Stenocercus tricristatus (Duméril)

Torres-Carvajal, Omar, 2007, A TAXONOMIC REVISION OF SOUTH AMERICAN STENOCERCUS (SQUAMATA: IGUANIA) LIZARDS, Herpetological Monographs 21 (1), pp. 76-178 : 161-162

Stenocercus tricristatus (Duméril) ( Fig. 22 )

Ophryoessoides tricristatus Duméril , in Duméril and Duméril, 1851:66. Holotype: MNHN 6825 , a male from ‘‘Brésil [ Brazil]̕̕; Duméril, 1856:531; Etheridge, 1966:89; Etheridge, in Peters and Donoso-Barros, 1970:215.

Liocephalus tricristatus Boulenger, 1885 a: 170 .

Leiocephalus tricristatus Amaral, 1937:178 ; Burt and Burt, 1933:29.

Stenocercus tricristatus Frost, 1992:43 ; Cadle, 2001:184.

Diagnosis.—Among species of Stenocercus , S. dumerilii , S. quinarius , S. scapularis , S. sinesaccus , S. squarrosus , and S. tricristatus are unique in lacking caudal fracture planes. Of these species, only S. dumerilii , S. quinarius , S. squarrosus , and S. tricristatus have a pyramidal head, as well as enlarged, dorsally-projected posterior supraciliaries. S. tricristatus can be distinguished from S. dumerilii (character states in parentheses) by having blunt posterior supraciliaries (posterior supraciliaries distinctly pointed), tibia shorter than thigh (tibia about as long as thigh), 33 scales around midbody (41–50), and by lacking enlarged scales above tympanum (two enlarged scales above tympanum). From S. quinarius and S. squarrosus (character states in parentheses) it can be distinguished by having a longer—63% of total length—tail (50–52% and 44–47%, respectively), 33 scales around midbody (47–56 and 46–53, respectively), and three longitudinal crests including one vertebral and two dorsolateral (five including one vertebral, two dorsolateral, and two lateral). In addition, males of S. tricristatus are unique in having large brown marks, bordered with yellow, vertically arranged on flanks ( Fig. 22 ).

Description.—(1) Maximum SVL in males 60 mm (n = 1); (3) vertebrals 22; (4) paravertebrals 28; (5) scales around midbody 33; (11) subdigitals on Finger IV 16; (12) subdigitals on Toe IV 19; (13) posthumeral pocket absent; (14) postfemoral pocket absent; (16) scales on occipitoparietal region large, keeled or wrinkled, juxtaposed; (18) row of enlarged supraoculars occupying most of supraocular region absent; (20) preauricular fringe inconspicuous or absent; (21) neck folds absent; (22) lateral and dorsal nuchals similar in size; (23) posterior gulars rhomboidal, projected posteriorly, strongly keeled and imbricate, not notched; (24) lateral and dorsal body scales similar in size; (25) vertebrals larger than adjacent paravertebrals; (26) dorsolateral crest present; (27) ventrals keeled, imbricate, mucronate; (28) scales on posterior surfaces of thighs keeled, imbricate; (29) inguinal granular pocket absent; (30) inguinal groove absent; (32) tail not compressed laterally; (33) tail length 63% of total length; (34) caudal autotomic segments absent; (35) caudals not spinose; (36) dark brown stripe extending anterodorsally from subocular region to supraciliaries present; (38) dark patch extensively covering gular region in adult males absent; (39) black patch on ventral surface of neck in adult males absent; (40) dark midventral longitudinal mark such as faint line, conspicuous stripe, or extensive patch in adult males absent; (41) dark patches on ventral surface of thighs in adult males absent; (42) postxiphisternal inscriptional rib articulation type unknown (KU 179058 identified as Stenocercus tricristatus in Torres-Carvajal [2004 a] corresponds to S. prionotus .)

Color in life.—Dorsum brown with transverse dark brown marks that have a yellowish-white border; similar marks with black borders arranged vertically on flanks; triangular, dark brown interorbital mark with yellowish-white border; tail with dark brown transverse rings with yellowish-white margins; venter light brown ( Duméril, 1856 [color plate]; Duméril and Duméril, 1851).

Distribution.— Stenocercus tricristatus was described from Brazil without specific locality data and no further collections of this species have been reported. However, there is evidence ( Ávila-Pires, 1995) suggesting that the holotype of S. tricristatus was collected in Minas Gerais ( Fig. 13 ).

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. 13.—Distribution of seven species of Stenocercus in South America. Question mark indicates possible distribution of S. tricristatus.