Cordylid Lizards Research Articles

Burrow site selection in the Sungazer (Smaug giganteus): a threatened South African endemic lizard

ABSTRACT Elucidating factors that drive microhabitat selection in a species is important for informing the conservation management of the species. For species that use microhabitats as long-term refuge sites, selection pressures are likely to be strong because the microhabitat must fulfil their eco-physiological and life history requirements. Smaug giganteus (Sungazer) is a threatened (Vulnerable) cordylid lizard species in the highveld grasslands of South Africa – a key agricultural area in the country. Individuals dig burrows as refuges, which increases their sensitivity to habitat transformation. In addition, previous attempts to translocate populations have failed due to a lack of knowledge about their specific microhabitat requirements. We assessed microhabitat characteristics that may influence burrow site selection by measuring vegetation characteristics surrounding Sungazer burrows and comparing these to vegetation at randomly selected sites. We also recorded orientation, aspect, soil composition, and the presence of other animal dung. Sungazers selected sites with sparse vegetation cover, and where grass height was short, but had no preference for soil composition. There was no relationship between the presence of ungulate dung and the placement of Sungazer burrows. Most Sungazer burrows were orientated in a northerly direction on north-facing slopes, suggesting that burrow placement has thermoregulatory advantages. We recommend that to identify suitable sites for Sungazer translocations, landscapes are thoroughly surveyed with cognisance to the findings in this study, and that a soft-release translocation protocol follows to maximise translocation success.

Body size and substrate use affect ventral, but not dorsal, brightness evolution in lizards.

Substrate properties can affect the thermal balance of organisms, and the colored integument, alongside other factors, may influence heat transfer via differential absorption and reflection. Dark coloration may lead to higher heat absorption and could be advantageous when substrates are cool (and vice versa for bright coloration), but these effects are rarely investigated. Here, we examined the effect of substrate reflectance, specific heat capacity (cp), and body size on the dorso-ventral brightness using 276 samples from 12 species of cordylid lizards distributed across 26 sites in South Africa. We predicted, and found, that bright ventral colors occur more frequently in low cp (i.e., drier, with little energy needed for temperature change) substrates, especially in larger body-sized individuals, possibly to better modulate heat transfer with the surrounding environment. By contrast, dorsal brightness was not associated with body size nor any substrate thermal property, suggesting selection pressures other than thermoregulation. Ancestral estimation and evolutionary rate analyses suggest that ventral brightness rapidly differentiated within the Cordylinae starting 25 Mya, coinciding with an aridification period, further hinting at a thermoregulatory role for ventral colors. Our study indicates that substrate properties can have a direct role in shaping the evolution of ventral brightness in ectotherms.

Morphological and molecular diagnosis of two new species of Trypanosoma Gruby, 1843 infecting South African cordylid lizards (Squamata: Cordylidae: Cordylinae), Trypanosoma (Squamatrypanum) ndumoensis n. sp. and Trypanosoma (Trypanosoma) tokoloshi n. sp.

Despite reptile trypanosomes forming a large group, the majority of species descriptions are data deficient, lacking key characteristic data and supporting molecular data. Reptile hosts show potential to facilitate transmission of zoonotic trypanosomiases and offer key information to understanding the genus of Trypanosoma. Several species of squamates from different localities in South Africa were screened molecularly and microscopically for trypanosomes in the present study. Based on the combination of morphological and molecular analyses, two new species of Trypanosoma, Trypanosoma (Squamatrypanum) ndumoensis n. sp. and Trypanosoma (Trypanosoma) tokoloshi n. sp., infecting South African cordylid lizards (Cordylidae: Cordylinae) are described in this study. The first molecular data for a South African reptile trypanosome is provided herewith.

