Wednesday, June 24, 2015

[Herpetology • 2015] Riolama inopinata • A New Species of the Pantepui endemic Genus Riolama (Squamata: Gymnophthalmidae) from the summit of Murisipán-tepui, with the Erection of A New Gymnophthalmid Subfamily


Riolama inopinata Kok, 2015
Figure 3. Riolama inopinata sp. nov. A
, IRSNB 2679, male holotype in life. B, IRSNB 2680, male paratype in life. C, ventral view of the anaesthetized holotype (grid squares = 5 mm). D, lake on the summit of Murisipán-tepui, showing the macrohabitat of the new species (18 June 2012)

The gymnophthalmid lizard Riolama inopinata sp. nov. is described from the summit of Murisipán-tepui, Bolívar State, Venezuela. The new species is characterized by its small size, slender body, short neck, chestnut brown dorsum with two conspicuous orange-brown dorsolateral stripes, 30 or 31 mid-dorsal scales, and 18 or 19 ventral scales in transverse rows, 28 scales around midbody, seven supralabials, five or six infralabials, subdigital lamellae divided in small granular scales, ten or 11 small femoral pores in males, dorsal surface of tongue covered with oblique chevron-shaped plicae interrupted by a small midsection of imbricate scale-like papillae, and a small weakly bilobed hemipenis having the sulcus spermaticus flanked by an extensive nude area on each side, and the asulcate and lateral faces of the organ with short series of small roughly equidistant, feebly developed flounces, each bearing a single medial hook-shaped spine. Molecular phylogenetic analyses based on one nuclear and two mitochondrial DNA genes confirm the allocation of the new species to the genus Riolama, but do not support the assignation of Riolama to the subfamily Cercosaurinae as previously suggested based on overall morphological similarities, nor to any other known subfamily of the Gymnophthalmidae. Therefore, a new subfamily, the Riolaminae, is proposed to accommodate the genus. 

Keywords: endemism; Guiana Shield; hemipenes; microteiid; molecular phylogeny; Riolaminae; tepuis


Figure 1. A, map of the Pantepui region, showing the distribution of Riolama species. The white rectangle corresponds to the area enlarged in (B). B, distribution of known Riolama species occurring east to the Rio Caroní (blue lines) in Venezuela and western Guyana. The white rectangle corresponds to the area enlarged in Figure 2A.

Figure 2. A, detailed satellite map of the Los Testigos Massif showing the type locality of Riolama inopinata sp. nov. (blue star) and neighbouring mountains. B, aerial photograph of Murisipán-tepui and neighbouring mountains, taken from the north.
Photograph: C. Brewer-Carías. Satellite maps, ©Google Maps.  DOI: 10.1111/zoj.12241

Lake on the summit of Murisipán-tepui, showing the macrohabitat of Riolama inopinata sp. nov.  (18 June 2012)

Figure 3. Riolama inopinata sp. nov. A, IRSNB 2679, male holotype in life. B, IRSNB 2680, male paratype in life. C, ventral view of the anaesthetized holotype (grid squares = 5 mm). D, lake on the summit of Murisipán-tepui, showing the macrohabitat of the new species (18 June 2012). Photographs by the author.

Systematic account

Order Squamata
Suborder Sauria

Family Gymnophthalmidae
Riolama inopinata sp. nov.


Holotype: IRSNB 2679 (field number PK 3660, Fig. 3A, C), a male collected by Philippe J. R. Kok, 19 June 2012 at 11:00 h, summit of Murisipán-tepui, Bolívar State, Venezuela (5°52′08″N, 62°04′28″W; 2400 m a.s.l.).

Paratype: One male (IRSNB 2680, field number PK 3558, Fig. 3B) collected by Philippe J. R. Kok, 19 June 2012 at 08:45 h, summit of Murisipán-tepui, Bolívar State, Venezuela (5°52′10″N, 62°04′31″W; 2413 m a.s.l.).

Etymology: The specific name, meaning ‘unexpected’ in Latin, is considered a noun in apposition and refers to the unforeseen discovery of a Riolama species on a tepui from the Los Testigos Massif.





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Riolaminae subf. nov.
Content: Riolama Uzzell, 1973.

Diagnosis
(1) Head scales without striations or rugosities; (2) single frontonasal and frontal; (3) dorsal scales hexagonal, uniformly keeled; (4) tympanum heavily pigmented and feebly recessed; (5) digits depressed with swollen tips; (6) absence of claw on the first finger; (7) oblique plicae rather than papillae on the anterior and posterior surfaces of tongue; (8) hemipenis weakly bilobed, sulcus spermaticus flanked by an extensive nude area on each side, asulcate and lateral faces of organ with short series of small roughly equidistant feebly developed flounces, each bearing a single medial hook-shaped spine.


Philippe J. R. Kok. 2015. A New Species of the Pantepui endemic Genus Riolama (Squamata: Gymnophthalmidae) from the summit of Murisipán-tepui, with the Erection of A New Gymnophthalmid Subfamily. Zoological Journal of the Linnean Society. 174(3); 500–518. DOI: 10.1111/zoj.12241

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