Memoria de la Fundación La Salle de Ciencias Naturales 2007 (“2006”), 166: 7-27 A revision of the South American snake genus Thamnodynastes Wagler, 1830 (Serpentes: Colubridae, Tachymenini). II. Three new species from northern South America, with further descriptions of Thamnodynastes gambotensis Pérez-Santos and Moreno and Thamnodynastes ramonriveroi Manzanilla and Sánchez †Joseph R. Bailey and Robert A. Thomas Abstract. Three new species of the snake genus Thamnodynastes are described from northern South America: T. ceibae from the Lake Maracaibo Basin of Venezuela, T. dixoni from the Llanos of Colombia and Venezuela, and T. paraguanae from the coastal areas of the Guajira Peninsula of Colombia from the northern Lake Maracaibo Basin and Paraguaná Peninsula of Venezuela. Further descriptions are provided for T. gambotensis and the recently described T. ramonriveroi. Key words. Serpentes. Colubridae. Xenodontinae. Tachymenini. Thamnodynastes. Revisión de las serpientes suramericanas del género Thamnodynastes Wagler 1830 (Serpentes: Colubridae, Tachymenini). II. Tres nuevas especies del norte de Suramérica, con descripciones adicionales de Thamnodynastes gambotensis Pérez-Santos y Thamnodynastes ramonriveroi Manzanilla y Sánchez Resumen. Se describen tres especies del género Thamnodynastes del norte de Suramérica: Thamnodynastes ceibae proveniente del sur de la hoya del lago de Maracaibo, T. dixoni de la región llanera de Venezuela y Colombia y T. paraguanae de las áreas costeras de la península de la Guajira en Colombia, norte de la hoya del Lago de Maracaibo y península de Paraguaná en Venezuela. Se presentan descripciones adicionales de Thamnodynastes gambotensis y T. ramonriveroi. Palabras clave. Serpentes. Colubridae. Xenodontinae. Tachymenini. Thamnodynastes. Introduction The herpetological literature of northern South America is liberally sprinkled with specimens identified as “Thamnodynastes sp.” This is due to the fact that Thamnodynastes is among the most misunderstood snake genera in the world, coupled with confusion about the definition of T. strigilis (virtually every Thamnodynastes specimen with keeled dorsal scales is classified as this species). Bailey et al. (2005) resolved the problem by, after examining its syntypes, placing T. strigilis (Thunberg 1787) in the synonomy of T. pallidus (Linnaeus 1758), thus facilitating the assignment of new names and clarifying relationships within the genus. The following species of Thamnodynastes are components of the Venezuelan and Colombian herpetofaunas: T. chimanta Roze 1958, T. corocoroensis Gorzula and 8 Revision of the South American Thamnodynastes Ayarzagüena 1995, T. duida Myers and Donnelly 1996, T. marahuaquensis Gorzula and Ayarzagüena 1995, T. pallidus (Linnaeus, 1758) and T. yavi Myers and Donnelly 1996. Our long-term study of the genus revealed the additional presence of three undescribed species distributed in these two countries, each clearly distinct from one another. Materials and Methods All scale counts, notations, and terminology used herein follow the standard for snake systematics. We record: numbers of supralabials and note which of those are in contact with the eye; numbers of loreals, pre and postoculars, and temporals (members of this genus most often have primary temporals that touch the rear of the postoculars and secondary temporals that touch the rear of the primaries, and there are often tertiary temporals that touch the secondaries); and infralabials, noting how many touch the primary and secondary genials. Beyond these scale features, Thamnodynastes species have the usual colubrid complement of head scales (one rostral, two internasals, two prefrontals, one frontal, two parietals, two supraoculars, two pairs of nasals, one mental, and two pairs of genials). Any anomalies are mentioned. Ventral scale counts were taken as suggested by Dowling (1951a); subcaudal counts include the number of double rows as well as the terminal spine. Scale row reductions are recorded in the manner of Dowling (1951b), with the modifications and summarization model of Thomas (1976). Measurements of the body were taken in a straight-line with a meter stick: total length is from the tip of the snout to the tip of the tail, tail length from the rear of the cloacal plate to the tip of the terminal spine (for both measurements and counts, specimens lacking an obvious terminal spine were considered to have incomplete tails). Head measurements were taken with calipers to the nearest millimeter. Head length was measured from the front face of the rostral to the rear margin of the right angle of the jaw; head width was taken at the widest point, and eye length was taken in a straight line from the anterior margin of the eye to the rear margin. Mention of the projections of the eye are a description of where, on the lateral surface of the head (using named scales as a reference), the measured