Alexandresaurus, RODRIGUES & MACHADO PELLEGRINO & DIXO & VERDADE & PAVAN & SUZART ARGOLO & SITES, 2007

RODRIGUES, MIGUEL TREFAUT, MACHADO PELLEGRINO, KATIA CRISTINA, DIXO, MARIANNA, VERDADE, VANESSA KRUTH, PAVAN, DANTE, SUZART ARGOLO, ANTÔNIO JORGE & SITES, JACK W., 2007, A New Genus of Microteiid Lizard from the Atlantic Forests of State of Bahia, Brazil, with a New Generic Name for Colobosaura mentalis, and a Discussion of Relationships Among the Heterodactylini (Squamata, Gymnophthalmidae), American Museum Novitates 3565 (1), pp. 1-28 : 5-15

Alexandresaurus , new genus

DEFINITION: A large and slightly elongate gymnophthalmid (maximum SVL 70 mm) with distinctive ear opening and eyelid, large tail (1.63%–2.36% SVL), and slender pentadactyl limbs; first toe lacking a claw. Frontonasal single; prefrontals, frontoparietals, parietals, and interparietals present. Parietals and interparietal longer than wide. Collar fold absent. Two pairs of genials and three supraoculars. Dorsal scales anteriorly smooth, isodiametric or subrectangular in occipital region, becoming progressively narrower, more elongate and rounded toward arm level and then lanceolate, strongly keeled, with lateral sides almost juxtaposed. Occipitals absent. Ventrals longer than wide, smooth, in four regular transverse series identical in size. Males with a continuous series of very conspicuous pores with no gap between preanal and femoral; pores absent in females. Hemipenis without evident bilobation, sulcus spermaticus single, marginated by a naked area which is also present on the opposite side of sulcus. Between naked areas two symmetrical series of continuous transverse rows of comb-like flounces with minute spines or irregular tooth-like structures. A series of enlarged spines near the base of hemipenis.

CONTENT: Alexandresaurus camacan new species; monotypic.

ETYMOLOGY: A homage to the Brazilian naturalist Alexandre Rodrigues Ferreira, born in Salvador, state of Bahia, as a recognition for his effort to document the natural history of Brazil at the end of the 18th century. After pursuing natural history studies under Vandelli at the University of Coimbra, Alexandre headed the famous viagem filosófica (‘‘philosophical voyage’’) to Brazil at the end of 18th century. He remained in Brazil until 1789 where, among other places, he traveled extensively along the Rio Negro, Madeira and Guaporé in the Brazilian Amazon. The travels of Alexandre were part of a larger project to publish what was meant to be a monumental natural history of the Portuguese colonies ( Farias, 2001). The plan was abandoned by the end of 1807 when the royal family escaped to Brazil against the backdrop of Lisbon’s imminent conquest by Napoleonic forces. Most of the collections assembled by Alexandre during the more than 35,000 km traveled in Brazil were published by other naturalists following the request of part of the material by Étienne Geoffroy Saint Hilaire, who was present in Lisbon during the subsequent conquest.

COMPARISONS: Considering the now recognized multiple origins of character complexes associated with fossoriality in gymnophthalmid lizards, and the chaotic state of their taxonomy based on external attributes (until recently), we compare Alexandresaurus with all other gymnophthalmids while emphasizing the external morphological differences with the genera Iphisa , Colobosaura , Colobodactylus , Heterodactylus , and Stenolepis . Except for the latter, this group of genera was recovered by Pellegrino et al. (2001) as a wellsupported clade that included the closest relatives of Alexandresaurus . Stenolepis , although not included in that study, was tentatively allocated to the same radiation.

