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Scale anomalies in the Little Whip Snake Suta flagellum (Elapidae)


Abstract and Figures

The occurrence of ventral (‘belly’) scale anomalies was examined in three populations of the Little Whip Snake Suta flagellum in remnant native grasslands near Melbourne. Ventral scale anomalies occurred in similar frequencies in all three populations and overall affected 35% of snakes. Nine types of anomalies were identified, three of which comprised 65% of the affected snakes, and there was a tendency for some types to occur together. The frequency and types of anomalies in the adult and juvenile size classes was similar, indicating that they have little effect on the survival of individuals. Significantly more females than males had ventral scale anomalies and there was also a significant association between sex and the location of anomalies, with males having significantly more subcaudal (tail) scale anomalies than females. Half-scale anomalies occurred more frequently on the left than on the right side. The possible significance of the ventral scale anomalies is discussed.
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Volume 138 (2) April 2021
Published by e Field Naturalists Club of Victoria since 1884
Volume 138 (2) 2021 April
Editors: Gary Presland, Maria Gibson, Sue Forster
Editorial Assistant: Virgil Hubregtse
Research Reports An assessment of nest box occupancy and program eectiveness in a
bushre recovery program in Warrumbungle National Park, northern
inland New South Wales, by Jessica K Murphy and Sophia C Dunn...............36
Scale anomalies in the Little Whip Snake Suta agellum (Elapidae),
by Grant S Turner...................................................................................................45
Naturalist Notes Further observations of Australasian Grebe Tachybaptus novaehollandiae
activity on two waterbodies in Clayton, Victoria, by Virgil Hubregtse............53
If this is Dacryopinax spathularia, look what we’ve been missing!
by Sue Forster...........................................................................................................56
Honours 2020 Australian Natural History Medallion: Craig Morley,
by Maxwell Campbell..............................................................................................61
Australian Natural History Medallion Trust Fund .......................................................................... 64
ISSN 0042–5184
Front cover: Little Whip Snake Suta agellum (Elapidae). Photo Grant S Turner.
45Vol 138 (2) 2021
Research Report
In snakes, anomalous or abnormal scales have
been documented in a wide variety of taxa;
most of these have been located on the head
and also on the ventral surface (‘belly’) of
snakes rather than on the body (Martof 1954;
Barton 1956; King 1959; Clarke and Callison
1967; Peters 1969; Plummer 1980; Murphy et
al. 1987; Arnold and Bennett 1988; Schwaner
1990; Merilä et al. 1992; Lindell et al. 1993;
Shine et al. 2005; Laia et al. 2015; Brown et al.
2017). Ventral scales are the repetitive series of
enlarged transverse scales that extend from the
underside of the neck through to the tail tip.
Anomalous ventral scales have been shown to
occur either as a consequence of embryos be-
ing subjected to temperature extremes or as
an expression of abnormal genetic control of
development (Fox 1948; Fox et al. 1961; Vin-
egar 1973, 1974; Osgood 1978; Plummer 1980;
Murphy et al. 1987; Brown et al. 2017). ey
can be the external manifestation of underlying
skeletal deformities, such as the duplication of
ribs (King 1959; Osgood 1978; Schwaner 1990;
Merilä et al. 1992; Löwenborg et al. 2011). Skel-
etal deformities have been shown to aect lo-
comotor performance and survival in snakes
(Arnold and Bennett 1988; Jayne and Bennett
1990; Forsman et al. 1994). e overall fre-
quency of anomalies (or gross abnormalities)
in snake populations is one of several measures
of embryonic developmental stability in reptile
populations (Sarre and Dearn 1991; Forsman et
al. 1994; Löwenborg et al 2011).
ere are few studies of scale anomalies in Aus-
tralian snakes. Schwaner (1990) presented an
analysis of scale and underlying skeletal anom-
alies in insular and mainland populations of
the Tiger Snake Notechis scutatus. Schwaner et
al. (1988) also examined insular populations of
Carpet Pythons Morelia spilota imbricata and
found a high proportion of individuals pos-
sessed ventral scale anomalies though the sam-
ple size was small. Brown et al. (2017) made a
comprehensive study of two types of head scale
anomalies (asymmetry and fragmentation) in
the Slaty-grey Snake Stegonotus cucullatus and
found that scale asymmetry was directional
(favouring le over right) and that scale frag-
mentation was more prevalent in females than
males. Shine et al. (1988) observed individual
variation in the number and position of anom-
alous subcaudal scales in Red-bellied Black
Snakes Pseudechis porphyriacus and Water
Pythons Liasis fuscus and discussed their use
as natural markers in mark-recapture studies.
