Phymaturus agilis, Scolaro, José Alejandro & Ibargüengoytía, Nora Ruth, 2008

Scolaro, José Alejandro & Ibargüengoytía, Nora Ruth, 2008, When starvation challenges the tradition of niche conservatism: On a new species of the saxicolous genus Phymaturus from Patagonia Argentina with pseudoarboreal foraging behaviour (Iguania, Liolaemidae), Zootaxa 1786, pp. 48-60 : 52-57

Phymaturus agilis sp. nov.

( Figures 1 and 2 )

Type material. Holotype: MLP.R. 5343, adult male, collected in rocky tableland (41º 25’ 40’’ S; 69º 45’ 07’’ W; 1030 m asl), neighbour Provincial road 6 south of Ingeniero Jacobacci, Rio Negro Province, Argentina. Collected by J.A. Scolaro and O.F. Tappari, 10 March 2006.

Paratypes: MLP.R. 5344, adult male; MLP.R.5345, adult female; MLP.R. 5346, adult female; JAS-DC 1644, adult male and JAS-DC 1119, adult female. All specimens have the same data of collection as the holotype.

Etymology. The specific name agilis refers to the ability of this lizard to climb and forage on large Lycium spp . (~ 2–3 m) shrubs, an unusual behaviour in the genus Phymaturus . We suggest the vernacular English name “Climber lizard” and the Spanish name “Lagarto trepador” for this species.

Diagnosis. Phymaturus agilis exhibits slight sexual differences in body size, being females larger than males. However, sexual dichromatism is not observed. The species is a member of the patagonicus group of the genus, distinguished from the flagellifer (= palluma) group in having flat imbricate superciliar scales rather than rectangular and non-overlapping, slightly spiny and non-rugose caudal scales in verticilles (as seen among members of the flagellifer group). Additionally, it presents the Meckel’s groove fused. It has also the subocular scale fragmented (in 4–5 scales) and separated from supralabials by 2–3 rows of lorilabials, as in most species of the flagellifer group, but not seen in the majority of members of the patagonicus group. Phymaturus agilis can be distinguished from other members of the patagonicus group in having a unique and homogeneous colour pattern with only slight intersexual differences, by showing an attenuate incomplete ringed tail of 2x 1 scales of red brick-like dark and light respectively, and a ventrally intense orange-red bricklike colour.

Phymaturus agilis differs from the sympatric P. spectabilis in having more fragmented the subocular scale, being fragmented in only two scales in P. spectabilis ; in addition, in P. agilis the subocular scale is separated from supralabials by 2–3 rows of lorilabials, while in P. spectabilis is separated by only one row of lorilabials (see more details in the results paragraph). Phymaturus spurcus ( Lobo & Quinteros 2005a) exhibits 3–4 fragmented suboculars and two rows of lorilabials separating suboculars and supralabials (our own data), resulting significantly different from P. agilis (Student’s t- test = 4.4; df = 41; P <0.01). Phymaturus agilis differs from P. calcogaster , because this last species shows the subocular fragmented in four scales, separated from the supralabials by two rows of lorilabials, and similar wide of rostral and mental scales ( Scolaro & Cei 2003; Scolaro et al. 2005), and from P. indistinctus , because it shows the subocular frequently fragmented in two scales and two rows of lorilabials between suboculars and supralabials. Phymaturus agilis differs from P. patagonicus , P. excelsus , P. tenebrosus , P. ceii , P. somuncurensis , because these species exhibit non divided subocular scale, and separated from the supralabials by a single row of lorilabials. From P. z a p a l e n s i s, P. payuniae and P. nevadoi differs because in these species there is strong sexual dichromatism, absent from P. agilis . In addition, the high number of scales around midbody and on the ventral surface differentiates P. agilis from P. patagonicus , P. spurcus , P. excelsus , P. spectabilis , and P. tenebrosus .

