Bipes biporus Cope, 1894, Cape San Lucas, Baja California, Mexico.
OTHER COMMON NAMES
English: Mole lizard; French: Bipedides; German: ZweifussDoppelschleichen; Spanish: Ajolote.
The two-legged wormlizard has an average body length of 7.5-8.3 in (190-210 mm). Its tail is approximately 10% of total length. It has a midbody diameter of 0.23-0.27 in (6-7 mm). It is typically pink or flesh-colored uniformly, but some specimens are white ventrally. It has five claw-bearing digits on each limb and two preanal pores. It has a caudal autotomy restriction site at a single point
on the tail less than 10 annuli posterior to the cloacal opening. The tail is not regenerated subsequent to autotomization.
Western half of the Baja California peninsula. HABITAT
The two-legged wormlizard inhabits sandy soils. These reptiles can be found by digging to depths up to 6 in (15 cm) below the soil surface. Bipes biporus is often found in association with the roots of mesquite shrubs. It can sometimes be found on the soil surface under debris or rocks, especially at night.
Bipes biporus are active throughout the year, in any season. They inhabit shallow burrow systems, with an average depth of 0.98 in (2.5 cm) below the soil surface. B. biporus exhibit diurnal vertical movements; studies indicate that they may be found closer to the surface in early morning hours, which is suggestive of thermoregulatory behavior. It is possible that B. biporus also moves horizontally with respect to shade around surface objects such as trees or shrubs in order to thermoregu-late. Some data suggest that they are more likely to be found in sunny locations and/or nearer to the surface during early parts of the day.
Bipes biporus leaves it burrow systems at times and travels on the surface of the soil, especially at night. These animals move clumsily on the surface, using a combination of rectilinear locomotion of the body and overhand strokes of the short front limbs.
Bipes biporus feeds mainly on termites, insect larvae, and ants found below the soil surface. Evidence also exists that Bipes occasionally feeds on spiders and insects, which are surface-active prey, indicating that at least some feeding occurs outside of the tunnel system. Field studies indicate that B. biporus are more likely to be found outside of their tunnel systems during the night.
Female Bipes biporus become sexually mature once a body size of approximately 7.3 in (185 mm) is achieved, usually at approximately 45 months of age. Females lay eggs in clutches of one to four during the dry season. Hatchlings appear in late September, which is just before the rainy season, ensuring food availability for growing young. Field observations indicate that only about half the adult females are gravid in any given year, which has led to the suggestion that B. biporus are reproduc-tively active every other year.
CONSERVATION STATUS Not listed by the IUCN.
SIGNIFICANCE TO HUMANS None known. ♦
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