Most character states for the taxa compared here are summarized in appendix 1. Alexandresaurus differs from Iphisa (data for the latter in parenthesis) by having: two pairs of genials (one); several rows of lanceolate and keeled dorsal scales (smooth, in two longitudinal rows); ventral scales regularly transverse in four longitudinal rows (not in transverse rows and in two longitudinal rows); and regularly transverse rows of gulars (not regular). Alexandresaurus also differs from Iphisa in having a naked area opposite to the sulcus spermaticus and large spines at the base of the hemipenis (naked area absent and only small spines at base of the organ). From Colobosaura Alexandresaurus can be distinguished from Colobosaura by its smooth neck scales and small, smooth, and posteriorly rounded scales in the first 7–8 dorsal rows, rarely two enlarged nuchals are present at the central part of the second dorsal row; occipitals are never present. In Colobosaura neck scales have keels; there are several enlarged scales, much wider than long, in the first eight dorsal rows, the first two characteristically smooth and enlarged, forming an occipital pair separated or not by a smaller scale; the posterior 5–6 dorsal rows are striate or multicarinate. Ventral scales in Alexandresaurus are longer than wide, laterally juxtaposed, round- ed posteriorly, identical in size and shape, regularly arranged transversally and in four longitudinal series. In Colobosaura there are also four longitudinal rows of quadrangular ventral scales, but they are not regularly transversal and are irregular in size and shape, laterally imbricate, and in the first ventral rows midline scales always distinctively wider than long; the external ventral rows are slightly wider than long in Colobosaura mentalis , whereas the reverse occurs in Colobosaura modesta . The latter species also differs from Alexandresaurus by having only three pairs of genials. As in Alexandresaurus , the hemipenis of Colobosaura mentalis also has a naked area on the side of organ opposite to the sulcus, as well as flounces of right and left lobes medially interrupted by a naked area, a character absent in the former species. The only other species referred to Colobosaura was Perodactylus kraepelini . It is a young female (SVL 5 40 mm) described by Werner in 1910 having Puerto Max: Paraguay as type locality. We have not examined the holotype, which is lost from the Hamburg Zoological Museum according to Dr. J. Hallermann (in litt.); based on the original description, this species is identical to Colobosaura modesta , an opinion advanced long ago by Amaral (1933). The distributional data agree with this interpretation because the type locality is in the area of occurrence of C. modesta . The only character that until now has precluded synonymy between C. modesta and C. kraepelini was Werner’s reference to the tongue of his specimen as having ‘‘oblique plicae like Alopoglossus ’’. Based on the agreement of all other characters mentioned in the description we think that Werner was in error in describing the tongue, evidently a strange character and restricted to Alopoglossinae . Alexandresaurus differs from Stenolepis , Colobodactylus , and Heterodactylus in having a pair of prefrontals (absent). It further differs from Stenolepis by having small dorsal neck scales (large, in 3–4 longitudinal rows), larger scales on the sides of neck (small, some almost granular), ventral and gulars in regularly transverse rows (not so), and smooth scales near venter (keeled). In Colobodactylus and Heterodactylus the parietals are wider than long in contrast to the longer than wide parietal scale observed in Alexandresaurus and other Heterodactylini . This difference is probably due to a possible scale rearrangement in Heterodactylus and Colobodactylus in which parietals (and interparietal in Colobodactylus ) were divided and their posterior regions incorporated into the highly conspicuous occipitals that characterize both genera. This hypothesis, further discussed under a phylogenetic framework below, reveals that even head scales traditionally used in taxonomic descriptions may not be strictly homologous. This is another example of the taxonomic confusion that may result from uncritical use of morphological characters in microteiid systematics. Alexandresaurus also differs from Colobodactylus and Heterodactylus in having five toes and smooth flank scales (only four toes and flank scales keeled in the latter genera). Heterodactylus further differs from Alexandresaurus by the absence of external ear, absence of frontoparietals, and absence or extreme reduction of interparietal. Finally, the hemipenis of Heterodactylus is very different from that of Alexandresaurus . The organ is distinctively bilobate with a centripetal sulcus spermaticus surrounded by a naked area. The asulcate side of the organ has a series of continuous and unornamented naked flounces containing only one spine at each edge, very different from the interrupted flounces containing spines in a comb-like arrangement observed in Alexandresaurus .

Alexandresaurus differs from members of Alopoglossinae by having imbricate, scalelike papillae covering the tongue (oblique plicae), and from Rhachisauridae by having a distinctive ear opening and eyelid (absent), five toes (four), a normal body (clearly elongate), presence of frontoparietals (absent), and a nostril at the nasal border (in the center of the nasal scale). From all other Gymnophthalminae Alexandresaurus differs by having five toes (fifth toe reduced or absent), a distinctive eyelid (absent in all Gymnophthalmini except for Tretioscincus ), nostril at the nasal border (in the center of the nasal scale), a wide and flattened clavicle enclosing a fenestra (simple, boomerang shaped and without fenestrae), nasal bones in contact at midline but broadly separated anteriorly (totally separated by contact between frontal and premaxilary), and, among other characters, by having straight lateral processes of the interclavicle (posteriorly oriented). Alexandresaurus also differs from all Cercosaurinae by having a distinctive sternal fontanelle process (absent), a glossohyal separated from basiyal (fused), nasal bones broadly separated anteriorly (in broad contact), and postorbital covering postfrontal (covered by postfrontal).