Description of the holotype. A medium-sized lizard; snout-vent length (SVL) 88.3 mm; tail regenerated; head length 16.4 mm; head width 15.0 mm; eye-nose distance 5.7 mm; forelimb length 29.7 mm; hindlimb length 46.3 mm; axilla-groin distance 46.3 mm (52.4 % of SVL); fourth finger length 10.1 mm; fourth toe length 14.7 mm; scales in dorsal surface of the head 19; scales around midbody 225; ventral scales between mental and precloacal pores 165; scales between rostral and frontal 11; supralabial scales 9-9; infralabial scales 9-9; subdigital lamellae on fourth finger 23; subdigital lamellae on fourth toe 27; precloacal pores 13; cephalic scales granular, almost smooth; supraorbital semicircles with large bulky scales, rounded, with an small azygous anteriorly, incomplete posteriorly on both sides; no distinct enlarged supraoculars; eight imbricate upper ciliaries; subocular fragmented in 4-4 almost rectangular scales, slightly shorter than eye diameter, separated from supralabials by 3-3 irregular rows of lorilabials; preocular separated from lorilabial row by two scales; temporals smooth irregularly quadrangular, in 8–9 rows from auditive opening to the subocular; external auditory meatus enlarged, subtriangular transversally, with few notably enlarged (3–4) scales on its anterior border and diminute granular scales on posterior border; rostral more wide than high, separated by two small scales from nasals; nasal moderate, lateral, surrounded by nine small scales; nasals separated by five small irregular scales; parietals irregular and rough with evident interparietal, surrounded by nine scales; nuchals granular in 4–5 irregular rows; post-auricular folds evident with interposed transversal folds with round, almost granular, scales; mental subpentagonal less wide but higher than rostral, surrounded by four irregular rectangular scales; two rows of 6-5 bilateral postmentals decreasing behind; dorsal scales small, round and juxtaposed; middorsal scales slightly enlarged decreasing smaller and granular toward ventro-laterals; ventrals larger than dorsals, almost pentagonals, imbricate and smooth; two gular folds with rounded, smaller scales; 67 gulars between auditory meatus; caudal scales quadrangular regularly imbricate in verticiles, proximally larger and smooth on dorsum, or softly keeled, distally more rectangular and keeled; scales in limbs round and slightly keeled in the upper side, granular and rounded in the lateral region, larger imbricate and flat in the lower side, infracarpals and infratarsals with round margins, becoming trifid to the base of fingers and toes. Subdigital lamellae of fingers keeled; claws moderately long.

Coloration. Males and females do not show clear differences in coloration. There is an irregular and discontinuous pattern of speckled black spots, more dispersed and attenuated in two dorso-lateral stripes, on a greyish and light brown background. The black spots pattern finish in the base of the tail in males, while in females it extends until the first third of the tail.The head is dark brown in males and females. The middle vertebral line is conspicuous. Ventrally, the males show a yellow and brick-like coloration from the throat zone to the tail, being darker in the tail. Orange anal pores. In females the throat zone, and the upper part of the chest is grey, but then turns reddish in the middle chest extending, like in males, along the tail. In both sexes the throat, the ventral side of the hands and legs are light grey, but the ventral zone of the legs are bricklike coloration. In the dorsal side of the tail there are 23/24 incomplete rings of two verticilles of orange/darkbrown scales, separated by one verticil conformed by one pale-orange or yellowish scale. These rings cannot be distinguished ventrally, where ground colour is dark red. Dorsal side of legs and throat folds are light grey irregularly spread with small black spots. Body flanks are light grey without black spots, but with some small orange scales. The abdominal orange-red coloration disappears in the individuals kept in alcohol; the rings still in the fixed exemplars, but the orange coloration diminish, as well as the one of the thighs ( Fig. 1 a, b; Fig. 2 a).

