MORPHOMETRIC ANALYSIS OF SPINY TAILED LIZARD (SAARA HARDWICKII) FROM LESSER CHOLISTAN DESERT, BAHAWALPUR, PUNJAB, PAKISTAN

S. Khalil^1,*, A. H. Rana¹ and T. Hussain¹

¹Department of Forestry Range and Wildlife Management, University college of Agriculture and Environmental Sciences, The Islamia University of Bahawalpur, 63100, Pakistan

*Corresponding Author’s Email: sangam.khalil@iub.edu.pk

ABSTRACT

Current study was conducted to collect the data on morphometric of spiny-tailed lizard (Saara hardwickii) in lesser Cholistan desert area, Punjab, Pakistan. Fifty one spiny- tailed lizards were collected from poachers with the help of the Punjab Parks & Wildlife Department, Pakistan. Among them 23 were male, 21 were females and 7 were hatclings. Total body mass recorded was: Female=17.50-102 g, Male=19-174.50 g). Total body length (BL) ranged in male: 16-20 cm and female 12-15 cm). Snout vent length (SVL) measured for all specimens were; male 8-16.70 cm and female 7.70-14.05 cm). Tail length (TL) was ranged from 13-19 cm in male and 14-160cm in female and spines on tail were 25-31 in male and 21-25 in female. Comparison between male and female morphometric was made using the Analysis of Co-Variance (ANCOVA). The f-ratio value was 19.291. The result is significant at p < .01. Habitat destruction and illegal trading have devastated the survival and existence of Indian spiny-tailed lizard and make it conservation dependent. Detail study is required on ecology of spiny-tailed lizard for its management and conservation in lesser Cholistan desert; one of major areas of its distribution in Pakistan.

Key Words: Spiny-tailed Lizard, Cholistan, Morphometrics, Growth.

https://doi.org/10.36899/JAPS.2022.1.0425
Published online June 14, 2021

INTRODUCTION

Eight families represent lizards in Pakistan: Varanidae, Chamaeleonidae, Lacertidae, Scincidae, Gekkonidae, Eublepharidae, Uromastycidae, and Agamidae (Khan, 2006). The genus Saara (Family Uromastycidae) is represented by three species in the world (Wilms et al., 2009), of which two, Seistan Spiny-tailed Ground Lizard (Saara asmussi) and Spiny-tailed Ground Lizard of Indus Valley (Saara hardwickii), occur in Pakistan. In Pakistan, Spiny-tailed Lizard is distributed all over the Indus Valley extending up to Las Bela, south Baluchistan. The lizard is facing a threat of illegal trapping in the Chakwal District (Rais et al., 2012).

The lizard occurs in soils with clayey to hard texture areas with sparse xerophytic vegetation (Sanjay et al., 2013; Ramesh and Sankaran, 2013). A few studies are available on the diet of Uromastids from different parts of the world, using fecal pellet analysis and field observations on its foraging. Uromastyx aegyptia microlepis also called Arabian Spiny-tailed Lizard, feeds on plants and insects (Mansour, 2001) while occasional scavenging activity of different lizard species is also known (Castilla et al., 2011; Perez-Cembranos, 2015; Baeckens et al., 2017; Perez-Cembranos et al., 2017). Spiny-tailed Lizard is primarily herbivorous (Dutta and Jhala, 2007; Sanjay et al., 2013) and may incidentally ingest insects and nematodes along with the vegetation (Sanjay et al., 2005).

Spiny-tailed lizards have uneven distribution in Pakistan, India and Afghanistan (Wilms et al., 2009). In India, it is the only lizard that is herbivorous and is distributed mainly in the Rajasthan desert called Thar and Gujarat (Das, 2002; Daniel, 2002; Ramesh and Ishwar, 2008; Wilms et al., 2009; Das et al., 2013). Once common, these species now appear in small, fragmented and diminishing populations and are considered threatened due to territory destruction and unlawful collection for domestic trade (Das et al., 2013). In Rajasthan, outskirts of the Thar Desert, this species is only identified in the enclosed area of Bardod, Alwar District (Sharma, 2002).

Spiny-tailed lizard is found mainly on fruits, grasses, flowers and shrub leaves, and fulfills its water requirements by feeding on the digestion of subcutaneous fat (Daniel, 2002; Khan and Mahmood, 2004). Usually, the Uromastyx activity is low in the winter season and gets increased in summer and spring seasons. The mating occurs in months of March and April. Around 14 eggs are laid by females between the months of April, May and June (Daniel, 2002; Das, 2002; Khan and Mahmood, 2004). The most known number of populations of the solitary burrow dweller is 10-100 per square kilometer, usually with almost 50 grownups in a specific group (Bhatnagar et al. 1973; Das, 2002; Knapp, 2004). Huge territories are being occupied by them, but there are very few known details about their territoriality.