Partitioned parturition: Birthing asynchrony in cordylid lizards

AbstractHatching/birthing asynchrony, when siblings emerge at least 12 h apart, is thought to be a significant driver of phenotypic variation and group cohesion that is commonly reported in invertebrates and birds, but rarely in squamates. We examined birthing asynchrony in African cordylid lizards (Cordylidae), a clade characterized by a wide range of sociality (a hypothesized evolutionary driver of this unique phenomenon). We monitored parturition from wild‐caught mothers from four species, which vary in their conspecific grouping behaviour. In two species, most litters were born asynchronously, over a maximum of 3–4 days respectively. The other two cordylids also exhibited asynchronous birth in all litters with more than one offspring, although this was not applicable for most litters because there was a prevalence of singleton litters. Our study uncovered birthing asynchrony in a novel taxonomic group, which suggests it evolved convergently in at least two social lizard clades from different continents. Furthermore, the function of birthing asynchrony and limiting litter size to a single offspring may be similar in social animals. We discuss the potential significance of this rare phenomenon in this disparate taxon, and compare it with other more well‐studied taxa, in order to guide future research directions.

Social and spatial patterns of two Afromontane crag lizards (Pseudocordylus spp.) in the Maloti‐Drakensberg Mountains, South Africa

AbstractUnderstanding the evolution of vertebrate sociality requires comparative data on social associations across the vertebrate phylogeny. In the case of group‐living lizards (i.e. species that live in stable social aggregations often associated with a shared resource), most work has focused on the Egerniinae in Australia, resulting in a taxonomic and geographic skew to our understanding of reptile sociality. The African cordylid lizards (Cordylidae) are also a promising system to study the evolution of sociality because grouping behaviour varies across the clade. Here, we studied the conspecific grouping behaviour of two crag lizards, Pseudocordylus langi and P. melanotus subviridis that occur at high elevations in the Maloti‐Drakensberg Mountains of South Africa. To better understand their social organisation and mating system, we also present data on their spatial distribution, sexual dimorphism, and bite force. Both Pseudocordylus spp. were sexually dimorphic in morphology (males had larger heads than females of similar body size), colouration (males were more colourful) and female P. langi had a weaker bite force than males. Both P. langi and P. m. subviridis were associated with rocky habitat on the mountainside (e.g. cliffs, rock buttresses, and rock outcrops) and both were spaced apart and rarely in groups (79% of P. langi and 90% of P. m. subviridis were observed alone). Based on our findings, we hypothesise that both Pseudocordylus spp. have a territorial social structure and a polygynous mating system. This novel natural history information about crag lizards supports the assertion that Cordylidae is another model system for examining the evolution of sociality.

Non-invasive monitoring of glucocorticoid metabolite concentrations in urine and faeces of the Sungazer (Smaug giganteus).

Developing non-invasive techniques for monitoring physiological stress responses has been conducted in a number of mammal and bird species, revolutionizing field-based endocrinology and conservation practices. However, studies validating and monitoring glucocorticoid concentrations in reptiles are still limited. The aim of the study was to validate a method for monitoring glucocorticoid metabolite concentrations in urine (uGCM) and faeces (fGCM) of the cordylid lizard, the Sungazer (Smaug giganteus). An adrenocorticotropic hormone (ACTH) challenge was conducted on one male and two females with both urine and faecal material being collected during baseline and post-injection periods. Steroid extracts were analysed with four enzyme immunoassays (EIAs)namely: 11-oxoaetiocholanolone, 5α-pregnane-3β-11β-21-triol-20-one, tetrahydrocorticosterone, and corticosterone. A considerable response in fGCM and uGCM concentrations following ACTH administration was observed in all subjects, with the 5α-pregnane-3β-11β-21-triol-20-one and tetrahydrocorticosterone EIAs appearing to be the most suited for monitoring alterations in glucocorticoid metabolite concentrations in S. giganteus using faeces or urine as hormone matrix. Both EIAs showed a significantly higher concentration of glucocorticoid metabolites in faeces compared to urine for both sexes. Collectively, the findings of this study confirmed that both urine and faeces can be used to non-invasively assess adrenocortical function in S. giganteus.

