDH, LDH-1, MPI. d GP-2, CAP, LDH-1. e CAP, GAPDH, LDH-1, AAT-1, MPI. f LDH-1, CAP.

species. Adler (1996) suggested that these spec- at a second (Table 1). Populations from these imens represented a separate species from high- two species were tentatively identified as a single elevation populations (T omiltemi and T gran- species, T. sp. F, by Hanken (1983a) because dis) based on their low elevational range and they clustered together in a phenetic (UPGMA) the "lowland association" of sympatric amphib- analysis based on genetic distance. Recognition ians and reptiles. He also (Fig. 5) depicts the of two species was suggested earlier by Freeman geographic and elevational distribution of T in- (1977), based on analysis of external morphol- fernalis (identified as Thorius undescribed spe- ogy, and is warranted at this time by their ge- cies) vis-a-vis other plethodontid salamanders netic and morphological distinctiveness, includ- recorded from central and western Guerrero. ing osteology (see above). This decision is sup- ported by a recent phylogenetic analysis of Han- DIscussIoN ken's (1983a) original allozyme data, in which populations from these two species do not clus- Allozyme comparisons.-Hanken (1980, ter 1983a) as sister taxa (M. J. Mahoney, unpubl.). used protein electophoresis to examine genetic Salamanders from southern and western Oa- differentiation among 69 populations of xaca Thorius are more similar in allozymes to T grandis distributed throughout the range of the and genus T omiltemi than other members of the ge- in southern Mexico. Here we summarize these nus (DN as low as 0.24). One of the Oaxacan results as they pertain to T omiltemi and species T gran- (populations 64-66) comprises small dis (Hanken's T. sp. F, populations 58 adults and 59-and has been assigned to T minutissimus 60, respectively; Table 1). No data are available (Hanken, 1983a). The other Oaxacan popula- for T infernalis. tions (61-63) comprise relatively large animals Thorius omiltemi and T grandis are more that sim-lack maxillary teeth and which likely rep- ilar to each other biochemically than either resent isan undescribed species. The mean DN be- to any other species. Mean pairwise genetic tween dis- the two Guerreran species (T omiltemi tance (DN; Nei, 1972) between populations and T grandis) of and the apparently undescribed the two species equals 0.21 (0.18-0.24). This Oaxacan val- species equals 0.42; pairwise interspe- ue is nearly twice that obtained between cific valuestwo range from 0.24-0.60 (mean values populations of T grandis separated by a aredistance 0.37 to T omiltemi and 0.53 to T grandis). of approximately 9 km (populations 59Genetic vs 60; distances to all other congeners are DN equals 0.11). There are fixed allelic differ-large; in Hanken's UPGMA dendrogram clus- ences between the species at one allozyme tering locus all 69 populations sampled (Hanken, and significant differences in allelic frequencies 1983a; Fig. 2), the above four species joined the

