Polychrus peruvianus (Noble, 1924)

Koch, Claudia, Venegas, Pablo J., Garcia-Bravo, Antonio & Boehme, Wolfgang, 2011, A new bush anole (Iguanidae, Polychrotinae, Polychrus) from the upper Maranon basin, Peru, with a redescription of Polychrus peruvianus (Noble, 1924) and additional information on Polychrus gutturosus Berthold, 1845, ZooKeys 141, pp. 79-107 : 87-92

Polychrus peruvianus (Noble, 1924)

Polychroides peruvianus Noble, Occasional Papers of the Boston Society of Natural History, 5: 109. - Terra typica: near Querocotilla, province of Cajamarca, Peru. - 1924

Polychroides peruvianus - Burt and Burt, Transactions of the Academy of Science of St. Louis, 28: 40. - 1933

Polychrus peruvianus - Etheridge, Herpetologica, 21: 167. - 1965

Polychrus peruvianus - Gormanet al., Breviora, 316: 5. - 1969

Polychroides peruvianus - Peters and Donoso-Barros, Smithsonian Institution Press, Washington D.C. & London: 232. - 1970

Polychroides peruvianus - Peters and Donoso-Barros, Smithsonian Institution Press, Washington D.C. & London: 232. - 1986

Polychrus peruvianus - Lehr, Natur und Tier-Verlag: 203. - 2002

Polychrus peruvianus - Yánez-Muñozet al., Check List, 2 (2): 63. - 2006

Diagnosis

(Tab. 2). (1) A Polychrus with a maximum known SVL of 152 mm; (2) males larger than females; (3) a prominent dorsal and gular crest present; (4) 52 to 74 scales around midbody; (5) 56 to 70 paravertebral scales from the occipital region to the level of the posterior edge of the thigh; (6) femoral pores 6 to 13 on one side; (7) lamellae on finger IV 25-33; (8) lamellae on toe IV 32-43; (9) tail 1.29-3.15 times longer than SVL; (10) paravertebral scales unicarinate; (11) ventral scales uni- to tricarinate, rarely multicarinate; (12) gular scales oval, striated, much larger than ventrals; (13) a prominent sexual dichromatism present.

Description.

A Polychrus with a maximum SVL in males of 152 mm, in females of 147 mm. Head 0.21-0.28 times SVL, 1.37-1.84 times as long as wide and 0.69-1.08 times as wide as high. Snout bluntly pointed; canthus rostralis well pronounced. Neck narrower than the head, and slightly narrower than the anterior part of the body. Limbs well developed, forelimbs 0.46-0.57 times SVL, hindlimbs 0.58-0.69 times SVL. Tail almost round in cross section, tapering toward the tip; 1.29-3.15 times SVL.

Rostral trapezoid, striated, about two times as wide as high. Most of the individuals (18/23) lack sutures on the posterior margin of the rostral, three specimens possess one very short median suture, one specimen exhibits a median suture that half divides the rostral and another specimen exhibits two short sutures on the posterior margin. Rostral bordered posteriorly by 2-4 scales, mostly 3 (17/23). Postrostral scales striated. Scales on snout heterogeneous in size, irregularly polygonal, juxtaposed, rugose or swollen; 1-4 scales, mostly 2 (14/23) across snout between second canthals. Two striated canthals between nasal and supraciliaries (3 in one specimen: ZFMK 90829). Supraorbital semicircles distinct, with 8-12 scales, separated medially by 1 scale (Fig. 4A). Scales on supraocular region distinctly smaller than those on snout, polygonal, juxtaposed, flat, smooth or slightly striated; irregularly arranged, except for a row of smaller scales adjacent to the supraciliaries. Supraciliaries 8-12 (n=23), juxtaposed, smooth; in a continuous series with canthals. Scales on parietal region, irregular polygonal, juxtaposed, flat, smooth or slightly striated, slightly smaller than those on snout. Scales on interparietal region polygonal, juxtaposed, rugose or swollen, almost the same size as those on the parietal region. Parietal eye absent. Loreal region has one striated scale. Nostril directed laterally, in the centre of a single nasal or slightly anterior to the center. Nasal scale has polygonal margins and is in broad contact with second supralabial. 3-6 internasals. Eye diameter 0.25-0.31 (n=23) times as long as head length. Eyelids partially fused together, covered by granules of almost same size throughout the eyelids. A continuous series of 1-3 preoculars, 2-4 suboculars, which are in direct contact with supralabials, and 3-5 postoculars. Supralabials 5-10, strongly striated with 2-5 keels; followed to commissure of mouth by 2-4 slightly smaller scales. Temporal region has polygonal or rounded, juxtaposed, flat, and smooth or slightly striated scales, nearly the same size as those of parietal region; delimited dorsally by a single row of 3-5 (n=23) enlarged supratemporal scales. Ear opening, vertically oval, with smooth margin; tympanum superficial (Fig. 4B).