The relationship between generation gland morphology and armour in Dragon Lizards (Smaug): a reassessment of ancestral states for the Cordylidae

Abstract To substantiate the claim of a relationship between generation gland morphology and degree of body armour in cordylid lizards, we studied the nine species in the genus Smaug. We predicted that well armoured species in this clade will have multi-layer generation glands, and lightly armoured species two-layer glands. Gland type was determined using standard histological techniques after sectioning a glandular patch of one adult male per species. A total of 133 specimens were examined for data on tail and occipital spine lengths (which were used as indicators of armour). We found that species with multi-layer generation glands (S. giganteus, S. breyeri, and S. vandami) have relatively long tail and occipital spines, while species with two-layer glands (S. mossambicus, S. regius, S. barbertonensis, S. warreni, and an undescribed species) have relatively short spines. Smaug depressus possesses both multi-layer and two-layer glands, and this variation was linked to regional variation in spine length. An ancestral state reconstruction for the Cordylidae showed that the two-layer state always results from the reduction of layers from a multi-layer precursor, and that reduction always culminates in two-layer glands and not in one-layer glands. This finding suggests that the one-layer state in the Ninurta-Chamaesaura-Pseudocordylus clade is most probably plesiomorphic, and therefore the ancestral state at the Cordylidae and Cordylinae nodes. Given the observed relationship between type of generation gland and body armour, this finding would suggest that the most recent common ancestor of the Cordylidae was lightly armoured.

Functional trade-off between strength and thermal capacity of dermal armor: Insights from girdled lizards

The presence of dermal armor is often unambiguously considered the result of an evolutionary predator-prey arms-race. Recent studies focusing predominantly on osteoderms – mineralized elements embedded in the dermis layer of various extant and extinct vertebrates – have instead proposed that dermal armor might exhibit additional functionalities besides protection. Multiple divergent functionalities could impose conflicting demands on a phenotype, yet, functional trade-offs in dermal armor have rarely been investigated. Here, we use high-resolution micro-computed tomography and voxel-based simulations to test for a trade-off between the strength and thermal capacity of osteoderms using two armored cordylid lizards as model organisms. We demonstrate that high vascularization, associated with improved thermal capacity might limit the strength of osteoderms. These results call for a holistic, cautionary future approach to studies investigating dermal armor, especially those aiming to inspire artificial protective materials.

A new lizard malaria parasite Plasmodium intabazwe n. sp. (Apicomplexa: Haemospororida: Plasmodiidae) in the Afromontane Pseudocordylus melanotus (Sauria: Cordylidae) with a review of African saurian malaria parasites.

BackgroundSaurian malaria parasites are diverse apicomplexan blood parasites including the family Plasmodiidae Mesnil, 1903, and have been studied since the early 1900s. Currently, at least 27 species of Plasmodium are recorded in African lizards, and to date only two species, Plasmodium zonuriae (Pienaar, 1962) and Plasmodium cordyli Telford, 1987, have been reported from the African endemic family Cordylidae. This paper presents a description of a new malaria parasite in a cordylid lizard and provides a phylogenetic hypothesis for saurian Plasmodium species from South Africa. Furthermore, it provides a tabular review of the Plasmodium species that to date have been formally described infecting species of African lizards.MethodsBlood samples were collected from 77 specimens of Pseudocordylus melanotus (A. Smith, 1838) from Platberg reserve in the Eastern Free State, and two specimens of Cordylus vittifer (Reichenow, 1887) from the Roodewalshoek conservancy in Mpumalanga (South Africa). Blood smears were Giemsa-stained, screened for haematozoa, specifically saurian malaria parasites, parasite stages were photographed and measured. A small volume was also preserved for TEM studies. Plasmodium and Haemoproteus primer sets, with a nested-polymerase chain reaction (PCR) protocol, were employed to target a fragment of the cytochrome-b (cyt-b) gene region. Resulting sequences of the saurian Plasmodium species’ isolates were compared with each other and to other known Plasmodium spp. sequences in the GenBank database.ResultsThe presence of P. zonuriae in both specimens of the type lizard host C. vittifer was confirmed using morphological characteristics, which subsequently allowed for the species’ molecular characterisation. Of the 77 P. melanotus, 44 were parasitised by a Plasmodium species, which when compared morphologically to other African saurian Plasmodium spp. and molecularly to P. zonuriae, supported its description as a new species Plasmodium intabazwe n. sp.ConclusionsThis is the first morphological and molecular account of Plasmodium species within the African endemic family Cordylidae from South Africa. The study highlights the need for molecular analysis of other cordylid Plasmodium species within Africa. Future studies should also include elucidating of the life-cycles of these species, thus promoting the use of both morphological and molecular characteristics in species descriptions of saurian malaria parasites.

