Riama, 2005

Doan, Tiffany M. & Castoe, Todd A., 2005, Phylogenetic taxonomy of the Cercosaurini (Squamata: Gymnophthalmidae), with new genera for species of Neusticurus and Proctoporus, Zoological Journal of the Linnean Society 143 (3), pp. 405-416 : 411-412

RIAMA GRAY COMB. NOV.

Type species: Riama unicolor Gray, 1858: 446 .

Definition: Tongue with imbricate, scalelike papillae. Head scales smooth without striations or rugosities: single frontonasal, frontal, and interparietal; paired frontoparietals and parietals; prefrontals absent; nostril pierced in a single nasal; nasals not in contact. Eyelids developed, lower with a translucent disc divided into several scales. Posterior gulars squarish. Limbs pentadactyl; digits clawed. Dorsal scales quadrangular or hexagonal, elongate, smooth, striate, rugose, or keeled, juxtaposed, forming transverse series only. Ventrals large, smooth, quadrangular, juxtaposed, forming regular longitudinal and transverse series. Femoral pores usually present in males and females; preanal pores present or absent in males or females. Tail cylindrical.

Diagnosis: Riama differs from members of Alopoglossinae by having its tongue covered in imbricate, scale-like papillae instead of oblique plicae ( Harris, 1994), from Gymnophthalminae by having moveable eyelids, from Rhachisaurinae by having external ear openings, and from Ecpelopinae by lacking prefrontal scales. Within Cercosaurinae (sensu Castoe et al., 2004) , Riama differs from all genera except Pholidobolus , Proctoporus , and Petracola by lacking prefrontal scales. It differs from Proctoporus by having a divided palpebral disc, from Pholidobolus by lacking two medial rows of widened gulars, and from Petracola by lacking the combination of smooth dorsal scales and femoral pores per hind limb in both sexes less than six (exclusive of preanal pores).

KEY TO THE SPECIES OF NEUSTICURUS DUMÉRIL & BIBRON

1a. Single frontonasal...............................................................................2

1b. Paired frontonasals..............................................................................4

2a. Uniformly small dorsal scales.....................................................................3

2b. Heterogeneous dorsal scales: large keeled scales intermixed with small flat scales.................... N. rudis

3a. Deeply recessed tympanum............................................................... N. medemi

3b. Slightly recessed tympanum................................................................. N. tatei

4a. Dorsal scales in longitudinal rows only................................................... N. bicarinatus

4b. Dorsal scales in transverse and oblique rows only............................................. N. racenisi

KEY TO THE SPECIES OF PETRACOLA GEN. NOV.

1a. Three supraoculars, supralabial-subocular fusion absent................................ P. ventrimaculatus

1b. Four supraoculars, supralabial-subocular fusion present.................................... P. labioocularis

Content: Riama includes 24 species ( Table 1 ).

Distribution: Riama occurs throughout the Andes of central Peru, Ecuador, Colombia, and Venezuela, the Cordillera de la Costa of Venezuela, and the northern range of the island of Trinidad.

Remarks: Gray’s (1858) description of Riama included some erroneous characters, such as a lateral longitudinal fold that he used as evidence to state that the genus was related to amphisbaenians and Bachia . Although we have not been able to examine the type specimen of this genus, it appears from his detailed drawing that the type specimen was average and did not actually have a lateral fold, but a very thin row of reduced lateral scales. Preservation of a specimen that had not recently eaten or had been dehydrated before or after fixation may have led to the overlapping of dorsal and ventral scales, producing what appeared to be a lateral fold.