Stenocercus trachycephalus (Duméril) (Dumeril)

Torres-Carvajal, Omar, 2007, A TAXONOMIC REVISION OF SOUTH AMERICAN STENOCERCUS (SQUAMATA: IGUANIA) LIZARDS, Herpetological Monographs 21 (1), pp. 76-178 : 160-161

Stenocercus trachycephalus (Duméril)

( Fig. 22 )

Holotropis trachycephalus Duméril , in Duméril and Duméril, 1851:70. Syntypes: MNHN 1787 (2), 2393 (2), 2394 (2) from ‘‘ Nouvelle-Grenade , et en particulier Santa-Fé de Bogota [Departamento Cundinamarca, Colombia]̕̕; Duméril, 1856:539.

Liocephalus trachycephalus Boulenger, 1885 a: 169 .

Leiocephalus ornatus trachycephalus Burt and Burt, 1930:12 ; Burt and Burt, 1931:272; Burt and Burt, 1933:28; Burt and Myers, 1942:303.

Ophryoessoides trachycephalus Etheridge, 1966:89 ; Etheridge, in Peters and Donoso-Barros, 1970:214.

Stenocercus trachycephalus Fritts, 1974:65 ; Ayala, 1986:563; Frost, 1992:43.

Diagnosis.— Stenocercus trachycephalus is distinguished from other species of Stenocercus except S. lache by having imbricate scales on the posterior surface of thighs, a welldeveloped postfemoral mite pocket, and by lacking an antehumeral mite pocket and neck folds. It differs from S. lache (character states in parentheses) by having weakly to moderately keeled ventrals (smooth), a strongly laterally compressed tail in adult males (weakly compressed), fewer (43–67, X = 52.54) scales around midbody (61–74, X = 67.03), and by lacking postxiphisternal ribs in contact medially (postxiphisternal inscriptional ribs continuous medially). In addition, the black ventral nuchal patch in adult males of S. lache is usually continuous with the black midventral patch; these patches are not in contact in S. trachycephalus .

Description.—(1) Maximum SVL in males 89 mm (n = 44); (2) maximum SVL in females 79 mm (n = 31); (3) vertebrals 34–53; (4) paravertebrals 45–64; (5) scales around midbody 43–67; (6) supraoculars 3–6; (7) internasals 2–5; (8) postrostrals 4–7; (9) loreals 2–4; (10) gulars 18–29; (11) subdigitals on Finger IV 15–20; (12) subdigitals on Toe IV 21–31; (13) posthumeral mite pocket absent; (14) postfemoral mite pocket distinct with slit-like opening; (15) parietal eye visible through interparietal cornea in 77% of specimens; (16) scales on occipitoparietal region small, keeled, imbricate; (17) projecting angulate temporals absent; (18) row of enlarged supraoculars occupying most of supraocular region absent; (19) scales on frontonasal region weakly imbricate anteriorly; (20) preauricular fringe present; (21) neck folds absent; (22) lateral and dorsal nuchals similar in size; (23) posterior gulars rhomboidal, smooth or slightly keeled, imbricate, not notched; (24) lateral and dorsal body scales similar in size; (25) vertebrals larger than adjacent paravertebrals; (26) dorsolateral crest absent; (27) ventrals smooth or slightly keeled, imbricate; (28) scales on posterior surfaces of thighs keeled, imbricate; (29) inguinal granular pocket absent; (30) inguinal groove absent; (31) preanals not projected; (32) tail strongly compressed laterally in adult males; (33) tail length 60–71% of total length; (34) caudal whorls per autotomic segment three; (35) caudals not spinose; (36) dark brown stripe extending anterodorsally from subocular region to supraciliaries absent; (37) dark patch extensively covering gular region in 26% of females; (38) dark patch extensively covering gular region in adult males absent; (39) black patch on ventral surface of neck in 91% of adult males; (40) dark midventral longitudinal mark such as faint line, conspicuous stripe, or extensive patch in 89% of adult males; (41) dark patches on ventral surface of thighs in adult males absent; (42) postxiphisternal inscriptional ribs not in contact midventrally, Patterns 1A and 2A.

Color in life.—Dorsum dark brown, emerald green, or olive-green, with scattered yellow spots that form transverse lines in some males, and with a series of dark transverse marks longitudinally arranged over vertebral line in some specimens; light dorsolateral stripe between eye and base of tail in some specimens; dorsum of head uniform dark brown or dark olive-green; vertical yellow line on shoulder in some specimens; flanks and dorsal aspect of limbs with scattered yellow spots in some specimens; ventral surface of body between fore and hind limbs orange in adult males (usually with wide black midventral patch), and cream or yellowish cream in females; gular region light blue or yellow in males and cream or yellowish cream in females; ventral surface of neck in most males with wide, black transverse band, sometimes bordered with yellow posteriorly; black ventral nuchal patch not in contact with black midventral patch.

Natural History.—Clutch size in S. trachycephalus is two eggs, with an incubation time of approximately six months ( Osorno, 1938). A female (ICN 2853) contained two oviductal eggs of 16.62 mm X 8.72 mm and 16.75 mm X 9.34 mm. Volume of these eggs was 661.7 mm 3 and 765.1 mm 3, respectively. The diet of this species includes flies, bumblebees, other insects, and earthworms; this species is known to bury itself and remain underground for several weeks ( Osorno, 1938).

Distribution.— Stenocercus trachycephalus is known from the northern Andes (4 ° N–6 ° N) in the eastern Cordillera of Colombia ( Fig. 16 ). This species occurs at elevations between 1749–3800 m in Departamentos Boyacá, Caldas, Cundinamarca, Norte de Santander, and Santander. S. trachycephalus might occur in sympatry with S. lache and S. santander ( Fig. 16 ).

Figures

FIG. 22.—Six species of Stenocercus. (A) S. stigmosus (PVE); (B) S. torquatus (MLU); (C) S. trachŋcephalus (JMR); (D) S. tricristatus (illustration from plate XXII in Duméril, 1856); (E) S. Ʋariabilis (MLU); (F) S. Ʋarius (LAC).

FIG. 16.—Distribution of four species of Stenocercus in Colombia and Venezuela.