Morphological variation.The sample analysed comprises 7 adult males and 17 adult females. Preliminary observations allow us to establish minor morphological sex differences, being females slightly larger in body size than males. However, as expected, axilla-groin distance differs significantly between sexes, being greater in females (t = 2.6, P <0.01; range in females = 38.7–51.6 mm, mean = 47.8 mm, SD = 3.8, representing 47.1–58.7% of SVL; range in males = 36.9–46.5 mm, mean = 42.2 mm, SD = 3.0, representing 46.7–53.9 % of SVL). Other morphometric variables include head length = 14.6–18.8 mm representing 18.0–21% of SVL, head width = 13.6–15.8 mm, tail length = 81.0– 105.9 mm, representing 1.08–1.23 times of SVL. Variation in meristic traits is as follows: scales around midbody 220–240 (mean = 227.8; SD = 9.1), dorsal head scales 19–22, ventrals 158–176 (mean = 169.0; SD = 8.6), precloacal pores 7–13 (mean = 10; SD = 1.9) restricted to males, fragmented subocular scales in 3–5 (mean = 4.2; SD = 0.7), scales surrounding interparietal 6–9 (mean = 7.1; SD = 0.9), scales contacting mental 4–6 (mean = 4.2; SD = 0.5), scales between rostralinterparietal 14–17 (mean = 15.6; SD = 0.8). Further traits (means and ranges) are shown in Tables 1 and 2 . All specimens show strong ventral coloration (brick-like red).

Geographic distribution. Phymaturus agilis was found on isolated volcanic outcrops on the tableland of the type locality. More explorations in neighbouring areas are necessary in order to determine the whole species range.

Natural history. Phymaturus agilis occurs in an isolated basaltic plateau, at elevations over 1000 m. The geological history of this geographical zone has originated several similar altitudinal plateaus, where this and other lizard species tend to live relatively isolated (Scolaro 2006).

Even though the ecology of Phymaturus agilis remains largely unknown, preliminary field observations revealed remarkable information. In contrast to other Phymaturus , this lizard exhibits the ability to climb and forage on large shrubs (up to 3 m) of the species Lycium chilense and Lycium gillesianum , to feed on fresh fruits and flowers. Specimens have also been observed foraging on the herbaceous species Amsinkia calycima. This pseudoarboreal foraging behaviour has never been reported for other Phymaturus species. However, since the ecology of most of these lizards is still poorly known (almost entirely unknown in the case of some species), it remains possible that other species of this genus also climb on shrubs to forage. Regarding experimental diet, Phymaturus agilis accepts Tenebrio molitor (mealworms) when kept in captivity, as previously observed in Phymaturus zapalensis ( Boretto & Ibargüengoytía 2005) . This last observation might also suggest the incomplete available information on the ecology of Phymaturus lizards, whose diets have largely been considered almost exclusively herbivorous ( Cei 1986; Lobo & Quinteros 2005b; Scolaro 2006; Pincheira- Donoso et al. 2007). The reproduction of P. agilis is probably viviparous, as observed in all the remaining species belonging to this clade ( Lobo & Quinteros 2005b; Pincheira-Donoso et al. 2007).

This biotope is found inside the arid district of the Monte Austral, a steppe showing open ground, with gravel and effusive rocks. The dominant landscape is the barren steppe, with shrubby, low herbaceous coverage, with bare soil percentages above 50%. The dominant vegetation is composed by cushion bushes and sparse large clumps, the Floristic Physiognomy Dominion are low shrubby steppes (with Nassauvia glomerulosa “colapiche”, Chuquiraga oposittifolia “quilimbay”, Mulinum spinosum “neneo”, Senecio filaginoides “charcao”, Stillingia patagonica “ Mata loca”, Junellia spp ., Amsinkia calycina “Ortiga”, Acaena splendens “Abrojo”, Perezia spp ., Ephedra spp . “Solupe”, Fabiana patagonica, Grindelia coronensis “melosa”, Austrocactus patagonicus “cactus”), and mean shrubby-grass steppes (with Prosopis denudans “algarrobillo patagónico”, Lycium chilense “yaoyín”, Lycium gillesianum, Adesmia patagonica , A. volckmanni “Mamuel choique”, Schinus johnstonii “Molle”, and bund grasses ( Stipa papposa “coirón”, Poa ligularis “coirón poa”, Bromus catharticus ) ( Cabrera 1971).

Other reptile species coexisting with Phymaturus agilis are the iguanids Liolaemus elongatus , L. bibronii , L. rothi , Diplolaemus sexcinctus and the gekkonid Homonota darwinii . The colubrid snakes Philodryas patagoniensis and Philodryas trilineata , and the viperid Bothrops ammodytoides are also common in the same locality, representing potential predators.

