HARVARD UNIVERSITY Library of the Museum of Comparative Zoology U/Ul 31^9 „OS. COMP. ZOOI„ LIBRARY OCCASIONAL PAPERS JAN 1 S 1982 ^ . , n 'N R V A R 3 or tne u.NiiveRSJTY MUSEUM OF NATURAL HISTORY The University of Kansas Law rence, Kansas NUMBER 97, PAGES 1-10 JANUARY 15, 1982 A NEW SPECIES OF TROPIDURUS (SAURIA, IGUANIDAE) FROM THE ARID CHACOAN AND WESTERN REGIONS OF ARGENTINA by Jose M. Cei^ The South American iguanid hzards of the genus Tropidurus foiTTi a widely ranging and diverse group of species, with repre- sentatives on l)oth sides of the Andes. Those species that occur mainly or entirely to the west of the Andes seem to fall into two distinct species groups. The peruviamis group (peruviamis, tigris, thoracicus, theresiae, theresoides, tarapacensis) is characterized by small, juxtaposed body scales (116-165 around midbody) and an inconspicuous, often discontinuous row of vertebral scales; the oc- cipitalis group (occipitalis, koepckeorum, stolznianni) is character- ized by large, keeled, imbricate body scales (48-106 at midbody) and a continuous row of enlarged vertebral scales ( Mertens, 1956; Donoso Barros, 1966; Dixon and Wright, 1975). The Galapagoan species are all similar to occipitalis and may be included in that group. East of the Andes this dichotomy appears to be represented by T. melanopJeurus and T. spimdosus. Tropidurus melanopleurus occurs along the eastern slopes of the Andes from extreme south- eastern Peru through Bolivia to extreme northwestern Argentina, and resembles the peruviamis group by having minute body scales (160-222 around midbody) and an inconspicuous and sometimes discontinuous vertebral scale row. Tropidurus spinulosus occurs at higher latitudes along the eastern Andean slopes, but extends east- ward into the arid lowlands of Bolivia, western Mato Grosso, and western Paraguay; it resembles the occipiialus group by having ' Departamento Ciencias Naturales, Universidad Nacional de Rio Cuarto, Prov. de Cord()l)a, Argentina. Personal address: Rancho Somuncura, Rua Fausto de Figueiredo, Birre-2750, Cascais, Portugal. 2 OCCASIONAL PAPERS MUSEUM OF NATURAL HISTORY large, imbricate, keeled body scales (83-101 around niidbody) and a conspicuous vertebral scale row. The remaining eastern species vary widely in body scale size, but differ from both the penwionus and occipitalis groups in lack- ing a vertebral scale row. Although the taxonomic relationships of these eastern taxa are not clear, they may be referred to as the torquatus group. This group occupies an enonnous range, from northeastern Colombia through Venezuela and the Guianas, south- ward in eastern Brasil to the Parana Basin, and westward into Argentina and Bolivia. Four species of the torquatus group were recognized by Etheridge (in Peters and Donoso-Barros 1970) — torquatus, hispidus, liygomi, and bogerti. However, more recent studies by Trefaut Rodrigues of the Zoological Museum of Sao Paulo (Vanzolini: pers. comm.) indicate that several additional taxa may be recognized in the eastern and northern parts of the range. In the southwestern part of the range of the torquatus group, in the arid Chacoan and western areas of Argentina, populations of this group have been referred to as Tropidurus hispidus (Boulenger, 1902; Peracca, 1985, 1904), or as T. torquatus hispidus (Burt and Burt, 1931; Helbiich, 1960; Hoogmoed, 1973). Burt and Burt (1931) considered these southwestern populations to represent in- termediates between torquatus and hispidus, thereby justifying the recognition of hispidus as a subspecies of torquatus. Most subse- quent authors have followed this arrangement. However, careful study has revealed that these southwestern populations represent an undescribed species of Tropidurus distinct from both the neigh- boring population of the torquatus group to the east, and the popu- lations usually referred to hispidus far to the north. The new species is named for Dr. Richard E. Etheridge in recognition of his careful and substantial contribution to this paper. Tropidurus etheridgei new species Figure 1 Holotype. — The University of Kansas Museum of Natural His- tory (KU) 186101, an adult male from Mina Claveros, 1200 m, northeastern slopes of the Sierras de Cordoba, Provincia de Cor- doba, Argentina (31°45'S; 65°5'W), collected on 3 January 1980 by Jose M. Cei. Paratypes.