Boyd's forest dragon

Boyd's forest dragon (Lophosaurus boydii, formerly Hypsilurus boydii) is a species of arboreal agamid lizard found in rainforests and their margins in the Wet Tropics region of northern Queensland, Australia. It is the larger of the two species of Lophosaurus found in Australia. The other species, the southern angle-headed dragon, L. spinipes, is found in southern Queensland and northern New South Wales.

Etymology
The generic name Lophosaurus stands for "crested lizard", from the Greek lophos for "crest", and saurus for "lizard". The specific name, boydii, is a reference to English-born John Archibald Boyd (1846–1926), who lived in Fiji from 1865 to 1882 and then on a sugar plantation at Ingham, Queensland, and collected specimens for the Australian Museum. The binomial authority is William John Macleay, who provided the original description of the species in 1884.

Geographic range and habitat
The species is restricted to rainforests and their margins in northern Queensland, Australia, from just north of Townsville to near Cooktown. It is found in both upland and lowland rainforest, and is often seen around Lake Eacham (Yidyam) and Lake Barrine, and in parts of Malanda Falls Conservation Park and at Mossman Gorge.

It is recorded using tree-hollows.

Description
Boyd's forest dragons are generally brown or grey above, with some individuals having a green flush. The body is laterally compressed. They have very enlarged cheek scales, a prominent nuchal crest, and a yellow dewlap under the chin that is edged with enlarged spines. The tympanum is large and superficial. A dorsal crest, discontinuous with the nuchal crest, consisting of enlarged, hardened and pointed scales, runs down to the base of the tail.

Adults are sexually dimorphic, with males larger than females and having larger, blockier heads. Adult males grow to an average body length (snout-vent length) of about , with the tail adding another ; average body length for adult females is about  and tail length is about . Average body mass for adult males is about , and for females is about .

Behavior
Boyd's forest dragons spend the majority of their time perched on the trunks of trees, usually at around head height, although daily movements can exceed  on the ground. When approached, they will usually move around to the opposite side of the tree, keeping the trunk between them and their harasser.

Unlike most other lizards, Boyd's forest dragons don't bask in the sun, instead letting their body temperature fluctuate with air temperature (thermoconforming rather than thermoregulating). The one possible exception to this general rule is gravid (pregnant) females, which are often observed sitting on or beside forest roads and exhibit elevated body temperatures.

Boyd's forest dragons typically commence activity at dawn and cease activity at dusk, remaining active even when it rains. Activity is highly seasonal, all but ceasing during the cooler months, when lizards typically move into the rainforest canopy.

Both males and females appear to be territorial, with males defending an area of around 1,000 square metres (0.247 acre). Female territories are smaller, with male territories often containing the territories of more than one female.

Hatchlings, juveniles and smaller adults can often be found 'sleeping' at night at the ends of tree branches with their head pointing back towards the trunk.

Diet
Boyd's forest dragons are sit-and-wait predators, catching prey that they spy from their perches, although once on the ground, they will frequently move over a wider area, catching prey as they go.  Their diet consists primarily of invertebrates, with earthworms making up a relatively high proportion. Small fruits and vertebrates are also occasionally consumed.

Reproduction
Reproduction is via eggs, with clutch sizes varying from one to six eggs. Eggs are about  long and  wide, and weigh about . Egg size and weight are both higher in upland populations. Females in lowland populations may lay more than one clutch in a season, but clutch sizes are typically smaller than those laid by upland females. The eggs are laid in shallow nests, often in rainforest clearings — both natural and man-made (the verges of roads are particularly popular). The eggs take about 100 days to incubate.

Sexual maturity is achieved in around one to two years in lowland populations but probably takes at least a year longer in upland populations.

Predators
Known predators of juvenile and adult forest dragons include grey goshawks and feral pigs. Slaty-grey snakes (Stegonotus cucullatus) have also been known to eat forest dragon eggs.

Parasites
Small orange mites are commonly found on the dewlap and in the groin areas of the legs.

References

Further reading
Boulenger GA (1885). Catalogue of the Lizards in the British Museum (Natural History). Second Edition. Volume I. ... Agamidæ. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xii + 436 pp. + Plates I-XXXII. (Gonyocephalus boydii, pp. 297–298).
Macleay W (1884). "Notes on some Reptiles from the Herbert River, Queensland". Proc. Linnean Soc. New South Wales 8: 432-436. (Tiaris boydii, new species, pp. 432–433).

External links
Boyd's Forest Dragon
Tropical Topics
The Reptile Database

Category:Lophosaurus
Category:Agamid lizards of Australia
Category:Reptiles of Queensland
Category:Endemic fauna of Australia
Category:Reptiles described in 1884
Category:Taxa named by William John Macleay