Some Like It Hot: Camera Traps Unravel the Effects of Weather Conditions and Predator Presence on the Activity Levels of Two Lizards.

It is generally assumed that favourable weather conditions determine the activity levels of lizards, because of their temperature-dependent behavioural performance. Inactivity, however, might have a selective advantage over activity, as it could increase survival by reducing exposure to predators. Consequently, the effects of weather conditions on the activity patterns of lizards should be strongly influenced by the presence of predators. Using remote camera traps, we test the hypothesis that predator presence and weather conditions interact to modulate daily activity levels in two sedentary cordylid lizards, Karusasaurus polyzonus and Ouroborus cataphractus. While both species are closely related and have a fully overlapping distribution, the former is a fast-moving lightly armoured lizard, whereas the latter is a slow-moving heavily armoured lizard. The significant interspecific difference in antipredator morphology and consequently differential vulnerability to aerial and terrestrial predators, allowed us to unravel the effects of predation risk and weather conditions on activity levels. Our results demonstrate that K. polyzonus is predominantly active during summer, when ambient temperatures are favourable enough to permit activity. In contrast, a peak in activity during spring was observed in O. cataphractus, with individuals being inactive during most of summer. While favourable weather conditions had a strong effect on the activity levels of K. polyzonus, no such relationship was present in O. cataphractus. Contrary to our hypothesis, the presence of terrestrial predators does not seem to affect daily activity levels or alter the influence of weather conditions on activity levels. We conclude that inactivity in O. cataphractus appears to be related to seasonal differences in vulnerability to predators, rather than the presence of predators, and highlight the importance of additional selective pressures, such as food abundance, in determining the species’ activity levels.

What doesn't kill you might make you stronger: functional basis for variation in body armour.

1. Predation has been proposed to be a selective agent in the evolution of morphological antipredator strategies in prey. Among vertebrates, one of the morphological traits that evolved multiple times is body armour, including carapaces, thickened keratinized scales and plates of dermal bone. 2. It has been generally assumed that body armour provides protection against a predatory attack; yet, few explicit tests of the hypothesis exist. Cordylidae, a relatively small family of southern African lizards, show considerable variation in the degree of body armour. Hence, this family provides an opportunity to test the hypothesis that body armour serves as protection against predators. 3. Experiments were conducted to test whether the bite forces of four species of mammalian predators were high enough to penetrate the skins of Karusasaurus polyzonus, Namazonurus peersi, Cordylus cordylus and Cordylus macropholis, as well as those of Ouroborus cataphractus individuals originating from three localities that differed in their predator diversity. Furthermore, histological techniques were used to test whether variation in skin toughness was associated with concomitant changes in the degree of epidermal (i.e. β-keratin) and dermal (i.e. osteoderm) armour. 4. The skin toughness values for four out of five cordylid lizards tested in this study were well below the bite forces of the mammalian predators. In contrast, the thick osteoderms in the dermis of O. cataphractus can withstand bites from several mongoose species. However, the significant variation in body armour that is present between the three populations of O. cataphractus does not seem to be related to predator diversity. 5. It is concluded that body armour can serve as protection against predation in O. cataphractus, but that alternative selection pressures, such as thermoregulation or predation by snakes, presumably underlie variation in defensive morphology in the other cordylid lizards.