Alexandresaurus camacan , new species figures 1–4

HOLOTYPE: MZUSP 93201 , an adult male from Una (15 ° 10 9 S, 39 ° 03 9 W): state of Bahia: Brazil, collected by Marianna Dixo on 01 November 1999, field number md-1106.

PARATYPES: All from the state of Bahia, Brazil . MZUSP 93179–93200 , Una, collected by M. Dixo between 24 January 1999 and 27 February 2000 ; MZUSP 93331 , Ilhéus, collected by W. Bokerman on December 1971 ; MZUSP 93462–93464 Ilhéus ( CEPLAC, sede regional), A. Argolo leg., collected respectively on July 1990, 24 April 1991 , and 12 May 1999; MZUSP 93227–93228 , Jussari ( Serra do Teimoso ) collected by M . T. Rodrigues, D. Pavan, M. Dixo , and V. K. Verdade on March 2001 ; MZUESC 2431 , Ilhéus (Campus UESC), collected by C. N. Souza on 8 March 2002 ; RMNH 29741 , from Una, Ilhéus .

ETYMOLOGY: The specific epithet is a homage to the extinct Camacan Indians , a Botocudo group who lived in the exuberant forests of Bahia from north of Rio Pardo to Ilhéus.

DIAGNOSIS: A gymnophthalmid with ear openings and eyelids, and slender pentadactyl limbs lacking the claw on first toe. Frontonasal single; prefrontals, frontoparietals, parietals, and interparietals present. Parietals longer than wide. Collar fold absent. Two pairs of genials; three supraoculars. Dorsal scales in 30–38 rows, anteriorly smooth, isodiametric or subrectangular in occipital region, becoming progressively narrower, more elongate and rounded toward the arm, and posterior to the arm becoming more lanceolate, strongly keeled, with lateral sides almost juxtaposed. Occipitals absent. Ventrals longer than wide, smooth, in four regular longitudinal and 15–19 transverse rows, identical in size. Scales around body 29–35; 11–15 and 16–20 infradigital lamellae under finger IV and toe IV respectively. Males with a series of 20–25 very conspicuous pores without gap between preanal and femoral; pores absent in females.

DESCRIPTION OF HOLOTYPE (fig. 2A–C): Rostral broad, wider than high, contacting first supralabial, nasal, and frontonasal. Frontonasal pentagonal, twice as wide as long, contacting rostral, nasal, loreal, and prefrontals. Prefrontals slightly wider than long, in broad contact at midline. Frontal hexagonal, with almost parallel lateral margins, slightly longer than wide, anteriorly indenting the prefrontal and posteriorly the frontoparietal sutures. Frontoparietals pentagonal, larger than prefrontals, in slight contact, strongly indented by the interparietal. Interparietal longer than wide, longer and narrower than frontal, as long as and narrower than parietals. Parietals heptagonal, marginated laterally by two temporal scales with approximately the same size, anteriorly by the third supraocular and frontoparietal, medially by the interparietal, and posteriorly by the first dorsals. Three supraoculars, first the smallest, second and third about the same size, second slightly wider, its longest suture with frontal, third slightly longer, in broad contact with frontoparietal. Nasal above first supralabial, large, longer than high, with the nostril in the center and lower part of scale, indenting suture with labial. Loreal posterior to nasal, narrower and diagonally oriented; contacting posteriorly first superciliary, preocular, and frenocular. Frenocular below preocular, followed posteriorly by a long subocular wider anteriorly and indenting suture between preocular and frenocular. Seven supralabials, third and fourth under the eye, fifth the highest and contacting two smaller scales following posteriorly the subocular, the smallest one clearly a postocular; seventh supralabial the smallest, in contact with the granules surrounding anterior margin of ear. Three superciliaries, first largest, wider anteriorly, longer than first supraocular, contacting preocular, loreal, first and second supraoculars, second superciliary and upper eyelid. Central part of eyelid with a semitransparent undivided disc surrounded by small and slightly pigmented granular smooth scales. Lower eyelid with eight strongly pigmented palpebrals. Temporal region with few smooth and juxtaposed scales, irregular in size and shape, between parietals and supralabials; the larger as large as the sixth supralabial. Ear opening surrounded by a series of very small and juxtaposed rounded granules; external auditory meatus large, tympanum distinct, subovoid, recessed. Lateral surface of neck with smooth, imbricate and mostly longer than wide scales, larger dorsally. All head scales smooth and juxtaposed with scattered sensorial organs.

