Cnemidophorus Wagler

Harvey, Michael B., Ugueto, Gabriel N. & Gutberlet, Ronald L., 2012, 3459, Zootaxa 3459, pp. 1-156 : 102-109

Cnemidophorus Wagler

Figures 64–65

Cnemidophorus Wagler 1830: 154 . Type species Seps murinus Laurenti subsequently designated by Fitzinger (1834).

Diagnosis.— Cnemidophorus is the only genus of Teiidae with a single pair of preanal spurs in males and proximal hemipenial laminae ornamented in short papillae. Female Cnemidophorus can be distinguished from all other teiids by the combination of long first supraciliaries, long first supralabials with straight ventral margins, subtriangular to subcircular nostrils, five regular parietals, smooth ventrals, and a continuous postaxial row of keeled, serrate scales separating the digital lamellae of all five toes.

Content.— Sixteen species, each assigned herein to one of four species groups.

Definition.—Small to medium lizards reaching 159 ( Cnemidophorus murinus ) mm SVL ( Tables 9–11); posterior maxillary and dentary teeth longitudinally compressed, tricuspid; pupil reniform.

Prefrontal usually separated from nasal (except in Cnemidophorus arenivagus ), separated from or in contact with first supraciliary; frontal entire, lacking longitudinal ridge, its posterior suture contacting third supraocular; scales of frontoparietal region smooth, outwardly convex to flat (key-hole shaped depression absent); frontoparietals paired; parietals consisting of five regular scales; interparietal entire, its relative size varying among species; medial pair of enlarged occipitals present in some species, absent in others; occipitals 11–24; supratemporals slightly to moderately enlarged, separated from parietals by one or more scales.

Rostral groove usually absent; nostril usually subtriangular to subcircular, centered or slightly to mostly anterior to nasal suture; loreal single; supraoculars eight (rarely 9–11); first supraocular entire, variable in size, usually broadly contacting second supraocular; circumorbital semicircles consisting of 4–17 small scales; supraciliaries 8–13, separated from supraoculars by 1–3 rows of 21–96 granular scales; first supraciliary long, greater than one-half as long as second; angulate keel extending from first subocular to elongate subocular below eye; suboculars four (rarely 3 or 5); first subocular usually entire, usually contacting first supraciliary, usually contacting supralabials (most species) or usually separated from supralabials by anterior expansion of second subocular ( Cnemidophorus ruthveni , C. vanzoi , and many C. murinus and C. arubensis ); patch of slightly to distinctly enlarged scales in front of auditory meatus; auricular flap and preauricular fold absent.

Supralabials 11–15 (usually 12); first supralabial subequal to or larger than second, its ventral margin straight (rarely curved); infralabials 10–15; first pair of chinshields broadly contacting infralabials and forming a medial suture greater than or equal to half their length; interangular sulcus absent; anterior gulars 15–37; gular patch absent; posterior gulars 11–22; intertympanic sulcus absent; larger anterior gulars undergoing sharp transition to smaller posterior gulars at intertympanic crease; mesoptychials not or moderately enlarged; gular fold lacking serrated edge.

Dorsals smooth; scales on flank subequal to middorsals, supported by small apical granules, not projecting laterally; scales on rump much smaller than proximal subcaudals; scales of chest large and flat; pectoral sulcus absent; ventrals smooth, in 28–40 transverse and 8–12 longitudinal rows; lateral-most ventrals flanked by small scales (i.e., ventrals not gradually decreasing in size on flanks); preanals 4–7; preanal plate present, bordered by subtriangular scales; preanals one-half as large to larger than scale anterior to them; in males, preanal spurs 1/1; postcloacal buttons and postanal plates absent; scales on dorsolateral edge of tail like those on top and sides, denticulate edge and dorsolateral crests absent; caudal annuli complete; proximal subcaudals smooth ( Cnemidophorus murinus and C. nigricolor groups ) or keeled ( C. lemniscatus and C. vanzoi groups ).