On the nutrition and feeding habits of this spiny tailed lizard, there have been several studies already carried out which indicated that this lizard is strictly herbivorous Anderson, (1898) Purves, (1915), Smith, (1935), Krishna (1955), Krishna and Dave (1956), Schmidt and Inger (1957), Cloudsley-Thompson and Chadwick (1964), Minton (1966) and Sharma (1977, 2002), Smith (1935) and Mayhew (1968) reported that the teeth of the young lizards differ from that of the adults, and they also feed on insects (Mertens, 1969; Pope, 1960 and Minton, 1966). But Pradhan, (1971), Bhanotar et al. (1972, 1973) and Pradhan et al. (1973) stated that the adult lizards are also insectivorous through their observations are established on the basis of feeding of this lizard in custody.

Indian spiny-tailed lizard is commonly found in the Desert of Rajasthan Called Thar, in India. However, despite a ban, there is still an excessive amount of killing off this lizard by humen for its fat, meat and skin, and the trade for its economic value. The tail is considered to be a great delicacy, the meat is said to be excellent and sweet, and the oil is extracted for medicinal purposes. These demands have placed the lizard on the endangered list. Habitat destruction on a large scale is another threat to this lizard's survival in the Thar Desert (Sharma, 2002).

During the summer months, this lizard emerges from its burrow in the early morning (between 8-9 am) (Sharma, 2002) and is active until an hour or two before sunset. But in winter, it comes out in the late morning (between 9.30-10.30 am) (Schmidt and Inger, 1957) and is active only during the warm hours of the day. Basking was noted. When emerging from its burrow, this lizard often raises itself as high as possible on its forelimbs to look around. It has a strict homing instinct and, when alarmed, will immediately run back to its burrow, even from a considerable distance (Sharma, 2002). When alarmed, the lizard's tail would often become slightly curved with the tip directed upward. It maintains this posture even when being chased (Schmidt and Lnger, 1957).

The Indian spiny-tailed lizard belongs to the Agamidae family and is one of the most unique reptiles. According to Wilms et al. (2009) its generic name has been recently resurrected from Uromastyx hardwickii to Sara hardwickii. These unique lizards live in twisting burrows (2 m long; 6– 8 cm wide) for living safely. The spiny-tailed lizard can be found now in the Indian Wildlife (Protection) Act (Schedule II) and CITES (Appendix II). Although the Red list of 1998 IUCN had listed this specific lizard as vulnerable, it has gone missing in the recent list. 'Sandho' is the local name given to it in Gujarat and is mercilessly hunted due to its aphrodisiac value. The ongoing land developments are already displacing these lizards due to the construction of a large number of housing and industrial units across rural Kachchh (Anonymous, 2017).

Most herpetological studies in Pakistan were very old and restricted mainly to the Pakistani provinces of Sindh and Balochistan (Murray, 1884; Boulenger, 1920; Smith, 1935; Minton, 1966; Mertens, 1969). Succeeding and quite latest research (Dubios and Khan, 1979; Khan, 1985, 1991, 1993 a, b; Khan and Baig, 1988, 1992; Baig, 1988a, c, 1989, 1990, 1992, 1996, 1997, 1998a, b, Baig et al., ; Khan and Tasnim, 1990; Baig and Bohme, 1991, 1996) created to uncover Pakistan's herpetological wealth. With the exception of Khan (1985), unluckily, everything else is correlated to parts of Pakistan other than Cholistan. 15 species from the region have already been documented by Khan (1985). An effort is being made for the Cholistan Desert exploration, a different and vital region in Pakistan.

MATERIALS AND METHODS

Study Area: The present study was conducted at random selected sites in Cholistan, Punjab, Pakistan. The selected sites were Lal Suhanra (29° 19°N, 71° 55°E) and Field Area of Islamia University Bahawalpur (29° 23° N, 71° 41°E) that specifically represents habitat of the desert. The area features a typical arid landscape with an annual average temperature of about 40.6°C and an average yearly rainfall of about 200 mm. The area consists of dunes, shrubs, and grasses.

Data Collection: The field research was conducted at study sites in lesser Cholistan desert from August 2018 to August 2019. Adult Spiny-Tailed lizards were collected from poachers with help of Punjab Wildlife Department, Pakistan. The spiny-tailed lizards were searched, near Lal Sohanra. The individuals of spiny-tailed lizards were also captured opportunistically, typically by coaxing them from refugia. At the point of capture, Snout to vent length (SVL) (+/- 0.1 cm) and tail length (TL; +/- 0.1 cm) was measured by using a steel scale and LCD vernier calliper. Body mass (BM; +/- 0.5 g) was calculated by a weighing balance (SK-5K Model) having range of 1g to 5kg. Growth rate was also observed by counting scales and on the basis of scales; adults and hatchlings were categorized (see table 1.1).