Mental broad, wider than high. Postmental heptagonal, wider than long. Two pairs of genials, both contacting infralabials; the first smaller, in broad contact at midline; second pair contacting only anteriorly and reaching the level of labial comissure. An enlarged pair of symmetric flat and chevron-like scutes follows second pair of genials, preventing their contact posteriorly. Six infralabials, second the largest. Gulars smooth, imbricate, rounded posteriorly, in seven transversal rows; at midline similar to ventrals, much smaller toward side of neck. Gulars followed by a distinct interbrachial region with seven much larger and elongate scales, about twice as long as gulars. Collar fold absent.

Dorsal scales imbricate and arranged in regular transversal rows; smooth, isodiametric or subrectangular in occipital region, becoming progressively narrower, more elongated and rounded at arm level and then posteriorly lanceolate, strongly keeled, with lateral sides almost juxtaposed. Thirty transverse rows between interparietal and the posterior level of hind limbs. Lateral scales about the same size as dorsals but smooth, strongly imbricate laterally, less acuminate and more diagonally arranged than dorsals; those closer to ventrals larger. A distinctive area with granular scales surrounds the area of arm insertion. Thirtyone scales around midbody. Ventral scales smooth, longitudinally imbricate, laterally juxtaposed, longer than wide, rounded posteriorly; 17 transverse rows from interbrachials (excluded) to preanals. Six scales in precloacal region, central and paramedials the largest. Total pores 23, continuous, with no gap between femoral and preanal ones.

Scales of tail smaller than midbody dorsals, but otherwise identical; keeled, lanceolate, strongly imbricate longitudinally; those from base of tail slightly larger ventrally, becoming gradually identical around tail toward the extremity.

Forelimbs with large, smooth, and imbricate scales; those on ventral part of brachium much smaller. Anterior and ventral parts of hind limbs with irregularly large, smooth, and imbricate scales, identical to the correspondent parts of fore-limbs. Posterior part of hind limbs with granular, juxtaposed scales, grading progressively to larger, imbricate, and keeled scales in dorsal part of tibia. Carpal and tarsal scales large, imbricate; supradigital lamellae, smooth imbricate. Palmar and plantar surfaces with smooth, small granules; infradigital lamellae single, 12 on Finger IV and 19 on Toe IV. Toes and fingers, except for Finger I, clawed, and respectively in the following relative sizes: 1, 2 5 5, 3 5 4 and, 1, 2, 5, 3, 4.

Dorsal surfaces of body and tail and lateral part of tail dark brown with an irregularly distributed darker punctuation smaller than one fourth of the scale size. Flanks predominantly yellowish to cream, as the ventral parts of body and tail, but strongly mottled by an irregularly black pattern. Lateral parts of head with an identical pattern, black blotches concentrated in central parts of supra- and infralabials, yellow at their sutures. Ventral parts of body and tail creamy yellow, immaculate, except in the external rows of gulars and ventrals, which present irregular black spots. Ventral part of tail becomes gradually darker toward the extremity. Limbs dark brown dorsally, irregularly mottled with yellow; creamy yellow and immaculate ventrally.

Hemipenis partly everted at preservation except for the apex; bilobation not evident; sulcus spermaticus single, marginated by an enlarged naked area that is also present, but narrower, on the opposite side of sulcus. Between naked areas of the organ, two symmetrical series of 29 (or more) continuous transverse rows of comb-like flounces with minute spines or irregular tooth-like structures. Flounces continuous even near basal part of the organ where their ornamentation is medially interrupted by a small area without spines. A basal series of very enlarged spines is present near the base of hemipenis in its asulcate face.

Measurements of the holotype: snout-vent length: 66 mm; tail length: 145 mm.