Enlarged scales of brachium connected by granular ( Cnemidophorus murinus , nigricolor , and vanzoi Groups ) or small to large subtriangular plates ( C. lemniscatus Group) on dorsal surface of arm; size and proximal extent of preaxial and postaxial brachial scales varying among species; antebrachial scales enlarged and smooth, widely ( C. murinus and C. vanzoi Groups ) or narrowly ( C. lemniscatus and C. nigricolor Groups ) separated from preaxial brachial scales; postaxial antebrachial scales granular; subdigital lamellae of hand homogeneous in size, mostly divided at phalangeal articulations, 14–28 under fourth finger.

Prefemorals 5–10; femoral and abdominal pores 23–86 in continuous row on each side (abdominal pores not separated from femoral pores by gap); each compound pore-bearing scale consisting of partially fused prefemoral or abdominal scale and 2–6 granular scales; 1–6 scales separating right and left pore rows; scales at heel relatively small and numerous; tibiotarsal shields present ( Cnemidophorus lemniscatus , C. nigricolor , and C. vanzoi Groups ) or absent ( C. murinus Groups ); tibiotarsal spurs absent; lamellae under fourth toe 26–46; distal lamellae of fourth toe smooth; continuous row of low serrate keeled scales completely separating digital lamellae along postaxial edge of all toes; noticeably enlarged postaxial scales between fourth and fifth toe absent; fifth toe well-developed, base of its claw extending beyond level of skin between third and fourth toes when adpressed.

β- keratin containing layers of dorsal scales folded into macrohoneycomb; dorsal and caudal scales with one subterminal lenticular scale organ; ventrals lacking scale organs; generation glands present, usually unpigmented (pigmented in Cnemidophorus murinus Group).

Snout same color as dorsal head scales; specimens of Cnemidophorus leucopsammus and C. rostralis sometimes with tan cast but lacking decidedly red snout. In juveniles, light vertebral stripe present, usually solid and straight (most species), split and straight (C. l. espeuti, C. l. lemniscatus , C. vanzoi ), breaking into very few or numerous spots ( C. flavissimus , C. nigricolor ), or very faded, almost absent ( C. gramivagus , C. leucopsammus , C. murinus , C. cf. nigricolor , C. rostralis , C. ruthveni ); light paravertebral stripes present and straight (most species) or faded and/or broken into spots ( C. leucopsammus , C. nigricolor , C. cf. nigricolor , C. rostralis ); paravertebral stripes usually broken at some point along their length in juvenile C. flavissimus (coded as continuous in phylogenetic analysis, because most of stripe remains solid); paravertebral stripes of C. murinus and C. ruthveni very inconspicuous, faded and often difficult to discern but nonetheless present and straight; dark dorsolateral field solid in all species (present but very faint and sometimes difficult to observe or only distinct posteriorly in C. arubensis , C. leucopsammus , C. murinus , C. nigricolor , C. cf. nigricolor , C. rostralis , C. ruthveni ); dorsolateral light stripe solid and extending to tail (most species) or broken into spots ( C. leucopsammus , C. nigricolor , C. cf. nigricolor , C. rostralis ); dorsolateral light stripe of C. murinus and C. ruthveni very inconspicuous, faded and often difficult to discern but nonetheless present and extending to tail; dark lateral field usually solid and distinct at least posteriorly (most species) or absent ( C. leucopsammus , C. nigricolor , C. cf. nigricolor , C. rostralis ); upper lateral light stripe solid and extending to groin (most species), broken into spots not always coinciding with stripes ( C. arubensis , C. leucopsammus , C. nigricolor , C. cf. nigricolor , C. rostralis ), or absent ( C. murinus , C. ruthveni ); lower lateral light stripe solid and extending to groin ( C. arenivagus , C. flavissimus , C. lemniscatus gaigei , C. l. splendidus, C. cf. lemniscatus , C. senectus ), broken into spots not always coinciding with stripes ( C. arubensis , C. l. espeuti, C. gramivagus , C. l. lemniscatus , C. leucopsammus , C. nigricolor , C. cf. nigricolor , C. rostralis , C. vanzoi ), or absent and instead replaced by large spots ( C. murinus , C. ruthveni ); thigh with light spots. Adult males with small (most species) or large ( C. murinus , C. ruthveni ) light spots on flanks; turquoise ventrolateral spots always absent (some specimens of predominantly blue species may have blue flank spots invading ventrolateral areas but these are not homologous to turquoise spots present in other teiids); venter immaculate (pale or black in melanic species); juvenile of all species undergoing considerable ontogenetic changes in coloration, less conspicuously so in C. murinus and C. ruthveni and most distinct in C. flavissimus .

