Friday, June 24, 2016

Beach Runner, Cnemidophorus lemniscatus (Family Teiidae)

Lacerta lemniscata Linnaeus 1758: 209

Cnemidophorus lemniscatus — Duméril & Bibron 1839: 129.

Other common names: striped runner, foot-shaker.

Size: 91 (34−91) mm male SVL; 63 (47−75) mm female; tails are 2.1−2.2 times the SVL. Identification: A bright green and yellow striped lizard with spots; head longer than broad; narrow snout rounded from above and in profile; rostral pentagonal; nostrils lateral, nasal scales extend dorsally behind rostral and make contact on the midline; frontonasals scales are hexagonal; the frontoparietals are quadrangular and meet on the midline; supraoculars 4−7, separated from 5−7 supraciliaries by one or two rows of granular scales; suboculars 3−5; preoculars absent; postoculars form a row of 3−4 small scales; ear opening large, tympanum visible. Dorsal and lateral scales are granular; ventral scales smooth, rectangular; in eight longitudinal rows and about 30 transverse rows. Most easily confused with Ameiva atrigularis, but that species has 10 longitudinal rows of ventral plates, and attains a larger Size: Smooth ventral scales distinguishing it from Kentropyx, which has 14 transverse rows of keeled ventral scales. Ten light dorsolateral stripes 3−4 scale rows wide, each separated by a dark stripe 5−9 scales wide. Scales around midbody 123 and 124 in two specimens; ventral scales 29 and 31 transverse rows in two specimens. Anterior dorsal surface of front legs covered with plate-like scales that overlap; granular scales cover the rest of the legs. Hind legs with overlapping plate-like scales on the anterior and ventral surfaces, granular scales dorsally and posteriorly. Scales on tail quadrangular, overlapping and keeled. Fingers compressed with 15−17 lamellae on fourth digit; toes compressed with 30−33 lamellae on fourth digit. Live females have a brown back with white stripes and dorsolateral stripes are green on the anterior; anterior venter of females is white, posteriorly it is green-yellow; females also have a brown tail. Males have lateral stripes that are replaced by 2−3 rows of white spots, posteriorly the dorsolateral region is blue-green, and the tail is blue. Both sexes have the ventral surface of the tail colored blue or green.

Distribution: A disjunct distribution from Central America to northern Brazil, including Trinidad (including Chacachacare and Huevos islands), Tobago, Little Tobago; present on some islands off north central Venezuela, west of Trinidad & Tobago. It has been introduced into Florida. C. lemniscatus is a species complex containing several cryptic and sibling species and clones. The Trinidad and Tobago populations are bisexual.

Habitat: A beach-savanna lizard that will enter forest and colonize open sunny areas; forage on open ground using bushy areas for shelter; abundant along Manzanilla Bay Beach and at Icacos Beach; use burrows for shelter, one burrow examined was 17−20 cm in depth.

Biology: Diurnal. Diet: Arthropods, mostly insects but also earthworms, flowers of Portulaca. Predators. hawks, the snake Oxybelis aeneus, and the tegu lizard, Tupinambis. Ameiva will chase Cnemidophorus, this may be attempted predation, or competition for territory. Cnemidophorus stop abruptly between spurts of rapid, often bipedal, locomotion; they will lift one of their front legs and vibrate or wave their feet; this may represent a territorial display, or have other social significance.

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