VARIATION: Males are slightly larger than females but have much longer tails: maximum SVL for males and females was 70 mm and 66 mm. Tail length varied respectively in males and females from 1.76 to 2.36 and 1.8 to 2.03 times SVL (fig. 5: r 2 males 0.93; r 2 females 0.29). No sexual differences were found in squamation. Variation in meristic characters (N 5 28) was the following (mean and standard error, respectively, in the parenthesis): dorsal rows, 28–30 (29 and 0.72); ventrals 15–19 (16.8 and 1.06); scales around midbody 29–35 (31.5 and 1.42); infradigital lamellae under finger IV 11–15 (12.9 and 0.19); and infradigital lamellae under Toe IV 16– 20 (18.1 and 1.0). All specimens show three supraoculars and three superciliaries. All the specimens have seven supralabials, and all have six infralabials except RM 29791, which has seven. One specimen (MZUSP 93187) has four ventral rows fused midventraly resulting in two longitudinal rows of ventrals. We note that this arrangement is similar to the pattern found in Iphisa , but differs from it because the rows of scales are regularly arranged transversally in Alexandresaurus and not so in Iphisa . Only males have pores, they are absent in females. Pores are highly conspicuous, placed in distinctively elevate scales, aligned on each side without gaps between preanal and femoral. Total number of pores varied from 20–25 (N 5 16). Sexual color dichromatism is evident; males are characterized by dark coloration in the flanks mottled with yellowish or whitish blotches and a reddish venter; females and juveniles are more dull colored having unpatterned light brown flanks and a creamy white venter.

OSTEOLOGY (figs. 3–4): The following description is based on two alizarin-prepared skeletons (MZUSP 94252–53). Premaxillary as long as wide, contacting but not articulating laterally with the maxillary. Its dorsal lamina triangular posteriorly, long, just covering anteriorly the nasals and deeply indenting their suture, preventing their anterior contact. Twelve premaxillary conical teeth. Nasals large, longer than wide, wider anteriorly, diagonally arranged, widely separated anteriorly, posterior third in midline contact, covering frontal anteriorly. Frontal longer than wide, wider posteriorly, covering parietal and articulating with it by a pair of frontoparietal tabs. Parietal longer than wide, wider and concave posteriorly and covering laterally the occipital region. Epipterygoid contacting externally a descending epipterygoid process of parietal. Maxillary dorsally contacting nasal, and lateral parts of frontal and lacrimal, without overlapping, and extensively covering prefrontal and jugal; 21 maxillary teeth. Prefrontal large, its posterior process long but not reaching the level of middle of orbit; in broad contact with frontal. Lacrimal large, very conspicuous, contacting prefrontal and maxillary and indenting the orbit. Postfrontal and postorbital single. Postfrontal triangular, contacting jugal, frontal, postorbital and jugal, closing posteriorly the orbita. Postorbital long and wide, contacting squamosal posteriorly, almost closing the supraorbital fenestra. Squamosal long, posteriorly curved and abutting the top of quadrate. Supratemporal fenestra almost closed and strongly constrained laterally by parietal and postorbital. Supratemporal present, in straight contact with posterior part of parietal and squamosal. Fifteen scleral ossicles in the eye. Vomer, palatine, pterygoid, ectopterygoid, and pterygoid present. Vomer, palatine, premaxillary, and maxillary in contact restricting the fenestra exochoanalis. Infraorbital fenestra large, bordered posteriorly by ectopterygoid. Stapes rodlike, wider at the base. Sutures between supraoccipital, exoocipital, basioccipital and the otic area of skull are not as visible as those between basioccipital and basisphenoid. In the lower jaw dentary, articular, splenial, angular, and supraangular are distinct; there are 14–15 dentary teeth, conic anteriorly, bicuspid or tricuspid posteriorly.

Glossohyal long, fused to basihyal. First ceratobranchial curved posteriorly; hypohyal and ceratohyal present. A second short pair of ceratobranchials is present and positioned parallel to the anterior part of trachea.

Anterior part of clavicle very enlarged, flattened, enclosing a fenestra. Interclavicule long, cruciform, with very long lateral processes reaching the sternum but not sternal fenestra. Scapulocoracoid with coracoid, scapular, and scapulocoracoid fenestrae; suprascapula present. Sternum with a large fenestra, receiving three sternal ribs and a xiphisternum with two inscriptional ribs. Ilium, ischium, and pubis present, the latter with a conspicuous pectinate apophysis. Hypoischium long, larger at the base, almost reaching the preanal border; a small elongate preischium and a small quadrangular ossificate prepubis are present.