Statistical Analysis: Analysis of Co-Variance (ANCOVA) was done to compare the male and female morphometry. All statistics were performed in the program SPSS with level of significance (α 0.05 %)

Table 1.1: Body measurements for all captured individuals of Spiny-tailed lizard.

RESULTS AND DISCUSSION

51 individuals (23M, 21F, 7 Hatchlings) were captured across the study sites from August 2018 to August 2019. Based on morphometric measurements, males were significantly longer and more substantial than females and also heavier at a given SVL (snout to vent length) than females (Table 1.2).

Table 1.2: Spiny-tailed lizards Snout vent length (SVL (cm) and Body mass (BM (g) for all individuals. Means include one standard error. Statistics provided for non-hatchling male and female comparisons.

Males (12.96 ± 0.21 cm) were significantly longer than females (11.57 ± 0.16 cm; ANCOVA; F1,83 = 19.68, p < 0.001) with no significant effect of year (ANCOVA; F1,83 = 0.189, p = 0.665). In addition, Males (76.95 ± 3.40g) were significantly heavier than females (48.88 ± 1.96 g; ANCOVA; F1,83 = 27.621, p < 0.001) with no significant effect of year (ANCOVA;F1,83 = 0.744, p = 0.391). Males were significantly heavier at a given SVL than females after log transforming both variables (ANCOVA; F1, 83 = 6.010; p = 0.016) with the assumption of homogeneous slopes (ANCOVA; F1, 83 = 0.568, p = 0.453) (Figure 1.1).

Both were combined for comparison. Male SVL and BM (12.77 ± 0.30 cm; 72.26 ± 4.66 g) were not significantly different (t-Test; t14.75 = -0.655, p = 0.522; t17.08 = -1.704, p = 0.107). However, females (12.58 ± 0.26 cm; 59.50 ± 4.12 g) were significantly longer and heavier than males (11.13 ± 0.20 cm; 43.88 ± 2.29 g; t-Test; t17.31 = -4.391, p < 0.001; t11.77 = -3.315, p = 0.006). Males were heavier at a given SVL than females (ANCOVA; F3,97 = 6.701, p < 0.005) with the assumption of homogeneous slopes (ANCOVA; F3,97 = 0.328, p = 0.805).

Body composition index was not significantly different in males (Figure 4.2; t15.26 = 0.598, p = 0.559) or female t-Test; t11.20 = 1.288, p = 0.224). Likewise, BCI was not significantly different across sites in females (Figure 1.2; t28.52 = -0.106, p = 0.917). However, body composition index (BCI) was significantly greater in males (Figure 1.3; t-Test; t13.28 = -2.538, p = 0.024).

Growth rate in SVL and BM did not significantly differ between males (0.157 ± 0.091 mm/day; 0.079 ± 0.120 g/day) and females (-0.032 ± 0.056 g/day; t-Test; t18.13 = 2.039, p = 0.056; t14.08 = 0.843, p = 0.413). Snout-vent length growth rate did not significantly vary with initial SVL (LSR; F1, 22 = 0.204, p = 0.656), and BM growth rate did not significantly vary with initial BM (LSR; F1, 22 = 0.194, p =0.664). Growth rates were not significantly different across years at PB for SVL or BM (t-Test; t12.88 = -0.516, p = 0.6143; t19.19 = -1.219, p = 0.238). In SVL growth rate was 0.375 ± 0.375 mm/day and BM growth rate was 0.039 ± 0.034 g/day (N = 2). In 2019, total body fat (TBF) was 66%, 57% in males, and 82% in females (Figure 1.4).

Combining both season of the years of range wide captures, 79.6% were in two consecutive size classes, ranging from 10.26 to 15.25 cm and size class distribution between sexes was significantly different (X25 = 12.692; p = 0.026). Sex ratio of all captures was male biased and did not fluctuate considerably between seasons (X21 = 2.504, p = 0.114). Sex ratio was male biased and did not differ significantly between season of years (X21 = 0.396, p = 0.842). Size class distribution was not significantly different between sites (X25 = 6.483, p = 0.262), nor was sex ratio of captures (X2 < 0.001, p = 1).