Several authors mention the occurrence of ven-
tral scale anomalies incidentally, when describ-
ing individual snakes (e.g. Trinca et al. 1971;
Schoeld 1972).
is work is concerned with a description
of the types, frequency, and patterns of occur-
rence of anomalous ventral scales in the Lit-
tle Whip Snake Suta agellum. is species is
a small, nocturnal, live-bearing elapid snake
found throughout much of Victoria, south-
eastern NSW and the south-east corner of SA
Scale anomalies in the Little Whip Snake Suta agellum (Elapidae)
Grant S Turner
103 Settlement Road, Bundoora, Victoria 3083.
e occurrence of ventral (‘belly’) scale anomalies was examined in three populations of the Little Whip Snake
Suta agellum in remnant native grasslands near Melbourne. Ventral scale anomalies occurred in similar fre-
quencies in all three populations and overall aected 35% of snakes. Nine types of anomalies were identi-
ed, three of which comprised 65% of the aected snakes, and there was a tendency for some types to occur
together. e frequency and types of anomalies in the adult and juvenile size classes was similar, indicating
that they have little eect on the survival of individuals. Signicantly more females than males had ventral
scale anomalies and there was also a signicant association between sex and the location of anomalies, with
males having signicantly more subcaudal (tail) scale anomalies than females. Half-scale anomalies occurred
more frequently on the le than on the right side. e possible signicance of the ventral scale anomalies is
discussed. (e Victorian Naturalist 138 (2), 2021, 45–52)
Keywords: scale anomalies, frequencies, types, ventral, subcaudal
46 e Victorian Naturalist
Research Report
and is a particularly common inhabitant of ba-
salt plains grasslands near Melbourne (McCoy
1878; Rawlinson 1965; Jenkins and Bartell 1980;
Cogger 2014; Robertson and Coventry 2019).
Elapid snakes have undivided ventral scales be-
tween the neck and the vent, while those on the
underside of the tail (called subcaudal scales)
may be divided or undivided (or a combina-
tion of both) depending on the species (Greene
1997; Shea et al. 1993; Cogger 2014). Suta a-
gellum, along with all other species of the genus
Suta, is distinguished as having an entire anal
scale and undivided subcaudal scales (Rawlin-
son 1965; Coventry and Robertson 1991; Cog-
ger 2014). Male and female S. agellum have the
same body length (Shine 1988; Turner 2019)
but males have signicantly longer tails (Turner
2019) and hence larger numbers of subcaudal
scales compared to females (males 29–40, fe-
males 20–29; n = 68; Rawlinson 1965). Several
authors had previously noted the occurrence
of anomalous ventral scales in S. agellum, but
their types and frequency were not examined
(McCoy 1878; Rawlinson 1965; Turner 1989).
As part of a population census of S. agel-
lum, three disjunct populations occurring
on the basalt plains to the north and west of
Melbourne at Bundoora (37o42' S, 145o03' E),
Somerton (37o38' S, 144o58' E) and Deer Park
(37o46' S, 144o46' E) were examined from 1990
to 1994. Sampling was conducted throughout
all months of the year. e snout-to-vent length
(SVL) was measured to the nearest millimetre
and snakes were classed as either juvenile (=im-
mature) or adult on the basis of the known
sizes at sexual maturity (males SVL205 mm,
females SVL232 mm; Shine 1988). Sex was
determined by visual examination of the tail
shape (see Turner 1992, 1999). e habitat at
each locality consisted of remnant native grass-
land of varying quality with abundant surface
basalt rock, some exfoliations, dry stone walls
and stony rise. e approximate area of the sites
were: 80 ha (Bundoora), 100 ha (Somerton),
and 250 ha (Deer Park). Each was surrounded
by housing/industrial estates and/or farm-
land. For more detailed site descriptions and
methodology, see Turner (2019).