Mental striated, two to 2.5 times as wide as high, posteriorly notched, followed by a median sulcus that almost or at least divides the mental half. Postmentals 3-4 (n=23), striated, lateral ones larger than median scale. Infralabials 5-10, strongly striated with 3-8 keels; followed to commissure by 2-4 distinctly smaller scales. Lateral scales on chin and gular flap oval, in posterior part more or less drawn-out, imbricate, flat and strongly striated with 1-8 keels. A row of 8-14 (n=23) raised, lobe-shaped, striated scales forming a mid-chin crest and merging into a gular flap that reaches the posterior level of the forelimbs (Fig. 4C). 28-38 (n=23) gular scales in transverse line between the two tympani. In posterior part of gular fan, most of the scales are separated from each other by a narrow stripe of extensible skin covered with granules.

Scales on nape anteriorly relatively small, almost rounded, juxtaposed and convex; posteriorly grade into dorsals and merge ventrally with gulars. Middorsal crest present; in adult males it is composed of 20-28 lobe-shaped scales, reaching from behind the occiput to the level of the hindlimbs, in females or juvenile males it is composed of 7-19 lobe-shaped scales, present only on anterior part of the dorsum. Lateral dorsals are oval or slightly lanceolate and are almost the same size throughout body, imbricate, flat; unicarinate in paravertebral region; number of keels augments in direction of ventral body part.

56-70 scales in a paravertebral line between occiput and posterior margin of hindlimbs. Ventrals imbricate, distinctly more overlapping and slightly smaller than dorsals, strongly lanceolate, uni- to multicarinate; in thorax region slightly smaller, in abdominal region arranged in oblique and transverse rows. A gradual transition between dorsal, lateral and ventral scales. Scales around midbody 52-74 (n=47). Preanal pores absent. Femoral pores 6-13 (n=47) (Fig. 4E).

Tail with imbricate, rhomboid, flat, sharply keeled scales, slightly larger than dorsals; in longitudinal and oblique rows, keeles aligned longitudinally. Original tail ending more or less pointed.

Scales on forelimbs slightly smaller than dorsals, imbricate and more or less lanceolate, uni- to tricarinate. Scales on hindlimbs slightly smaller than dorsals, imbricate and more or less lanceolate, unicarinate on dorsal surface and uni- to tricarinate on ventral surface. Subdigital lamellae of fingers and toes single, short, multicarinate, 25-33 (n=47) under fourth finger, 32-43 (n=47) under fourth toe (Fig. 4D).

In life, when unstressed, the dorsal ground colouration of males (Fig. 5A) and females (Fig. 5C), is lime green on body, limbs and tail. Back and tail with dark blotches that are at least as broad as the green interspaces, with the first blotch beginning directly behind the head in females, or adjacent to a small white nuchal crossline in most males. Most specimens possess 5 of such saddle blotches on the dorsum, which are broadest in the vertebral region and decrease in width on the flanks. Blotches are more distinct in males, and are rarely found, or even absent, in females, and normally intermixed with scales of green ground colour. Additionally, some specimens possess white or pinkish and/or turquoise scales or small blotches on the lateral body parts (Fig. 5E). Head in females dorsally, laterally and ventrally lime green; in males dorsally and laterally brownish or orange brown and in some individuals spotted with white, ventrally lighter brown or yellowish, sometimes almost whitish. Scales of gular crest are white in most specimens of both sexes and extensible skin of exposed gular sac is orange, yellowish or pinkish (Fig. 5A). Females mostly with an oblique white line on both sides from behind the eye to the insertion of the forelimbs and with a straight line, about 3 to 4 scales in width, laterally between the axilla and the insertion of the hindlimbs. Venter of both sexes, lime green without special markings.

Under stress, colouration of body, limbs and tail changes into a dark brown in both sexes (Fig. 5B, D), in which case the dark saddle blotches become less evident. If the animal possesses white markings, these become even more prominent. Head colouration of females (Fig. 5D) changes into dark brown, but remains as in the unstressed mood in males (Fig. 5B).

In preservative, dorsal pattern remains similar to the pattern in life but colouration changes into bluish or brownish. Heads of males are dorsally and laterally brownish, and ventrally cream colour or whitish. Venter of both sexes pale blue, green or brown.

