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Rhadinaea macdougalli SMITH & LANGEBARTEL, 1949

IUCN Red List - Rhadinaea macdougalli - Data Deficient, DD

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Higher TaxaColubridae (Dipsadinae), Colubroidea, Caenophidia, Alethinophidia, Serpentes, Squamata (snakes)
Common NamesE: MacDougall's Graceful Brown Snake
S: Hojarasquera de MacDougall 
SynonymRhadinaea macdougalli SMITH & LANGEBARTEL 1949: 413 (1950)
Rhadinaea macdougalli — LINER 1994
Rhadinaea macdougalli — LINER 2007
Rhadinaea macdougalli — WALLACH et al. 2014: 640 
DistributionSE Mexico (Oaxaca, Veracruz)

Type locality: Mexico: near Buena Vista, at crest of Sierra Madra, directly N of Rio Grande, Oaxaca  
TypesHolotype: INHS (= UIMNH) 3775; T. MacDougall; March 7, 1949. 
DiagnosisDiagnosis. Amember of the genus Rhadinaea, with 17 scale rows, ventrals about 119, caudals about 75, in males; no supraanal keels; maxillary teeth 16 + 2, with a short but well-defined di­ astema preceding the two rear teeth; hemipenis capitate, sulcus divided, with about 22 large spines in a belt around the middle, and numerous fine spines to base. Sides below upper part of fourth scale row darker than back, faintly bor­ dered above by a light linfe; no other stripe on body; head with a light line through the supra­ labials and another from upper rear margin of orbit to upper edge of last supralabial; belly immaculate except ends of ventrals, which are darker than adjacent dorsal scales (Smith & Langebartel 1949: 413).

Description. Portion of rostral visible from above two-thirds length of median internasal suture; latter entering 2.5 times into median pre­ frontal suture; frontal a littlejonger than its dis­ tance from tip of snout; nasal large, completely divided; loreal square; 3 preoculars and 2 post­ oculars on each side; temporals 1-2-3; eye large, its longitudinal diameter entering 1.5 times in its distance from tip of snout, one-half time in its distance from labial border; 8 supralabials, fourth and fifth entering orbit, seventh largest; 10 infra­labials, 5 in contact with anterior chinshields, 2, with posterior; anterior chinshields a little shorter than posterior, the members of each pair in con­tact throughout their length. Dorsals in 17 rows throughout body; scales absolutely smooth even in supraanal area, pitless; ventrals 119, subcaudals 75; anal divided. Maxillary teeth 16 -b 2, steadily increasing in size posteriorly to the sixteenth, the anterior one about two-thirds length of sixteenth; rear two teeth abruptly enlarged one-fourth more than preceding tooth. Hemipenis single, 8 caudals long, capitate,' calyculate, sulcus dividing opposite 6th caudal; a belt of 22 large spines of various sizes around middle third of hemipenis, below calyces; numer­ ous minute spines on basal third of hemipenis, which appears to be provided with longitudinal ridges; some minute spines also scattered among large spines (Smith & Langebartel 1949: 413).

Size: Total length 294 mm; tail 106 mm.

Coloration: Dorsal color a nearly uniform dull, dark brown; edges of each scale darker than middle; sides a httle darker than middorsum, the darker color abruptly terminating at a moderately distinct black line on upper part of fourth scale row; cen­ ters of scales in fifth scale row not as dark but lightly stippled, giving the effect of a faint light line; rest of dorsUm uniform. Head light brown above, little stippled with darker; a sharply defined white line extending from upper rear corner of eye through temporals to upper edge of last supralabial, there abruptly terminating, partly on the labial and partly on the scale imme­ diately above; another white line through rostral and across upper edges of the fifth and preceding supralabials, through the middle of the sixth, barely involving the anteroventral corner of the eighth, where it ends at the hp; both white stripes bordered by broad black lines, continuous except for that below the supralabial line which is inter­ rupted at each labial suture, producing the effect of a row of spots on the lower edges of the labials, one spot to each scale. Dorsolateral light line of body rather distinct as it nears head, curving laterally toward temporal stripe, but terminating abruptly in a rounded, black-edged, small expan­ sion which fails to reach the end of the temporal stripe by two scale lengths; a dark spot on each of the anterior four infralabials, two on the mental, and one on each anterior chinshield at its anterior end; a few flecks in lateral gular region. Ventrals and subcaudals entirely immacu­ late, white, except the extreme lateral ends which anteriorly are black tipped, elsewhere brown as the sides of the body and tail (Smith & Langebartel 1949: 413).

For an updated diagnosis see Myers 1974: 86. 
CommentGroup: Rhadinaea decorata group 
EtymologyNamed for Thomas MacDougall, collector, who for 10 years has assisted the senior author to become acquainted with the Tehuantepec area. 
  • Aguilar-López JL, Luría-Manzano R, Pineda E, Canseco-Márquez L 2021. Selva Zoque, Mexico: an important Mesoamerican tropical region for reptile species diversity and conservation. ZooKeys 1054: 127-153 - get paper here
  • Beolens, Bo; Michael Watkins, and Michael Grayson 2011. The Eponym Dictionary of Reptiles. Johns Hopkins University Press, Baltimore, USA - get paper here
  • Casas-Andreu, G., F.R. Méndez-De la Cruz and X. Aguilar-Miguel. 2004. Anfibios y Reptiles; pp. 375–390, in A.J.M. García-Mendoza, J. Ordoñez and M. Briones-Salas (ed.). Biodiversidad de Oaxaca. Instituto de Biología, UNAM-Fondo Oaxaqueño para la Conservación de la Naturaleza-World Wildlife Fund, México, D. F.
  • Heimes, P. 2016. Snakes of Mexico. Chimaira, Frankfurt, 572 pp
  • Liner, Ernest A. 2007. A CHECKLIST OF THE AMPHIBIANS AND REPTILES OF MEXICO. Louisiana State University Occasional Papers of the Museum of Natural Science 80: 1-60 - get paper here
  • Mata-Silva, Vicente, Jerry D. Johnson, Larry David Wilson and Elí García-Padilla. 2015. The herpetofauna of Oaxaca, Mexico: composition, physiographic distribution, and conservation status. Mesoamerican Herpetology 2 (1): 6–62 - get paper here
  • Myers, C.W. 1974. The systematics of Rhadinaea (Colubridae), a genus of New World snakes. Bull. Amer. Mus. nat. Hist. 153 (1): 1-262 - get paper here
  • Pérez-Higareda, Gonzalo, Marco A. López-Luna, David Chiszar and Hobart M. Smith 2002. Additions to and Notes on the Herpetofauna of Veracruz, Mexico. Bull. Chicago Herp. Soc. 37(4):67-68 - get paper here
  • Smith, H. M., & LANGEBARTEL, D. A. 1949. Notes on a collection of reptiles and amphibians from the Isthmus of Tehuantepec. J. Washington Acad. Sci. 39: 409-416.
  • Torres-Hernández, LA, Ramírez-Bautista A, Cruz-Elizalde R, Hernández-Salinas U, Berriozabal-Islas C, DeSantis DL, Johnson JD, Rocha A, García-Padilla E, Mata-Silva V, Fucsko LA, and Wilson LD. 2021. The herpetofauna of Veracruz, Mexico: composition, distribution, and conservation status. Amphibian & Reptile Conservation 15(2) [General Section]: 72–155 - get paper here
  • Wallach, Van; Kenneth L. Williams , Jeff Boundy 2014. Snakes of the World: A Catalogue of Living and Extinct Species. [type catalogue] Taylor and Francis, CRC Press, 1237 pp.
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