Snakes were inspected for the presence of
anomalous scales on the head, dorsal, lateral
and ventral surfaces. For each snake, anoma-
lies were hand-drawn and later grouped into a
number of dierent types, and the number of
anomalies and their location (anterior/mid/
posterior body, ventral or subcaudal) was re-
corded. In snakes with multiple scale anoma-
lies, the anomaly type(s) and the number of
each anomaly type were recorded. Herein, ‘ven-
tral scales’ refer to all scales on the underside
of the body and tail (i.e. including the vent and
subcaudal scales) while ‘pre-anal scales’ refer to
just the three ventral scales immediately before
(i.e. anterior to) the anal scale.
Statistical tests were employed to test for as-
sociations between the incidence of anomalies
and factors such as size class, sex, location of
anomalies, etc. e G-test for goodness of t
with Williams correction was used to test de-
viations from expected frequencies in both sin-
gle and two-way classications (i.e.' 2×2, 3×2
contingency tables; Sokal and Rohlf 1981). e
Student t-test was used to compare the means
of normally distributed data, and the result-
ing probabilities were two-tailed. As multiple
statistical tests were performed, FDR control
(Benjamini and Hochberg 1995) was employed
globally on the results, but did not change the
signicance of any result at the α = 0.05 level; prob-
abilities quoted below are therefore unaltered.
e overall frequency of ventral scale anoma-
lies obtained from pooling all data (over sex,
size class and population) was 35.2% (160 af-
fected; n=455). Most aected snakes had a
single anomaly (57.8%) while those with more
than six anomalies were uncommon (5.2%; see
Table 1—there were six snakes in which the
number of anomalies was not determined).
is latter gure included ve individuals
with large numbers of anomalies (from 10 to
22), and three stillborn neonates each with
more than 10 anomalies and gross deformities
(Turner 1998). When these individuals are ex-
cluded, as they are from all the analyses below,
a total of 242 ventral scale anomalies aecting
146 individuals were recorded with an average
1.66 scale anomalies per individual.
47Vol 138 (2) 2021
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e types and frequency of anomalies
Nine types of ventral scale anomalies were
identied (Fig. 1). Some types of ventral scale
anomalies represent a breaking of bilateral sym-
metry, a state in which the le and right sides of
the body are identical (or nearly so). Types B,
D, E and H (see Figs. 1 and 2) are examples of
such asymmetries, whereas types A, C, F and G
are not (see comments on type I below). Type
A and C anomalies consisted of scales divided
into right and le halves (sometimes referred
to as ‘cle’ scales in the literature) with no
overlap and some overlap respectively between
the halves. ey did not occur in conjunction
Table 1. Frequency and percentage frequency occurrence of the number of ventral scale anomalies in the
Little Whip Snake Suta agellum.
No. Anomalies 1 2 3 4 5 6 >6 Total
Frequency 89 32 16 6 1 2 8 154
% Frequency 57.8 20.8 10.4 3.9 0.6 1.3 5.2 100
Fig. 1. e nine types of anomalous ventral scales recorded in the Little Whip Snake Suta agellum.
48 e Victorian Naturalist
Research Report
with any other types of anomalies. Type B and
H anomalies consisted of the imposition of a
half-scale on one side of the body while type
E consisted of the imposition of two half-scales
on one side of the body; one or more of these
anomalies occurred in individual snakes. Type
D anomalies consisted of two consecutive ven-
tral scales in which one half of each scale was
fused together. Type F anomalies consisted of
incompletely formed ventral scales that did not
contact the dorsal scale row. Type I anomalies
consisted of scales with an uneven leading edge.
is anomaly type typically aected multiple,
consecutive ventral scales (but only one scale
was counted as being aected in the analyses
above) and they always occurred in conjunc-
tion with symmetry-breaking anomalies. Type
G anomalies consisted of a leading edge with a
cusp and typically occurred singly.
e percentage frequencies of each anomaly
type were: A 10.2%, B 41.8%, C 9.6%, D 13.0%,
E 6.2%, F 7.3%, G 4.5%, H 4.0% and I 3.4%.