Distribution and natural history.

In Peru, this species is distributed in the regions of Amazonas, Cajamarca, and Piura in the drainage basins of Río Huancabamba, Río Utcubamba and Río Marañón ( Schlüter 2010, Noble 1924, Gorman et al. 1969, Peters and Donoso-Barros 1970, Carrillo and Icochea 1995). Yánez-Muñoz et al. (2006) collected a male specimen from Pucabamba (04°57'01"S, 79°10'30"W, 1400 m a.s.l.), Province of Zamora-Chinchipe, and hence provided the first country record from Ecuador. Polychrus peruvianus inhabits the equatorial dry forest eco-region fide Brack (1986), but is also occasionally found in humid forests, at elevations of 600 to 1750 m a.s.l. ( Duellman 1979; Gorman et al. 1969; Noble 1924). We found the species at an elevation of 400 to 1330 m above sea level. Besides the few specimens we collected for preservation, we found many more animals of the same species in each sampled area and noted additional observations we could make. All lizards were exclusively found on trees or shrubs (preferred plant species: Acacia macracantha , Acacia riparia , Hura crepitans , Mutingia calabura , Sapindus riparium , Schinus molle , Solanum riparium ) alongside roads, paths, or small streams in heights between 1.5 m and 7 m above the ground. Hence the species can be considered as being highly arboreal. Only some specimens were found during the day (investigation hours: 9.30 a.m. to 4 p.m.) as they are perfectly camouflaged in the vegetation and difficult to detect between the green leaves. Daytime temperatures, when animals were found, were between 28.7°C and 35.9°C and humidity was between 41% and 63%. Most specimens were discovered after nightfall (investigation hours: 7 p.m. to 2 a.m.), when they were sleeping on branches and their bellies were shining brightly in the light of the headlamps. Nighttime temperatures were between 20.8°C and 28.3°C and humidity was between 53% and 75%. In Pucará, one individual could be observed at around 10 a.m., while it was eating little fruits of the tree Trema micrantha . Several times we found two, sometimes even three, specimens sleeping on the same tree. In Pucará, the species seemed to be very abundant and in one night we counted 24 adult and 3 juvenile specimens on 22 trees along a two kilometer long path section. One male and one female were found about only 0.5 m away from each other. This represents the encounter with the lowermost distance between two individuals. Other individuals were found with a distance of at least 1-2 m to the next conspecific, irrespective of sex. Although it seems that members of this species have small activity ranges, they live solitarily. Adult males exhibit a pronounced territorial behaviour and do not tolerate other males close to their branches. Under artificial conditions, a male being confronted with another male or even with its own mirror image, opened its mouth widely and extended its gular flap. Efforts to keep two males together in a cage of 3 × 2 m floor space and 2 m in height started with a non-ritualized damaging fight which lasted for around 10 minutes. After the fight the bigger male persecuted the other male in the cage and two days later the smaller male was found dead.

When discovered in a tree, the animals first react similarly as a chameleon: they compress their body laterally and try with very slow movements to take cover behind a stick or branch. Once grabbed, they expand their gular fan, open their mouth widely and try to bite the captor while they try, simultaneously, to free their bodies with strong twisting and turning movements. Similar observations were also made by Gorman et al. (1969) for Polychrus peruvianus and by Vanzolini (1983) for the genus Polychrus in general. In addition, we could observe a change in colouration in most captured animals to the above described stress colouration.

One gravid female (ZFMK 90822) was found in April 2009 at 10.35 p.m. sleeping in a tree at about 2.5 m above the ground, with an air temperature of 24.9°C and a humidity of 73%. It contained 5 oval eggs, 3 in the left and 2 in the right oviduct. In average these eggs had a length of 27.5 mm and a width of 16.2 mm. In December 2009, we collected 4 gravid females (ZFMK 90824, 90827, 90829, 90830) in different stages of gestation between 8-10.30 p.m. sleeping on trees in 2-5.5 m above the ground. Air temperature was between 25.5° C– 28°C and humidity was between 55-75%. ZFMK 90824 contained 10 almost spherical eggs with a diameter of 12 mm, of which 7 were positioned in the left and 3 in the right ovary. ZFMK 90827 contained 7 almost spherical eggs with a diameter of 6 mm of which 3 were positioned in the left and 4 in the right ovary. ZFMK 90829 contained 7 almost spherical eggs with a diameter of 8.9 mm of which 4 were positioned in the left and 3 in the right ovary. ZFMK 90830 contained 4 almost spherical eggs with a diameter of 9.4 mm, 2 were positioned in each of the ovaries.