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Higher TaxaGymnophthalmidae (Cercosaurinae), Sauria, Gymnophthalmoidea, Squamata (lizards)
Common Names 
SynonymKataphraktosaurus ungerhamiltoni ROJAS-RUNJAIC, BARRIO-AMORÓS, SEÑARIS, RIVA & CASTROVIEJO-FISHER 2021 
DistributionVenezuela (Amazonas)

Type locality: Caño Bejuco, near Tobogán del Cuao, Autana municipality, Amazonas state, Venezuela (5°05’58”N, 67°29’54”W; elevation 124 m)  
TypesHolotype: MHNLS 19960 (field number AJC 3014), adult male, collected on 14 July 2010 
DiagnosisDiagnosis: Kataphraktosaurus ungerhamiltoni is defined by the unique combination of the following characteristics: (1) small body size (49 mm SVL; female unknown); (2) dorsal surface of head with large, weakly keeled, symmetrical scales; (3) snout acuminate, moderately long; (4) two subtriangular internasals, each one as long as wide; (5) two large pentagonal frontonasals, more than two times longer than wide; (6) prefrontals absent; (7) frontal scale single, hexagonal, double-keeled; (8) two pentagonal frontoparietals, single-keeled; (9) interparietal large, subpentagonal, well-differentiated; (10) parietals large, polygonal, paired, flanking interparietal; (11) occipitals not differentiated; (12) temporal scales not differentiated; (13) lower eyelid developed, with palpebral disc divided into 5–7 unpigmented scales; (14) six supralabials; (15) six infralabials; (16) postmental absent; (17) three pairs of enlarged chin shields; (18) collar distinct, containing six enlarged scales; (19) dorsal scales heterogeneous, with large, longitudinally keeled scales intercalated by small irregular, granular to flat scales; (20) paravertebral rows of enlarged scales continuous; (21) ventral scales pentagonal, keeled, mucronate, imbricated; (22) ventral scales arranged in 20 transverse and eight longitudinal rows; (23) femoral pores inserted in a clump of 4–5 scales; (24) six femoral pores (three on each side) in males (female unknown); (25) tail slightly compressed; (26) tail with six pairs of longitudinal ridges around it (two dorsal submedian, two dorsolateral, two median laterals, two lower lateral, two ventrolateral, and two ventral submedian); (27) two subcaudal scales by verticil; (28) three keeled scales on the dorsal submedian ridge by verticil; (29) forelimbs and hind limbs pentadactyl; (30) subdigital lamellae on fourth finger 15–16; (31) subdigital lamellae on fourth toe 21–22 (32) digits clawed; (Rojas-Runjaic et al. 2021).

Kataphraktosaurus ungerhamiltoni is the unique representative of its genus. It can be readily distinguished from all the cercosaurine species with heterogeneous dorsal scalation (those in Centrosaura, Echinosaura, Gelanesaurus, Magdalenasaura, Neusticurus, and Potamites) by lacking a postmental scale (present in all the species of these genera, except in E. brachycephala, where it can be absent or reduced); having pentagonal, mucronate, strongly keeled, imbricate ventral scales (squared or rounded squares, usually flat, and not imbricated; only keeled in E. brachycephala, E. centralis, and E. horrida); and six femoral pores (total count) in males (≥ 6 in Echinosaura, ≥ 10 in Potamites, ≥ 20 in Centrosaura and Magdalenasaura, and > 30 in Gelanesaurus and Neusticurus). In addition, Kataphraktosaurus ungerhamiltoni differs from Centrosaura apodema by having symmetrical paired intersanals (not paired and asymmetrical), paired frontonasals (several small irregular scales in the frontonasal region), prefrontals absent (paired), a single frontal (divided), and femoral pores inserted in a clump of scales (in the center of a single scale). From the species in Echinosaura, it differs by its smaller SVL (adult male 49 mm vs. > 70 mm in Echinosaura) and by having large and well-defined interparietal and parietals (several irregular and small scales on the parietal region), three pairs of chin shields (usually one pair), two ventral scales per tail verticil (three or more scales), and femoral pores inserted in a clump of scales (in the center of a single scale). From the two species of Gelanesaurus by having homogeneous brown coloration around the nostril (a conspicuous blackish spot surrounding nostril), two continuous longitudinal ridges on dorsum (four), heterogeneous scales on the flanks of the body, with enlarged keeled scales (scales homogeneous, not tuberculated), gular scales keeled and juxtaposed (smooth and imbricated), and tail scales arranged in verticils (not arranged in verticils). From the two species of Magdalenasaura, it differs by having weakly keeled and wrinkled dorsal scales on head (smooth), small asymmetrical occipitals (large, paired, and symmetrical), enlarged strongly keeled dorsal scales (smooth to weakly keeled, not tuberculated), gular scales keeled and juxtaposed (smooth and imbricated), and femoral pores inserted in a clump of scales (in the center

of a single scale). From the species of Neusticurus, it can be distinguished by lacking prefrontals (present) and having paired internasals (absent) and a slightly compressed tail (strongly compressed). From the species of Potamites, it differs by lacking prefrontals (present), having internasals (absent), palpebral disc divided into several scales (undivided), and by its acuminate and moderately long snout (blunt and short snout). Kataphraktosaurus ungerhamiltoni shares with Rheosaurus sulcarostrum the absence of postmental scale and the presence of strongly keeled ventral and subcaudal scales. However, it can be readily distinguished from the later by lacking prefrontal scales (present) and by having: a pair of frontonasals (three); small, irregular and not differentiated occipitals (large and symmetrical); rostral and mental scales smooth (grooved); six infralabials (four); supra and infralabials smooth (supralabials keeled and infralabials with central striation); two continuous longitudinal ridges on dorsum (four); cloacal plate with four large smooth scales (six, keeled); six femoral pores in adult males (14–15 femoral pores); and femoral pores inserted in a clump of 4–5 scales (in clumps of 3–4 scales) (Rojas-Runjaic et al. 2021).

Color in life: Dorsal background reddish-brown, with some poorly defined, irregular, dark brown, and light brown blotches. Head with a well-defined light brown interocular stripe, finely bordered with dark brown. An ill-defined light brown dorsolateral stripe on each side extending from the posterodorsal corner of the eye to the neck. Supra and infralabial scales darker, with four–five pale vertical stripes; the most posterior the largest, dorsally reaching the eye and ventrally the geneials. Palpebral disc translucent. Iris copper. Ventrally, with some small irregular white spots on the geneials and an irregular ocher spot medially extending from the gular region to the chest; rest of the gular region dark brown. Chest, belly, undersurface of forearms, cloacal plate and anterior portion of tail dirty ocher; ventral surface of thighs and shanks variegate, with pale ocher and dark brown. First and second digits of hands and feet pale yellow. Palms and soles grayish brown (Rojas-Runjaic et al. 2021). 
EtymologyThis species is named in honor of Mr. Felix Unger-Hamilton, in recognition of his support and interest in the study and conservation of Venezuelan biodiversity and the description of new species. 
  • ROJAS-RUNJAIC, FERNANDO J.M.; CÉSAR L. BARRIO-AMORÓS, J. CELSA SEÑARIS, IGNACIO DE LA RIVA, SANTIAGO CASTROVIEJO-FISHER 2021. Discovery of an additional piece of the large gymnophthalmid puzzle: a new genus and species of stream spiny lizard (Squamata: Gymnophthalmidae: Cercosaurinae) from the western Guiana Shield in Venezuela. Zootaxa 4950 (2): 296-320 - get paper here
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