Anomaly types A, B and D together comprised
65% of the total. Types B, D, E and H were
more common on the le-hand rather than the
right-hand side of the ventral surface (t-test
(paired)=2.76, 93df, P=0.007). If the analysis
is restricted to just type B anomalies the result
is marginally signicant (t-test (paired)=2.01,
78df, P=0.048). In an adult snake with the larg-
est number of anomalous scales (n=22) only
types B, D and I were exhibited. No individuals
exhibited all anomaly types, though up to four
types were recorded in one snake. In snakes
with multiple anomalies (n=65), some patterns
were evident between certain types, though sta-
tistical analysis was not conducted due to the
small sample size. For example, type B anoma-
lies were most likely to occur with another of
the same type (n=15) rather than a dierent
type (n5 for all others). Type I anomalies most
oen occurred immediately following types
B, E or H or were interspersed between these
types (n=10). e leading-edge of scales with
type I anomalies were observed to ‘straighten-
out’ before the formation of other types of
anomalies in some snakes (n=7).
All types of scale anomalies were represented
in each of the three populations, with one ex-
ception. Type A anomalies were not recorded in
the Somerton population but were relatively com-
mon in the Deer Park and Bundoora populations.
e incidence of anomalies
(i) Populations: anomalies in each of the three
populations were found to occur in the fol-
lowing frequencies: Deer Park 30.3%, Bun-
doora 39.7% and Somerton 29.8%. ere
was no association between population and
the frequency of anomalies (3×2 contingency
table: G=2.14, 2df, P=0.343). For this reason,
and also because the types of anomalies and
the frequency of those types were very simi-
lar, the population data was pooled in the
analyses below.
(ii) Size class: adult and juvenile snakes exhib-
ited similar frequencies of ventral scale
anomalies: 54% (n=86) and 46% (n=74) re-
spectively (G=0.90, 1df, P=0.342). ere was
no association between size class and the oc-
currence of anomalies (2×2 contingency ta-
ble: G=0.28, 1df, P=0.595).
(iii) Sex: signicantly more females than males
possessed anomalies (G=9.27, 1df, P=0.002).
is result was signicant in both the adult
and juvenile size classes (2×2 contingency
Fig 2. Two type B (half-scale) anomalies (indicated
by arrows) on the anterior ventral surface of an adult
male Little Whip Snake Suta agellum.
49Vol 138 (2) 2021
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tables—adults: G=6.65, 1df, P=0.010; ju-
veniles: G=6.73, 1df, P=0.009). When size
classes were combined there was a highly
signicant association between sex and the
incidence of anomalies (2×2 contingency
table: G=13.19, 1df, P=0.0003). Mean num-
bers of anomalies per individual was 1.6 for
females and 1.7 for males and these were
not signicantly dierent (t=0.591, 111df,
P=0.556). ere was no association between
sex and whether anomalies occurred singly
or multiply (2×2 contingency table: G=0.116,
1df, P=0.773).
(iv) Location: anomalous ventral scales occurred
more commonly on the posterior third of
the body (especially the last 20 scales before
the vent and the subcaudal scales) with 72%
(113 of 157) located there. is distribu-
tion departed signicantly from uniformity
(G=97.4, 1df, P<<0.0001). Of all anomalies,
63% were restricted to ventral scales be-
tween the head and the vent and no anomaly
type was restricted to either these scales or
the subcaudal scales. Anomalous ventral
pre-anal scales were common, representing
35.7% of all anomalies, followed by subcau-
dal scale anomalies (22.9%). Anomalous
scales on the mid and anterior body were
uncommon, comprising 5.7% and 13.6% of
all anomalies respectively. Approximately one-
quarter (26.8%) of all subcaudal scale anoma-
lies aected the rst three subcaudal scales.
ree snakes had a divided anal scale (2.1%).