Twenty-seven procoelous presacral vertebrae, neural spines low, higher anteriorly hypopophyses present in the first six vertebrae; zigantrum-zygosphene present. Last presacral vertebra lacking ribs. Two sacral vertebrae. First caudal vertebrae with long transverse processes, lacking autotomic septa.

Humerus and femur are slightly larger than radius and ulna and tibia and fibula. Remaining elements of the forelimbs and hind limbs as in figure 4.

DISTRIBUTION AND NATURAL HISTORY

Alexandresaurus camacan is currently known only from four localities in the southern Atlantic rainforest region of the state of Bahia: Ilhéus, Una, Jussari (Serra do Teimoso), and Uruçuca. The maximum straight-line distance between the most distant of these localities is less than 60 km. Pristine tropical forest with high levels of humidity and rainfall (about 2,000 mm) regularly distribut- ed throughout the year, with a dense leaf litter, large trees reaching up to 30 m high and more than 50 cm diameter at breast height, and an abundance of bromeliads and other epiphytes, was the typical habitat in the Atlantic rainforest at this latitude. Most of this area is dominated by lowlands or low hills dissected by small- to medium-sized streams, interrupted by isolated higher mountains. The Serra do Teimoso is one these higher mountains reaching about 1,000 m altitude and receiving the highest levels of humidity at the top as a result of the orographic effect and condensation of air masses coming from the sea. Currently most of the forest cover is restricted to scattered patches of remnant forest, the Una reserve (Reserva Biológica de Una—ca. 11,500 ha) being the largest one. The largest area of original forest was destroyed by agriculture (for cacao plantations), cattle ranching, and timber harvest activities. In cacao groves (‘‘cabrucas’’ locally) where large and emergent trees have been preserved to shade the understory cacao plants, leaf litter is abundant and humidity is higher than in other disturbed areas.

The localities where Alexandresaurus camacan was collected show slight differences related to soil type, levels of humidity, and distance from the coast. Uruçuca (14 ° 33 9 S, 39 ° 18 9 W) is located on fertile soils originating from volcanic deposition and is intensely cultivated for cacao production. Ilhéus and the Reserva Biológica do Una (15 ° 10 9 S, 39 ° 03 9 W) are located near the coast on the sandy soils of Barreiras Formation and receive more rainfall. The RPPN (Reserva Particular do Patrimônio Natural; Serra do Teimoso; 15 ° 19 9 S, 39 ° 31 9 W) is an isolated peak toward the interior of the state and is covered by a semideciduous forest, along with cacao groves at the lower areas and tropical rainforest with high humidity levels near the top .

Pitfall traps were installed at Una, Serra do Teimoso, and Uruçuca to sample areas of primary and secondary forest and cacao groves. At Serra do Teimoso a series of pitfall traps also sampled semideciduous forest. Alexandresaurus camacan was always obtained in sheltered areas in primary forest or cacao groves, never in secondary forests. At Serra do Teimoso the only individual collected was found in semideciduous forest at high elevation (about 900 m) in the humid forest. No association between habitat categories and sex was detected (p. 0.05, chi-square test). Alexandresaurus camacan was always found in shady areas in primary forest or cacao groves, and never in secondary forests. Total abundance (F (2, 27) 5 1,06, p 5 0.36) and female abundance (F (2, 27) 5 0.32, p 5 0.73) did not vary significantly among habitats (forest interior, forest edge, and cacao groves), while male abundance did (F (2, 27) 5 4.70, p 5 0.018). Male abundance was significantly higher in forest edges than in cacao groves (p 5 0.03) and marginally higher than in forest interior (p 5 0.06).