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 HANKEN ET AL.-THORIUS OF GUERRERO 929 remaining species at DN > 0.5. doeurycea, Genetic and Thorius) distanc- in the Sierra Madre del es to species in Veracruz and Sur (Wake Puebla and Lynch, typically 1976; Papenfuss et al., exceed 1.0. 1983; Adler, 1996). Discovery of T infernalis at relatively low ele- Morphological novelty.-Perhaps the most vation unusu- shows that the genus is not restricted to al morphological feature of the three new cool spe-montane forests, and we suspect that it is cies of Thorius described from Guerrero is the far more widely distributed than is known at pronounced cranial and dental polymorphism present. Searches should be made especially in in T grandis. Adult females have large numbers extreme eastern Guerrero and western Oaxaca of maxillary teeth and relatively strong, firmly in an attempt to link the two areas of known articulated skulls. In sharp contrast, males distribution lack in central Guerrero and western maxillary teeth entirely and have weakly formed and southern Oaxaca. In the Sierra Madre del skulls. These sex-based differences are much Sur, Thorius apparently is widely distributed in less pronounced in T omiltemi, in which fir-pine-oak adult montane forest above 2500 m; the females only rarely have maxillary teeth, main and physiographic feature isolating T grandis are not seen at all in T infernalis, which from appears T omiltemi is a depression in the mountain to lack maxillary teeth in both sexes. Although crest that falls to approximately 1700 m near the sexual dimorphism involving various external headwaters of the Rio Yextla and the Rio Pa- features and premaxillary teeth is a commonpagayo, between Cerro Teotepec and Cerro Ca- phenomenon in plethodontid salamanders cho de Oro (Adler, 1996; Fig. 1). We expect (Wake, 1966; Staub and Paladin, 1997), dimor- Thorius to be found in mountains west and phism in skeletal morphology is rare (e.g., north Anei- of Cerro Toro Muerto, especially in the des hardii; Wake, 1963) and usually does remote,not in- extensive uplands around Cerro Baui- volve presence or absence of maxillary les. teeth. Cranial and dental polymorphism in T grandis provides yet another example of the pervasive ACKNOWLEDGMENTS association between morphological novelty and miniaturization in Thorius (Hanken, 1983b, The following people provided access to and 1985; Hanken and Wake, 1993). valuable information concerning specimens in Maxillary teeth are present in all adults of their personal or institutional collections: K. Ad- four species of Thorius (T schmidti, T aureus, T ler, J. Cadle, J. Campbell, W. Duellman, O. Flo- smithi, and T spilogaster) and absent from all but res-Villela, A. Kluge, T. Papenfuss, F. Parra, E. three of the remaining species (Hanken and Perez Ramos, L. Saldafia de la Riva, G. Schnei- Wake, 1994, 1998). Limited data for T minyde- der, J. Simmons, and B. Stein. Several people mus suggest that this species may also possess a helped collect specimens in the field, especially dental polymorphism similar to that seen in T J. Cadle, D. Eakins, J. F. Lynch, and T. Papen- grandis and T omiltemi. Based on outgroup com- fuss. N. Staub assisted our description of T in- parisons (Wake, 1966), presence of maxillary fernalis. K. Adler, S. Kuchta, H. Smith, and G. teeth represents the ancestral character state for Parra-Olea offered comments on the manu- the genus, with absence of teeth a derived state. script; G. Parra-Olea translated the abstract into The distant phylogenetic relationships and geo- Spanish. Research support was provided by the graphic distributions among species with or National Science Foundation (IBN-9419407 to without maxillary teeth suggests that one or JH, BSR-9019810 and DEB-9408347 to DBW), both traits may have evolved numerous times the Council on Research and Creative Work, within the genus. This topic will be addressed CU Boulder, and by the Museum of Vertebrate in a separate analysis. Zoology, the Center for Latin American Studies, and Sigma Xi (Alpha chapter), UC Berkeley. Distribution of salamanders in Guerrero.-Early The Direccion General de la Fauna Silvestre, herpetological investigations of Guerrero un- M6xico, provided collecting permits. derestimated the diversity of urodeles. Gadow, for example, failed to find any salamanders at LITERATURE CITED all: "For months have we searched Guerrero during the rainy season (there are thousands ADLER, of K. 1965. Three new frogs of the genus Hyla from the Sierra Madre del Sur of Mexico. Occ. Pap. places which, if they were on the Eastern Mus. slope, Zool. Univ. Mich. 642:1-18. would yield an abundance of Newts), but it was- . 1996. The salamanders of Guerrero, Mexico, in vain" (1905:204). Since the 1950s, however, with descriptions of five new species of Pseudoeury- numerous fieldworkers have encountered rep- cea (Caudata: Plethodontidae). Occ. Pap. Mus. Nat. resentatives of three genera (, Pseu- Hist. Univ. Kans. 177:1-28.

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SAVAGE, J. M. 1984. A new species _- , AND of J. montane F. LYNCH. 1976.rain The distribution, ecol- frog, genus Eleutherodactylus (Leptodactylus), ogy, and evolutionary from history of plethodontid sala- Guerrero, Mexico. Amphib.-Reptilia manders 5:253-260. in tropical America. Sci. Bull., Nat. Hist. SMITH, H. M. 1972. A new satellite Mus. of Los the Angeles Anolis Co. 25:1-65. ga- dovii species swarm (Reptilia: Sauria) in Mexico. J. Herpetol. 6:179-181. - , AND A. H. SAVITZKY. 1974. (JH) Another DEPARTMENT cryptic OF ENVIRONMENTAL, POPU- associate of the lizard Sceloporus LATION,formosus AND ORGANISMICin Guer- BIOLOGY AND UNI- rero, Mexico. J. Herpetol. 8:297-303. VERSITY MUSEUM, UNIVERSITY OF COLORADO, STAUB, N. L., AND J. PALADIN. 1997. BOULDER, The COLORADOpresence 80309-0334;of (DBW) DE- modified granular glands in male PARTMENT and female OF INTEGRATIVE Anei- BIOLOGY AND MU- des lugubris (Amphibia: Plethodontidae). SEUM OF VERTEBRATE Herpeto- ZOOLOGY, UNIVERSITY OF logica 53:339-344. CALIFORNIA, BERKELEY, CALIFORNIA 94720- WAKE, D. B. 1963. Comparative osteology of the plethodontid salamander genus 3160; Aneides. AND (HLF) J. DEPARTMENT Mor- OF BIOLOGY, phol. 113:77-118. BETHEL COLLEGE, MCKENZIE, TENNESSEE . 1966. Comparative osteology 38201. and PRESENT evolution ADDRESS: (JH) MUSEUM OF of the lungless salamanders, family COMPARATIVE Plethodontidae. ZOOLOGY, HARVARD UNIVERSITY, Mem. So. Calif. Acad. Sci. 4:1-111. 26 OXFORD STREET, CAMBRIDGE, MASSACHU- - , AND P. ELIAS. 1983. New genera and a new SETTS 02138. E-mail: (JH) jhanken@oeb. species of Central American salamanders, with a re- view of the tropical genera (Amphibia, Caudata, harvard.edu. Send reprint requests to JH. Plethodontidae). Contrib. Sci., Nat. Hist. Mus. Submitted: Los 23 Nov. 1998. Accepted: 10 March Angeles Co. 345:1-19. 1999. Section editor: A. H. Price.

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