Analysis of affected snakes: interactions
between factors
Tests of association between size class, sex,
location and anomaly type revealed only one
strong association, which was between the
location of ventral scale anomalies (catego-
ries: ventral scales excluding pre-anal scales,
pre-anal scales + anal scale, subcaudal scales)
and sex (3×2 contingency table: G=17.16, 2df,
P=0.0002; see Table 2). When the subcaudal
scales are excluded from the analysis, there was
a marginally signicant association between
the presence/absence of ventral scale anomalies
and sex due to females possessing signicantly
more anomalies than males (2×2 contingency
table: G=3.98, 1df, P=0.046). Conversely there
was a strong association between the pres-
ence/absence of subcaudal scale anomalies
and sex (2×2 contingency table: G=7.53, 1df,
P=0.006) with males possessing signicantly
more anomalies than females. is indicates
that subcaudal scale anomalies provided the
main contribution to the strong association
between the location of ventral scale anomalies
and sex. Anomaly type and size class were not
signicantly associated with any other variable
(Table 2).
Other scale anomalies
Several other types of anomalous scales oc-
curred, albeit rarely, and were not included in
the above analyses. An indented line or crease
running down the middle of the ventral surface,
usually terminating at the vent, was observed in
six snakes. Enlarged and sometimes irregularly
shaped dorsal scales were also recorded singly
(n=5). Some head scale anomalies were ob-
served: in one neonate a scale was fused to the
le parietal scale (enlarged head scale) while in
ve other (adult) snakes the suture separating
the le and right parietals was incompletely
formed. Additionally, variations in the number
of scales abutting the le versus the right pari-
etal scales (see Brown et al. 2017) were noted
but were not considered in this study. ere
were also instances of small amelanotic (white
or cream) patches on ventral and subcaudal
scales (n=15).
Table 2. Tableaux containing the probabilities from contingency table G-tests of association between the four
anomalous ventral scale variables in the Little Whip Snake Suta agellum. Statistically signicant results (i.e.
P<0.05) are in bold type.
Size Class Sex Location Type
Size Class 0.435 0.155 0.172
Sex 0.0002 0.713
Location – 0.547
Typ e
50 e Victorian Naturalist
Research Report
Whether the ventral scale anomalies document-
ed in S. agellum originate from the disruption
of normal development (a consequence of en-
vironmental disturbances for instance), genetic
stress (resulting from a loss of genetic diversity
or dri) or a combination of both has not been
determined in this work. In S. agellum the
overall percentage frequency of anomalies was
relatively high (35%) but falls within the broad
range reported in other studies of snakes (15%
to 92%, though some sample sizes were small;
Plummer 1980; Schwaner 1990; Merilä et al.
1992; Forsman et al. 1994). e high frequency
of anomalies in S. agellum would suggest some
degree of environmental and/or genetic stress
in the populations studied. To determine if this
is the case, a comparison with a relatively large
and undisturbed population of S. agellum
would be useful in establishing the natural or
‘background’ frequency of anomalies. Alterna-
tively, the examination of museum specimens,
which originate from multiple locations, popu-
lations and times, might also be useful in deter-
mining some measure of the natural frequency
of anomalies, though sample size might limit
the feasibility of this estimate (Museums Victo-
ria 2020: 288 specimens and only approximate-
ly 40% of these are from locations on the basalt
plains). Estimates of heterozygosity (i.e. ge-
netic diversity) of each population in this study
would also have been informative (though is
now not possible for two of the populations
due to localised extinctions, and fragmentation
of the third) as studies have consistently shown
an inverse (negative) relationship between the
occurrence of anomalies and heterozygosity
(Parsons 1990; Schwaner 1990). In S. agellum,
the frequency of anomalous ventral scales did
not dier signicantly between populations;
however, it may be notable that the highest fre-
quency of anomalies occurred in the smallest
population whose habitat was subject to the
greatest (anthropogenic) disturbance.
All six ventral scale anomalies identied by
Peters (1969) were among the nine types iden-
tied in this work (type 1=B, type 2=C, type
3=H, type 4=F, type 5=D, type 6=A) while the
further three anomalies in this study (types E,
G and I) were not. e predominance of type
B anomalies in S. agellum was consistent with
other studies (types B and C, Peters 1969; types
B, C and H, Schwaner 1990; types B and A, and
possibly type C also, Merilä et al. 1992; type
B, Plummer 1980). Most, but not all studies
(e.g. Schwaner 1990), have found a high pro-
portion of pre-anal scale anomalies (Plummer
1980, Merilä et al. 1992, Shine et al. 2005) as
in this work, although a signicant proportion
of anomalies was also found to aect subcau-
dal scales in S. agellum (22.9% versus 35.7%).