length of the eye falls when projected forward from the front margin of the eye. To place size in context, we report the total length size range for the top 25% of specimens. Abbreviations are as follows: Total length TL, snout-vent length SVL, head length HL, head width HW, and subcaudals SC. All tooth counts are of single series and all except the maxillary (most of which were done by cleaning in situ bones) are from prepared skulls. Particular care was taken with the maxillaries to count the smallest anterior tooth (or its socket), which is easily overlooked, thus rendering incorrect counts. When referring to maxillary teeth, “12+2G” means 12 prediastemal teeth followed by two grooved postdiastemal fangs. The conclusions of this study are based on the examination of specimens borrowed from collections cited in the Acknowledgments section. Mem. Fund. La Salle de Cienc. Nat. 166 9 Thamnodynastes paraguanae new species Figures 1, 2 and 3 Holotype. MBUCV 1468, from Norte de Paraguaná, Falcón State, Venezuela, collected by a Sr. Toledo, on 21 November 1964. Etymology. This species is named in allusion to its type locality, the Península de Paraguaná, Falcón State, Venezuela. Diagnosis. A Thamnodynastes with weakly keeled dorsal scales in 19-19-15 rows; hemipenis very slender without significant spines; maxillary teeth usually 13+2G; infralabials and chin usually heavily pigmented; ventrals and subcaudals generally fewer than neighboring species (see variation below). Description of holotype. An adult male 477 mm TL, tail 103 mm; tail/TL 21.6%; usual colubrid complement of head scales present; supralabials 8-8, IV&V entering orbit; infralabials 9-9, 5-5 infralabials contacting both genials on each side; loreals single; preoculars single; postoculars 2; temporals 2+3/2+3; ventrals 139; cloacal plate divided; subcaudals 57 and in two rows; dorsal scales keeled with one apical pit; abbreviated dorsal scale row formula 19-19-15, with the following complete formula: Opisthoglyphous diacranterian (grooved) maxillary teeth 13+2. Slender, head moderately distinct from neck; rostral visible from above; internasals nearly triangular, their common suture about equal to that of the prefrontals which are squarish; frontal slender, longer than its distance from the tip of the snout, equal to the length of the parietals; nasal divided, nostril prominent; eye rather large, its diameter half again its distance from the lip; projected eye length reaches the front of the nostril; supraoculars rather large, at the middle of the eye as wide as the frontal; head length 18.9 mm; head width 10.2 mm. Color and pattern (in preservative). Above dingy gray with a short nuchal pale stripe from the parietal notch, followed by a series of about 37 median pale spots one scale long before they fade out a few head lengths before the vent; along both sides of the pale-spot row is an inconspicuous row of dark spots about the size of one scale and centering on the 8th scale row; head almost uniformly dark with the eye-angle of jaw and labial markings largely obscured by supplementary pigment; chin dark with contrasting pale centers on the genials and anterior infralabials; throat paler than belly; the characteristic 4-stripe ventral pattern is evident only on the throat; elsewhere supplementary brown suffusion is general. The holotype has several long slits on the belly and the number tag is sewed into the lower jaw. 10 Revision of the South American Thamnodynastes Variation. There are too few specimens to accurately assess adult size, but the largest male we have is 477 mm TL, and the largest female is 605 mm TL; tail/TL 21.3-24.0% (χ = 22.7±1.2, n= 5) in males, 20.3-23.2% ( χ = 22.1±1.1, n= 7) in females; dorsal scale row formulae 19-19-15(16), scales weakly keeled, with the following summation of scale row reductions (n= 4): Ventrals 136-152 ( χ =146.5±7.3, n= 6) in males, 134-150 ( χ =141.0±5.6, n= 12) in females; cloacal plate divided (17); subcaudals 57-65 ( χ = 60.2±3.0, n= 6) in males, 54- 72 ( χ = 60.5±5.0, n= 10) in females; ventrals+subcaudals 193-218 ( χ = 205.1±10.1, n= 7) in males, 190-211 (χ =201.5±6.97, n= 8) in females; supralabials 7(2) or 8(32), supralabials entering orbit 3+4(2) or 4+5(32); infralabials 8(2) or 9(30), with 4(2) or 5(30) touching the genials; preoculars 1(30) or 2(2); postoculars 2(32); temporals 1+1+2(1), 1+2(1), 1+3(1), 2+2(9), or 2+3(14); prediastemal maxillary teeth 12(3), 13(10), or 14(1). A para-topotype (UMMZ 217112) is almost identical to the holotype except that it has only 136 ventrals, temporals 2+3, and it is the only specimen with two preoculars. This species overlaps with its geographic neighbors in ventral and subcaudal counts. However, much of the overlap in both counts is due to the inclusion of one female and her progeny (FMNH 5682 [the mother] and FMNH 23780-84, removed from the uterus [one additional embryo was left in place]).