Lutz's tree iguana  (Liolaemus lutzae)

Lutz’s tree iguana is classified as Vulnerable (VU) on the IUCN Red List (1).

Lutz’s tree iguana (Liolaemus lutzae) is a small, sand-dwelling lizard which is endemic to the coastal ‘restinga’ habitats of the Atlantic forest in Brazil (1) (3) (5). Its colouration and patterning provide good camouflage against sandy ground (3) (6), with a brownish-orange or tan stripe along the back and brown and cream speckling on the sides (3). The stripe along the back is bordered by grey stripes and brown and cream spots, which form incomplete ‘V’ shapes. Some individuals have a narrow, light stripe along the side (3).

In female and juvenile Lutz’s tree iguanas, the underparts usually lack markings, but in adult males the underparts and sides develop a yellow tinge, while the throat becomes dark grey and the abdomen becomes finely chequered with grey and white (3). In juveniles, the brownish-orange stripe on the back is not as bright as in adults (3). The male Lutz’s tree iguana grows larger than the female (2).

Like other Liolaemus species, Lutz’s tree iguana has a wedge-shaped snout which may help it to rapidly bury itself in sand to escape predators (3). The tail of Lutz’s tree iguana makes up just over half of its total length, and it has long, slightly curved claws (3).

One of only five reptile species endemic to the state of Rio de Janeiro, Brazil (5), Lutz’s tree iguana is restricted to just 200 kilometres of coastline (1) (3). It occurs from the Marambaia restinga in the west to Cabo Frio in the east (3) (5).

Lutz’s tree iguana is found in shrubby, coastal sand dune habitat known as ‘restinga’ (1) (5), part of the unique Atlantic forest ecosystem. It is restricted to strips of beach which may only be 50 to 100 metres wide in places (3) (5), and is usually found in areas of sand with a covering of sparse, short vegetation (3).

This species often shelters in debris washed up by the tide (3), and has even been known to use man-made objects such as plastic bottles and Styrofoam (7).

Lutz’s tree iguana is omnivorous, feeding on both arthropods and plant parts (4) (8). It is quite a selective feeder, eating the leaves and flowers of only four of the plant species growing in its habitat, and probably selecting these for their high water content and digestibility (4) (8) (9). The diet of Lutz’s tree iguana varies seasonally, with fewer insects and more plants eaten in the dry season (10). It also varies with body size, with the smallest individuals eating only arthropods, and the proportion of plant food in the diet increasing as the lizard grows (4).

When hunting arthropods, Lutz’s tree iguana uses a ‘sit-and-wait’ strategy, lying in wait for passing prey (8) (11). Individuals do not need to move around over large areas to find food and they therefore occupy relatively small home ranges, although those of males are larger and may overlap the home ranges of two or three females (11). Lutz’s tree iguana often shelters in debris, but also constructs extensive burrow systems which may have multiple entrances and extend up to a metre underground (3). If threatened by a predator, an individual may run to the burrow, flee into vegetation or dive under the sand, although its concealing colouration and habit of remaining motionless for long periods provide excellent defence against detection (3) (6).

The breeding season of Lutz’s tree iguana occurs between September and March, and is probably associated with rainfall. The female stores fat during drier periods, using it to help produce the first clutch of eggs at the start of the breeding season (12). Two eggs are usually laid, although clutch size may range from one to four, and the female may produce two or more clutches during the breeding season (12). Newly hatched Lutz’s tree iguanas have a snout-vent length of around 2.8 centimetres (2) (12). Males grow faster than females, but both sexes reach maturity from around eight to nine months (2). Few adult Lutz’s tree iguanas survive to breed again in the following year (13).

The main threat to Lutz’s tree iguana is the severe degradation and fragmentation of its beach habitats, mainly as a result of urban expansion and other human activities (1). ‘Restinga’ habitats in the state of Rio de Janeiro have been impacted by the removal of beach vegetation due to road construction, vehicle traffic, housing developments and trampling, and have also been affected by garbage dumping and recreational activities (5) (14) (15).

Human impacts have reduced both the size and distribution of Lutz’s tree iguana populations (14), and the most threatened beaches have the smallest populations of this species (5). Lutz’s tree iguana is classified as Critically Endangered on the list of threatened Brazilian fauna (16).

The most effective conservation measures for Lutz’s tree iguana will be the strict protection of its habitat and the restoration of beach vegetation (5) (15). Studies have already shown these measures to be effective. For example, a population at Barra de Tijuca beach declined between 1984 and 1991 (14), but began to recover after commercial trailers and volleyball courts were removed from the beach and fences were built to prevent vehicle access (17). An experimental introduction of this species into a new location has also been successful (7), raising the possibility of reintroducing Lutz’s tree iguana into areas from which it has disappeared (5).

Lutz’s tree iguana occurs in the Serra do Mar ‘biodiversity corridor’, an area established to connect remaining habitat fragments (18), but strict protection of the restinga areas will be necessary if these fragile habitats and the species they support are not to be lost (15).

Find out more about conservation in the Atlantic forest region:

• Conservation International: Biodiversity Hotspots - Atlantic Forest: 
  http://www.biodiversityhotspots.org/xp/Hotspots/atlantic_forest/Pages/default.aspx
• WWF: Atlantic Forests: 
  http://wwf.panda.org/about_our_earth/ecoregions/atlantic_forests.cfm
• SOS Mata Atlântica:
  http://www.sosmatatlantica.org.br/
• The Nature Conservancy:
  http://www.nature.org/wherewework/southamerica/brazil/work/art5080.html
• World Land Trust:
  http://www.worldlandtrust.org/projects/brazil.htm