Forsman et al. (1994) found some evidence that
mid-body anomalies may be more deleterious
than those located elsewhere on the ventral
surface. Given the similarity of most anomaly
types in this work to those found in other stud-
ies, where anomalies were shown to be a mani-
festation of underlying skeletal deformities, it
is likely that type B, E and H anomalies repre-
sent the duplication of a rib on one side of the
body, while type D anomalies could represent
the omission of rib on one side of the body.
Plummer (1980) stated that the predominance
of one anomaly type and its consistent location
on the body of individuals favoured a genetic
rather than an environmental cause. In S. a-
gellum type B anomalies occurred with at least
four times the frequency of any other type, and
almost 60% of anomalies occurred on either
the pre-anal or subcaudal scales (i.e. near or on
the ventral tail surface) which may suggest that
these anomalies in S. agellum are controlled
genetically. However, the tendency for type B
anomalies to occur more frequently on one
side (le) of the ventral surface, would seem to
contradict this as the same genes are known to
control development on both sides of the body
(Lӧwenborg et al. 2011).
e tendency for asymmetries to occur sig-
nicantly more oen on the le-hand side of
the ventral surface rather than the right in S.
agellum indicates directional rather uctuat-
ing asymmetry (see Parsons (1990) and Palmer
(1994) for a detailed discussion of asymmetry
types). is tendency has been recorded in
several other snake species in which anoma-
lies were correlated with corresponding asym-
metries in the male reproductive system, less
mating success, a higher incidence of tail inju-
ries, slightly lower survival and higher growth
rates (Shine et al. 2000; Shine et al. 2005; Razzetti
et al. 2007; Brown et al. 2017).
51Vol 138 (2) 2021
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A signicantly higher frequency of scale anom-
alies in one sex has been reported in only a
few studies (Arnold and Peterson 2002; Shine
et al. 2005; Brown et al. 2017). Signicantly
more female than male S. agellum possessed
ventral scale anomalies. Sex bias is unlikely to
be explained by environmental factors aect-
ing development as such factors should operate
equally on both sexes in utero and so is con-
sistent with a genetic origin of anomalies in S.
agellum. However, the main contribution to
the signicant association between sex and the
location of anomalies was due to males hav-
ing more subcaudal scale anomalies compared
to females, which in turn may be due to males
having longer tails (and hence higher numbers
of subcaudals). Further studies need to include
subcaudal scale counts in order to resolve this
It is unlikely that the ventral scale anomalies
observed in S. agellum have any direct func-
tional signicance, with only small numbers of
anomalies occurring in the majority of aected
snakes. Some scale anomalies, however, are
known to reduce the tness of individuals, lead-
ing to dierential survival in the wild (Dunn 1942;
Inger 1942, 1943; Forsman et al. 1994). Examples
of S. agellum with large numbers of anoma-
lies were observed in this study, and have been
reported in several other species, though oen
in conjunction with more severe and lethal
deformities (Bellairs 1965; Pendlebury 1976;
Turner 1998). e similar frequency and types of
anomalies occurring in the adult and juvenile
size classes in S. agellum would indicate that
anomalies do not signicantly aect survival,
though whether they aect other components
of tness (e.g. reproduction) is unknown. e
high frequency of anomalies reported in some
populations has led to the suggestion that ven-
tral scale anomalies do not confer a great se-
lective disadvantage to their carriers (Plummer
1980; Merilä et al. 1992). Forsman et al. (1994)
examined the inuence of scale anomalies on
survival in Adders Vipera berus and deter-
mined a signicant dierence in the frequency
of mid-body scale anomalies between captive-
born neonates and wild juveniles. ey argued
that anomalies may commonly persist despite
strong selection against them if: (i) they result
primarily from environmental stress, and (ii)
the position of anomalies determines their ef-
fect on tness.
