Survey guidelines for Australia’s threatened reptiles

Brigalow scaly-foot

Paradelma orientalis

Summary information

Distribution: the core of the species’ distribution is the central Brigalow Belt of Queensland (Cogger 2000; Ingram & Raven 1990). More recently, the distribution has been extended to the west (to the Chesterton Range near Charleville), to the south (Eena State Forest near Inglewood) and to the north (Ulcanbah Station and Bacchus Downs Station) (Schulz & Eyre 1997; Kutt et al. 2003). The Eena State Forest record is only 40 kilometres north of the NSW border, raising the possibility that the species extends into NSW.
Habit and habitat: the species has generally been considered to be largely restricted to brigalow Acacia harpophylla, woodland, although it has been recorded in eucalypt associations within this broad habitat type (Shea 1987; Cogger et al. 1993), a view concordant with the distribution of the species centred over the Brigalow Belt Bioregion. Wilson and Knowles (1988) indicated it was particularly common in association with sandstone ridges in this region, where it could be found under rocks. However, more recent surveys have extended the range of habitat preferences and localities beyond the Brigalow Belt. On Boyne Island, where the species is common, it inhabits a tall woodland of Corymbia and Eucalyptus species (E. clarksoniana, narrow-leaved ironbark E. crebra, and Queensland peppermint E. exserta), with a sparse upper-mid-stratum of mountain hickory Acacia falciformis, which the species uses for sap-feeding (Tremul 2000). The soils are shallow and stony, though there are few large rocks. In the northern part of the distribution, at Ulcanbah Station, the species occurs in gidgee Acacia cambagei woodland with occasional Eremophila and Carissa, and a ground cover of forbs and grasses with abundant fallen timber on cracking alluvial clays. On Bacchus Downs, the Brigalow scaly-foot occurs in poplar box Eucalyptus populnea woodland with occasional Eremophila on sandy-clay alluvial soils (Kutt et al. 2003). The extreme westernmost locality has an understorey of spinifex Triodia mitchelli, while at the southernmost locality the species has been found in open forest of narrow-leaved ironbark Eucalyptus crebra and grey box E. microcarpa with a subcanopy of Bribie Island pine Callitris columellaris and buloke Allocasuarina luehmanni on a loose sandy clay substrate, and in buloke closed forest with narrow-leaved ironbark emergents (Schulz & Eyre 1997). Many records are from Corymbia citriodora and ironbark-callitris associations on coarse-grained sediments (e.g. sandstone).

The Brigalow scaly-foot has been found by day only in sheltering sites (under rocks, fallen timber, sheets of bark on the ground in leaf litter at the base of trees and rarely under bark of fallen logs raised off the ground; Shea 1987; Wilson & Knowles 1988; Schulz & Eyre 1997; Kutt et al. 2003), and by night active on the ground and also on the lower trunks of rough-barked Acacias (Tremul 2000).

Activity period: on Boyne Island, the only population to have been subjected to any ecological study, Paradelma were found active at night between late August and early June, but only on nights when the maximum temperature was above 19°C (Tremul 2000). Individuals were recorded on trees between 7.00 pm and 1.20 am, but most observations were between 7.00 pm and 9.00 pm. There is no published evidence for diurnal activity by this species.

Survey methods

Until recently, most individuals have been collected by hand by opportunistic searching in likely sheltering sites, including under rocks on sandstone ridges (Wilson & Knowles 1988) and under timber and fallen bark on soil, particularly under slabs of stringybark and ironbark fallen from dead trees (Shea 1987; Schulz & Eyre 1997; Kutt et al. 2003). Tremul (2000) found the Brigalow scaly-foot to be readily located by nocturnal spotlight searches of preferred feeding stations: the trunks of the rough-barked mountain hickory Acacia falciformis, usually less than 2 metres above ground, and often close to the base of the tree. At these sites, the lizards lapped exuding sap from the trees, although they also feed on insects and spiders on the evidence from scats (Tremul 2000). Night surveys over a 48 day period (6 August to 22 September) at the beginning of the active period recorded 10 individuals, but only at ground temperatures above 19°C, and with a maximum ground temperature of 27°C. Surveys conducted later in the active period (25 February and 8 March) over a 12 night period when ground temperatures at the time of observation were 24°C or more, and maximum temperatures between 30–36°C, recorded 23 individuals.

Hence, it is recommended that the most appropriate survey method for this species combines diurnal hand-searches under rocks, fallen bark and timber and raking through piles of leaf litter with nocturnal spotlight searches on the ground as well as lower trunks of rough-barked, sap-exuding trees on warm nights, in appropriate habitats. A drift fence array with funnel traps is also a useful survey technique.

Similar species in range: Paradelma is morphologically similar to other large pygopods (Pygopus and Delma species), but can be readily differentiated from Delma species by having preanal pores, and from Pygopus species by having smooth dorsal and lateral body scales rather than slightly ridged to strongly keeled scales. It is possible that an inexperienced surveyor could mistake Paradelma for one of the large burrowing skinks, particularly Anomalopus verreauxii or A. leuckartii, but these have styliform front and hindlimbs with terminal claws on at least the front limbs rather than no trace of any front limbs, and a flattened flap-like hindlimb.

Potential records of the Brigalow scaly-foot should be supported by a good quality colour photograph. Photo vouchers or skin sloughs should be forwarded to the state fauna authority and appropriate state museum (Queensland Museum) for positive identification and databasing of the record.

Key references for Paradelma orientalis

Cogger, H.G., Cameron, E.E., Sadlier, R.A. & Eggler, P. 1993. The action plan for Australian reptiles. Australian Nature Conservation Agency, Canberra. 254 pp.

Cogger, H.G. 2000. Reptiles and Amphibians of Australia. Reed New Holland, Sydney.

Ingram, G.J. & Raven, R. 1990. An Atlas of Queensland’s Frogs, Reptiles, Birds & Mammals. Queensland Museum, Brisbane.

Kutt, A.S., Hannah, D.S. & Thurgate, N.Y. 2003. Distribution, habitat and conservation status of Paradelma orientalis Günther 1876 (Lacertilia: Pygopodidae). Australian Zoologist 32(2): 261-264.

Schulz, M. & Eyre, T. 1997. New distribution and habitat data for the pygopodid, Paradelma orientalis (Günther, 1876). Memoirs of the Queensland Museum 42(1): 212.

Shea, G.M. 1987. Notes on the biology of Paradelma orientalis. Herpetofauna 17(1-2): 5-6.

Tremul, P.R. 2000. Breeding, feeding and arboreality in Paradelma orientalis: a poorly known, vulnerable pygopodid from Queensland, Australia. Memoirs of the Queensland Museum 45(2): 599-609.

Wilson, S.K. and Knowles, D.G. 1988. Australia’s Reptiles. A photographic reference to the terrestrial reptiles of Australia. Collins, Sydney.