How & Dell: Reptile assemblages of the northeast Pilbara 
Elliott or pitfall traps. Subsidiary sites were checked daily 
for captures in Elliott traps, but also searched 
opportunistically (using a head-torch for night searches). 
Pitfall traplines were operated on 61 days of the 72 
days over which sampling occurred. 
All individuals captured were identified, measured 
and weighed prior to release. For several lizard taxa, 
individuals were also marked by toe-clipping before 
release. Voucher specimens were taken of all lizard 
species and examined in the laboratory to determine their 
sex and reproductive condition and to collect tissue 
samples for later molecular studies. The stomach contents 
of voucher specimens have been published separately as 
a study on the diet of selected species (Twigg et al. 1996). 
Analyses 
Assemblage analyses were carried out using the 
NTSYS (2000) program with an examination of the Bray- 
Curtis index of dissimilarity matrix clustered using the 
UPGMA method. 
Measures of diversity and evenness were derived from 
the software package on ecological methods (Krebs 2000) 
using the Shannon measure [H] and the a of the log 
series for diversity assessment and the Simpson index [E] 
for evenness. 
Results 
Herpetofaunal Assemblage 
The known herpetofaunal assemblage of the Abydos/ 
Woodstock stations consists of 5 species of amphibians in 
two families, 15 species of snakes in three families, a 
turtle and 51 species of lizards from five families (Table 
2 ). 
The only species previously known to occur on the 
study area but not collected during this survey were a 
legless lizard, Delma nasuta, and a skink, Ctenotus 
schomburgkii (Table 2). Both of these species were 
collected in the late 1950's, and an additional specimen of 
Delma nasuta was collected in 1963 (WA Museum 
records). 
During the final survey in October 1990, the second 
records of each of the elapid snakes Acanthophis wellsi 
and Pseudonaja modesta were obtained; single specimens 
of these had previously been collected in 1959 and 1958 
respectively (WA Museum records). However, Chapman 
(WA Museum pers. comm.) had seen A . wellsi in 1981 
near the airstrip and K. Young (WA Museum pers. 
comm.) recorded this species at Woodstock Homestead 
indicating that the species may be widespread but not 
commonly recorded. The only previous specimen of the 
blind snake Ramphotyphlops grypus from Woodstock was 
collected in 1953 (WA Museum records). The addition of 
25 previously unrecorded species during this survey of 
Abydos/Woodstock and the continued increase of new 
species recorded during the 72 days of sampling over 
three years suggests that additional species of reptile 
could still be recorded from the area (Fig 1). 
Activity of herpetofaunal species is strongly seasonal 
(Table 3). The highest number of species and individuals 
were recorded in the summer sampling period of each 
year. Fewer species and individuals were trapped during 
the spring sampling, and far fewer individuals were 
Figure 1. Accumulated capture of herpetofaunal species on the Abydos Plain between March 1988 and October 1990. Solid diamonds 
represent species captured by all techniques on all sampling days, open diamonds are species captured only by pitfall trapping. 
87 