—KlJ 186102-186108, 7 adult males, KU 186109- 186115, 5 adult and 2 immature females, collected with the holo- type. Diagnosis. — Tropidurus etheridgei is distinguished from other members of the genus, except those of the torquatus group, in lack- ing a vertebral ( middorsal ) scale row. It differs from the neighbor- ing eastern populations of the torquatus group in having: 1) dorsal A NEW SPECIES OF TROriDURUS Fig. 1. — Dorsal (upper) and ventral (lower) views of the holotype of Tropidurus etheridgei, an adult male (KU 186101), total length 251 mm. 4 OCCASIONAL PAPERS MUSEUM OF NATURAL HISTORY scales distinctly larger, 2) body more robust and tail more spinous, 3) canthus rostralis more evident and more concave, 4) cephalic scales more prominent and rugose, 5) few large acuminate scales on anterior margin of ear opening, 6 ) inf ralabials almost acuminate, and supralabials narrower and more prominent, 7) scales on the throat more spinous, 8) axillary and inguinal dennal pockets absent, and 9) ventral scales with evident melanophores in males. Com- pared with T. torquatus, it differs in having a larger and stouter body, distinctly larger dorsal scales, two nuchal pockets (one in torquatus), and different coloration. Compared with the northern- most Brasilian populations, it differs in having two nuchal pockets, supralabials, fewer large acuminate scales on the anterior margin of slightly smaller dorsal scales, more scale rows between subocular and ear opening, more acuminate narrow supralabials and infralabials, ventral scales with distinct melanophores in males and different dorsal coloration. It is easily distinguished from T. hijgomi, in having a much larger body size, different coloration, and lacking the broad, strap-like supraoculars of the latter. The rare T. hogerti from the Auyantepui massif (2500 m, Estado de Bolivar, Venezuela) is said to have tufts of spiny scales on the neck, as in Plica. Description. — Head length less than one fourth body length. Well developed antehumeral and lateral neck folds; two nuchal pockets, but no axillary or inguinal pockets. Snout slightly pointed; nostral scale large, wide, twice as wide as high; nasal in contact with rostral; nostril much smaller than nasal scale, opening antero- dorsally, nearer to tip of snout than to eye; ear opening elliptical, edged anteriorly by four or five large, acuminate scales, posteriorly by small, spinous scales; temporal scales irregular, weakly keeled and slightly acuminate; scales of frontal, parietal and occipital re- gions irregularly shaped, large and convex; occipital shield enlarged, rounded, widest posteriorly behind; eight enlarged supraoculars, larger than scales of interorbital region, separated from supercili- aries by two or three rows of smaller, irregular scales. Subocular scale large, undivided, separated from supralabials by two or three depressed rows of small scales; supralabials 6; infralabials 5, with prominent medial longitudinal ridge; mental polygonal; eyelid slightly fringed; scales on side of neck small, spinous, acuminate, mucronate, strikingly smaller than imbricate, keeled, scales on dor- sum of neck; scales across gular region between t)'mpana 47-48. Vertebral scale row absent; dorsal scales lozenge-shaped, regularly arranged, imbricate, distinctly keeled, mucronate, larger than ven- tral scales; scales on sides smaller, imbricate; ventral scales quad- rangular, smooth, increasing in size and irregular in gular region; upper caudal scales faintly keeled anteriorly, distinctly keeled pos- teriorly, spinous and mucronate; ventral caudal scales subtriangular, smooth, keeled posteriorly; scales around middle of body 80-82. A NEW SPECIES OF TROPIDURUS S Scales on dorsal surface of forelimb strongly keeled, imbricate; ventral forelimb scales smaller, triangular, smooth; dorsal thigh scales enlarged, faintly keeled, mucronate, imbricate; ventral thigh scales about same size, smooth; dorsal shank scales large, strongly keeled, mucronate; ventral shank scales large, strongly keeled, mucronate; ventral shank scales slightly smaller, smooth; enlarged scales of preanal region subtriangular; subdigital lamellae of fourth finger 23, on fourth toe 26, all tricarinate; claws of all digits short, strong, curved, 2 mm long. Hind limb and forelimb stout; when forelimb adpressed, fourth finger barely reaching groin; when hind limb adpressed, fourth toe crossing axilla. Coloration: Dorsum brownish gray, with irregular transverse dark markings with pale borders posteriorly; dorsum of tail pale brown with obscure transverse brown markings; head darker brown; black bar laterally on antehumeral region; throat white, mottled with dark gray; venter white with large pigmented black areas on femoral-cloacal region and belly. Females colored like males, ex- cept paler and without black areas ventrally. Measurements and variation of holotype and paratypes: Snout- vent length in adult males 81-109 mm, in adult females 83-103 mm (Table 1 ) . Males differ from females by having significantly larger forelimbs and hind limbs and fewer scales around midbody (79-84 versus 88-94). However, insignificant sexual differences in number of scales around midbody were noted in some Bolivian populations (Etheridge, pers. comm.). Subdigital lamellae 19-21 on fourth fin- ger, 24-27 on fifth toe, sexes combined. No notable individual or Table 1. Measurements of holotype and paratypes of Tropidunis etheridgei (mm) Total Snout Head Head Fore- Hind Axilla KU Number Length vent l^ength Width hinb limb groin 186101 Holotype $ 251 109 24 22 46 74 49 186102 S 212 92 21.5 19 40 64 41 186103 s _ zUu4 DEMCO, INC. 38-2931