Scale anomalies in S. agellum can provide a
natural, permanent marker and are a useful ad-
junct in identifying individual snakes. Shine et
al. (1988) described the use of anomalous sub-
caudal scales in identifying individual snakes
in mark-recapture studies of two snake spe-
cies in which there was sucient variability in
anomaly type and position. Brown et al (2017)
recorded the presence/absence of ventral-scale
anomalies on the posterior quarter of the body,
in addition to scale-clipping, to assist with the
identication of individual snakes. In S. agel-
lum the tendency for anomalies to occur in
particular locations (e.g. pre-anal scales) and to
consist mainly of only a few types, limits their
use as natural identication markers. None-
theless these anomalies have been successfully
used in conjunction with other identiers such
as sex, ventral coloration, and snout band pig-
ment for this purpose (Turner, unpublished
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Submitted 10 October 2019; accepted 10 October 2020
ResearchGate has not been able to resolve any citations for this publication.
Full-text available
Three populations of the Little Whip Snake Parasuta flagellum inhabiting remnant grasslands to the north and west of Melbourne were examined. Most snakes (79%) were located by day from Apr-Oct when inactive beneath surface stones resting either directly on soil or on other stones. During this period feeding and growth were minimal and no mortality was recorded. During the active season (Nov-Mar) significantly fewer snakes were located beneath stones compared to the rest of the year; instead they occupied soil cracks and cavities by day. The size structure of the three populations was bimodal, with adults most abundant (51 ‒ 61%), followed by juveniles (22 ‒ 36%); sub-adults were uncommon throughout the year. The three populations were very similar in almost all measures. The sex ratio in each population and in each size class was unity (1:1). Body size did not differ significantly between adult males and females, however, males had significantly longer tails than females at all sizes. Parturition occurred from late January through to mid-April, and sexual maturity was likely attained by the onset of the second winter. Snakes fed mainly, if not exclusively, on small skinks. Sloughing occurred typically twice per year in adults and at least three times per year in immature snakes during the active season. Sources of mortality included grass fires.
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The occurence of fatal congenital deformities in neonate Little Whip Snakes (Suta flagellum) are described.
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Victoria's reptiles are not often encountered by urban dwellers, with many species now threatened. You may have glimpsed a skink darting into the undergrowth, a snake slithering along a walking path or a blue-tongued lizard sunning itself near your garden shed. Yet the turtles, skinks, geckos, goannas, snakes and other reptiles that call Victoria home are fascinating and important members of urban and rural ecosystems. Reptiles of Victoria is the first regional guide to all reptiles known to occur in Victoria. It contains keys and illustrated descriptions to allow identification of the 123 native, introduced and vagrant reptile species and describes their biology, ecology, distributions and the habitats in which they live. It also indicates the level of risk that the venomous snakes pose to humans and includes a brief section on first aid for snake bites. Natural history enthusiasts and professional and amateur herpetologists will find this an essential guide.
We present a model to test Osgood’s (1978) proposition that viviparous snakes have optimal reaction norms for temperature‐sensitive meristic traits, such as scale counts. Our model predicts that traits that are subject to temperature effects during development will evolve a flat or \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $\textsf{U}$\end{document} ‐shaped reaction norm (average scale count as a function of developmental temperature). We tested this prediction by maintaining 67 female garter snakes (Thamnophis elegans) at eight different constant temperatures (21°–33°C) during pregnancy and making a series of scale counts on their newborn offspring ( \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $n=491$ \end{document} ). To insure that the experimental temperatures were ecologically relevant, we used automated radiotelemetry to record the body temperature of pregnant, free‐ranging females. The resulting temperature data allowed us to test the prediction that the inflection points of reaction norms would correspond to the average temperature experienced by embryos in the field. In line with predictions of the Osgood model, reaction norms were flat or \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $\textsf{U}$\end{document} ‐shaped. In the case of \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $\textsf{U}$\end{document} ‐shaped reaction norms, the inflection point of the curves corresponded to the average temperature imposed on embryos by free‐ranging females. In contrast to some past studies, none of the standard scale scores (ones commonly used in systematics) showed significant temperature effects in either sex. Reaction norms were flat. In contrast, incidences of various abnormalities showed \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $\textsf{U}$\end{document} ‐shaped reaction norms. Temperature effects were more pronounced in males than in females. The results have implications for systematics and for the evolution of canalization and phenotypic plasticity.