Thursday, April 1, 2021

[Herpetology • 2021] Kataphraktosaurus ungerhamiltoniDiscovery of An Additional Piece of the Large Gymnophthalmid Puzzle: A New Genus and Species of Stream Spiny Lizard (Gymnophthalmidae: Cercosaurinae) from the western Guiana Shield in Venezuela

Kataphraktosaurus ungerhamiltoni 
Rojas-Runjaic, Barrio Amorós, Señaris, De la Riva & Castroviejo-Fisher, 2021

Gymnophthalmids are a highly diverse group of Neotropical lizards and its species richness is still in process of discovery. The incorporation of molecular evidence and a noticeable increase in taxon and geographic sampling in systematic studies has led to the description of numerous new genera and species of gymnophthalmids (particularly in Cercosaurinae) in recent years. Herein we describe a new genus and species of cercosaurine lizard with crocodile-like morphology, from the Venezuelan Guiana Shield on the basis of molecular phylogenetic and morphological evidence. Kataphraktosaurus gen. nov. can be readily distinguished from all other genera of Cercosaurinae by a unique combination of morphological characters that includes heterogeneous dorsal scalation with enlarged and strongly keeled scales forming two paravertebral rows, ventral and subcaudal scales imbricated and strongly keeled, large and symmetrical cephalic scales, absence of postmental scale, palpebral disc translucent and divided, tail slightly compressed, all digits clawed, and only six femoral pores (three at each hindlimb) inserted in a clump of small scales. This genus is described as monotypic and only contains Kataphraktosaurus ungerhamiltoni sp. nov., which is known from one specimen and diagnosed by the same set of aforementioned characters. The secretive habits of this species and the remoteness of the locality may explain its singleton situation. Following the International Union for Conservation of Nature’s criteria, we categorized the new species as Data Deficient.

Keywords: Reptilia, Amazonia, biodiversity, Neotropics, Orinoco basin, phylogeny, reptile, systematics, taxonomy

FIGURE 7. Male holotype of Kataphraktosaurus ungerhamiltoni gen. nov., sp. nov. (MHNLS 19960) in life
 (a). Western slope of Serranía del Cuao seen from the Cuao River (b) and Tobogán del Cuao in Caño Bejuco (c), Amazonas state, Venezuela. Photos: F.J.M. Rojas-Runjaic.

Kataphraktosaurus ungerhamiltoni sp. nov.

FIGURE 1. Map of Venezuela indicating the geographic position of Caño Bejuco (yellow pentagon), near Tobogán del Cuao, Autana municipality, Amazonas state, Venezuela, type locality of Kataphraktosaurus ungerhamiltoni gen. nov., sp. nov.

FIGURE 3. Some Cercosaurinae lizards with crocodile-like morphology:
(a) Centrosaura apodema, from La Alfombra, Pérez Zeledón, Costa Rica; (b) Echinosaura brachycephala, from Mindo, Pichincha, Ecuador;
(c) Echinosaura horrida, from Puerto Quito, Pichincha, Ecuador; (d) Gelanesaurus flavogularis, from Archidona, Napo, Ecuador;
(e) Neusticurus arekuna, from Chivatón, Bolívar, Venezuela; (f) Neusticurus medemi, from Las Pavas, Amazonas, Venezuela;
(g) Potamites ecpleopus, from Juami river, Amazonas, Brazil; (h) Potamites erythrocularis, from Inambari, Madre de Dios, Peru.
Photos: C.L. Barrio-Amorós (a–f), F.J.M. Rojas-Runjaic (g), and G. Chávez (h).

Fernando J.M. Rojas-Runjaic, César L. Barrio Amorós, J. Celsa Señaris, Ignacio De la Riva and 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.