Hit or miss: Functional mechanisms underlying prey capture efficiency in three cordylid lizards

Prey capture is one of the most important behaviours in organisms as it directly determines energy acquisition, which in turn is vital for fitness and survival. The contribution of specific prey capture mechanisms to prey capture efficiency, however, remains largely unresolved, especially in groups where a variety of mechanisms is present, such as lizards. Using three sympatric cordylid lizards as model organisms, we investigated (1) the effect of lingual prehension on prey capture efficiency when feeding on small prey (i.e. termites) and (2) whether in species that use jaw prehension to capture prey, prey capture efficiency decreases with increasing predator-prey size ratio. Prey capture efficiency, defined as the proportion of termites that was captured at first attempt, was higher in the species using lingual prehension than in the similarly-sized species using jaw prehension. In contrast, the two species using jaw prehension had a similar prey capture efficiency, despite differences in body size. The observed variation in prey capture efficiency between lingual and jaw prehension is discussed in the light of foraging mode in lizards.

Generation glands of cordylid lizards: mechanism of secretion transfer to the environment

Cordylid lizards possess two types of holocrine epidermal glands involved in chemical communication, femoral glands and generation glands. We investigated how the glandular products of generation glands are dispersed to the environment, as it is assumed in earlier studies that glandular material of cordylid generation glands is transferred to the substrate via abrasion, similar to the situation in femoral glands. By means of scanning electron microscopy, we established that the outer gland surfaces of adult Cordylus cordylus, Hemicordylus capensis and Pseudocordylus microlepidotus show only localized signs of wear and tear, indicative of a very low abrasion rate. Using standard histological techniques and light microscopy, we studied the appearance of multi-layer generation glands in a series of individuals of different ages in Cordylus macropholis. In this species, generation glands are already conspicuous in neonates. The significant relationship between SVL and the number of generation layers that we recorded for C. macropholis suggests that abrasion is not the routine method of dispersal of glandular material. We did record significant differences in cross-sectional area and height between the outer and inner layers of multi-layer generation glands of Cordylus macropholis, but this is more likely attributable to ‘desiccation’ of the outer layer, rather than abrasion. Although we found signs of abrasion in cordylid generation glands, these appear minor. Evidence seems to suggest that a substantial part of the mature glandular generations remains intact and that probably only a liquid/semi-liquid component is dispersed to the environment. More research is, however, needed to confirm this.

The phylogenetic position of Ethiopia's sole endemic and biogeographically enigmatic cordylid lizard, Cordylus rivae (Squamata: Cordylidae), and a discussion of its conservation status

Although the genus Cordylus has received much recent attention, previous studies have failed to include all known species, particularly for biogeographically important taxa. Recent fieldwork targeted a previously known population of Cordylus rivae from the southeast of Ethiopia's Oromia region and we consequently found two individuals of this poorly documented species. We then sequenced 3 102 base pairs from both mitochondrial (12S, 16S) and nuclear (Kif24, MC1r, MYH, PRLR) gene regions for these individuals—the first ever genomic material for this taxon—and compared these data with those previously published for other Cordylus species. We analyzed these data using both phylogenetically relevant optimality criteria (i.e. Maximum Likelihood and Bayesian inference) as well as distance-based methods. Cordylus rivae forms a unique clade and groups closely with the other members of the East African Cordylus, particularly C. beraducci—the closest geographic neighbour. We discuss the biogeographic and conservation implications of C. rivae's current distribution and make some suggestions concerning future research into this poorly known species.

