Enyalioides palpebralis (Boulenger 1883)

Proposed standard English name: horned woodlizards

Proposed standard Spanish name: lagartijas de palo cornudas

Enyalius palpebralis Boulenger (1883:46). Holotype: BMNH 81.5.13.25 (RR 1946.8.9.8), from “Cashiboya [Departamento Loreto, 7°32'60''S, 74°52'60''W, 160 m], eastern Peru.”

Enyalioides palpebralis Boulenger (1885:116); Burt & Burt (1933:24); Peters & Donoso-Barros (1970:115).

Diagnosis. This species is different from other species of Enyalioides in having a superciliary triangular flap projecting posterolaterally over each eye; a wide postorbital process of the squamosal (process narrow in other species); a pair of enlarged dorsal tubercles on the posterolateral aspect of the parietal roof; and in lacking a posteriorly projecting squamosal process of the postorbital (Fig. 8; Wiens & Etheridge 2003). In addition most specimens of E. palpebralis have a discontinuous vertebral crest, with a small gap on the neck, and most lack femoral pores.

Description. (1) dorsal head scales conical or multicarinate, strongly projecting dorsally; (2) posterior superciliaries enlarged, pointed, and projecting laterally; (3) scales on lateral edge of skull roof just posterior to superciliaries strongly projecting; the projection is more pronounced in adults; (4) one or two enlarged pretympanic scales present; (5) gular scales conical or multicarinate, strongly projecting ventrally; (6) dorsal and lateral neck scales heterogeneous in size, granular and conical scales of various sizes present; (7) vertebrals larger than adjacent dorsals, forming distinct raised middorsal crest that usually (85.9%) extends onto tail as a pair of crests; (8) nuchal region with discontinuous (85.7%) and single middorsal crest; (9) dorsals usually (71.4%) keeled and heterogeneous in size (85.7%); (10) discontinuous longitudinal row of large conical scales between dorsals and flank scales present; (11) scales on flanks keeled or smooth, heterogeneous in size; largest scales are conical in some specimens; (12) ventrals keeled; (13) fore limb scales mostly keeled dorsally and ventrally; (14) hind limb scales mostly keeled dorsally and ventrally; scattered enlarged scales present dorsally; dorsal scales of pes homogeneous in size; (15) caudals heterogeneous, slightly increasing in size posteriorly on each segment (4–6 scales in lateral view), not modified as conspicuous spines (Fig. 3); (16) tail compressed laterally. Meristic and morphometric characters are presented in Table 1.

Coloration in life (Fig. 4). Dorsal background yellowish brown, dark brown, or greenish beige, with tan spots (males) or black marks forming reticulate bands; neck and shoulders with scattered dark brown spots; orange or red blotch on each side of neck in both sexes usually present; elongate tan blotch or irregular stripe extends from the dorsolateral surface of the head to a point dorsal to the insertion of the arm in females; flanks with reddish-brown reticulate pattern on greenish-gray background; venter white, whitish brown, or beige, with irregular black markings in juveniles; throat yellow in males and brownish in females; iris reddish tan (Meede 1984; Reichle et al. 2004; Duellman 2005); lining of mouth orange (Fig.4).

Natural history. Based on observations of specimens in captivity, Schulte (1998) described fights between males in which one combatant bites the other’s superciliary flap or nuchal crest and shakes it strongly; a male will also bite and hold a female by her nuchal crests during copulation. Clutch consists of 2– 4 eggs (ca. 24–28 X 12 –18 mm), which are laid under leaf-litter (Meede 1984; Schulte 1998). This species is a sit-and-wait predator, and it has been found in leaf-litter or perching on the bases of tree trunks (no higher than 1.7 m) in primary terra firme forest and primary forest edges, sometimes close to water (Avila-Pires 1995; Schulte 1998). Prey items of Enyalioides palpebralis include caterpillars, spiders, aquatic dipteran larvae, diplopods, chilopods, beetle larvae, grasshoppers, and ants (Meede 1984; Reichle et al. 2004).

Distribution. Enyalioides palpebralis occurs on the eastern slopes of the Andes and adjacent lowlands in Peru, northern Bolivia, and western Brazil at elevations between 100–1300 m (Fig. 9). This species is known to occur in sympatry with E. laticeps in southern Peru (Duellman 2005) and western Brazil (Avila-Pires 1995).

Remarks. Enyalioides palpebralis has been regarded as the only hoplocercine lacking femoral pores (Boulenger 1885; Avila-Pires 1995). Nonetheless, out of the 20 specimens examined, we found an adult male (AMNH 56401, SVL = 79 mm) from departamento Loreto in Peru that had one femoral pore on each side. Examined specimens of all other species of Enyalioides have at least one femoral pore on each leg except for E. laticeps, in which a few specimens also lack femoral pores (Table 1). Specimens of Hoplocercus and Morunasaurus have 2–5 femoral pores on each leg.