Figures

FIGURE 1. (a) Adult male holotype of Phymaturus agilis in life from Terra Typica, Río Negro, dorsal view. Photo: J. A. Scolaro, 10 - 03 - 2006. (b) Adult female paratype of Phymaturus agilis in life from Terra Typica, Río Negro, dorsal view. Photo: J. A. Scolaro, 10 - 03 - 2006.

FIGURE 2. (a) Adult female paratype of Phymaturus agilis in life from Terra Typica, Río Negro, ventral view. Photo: F. O. Tappari, 11 - 10 - 2007. (b) Adult of Phymaturus agilis foraging and feeding on a Lycium gillesianum shrub. Photo: Cynthia González, 26 - 11 - 2006.

Tables

TABLE 1. Means, standard deviations (SD) and ranges of some morphological traits measured in Phymaturus agilis. Measurements in mm and scale numbers; ratios as proportions.

Variable Snout-vent length (SVL)	Males (N = 7) Mean Range 83.8 74.7– 90.1	Females (N = 17) Mean Range 86.6 79.4–93.0	Both Mean SD 85.8 4.69
Tail length (TL)	92.2 81.0–105.9	93.7 85.6–103	94.6 5.23
Axilla-groin distance (AXGD) Head length (HDL)	42.2 36.9–46.5 16.1 14.6–18.8	47.8 38.7–51.6 16.4 15.5–17.9	44.9 3.75 16.3 0.86
Head width (HDW)	14.7 13.6–15.8	14.4 13.0–15.8	14.7 0.85
Eye-nose distance (ED) Forelimb length (FLL)	5.9 5.5–6.5 28.9 27.1–30.5	5.8 5.3–6.6 29.9 29.5–32.3	5.8 0.42 29.6 1.62
Hindlimb length (HLL)	44.6 39.6–47.1	43.9 37.9–46.8	44.1 2.7
Fourth finger length (FFL) Fourth toe length (FTL)	10.2 8.8–11.1 13.7 11.1–14.7	9.8 8.1–11.1 13.6 11.9–14.8	9.9 0.83 13.6 0.96
Dorsals in Head-Length (DS)	20.8 19–22	21.2 19–22	21.1 1.07
Scales surrounding interparietal Fourth toe subdigital lamellae	7.6 6–9 22.1 20–24	6.9 6–9 22.0 18–24	7.1 0.89 22.0 1.50
Fourth finger subdigital lamellae	27.4 25–29	26.7 24–29	26.9 1.63
Supralabial scale number (SLS) Infralabial scale number (ILS)	9.0 9–10 8.3 7–9	8.2 6–10 8.2 7–9	8.4 0.92 8.2 0.58
Scales contacting mental	4.3 4–6	4.2 4–5	4.2 0.51
Subocular scales (FSS) Lorilabial rows (LS)	3.8 3–5 2.9 2–3	4.2 4–5 2.4 2–3	4.2 0.73 2.5 0.51

TABLE 2. Variation in some morphological traits between Phymaturus agilis and P. spectabilis and P. s p u rc u s.

Variables	P. agilis N Mean SD	P. excelsus N Mean SD	P. spectabilis N Mean SD	P. spurcus N Mean SD
Snout-vent length Scales around midbody	24 85.8 4.7 11 227.8 9.1	12 79.4 8.4 8 201.7 13.8	31 83.9 4.4 7 206.6 10.3	12 81.4 9.1 11 224.4 14.6
Dorsals in head-length	24 21.1 1.1	12 19.9 0.8	31 20.9 0.7	12 20.9 1.1
Ventral scales Subocular scales	11 169.0 6.6 24 4.2 0.7	8 168.8 8.4 12 3.1 1.3	7 164.8 10.4 31 2.5 0.5	11 174.2 9.7 12 4.5 0.5
Lorilabial rows	24 2.5 0.5	12 2.1 0.3	31 2.1 0.4	12 2.3 0.5
Scales contacting mental Axilla-groin distance	24 4.2 0.5 24 44.9 3.8	12 4.1 0.3 11 41.9 3.4	31 4.3 0.6 31 43.9 4.6	12 4.5 0.5 10 46.1 3.8
Precloacal pores in males	11 10.2 1.9	4 9.7 0.5	11 10.3 1.9	7 9.7 2.4