Under pressure: morphological and ecological correlates of bite force in the rock-dwelling lizardsOuroborus cataphractusandKarusasaurus polyzonus(Squamata: Cordylidae)

Rock-dwelling lizards are hypothesized to be highly constrained in the evolution of head morphology and, consequently, bite force. Because the ability to generate a high bite force might be advantageous for a species' dietary ecology, morphological changes in head configuration that allow individuals to maintain or improve their bite force under the constraint of crevice-dwelling behaviour are to be expected. The present study addressed this issue by examining head morphology, bite force, and a number of dietary traits in the rock-dwelling cordylid lizards Ouroborus cataphractus and Karusasaurus polyzonus. The results obtained show that O. cataphractus has a larger head and higher bite force than K. polyzonus. In K. polyzonus, head width, lower jaw length, and jaw closing-in lever are the best predictors of bite force, whereas head height is the main determinant of bite force in O. cataphractus. Although the observed difference in bite force between the species does not appear to be related to dietary patterns or prey handling, the prey spectrum available for intake was greater in O. cataphractus compared to K. polyzonus. We discuss the influence of interspecific differences in anti-predator morphology on head morphology and bite force in these rock-dwelling species. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111, 823–833.

An evaluation of daily, seasonal and population-level variation in the thermal preference of a group-living lizard, Ouroborus cataphractus (Sauria: Cordylidae)

Ectotherms are known to function optimally within a specific range of body temperatures, bordered by two set-point values (i.e. preferred temperature range; ). Preferred body temperature stands central in understanding behavioural thermoregulation in a thermally dynamic temperate environment. In this study we determined for the group-living cordylid lizard, Ouroborus cataphractus, during the respective annual peak periods in food availability and scarcity. Body temperatures were recorded in ecologically realistic photo-thermal gradients using body-mounted, modified iButtons. In addition to studying seasonal and spatial variation in we also assessed daily variation and among-day repeatability of estimates. The mean among populations and across seasons was 29.8 ± 2.3°C (range: 26.8-32.6°C) and represents the lowest mean and range recorded for any cordylid lizard to date. Literature reports on the seasonal activity patterns and micro-spatial variation in thermal habitat quality of O. cataphractus suggest that the low minimizes thermoregulatory costs during summer, autumn, late winter and spring. The low is therefore expected to relax energy budgets and function as part of the adaptive strategy of the species to survive seasonal food stress in a semi-arid environment. The among-day repeatability of mean varied among populations and across seasons despite exposure conditions that were kept constant. The results of the present study suggest that estimates based on short term laboratory trials may be inaccurate due to potential high among-day individual variation and low repeatability in thermal preference.

Generation gland morphology in cordylid lizards: An evolutionary perspective

To elucidate the functional significance of the three distinct types of generation glands that have been identified among cordylid lizards, we mapped gland type to the terminal taxa in the most recent phylogenetic tree for the Cordylidae. We used the phylogenetic programme Mesquite and applied the principle of parsimony to infer character states for the ancestral nodes in the tree. For those species where information on gland type was not available from the literature, we conducted a histological investigation of generation gland morphology, using standard histological techniques. We included two species of the sister family Gerrhosauridae in the analysis to serve as outgroups. In both Gerrhosaurus typicus and G. flavigularis, scales immediately anterior to the femoral pores displayed glandular activity, but differed from generation glands of cordylids in the absence of mature glandular generations. Among the cordylids investigated, we identified a fourth type of generation gland in Pseudocordylus subviridis, P. spinosus, and in the two Hemicordylus species, one where the glands consistently comprise of two mature glandular generations. In H. capensis, both single- and two-layer type glands are present. Our reconstruction of ancestral character states suggests a minimum of six transformations from one gland type to another during the evolutionary history of the family. The reconstruction furthermore suggests that the single-layer type gland reappeared at least once (in Hemicordylus) in the Cordylinae after having been lost. The reconstruction also unequivocally shows that the pit-like multiple-layer type gland evolved directly from the single-layer type and not from the protruding multiple-layer type. The two-layer type gland appears to be an intermediary condition between the multiple-layer and single-layer types. The evolutionary transformation of generation gland type appears to be linked to changes in lifestyle and associated changes in degree of territoriality and the need for chemical communication.

