Records of the Western Australian Museum 17: 69-72 (1995). 
Body dimensions in Simoselaps and Vermicella (Elapidae): a method for 
determining sex in natural populations 
V.L.R. Clarke and R.A. How 
Department of Terrestrial Vertebrates, Western Australian Museum, Francis Street, Perth, 
Western Australia 6000 
Abstract - A total of 736 museum specimens of 11 different species of 
Simoselaps and Vermicella were examined in the laboratory. Snout-vent 
lengths and tail-vent lengths were measured and each specimen was sexed 
by dissection. Within species, females had larger snout-vent lengths than 
males, but for tail-vent lengths the converse was the case. The tail-body ratio 
for each specimen was determined by dividing the tail-vent length by the 
snout-vent length. Males and females of each species had a range of tail- 
body ratios which did not overlap. Tail-body ratios provide a simple and 
accurate method for sexing live fossorial snakes. 
INTRODUCTION 
Small fossorial snakes are among the most 
abundant snakes in parts of Australia but they are 
difficult to sample and have therefore attracted 
little study (Shine 1984). Fifteen species of small 
fossorial snake are found in Australia and eleven 
of these occur in Western Australia: Simoselaps 
anomalus, S. approximans, S. bertholdi, S. bimaculatus, 
S. calonotos, S. fasciolatus, S. littoralis, S. minimus, S. 
roperi, S. semifasciatus and Vermicella multifasciata. 
Four of them, S. approximans, S. calonotos, S. 
littoralis and S. minimus, are endemic to Western 
Australia (Storr et al. 1986). 
The nomenclature used for these fossorial snakes 
varies among researchers. Some recognise three 
separate genera within the group (bleelaps, 
Simoselaps and Vermicella). However, in this paper 
the generic nomenclature of Cogger (1992) has been 
followed, with all the burrowing snakes in Western 
Australia being placed in the genera Simoselaps and 
Vermicella. Details of the geographical location and 
range of each species are described in various texts 
(Storr 1967; Storr et. al 1986; Cogger 1992). 
Storr (1967), in his major revision of the 
burrowing snakes of Western Australia, provided 
data on the significance of body and tail 
dimensions in the group and pointed out the 
"...considerable correlation between the number of 
ventrals, total length and (inversely) relative length 
of tail." 
The aim of this study is to use museum 
specimens of fossorial snakes to relate sex to 
external body dimensions in an attempt extend the 
work of Storr (1967,1979) and provide a method of 
sexing snakes with reasonable confidence in the 
field. 
MATERIALS AND METHODS 
Eleven species and 736 specimens of fossorial 
snake occurring in Western Australia were 
examined in this study. All specimens are held at 
the Western Australian Museum. For each 
specimen the snout-vent length (SVL) and the tail- 
vent length (TVL) were measured to the nearest 
millimetre. Sex was determined by dissection and 
examination of the gonads. In tire case of juveniles, 
or where the internal organs were missing or 
damaged, the specimens were recorded as 
unsexed. In a few cases sex was determined for 
specimens with fractured bodies or broken tails 
that were not used in further analysis. For S. 
bertholdi and S. semifasciatus, both numerically 
abundant in the collection, only a sample of the 
available specimens was examined and measured. 
The tail-body ratio (TBR) was calculated by 
dividing the tail-vent length (TVL) by the snout- 
vent length (SVL) for each specimen. 
In the case of two species, S. fasciolatus and V. 
multifasciata, specimens from each of the subspecies 
found in two distinct geographical locations were 
examined to determine if there was a difference 
between the geographical populations in the TBRs. 
Simoselaps bertholdi is found throughout a large area 
of southern and central Western Australia and 
specimens from different geographical regions 
within its range were examined to see if the TBR 
between sexes varied with geographical region. 
These regions were the southwest of the State, the 
Pilbara-Gascoyne area in the northwest and the 
deserts in the east. 
The dimorphism in body dimensions between 
sexes in these fossorial snakes was evaluated by 
analysis of variance using the Statistix (1992) 
package. 