Hemipenis with pair of taβ- like and smooth apical awns; apical papillae and apical basin absent; asulcate expansion pleat well-developed, interrupting about 14–23 distal laminae; discontinuous distal laminae absent; 5–13 laminae proximal to expansion pleat; proximal laminae ornamented with short papillae.

Interspecific Relationships and Biogeography.— We identified suites of morphological characters to define four species groups ( Table 9) within Cnemidophorus . In our phylogenetic analysis, each of the four groups was monophyletic ( Fig. 66). Cnemidophorus vanzoi is sister to the C. murinus Group. Together, these large insular and vegetarian species are the closest relatives of the C. nigricolor Group in the ordered analysis, whereas the C. nigricolor Group is sister to the C. lemniscatus Group in the unordered trees. Within the C. nigricolor Group, the recently described species C. leucopsammus and C. rostralis are each other’s closest relatives.

Recent analyses of molecular characters (Giugliano 2009; Giugliano et al. 2006; Reeder et al. 2002) included only five of the taxa studied here ( Fig. 66). Each of these studies included C. lemniscatus , C. arenivagus , and C. gramivagus . Reeder et al. (2002) also included C. l. splendidus, whereas Giugliano (2009) also included C. vanzoi . Although these analyses agreed with our results in excluding Cnemidophorus vanzoi from an otherwise monophyletic C. lemniscatus Group, interspecific relationships within the C. lemniscatus Group differ from our results. Reeder et al. (2002, p. 18) called attention to the close relationship between C. l. splendidus and C. arenivagus and suggested, “that the specific status of ‘ C.’ lemniscatus splendidus merits reevaluation.” Cnemidophorus l. gaigei and C. l. splendidus are very similar morphologically. Their distributions are contiguous in western Venezuela (G. N. Ugueto , unpublished data) and, perhaps not surprisingly, appear to be sister species. Reeder et al. (2002) did not include molecular data for C. l. gaigei or C. l. espeuti in their analyses. Morphological evidence suggests that C. lemniscatus is monophyletic with three subspecies (C. l. gaigei , C. l. lemniscatus , and C. l. splendidus) if the insular taxon C. l. espeuti is excluded. However, we only examined a few specimens of C. l. gaigei , C. l. espeuti, and C. l. splendidus. There are differences in some scale counts (some of which were not scored in this study) among these taxa, and at least some of them may be distinct species. Additionally, the taxonomic situation of Cnemidophorus in northern South America, particularly in western Venezuela, is still unclear (G. N. Ugueto , unpublished data). The authors are currently reviewing C. l. espeuti and populations of C. lemniscatus in northwestern Venezuela, Colombia and Central America.

Most species of Cnemidophorus occur on islands of the southern Caribbean ( Ugueto & Harvey 2010), with only a few species of the C. lemniscatus Group occurring on the mainland. Interestingly, the most basal member of this group ( C. arubensis ) is also an insular species. Consequently, we can now conclude with relative certainty that Cnemidophorus evolved in the southern Caribbean. Moreover, the most parsimonious interpretation of our data is that C. lemniscatus , C. gramivagus , and C. arenivagus represent independent invasions of the mainland from an insular point of origin. The other mainland species of Cnemidophorus , C. cryptus and C. pseudolemniscatus , are parthenogens that arose from hybridization events involving C. lemniscatus and C. gramivagus ( Cole & Dessauer 1993; Reeder et al. 2002).

Remarks.— Reeder et al. (2002) partially resolved polyphyly of Cnemidophorus when they revalidated Aspidoscelis . As redefined here, Cnemidophorus is a morphologically and geographically cohesive group defined by a suite of synapomorphies. Other species left in the genus by Reeder et al. (2002) are here transferred to Ameiva , Ameivula , Aurivela , and Contomastix .