Influence of diet on prehension mode in cordylid lizards: a morphological and kinematic analysis

AbstractLizards exhibit a variety of mechanisms to capture prey, including lingual prehension, jaw prehension and lingual pinning. Despite being the topic of numerous studies, the link between prehension mode and diet remains poorly understood, especially in clades where multiple prehension modes are present. We addressed this issue by comparing the feeding behaviour and tongue morphology of a termite‐eating specialist Ouroborus cataphractus with that of a closely related dietary generalist Karusasaurus polyzonus. We used high‐speed videography to test the effect of prey species (termite vs. small cricket) and prey size (small vs. large cricket) on prehension mode. In addition, we included several other cordylid lizards representing the major clades in the family into our analysis to examine whether the prehension modes present in O. cataphractus characterize all cordylid species or whether they represent isolated occurrences. Finally, we investigated the morphology of the tongue in Cordylidae, with emphasis on O. cataphractus and K. polyzonus, using light and scanning electron microscopy techniques. Our data showed that the consumption of termites in O. cataphractus has resulted in the evolution of a novel lingual prehension mode, during which the ventral surface of the tongue is used to apprehend prey. This is in contrast to other lizards, which use the dorsal surface of the tongue to contact prey. Moreover, we demonstrated that this novel lingual prehension mode is accompanied by distinct morphological elaborations of the tongue surface. None of the other cordylid lizards tested in our study used lingual prehension during prey capture, except K. polyzonus, which used the tongue in a very small percentage of feeding trials. Overall, this study suggests that dietary specialization might underlie the evolution of novel prehension mechanisms in lizards.

The oldest known European Neogene girdled lizard fauna (Squamata, Cordylidae), with comments on Early Miocene immigration of African taxa

This paper reports on the first record of cordylid lizards from the locality of Merkur-North. The fossil history of girdled lizards is very poorly known and this group was rare during the Lower Miocene in Europe. The fossils described herein come from grey calcareous marls at the base of the so-called “Main Brown Coal Seam”. These marls are interpreted as reworked volcanic ash and the sediments are considered as early Miocene in age and are precisely equated with the MN 3a zone. For this reason, the cordylid fauna from this locality is older than previously described Miocene material and it represents the oldest known Neogene cordylids in Europe. The material of the dentary is very similar to that of Palaeocordylus bohemicus Roček, 1984, described from the younger locality of Dolnice near Cheb. The intramandibular septum of the dentary described herein, lying ventromedially from the alveolar canal, has a free posterolateral portion. It represents the first report of this structure in cordylids. The maxilla is only fragmentarily preserved. The size difference between the maxillary and dentary elements, the number of teeth and, especially their morphology evokes the possibility of two different taxa. Unfortunately, it is impossible to decide on the basis of such limited material if both finds represent independent forms or only extreme forms of the same taxon.

The Phylogenetic Affinities ofTrachylepis Sulcata Nigraand the Intraspecific Evolution of Coastal Melanism in the Western Rock Skink

The phylogenetic affinities of the melanistic subspecies Trachylepis sulcata nigra have never been investigated, and it was unclear if this subspecies represented a locally adapted population or a distinct species. Sequences from the nuclear marker RAG-1 (1149 bp), two novel rapidly-evolving nuclear markers KIF24 and EXPH5 (554 bp and 941 bp respectively), and the mitochondrial gene ND2 (1056 bp) were analysed from 84 individuals of T. s. sulcata and two individuals of T. s. nigra. Additionally, the range of T. s. nigra was estimated using museum records, and correlations between environmental variables and the occurrence of melanism were explored. Molecular analyses depict T. s. nigra as nested within a strongly monophyletic T. s. sulcata, suggesting this population is not genetically isolated or distinct. We therefore recommend T. s. nigra be synonymized with T. s. sulcata. The best predictor of melanism along the coastline in this population is a high number of fog days per year, a finding consistent with studies of melanism in cordylid lizards in southern Africa. Further sampling may determine gene flow levels occurring across the contact zone of melanistic and non-melanistic phenotypes and provide insight into selective forces maintaining this trait.