PHYLOGENETIC ANALYSES

Parsimony analyses to determine the phylogenetic placement of Alexandresaurus camacan and its relationships within the Heterodactylini , were first conducted on the partition composed of 42 morphological characters (38 of which are parsimony informative; appendix 2) with all states coded as unordered. This analysis recovered 211 most parsimonious trees; the poorly resolved strict consensus tree (L 5 106; CI 5 0.55 and RI 5 0.72; fig. 6A) left the position of Alexandresaurus unresolved within the Heterodactylini , but, although weakly supported, recovered the tribe as monophyletic (BS 5 58, Bremer value 5 4). Except for a well-supported sister relationship between Colobodactylus taunayi - Heterodactylus imbricatus (BS 5 95, Bremer value 5 4) this tree left all other ingroup taxa as an unresolved polytomy. Two other well-supported sistergroup relationships recovered by the morphological partition were those of Procellosaurinus tetradactylus - Micrablepharus maximiliani (BS 5 99, Bremer value 5 4) and Colobosauroides cearensis-Anotosaura vanzolinia (BS 5 88, Bremer value 5 2).

Combined analyses of the morphological and molecular partitions resulted in a single most parsimonious tree of 2,740 steps, 660 parsimony-informative characters, and CI 5 0.47 and RI 5 0.43 (fig. 6B). The recovered relationships are very similar to those suggested by the previous study of Pellegrino et al. (2001) based on molecular data only. The Heterodactylini was recovered with strong support (node 8: BS 5 92, Bremer value 5 11; see appendix 4). Within the Heterodactylini , A. camacan is weakly resolved as the sister group of I. elegans-C. modesta (node 5: BS, 50; Bremer value 5 2; see appendix 4); ( C. mentalis + S. ridleyi ) is recovered as a strongly supported clade (node 6: BS 5 100, Bremer value 5 18, see appendix 4); and both the monophyly of the clade ( Colobodactylus taunayi + H. imbricatus ) and that of its sister group ( A. camacan , C. modesta , I. elegans + C. mentali - S. ridleyi ) are strongly and moderately well supported (respectively, node 3: BS 5 99, Bremer value 5 13, and node 7: BS 5 75, Bremer value 5 5; appendix 4). The Gymnophthalmini represented by the Procelosaurinus-Micrablepharus clade (node 9: BS 5 100, Bremer value 5 28) is resolved as the sister clade of the Heterodactylini with high support (node 10: BS 5 96, Bremer value 5 11). Slightly different from the Pellegrino et al. (2001) hypothesis are the weakly supported sister relationship Rhachisaurus-Bachia (node 1: BS, 50, Bremer value 5 1) and the placement of Arthrosaura reticulata as the sister taxon of the C. cearensis-A. vanzolinia clade (node 13: BS 5 63, Bremer value 5 8). The monophyly of the ecpleopines was also strongly supported (node 15: BS 5 92, Bremer value 5 11).

Externally, the ( C. ocellata ( Rhachisaurus brachylepis - B. bresslaui )) clade was weakly supported (node 2: BS, 50, Bremer value 5 6), and the Heterodactylini-Gymnophthalmini clade (node 10) and the Ecpleopini clade (node 15) were recovered with high support indexes (BS 5 96, Bremer value 5 11; BS 5 92, Bremer value 5 11; fig. 6B, respectively).

Figure 7 shows the majority-rule consensus tree estimated using partitioned Bayesian method, which differs from that recovered from parsimony analysis (fig. 6B). The major difference refers to the paraphyly of the Heterodactylini with respect to the Gymnophthalmini, but this alternative topology is only weakly supported by posterior probabilities (PP 5 0.63). Bayesian tree is unique in recovering a quite well-supported sister relationship (PP 5 0.94) between I. elegans – C. modesta (PP 5 0.51) and C. mentalis – S. ridleyi (PP 5 1.0), with Alexandresaurus basal to this grouping (PP 5 0.94). Also, the sister-group relationship between Bachia and Cercosaura is highly supported (PP 5 0.99). Similar to the MP tree (fig. 6B), the support for Ecpleopini monophyly is high (PP 5 1.0), although its position is unresolved (fig. 7).

TAXONOMIC IMPLICATIONS: Our results show that the position of Colobosaura mentalis in the tree is incompatible with a monophyletic Colobosaura . This was also indicated in the analysis of Pellegrino et al. (2001), which although based exclusively on molecular data incorporated a much larger dataset. The sistergroup relationship between morphologically highly divergent species like Iphisa elegans and Colobosaura modesta , suggests the recognition of another new genus to allocate Colobosaura mentalis . We propose the following name to accommodate it:

Figures

Fig. 7. Phylogenetic tree estimated under Bayesian method of the combined morphology and molecular data set and posterior probabilities (above nodes) for clades recovered at the 50% majority rule consensus topology.