The spiny-tailed lizard is listed as a critically endangered species due in part to having a small number of remaining mature individuals, which are predicted to face further declines and habitat loss and fragmentation. The research results added to the limited literature on the species' morphology and across its range. Males were significantly heavier than females at a given SVL, but the research findings may be due to the temporal sampling period. Having larger males is a sexual size-dimorphic pattern that is common in lizards, as has been observed in multiple species (Fitch, 1981; Carothers, 1984; Wikelski and Trillmich, 1997; Beovides-Casas and Mancina, 2006; Pasachnik et al., 2012a; Pasachnik, 2013). Carothers (1984) found lizard species with longer males to have more male aggression. The research did not observe any male aggression, but this is likely due to sampling season being outside of the mating season and more secretive nature of spiny-tailed lizard. Although exact dates for females laying eggs are not known for spiny-tailed lizards, females are likely still recovering from the loss of mass due to oviposition during the dry season. It was suspected that females deposited their eggs between December and early February. Sampling needs to be done in other periods of the year to determine if this relationship holds year-round.

Maximum SVL for females reported here increases the known maximum length for females from 12.36 cm to 14.05 cm (Kohler and Hasbun, 2001). Body composition index did not significantly differ between years or between sexes suggesting no substantial decline in relative fitness occurred between the two years. However, BCI was significantly different in males between sites, with males being significantly heavier. The spiny-tailed lizards might be lessening activity levels to wait out the dry season. Earlier study showed using field metabolic rate that Sceloporus lizards living in seasonal habitats are less active during harsh hot, dry seasons (Nagy, 1982). Previous studies of spiny-tailed lizards have found BCI to differ across sites (Pasachnik et al., 2012a, Pasachnik, 2013).

The female growth rates were negative for both length and mass. This decrease in mass might be explained by their reportedly later oviposition (JPC pers. comm.), and reductions in length have been reported to occur in marine lizards during periods of low food availability (Wielski and Thom, 2000). However, arguments have been made that shrinkage can be attributable to measurement error in snakes (Madsen and Shine, 2002). Although only two growth rates for hatchlings were collected, a minimal increase was found in mass compared to the increase in length. The limited hatchling growth data suggest that hatchlings benefit from being longer, more so than heavier. An explanation for growing longer quickly may be that it puts them out of susceptible predation range for certain predators, whether by increasing their maximum avoidance speed or being too large to capture or ingest. However, Madsen and Shine (2002) explained this relationship between length and mass growth in hatchling pythons as the result of lack of feeding until individuals have fully absorbed their yolk.

Although Kohler and Hasbun (2001) described spiny-tailed lizard as occasionally possessing brown dorsal coloration, none of the spiny-tailed lizards captured in study showed this character (Henderson, 1973; Kohler, 1998; Morales-Mavil, 2015; Goode and Pasachnik, 2016) or grey-brown such as C. bakeri (Schulte and Kohler, 2010).

A majority of non-hatchlings of both sexes had tail breaks in 2019, which may be due to male competition, male aggression towards females, and defense against predators, including humans. Based on my observations, spiny-tailed lizards spend the majority of the time wedged in tree holes or fence posts during the dry season. When encountered, the only portion of the accessible individual was the tail. Spiny-tailed lizard tails are extensively spinose proximally, which would likely deter predators. However, the more distal parts of the rear do not have extensive spiny processes leaving them vulnerable to breakage during predation attempts. Similar refuge behavior has been observed in close spiny-tailed relatives (Malone et al., 2017).

This research sampling was limited to the dry season, and hatchling emergence did not commence until well into field seasons. Therefore, the sampling was biased against smaller individuals. That is, it lacked the majority of the first year of juvenile growth (August to February), and half of the fieldwork occurred while hatchlings were not present. A significantly different size class distribution was captured, which can be attributed to more hatchlings being caught in 2019. In 2019, efforts were made to include smaller refugia in searches, which were not included in the majority of searches in 2018 due to a lack of previous knowledge of hatchling behaviour.

Lower numbers of individuals in the largest size class agree with previous studies of spiny-tailed lizards (Pasachnik et al., 2012a, b; Pasachnik, 2013). Similar to other species of spiny-tailed lizards (Fitch and Henderson, 1978; Pasachnik et al., 2012a; Pasachnik et al., 2014), locals report hunters to prefer harvesting the largest spiny-tailed lizard individuals. Furthermore, hunting is concentrated towards gravid females during the nesting season.

Size class distribution shows no difference in captures and consists of a bell curve distribution with a median size class of 10.26 to 12.75 cm, which is likely, not indicative of the actual population. Due to the lack of data from months August through February, the distribution of my data is biased against small-sized individuals.

Conclusion: The present study is one of the first conservations attempts for Indian spiny-tailed lizards that shows that non-invasive techniques can be used successfully for the conservation of any reptile in the future. We concluded that the male lizard was longer in total length and SVL as compared to female. Also male specimens were heavier in body mass (BM) and darker in color than female specimens. Tail broken specimens were found mainly in males. Main damage caused to spiny tailed lizard (Saara hardwickii) is by poachers and illegal hunting. Law enforcement and awareness is mainly required for this species conservation and protection.

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