The Horned Agamas are easily distinguished from other agamid species by the appendage projecting from the rostral on their snout. All five (until recently only three) species are endemic to Sri Lanka, where they are found in moist montane forests. Other characteristics include irregular dorsal scales and the absence of a tympanum, gular pouch and dorsal crest.
In terms of behaviour these agamids are found lower down on tree trunks or on the ground. They feed mainly on worms and smaller insects. Manthey and Schuster consider them difficult captives because of their need for quiet and a stress-free environment: for that reason they are best left to specialists with experience.
A note is order on the "new" species, C. erdelen and C. karu. As I have not had the opportunity to read the paper by Pethiyagoda and Manamendra-Arachchi I am not certain how the new species were defined: however, it may be significant that in his 1955 paper Taylor listed some variants of C. stoddartii. See the Bibliography for details.
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|C. aspera, Scaly-Horned Agama||C. erdelen||C. karu|
|C. stoddartii, Mountain Horned Agama||C. tennentii, Leaf-Horned Agama|| |
|Species Name||Common Name||Distribution||Size||Notes|
|C. aspera||Scaly-Horn Agama, Sri Lankan Horned Agama||Sri Lanka||TL 82 mm, SVL 37mm||This species is found in pairs in montaine rainforest, living on low branches or in the leaf litter. It moves much quicker compared to C. stoddartii and C. tennentii. Scalation details: head scales small and irregular, each forming a small tubercle; larger tubercle behind superciliary edge; back of head has pair of low ridges that converge anteriorly; rostral projection slender, covered with small imbricating scales, all keeled, and length of head in males but rudimentary in females. Gular scales small and strongly keeled. Dorsal scalation: dorsal and lateral scales small with larger, irregular keeled scales interspersed; no dorsal or nuchal crests; some of the larger scales form transverse rows across the vertebral line with angles pointing posteriorly. Ventral scalation: ventral scales keeled. Tail: not compressed, all scales keeled. Other: preanal region has small scales. Coloration: brownish with darker marbling; rhombic light spot on rump; brown spots on arms which in males are edged with white. Reproduction: 2 eggs are laid.|
|C. erdelen|| ||Sri Lanka||?||Rostral appendage rudimentary or non-existent: otherwise similar to C. stoddartii. See EMBL database entry.|
|C. karu|| ||Sri Lanka||?||Faster than the other members of the genus and terrestrial, but lacks their fleshy protuberance: see EMBL database entry.|
|C. stoddartii||Mountain Horned Agama, Tusk-Horned Agama||Sri Lanka (central highlands)||SVL 8 cm, TL 24 cm||See also notes in Introduction on C. erdelen and C. karu. This species is also found in home gardens, but its usual altitudes are 1500-2100m. Everything about this agamid seems to be slow, including its eating, movements and mating. Scalation details: rostral appendage conical and sharply pointed, with base surrounded by a median pair of supralabials (or possibly a paired rostral - see Taylor) and 5 other small scales; nasals somewhat depressed and separated from each other by 6 scales; 4 canthal scales, canthus rather rounded; pair of low pyramidal scales in frontal region; supraoculars irregular, largest of the inner row benig separated from its fellow by 3 small scale rows; last 4 scales of inner row pass behind the eye; pair of knobs or bosses in parietal region, covered by a few large scales and separated from each other by approx. 7 scales and with a transverse row of slightly elevated scales in front of them; 2 large prominent elevated scales in temporal region above the tympanum; row of 3 large elevated contiguous scales behind the eye; 14 supralabials; 13 infralabials; group of larger scales on the edge of the upper eyelid, of which the largest 3-4 border the edge; mental small, separating the first postmentals; scales on chin quadrangular and forming definte rows. Dorsal scalation: scales on body very irregular; small nuchal crest begins behind occiptal bosses and continues to near level of arm insertion; no dorsal crest; transverse rows of larger scales somewhat larger than scales in between. Ventral scalation: all ventral scales on chin and body are smooth; scales on venter small, more or less regular, smooth. Tail: somewhat compressed, whorls indistinct and bordered posteriorly by large irregular scales; scales above and below keeled. Other: scales on limbs very unequal, a few keeled; scales above arm largest, forming a curving row; 4th toe much larger than 3rd.. Coloration (in preservative): blackish with series of 6 indistinct dorsal grey lines on larger scales; arms and legs barred with black and ultramarine; tail dimly barred with olive and grey; labials, chin, throat and area around angles of jaws whitish; ventrally olive with scattered grey flecks; larger lateral scales ultramarine. Reproduction: mating does not include biting by the male. Up to 4 eggs are laid.|
|C. tennentii||Leaf-Horned Agama, Rhinoceros Agama||Sri Lanka (Knuckles Mountains)||TL 26 cm, SVL 9cm||This species is found at altitudes of 900-1200m. It is sluggish in the same way as C. stoddartii but faster when attempting to capture prey. Scalation details: head scales small and irregular; ridge on each side of occiput; rostral appendage large in both sexes, fleshy, compressed, suboval and covered in scales and granules. 9 supralabials; 9-10 infralabials. Gular scales large, weakly keeled and quadrangular, forming regular longitudinal rows. Dorsal scalation: low toothed nuchal crest; scales on dorsum irregular and unequally sized, larger ones feebly keeled; lateral sales equal, large, strongly imbricated and pointing upwards and backwards; smooth or feebly keeled. Ventral scalation: ventral scales smaller. Tail: slightly compressed, scales keeled. Coloration: dorsally olive, irregularly marbled with brown; young have angular crossband between the eyes; sometimes white longitudinal lines are present; more or less distinct white line along hind side of thighs.|
Those wishing to find out more details on the two newer species of Ceratophora (C. erdelen and C. karu) are directed to A revision of the endemic Sri Lankan agamid lizard genus Ceratophora Gray, 1835, with description of two new species, Pethiyagoda, R. & K. Manamendra-Arachchi 1998, Journal of South Asian natural History 3 (1):1. I have not as yet read this work myself.