Populations of the Bornean gliding lizard, Draco cornutus, differ markedly in the colour of their gliding membranes. They also differ in local vegetation type (mangrove forest versus lowland rainforest) and consequently, the colour of falling leaves (red and brown/black in mangrove versus green, brown and black in rainforest). We show that the gliding membranes of these lizards closely match the colours of freshly fallen leaves in the local habitat as they appear to the visual system of birds (their probable predators). Furthermore, gliding membranes more closely resembled colours of local fallen leaves than standing foliage or fallen leaves in the other population's habitat. This suggests that the two populations have diverged in gliding membrane coloration to match the colours of their local falling leaves, and that mimicking falling leaves is an adaptation that functions to reduce predation by birds.
The taxonomy of freshwater crabs requires a paradigm change in methodological approaches, particularly in investigations that use morphological techniques. The traditional morphometric approach (two-dimensional measurements) tends to be inappropriate for the identification of freshwater crabs due to their variable external morphology and lack of gonopods (conventionally used for the identification of male crabs) in females. In this study, we explore the potential use of the geometric morphometric technique for identification of female freshwater crabs, and identify taxonomic key characteristics of species. The shape of the carapace could be a good characteristic for the identification of female crabs, especially when the geometric morphometric technique is used. It was observed that the shape of the carapace has an advantage over the shape of the pleon and chela because its relatively flat orientation allows more consistent and easier data preparation for geometric morphometric analysis. The geometric morphometric technique is inexpensive, relatively less time consuming to employ, and accurate. This technique is convenient when dissection to examine the gonopods is not possible, which can damage the specimen in the case of endangered or rare species. Since the technique was used herein for only two species, more compelling and extensive evidence is needed before the reliability of the method can be proven.
We describe two new species of skinks from Gunung Penrissen, Sarawak, Malaysia, in northern Borneo, Tytthoscincus batupanggah sp. nov. and T. leproauricularis sp. nov. Morphological and molecular analyses both corroborate the two new species as unique compared to all other Tytthoscincus and additional Sphenomorphus that are candidates for taxonomic placement in the genus Tytthoscincus. Despite their phenotypic similarity and sympatric distribution, a molecular analysis shows that the new species are not sister taxa and exhibit a deep genetic divergence between each of their respective sister taxa. We discuss how historical climatic and geographic processes may have led to the co-distribution of two relatively distantly related phenotypically similar species. In light of these discoveries, we also emphasize the importance of conserving primary montane tropical rainforest for maintaining species diversity.
A new species of stream toad of the genus Ansonia is described from Gunung Murud, Pulong Tau National Park, of northern Sarawak, Malaysia, Borneo. Ansonia vidua, sp. nov., is morphologically distinguished from its Bornean congeners by the following combination of characters: medium size (SVL of adult females 33.5-34.4 mm); body uniformly black-brown in life; absence of a visible pattern on dorsum or limbs; presence of two low interorbital ridges; shagreened skin on dorsum, sides and upper surfaces of the limbs with numerous homogeneously small, rounded warts; first finger shorter than second; reduced webbing between the toes and an absence of a sharp tarsal ridge. Uncorrected genetic distances between related taxa of > 4.3% in 16S rRNA gene support its status as a hitherto undescribed species.
Sexual ornamentation needs to be conspicuous to be effective in attracting potential mates and defending territories and indeed, a multitude of ways exists to achieve this. Two principal mechanisms for increasing conspicuousness are to increase the ornament's colour or brightness contrast against the background and to increase the size of the ornament. We assessed the relationship between the colour and size of the dewlap, a large extendible throat-fan, across a range of species of gliding lizards (Agamidae; genus Draco) from Malaysia and the Philippines. We found a negative relationship across species between colour contrast against the background and dewlap size in males, but not in females, suggesting that males of different species use increasing colour contrast and dewlap size as alternative strategies for effective communication. Male dewlap size also increases with increasing sexual size dimorphism, and dewlap colour and brightness contrast increase with increasing sexual dichromatism in colour and brightness, respectively, suggesting that sexual selection may act on both dewlap size and colour. We further found evidence that relative predation intensity, as measured from predator attacks on models placed in the field, may play a role in the choice of strategy (high chromatic contrast or large dewlap area) a species employs. More broadly, these results highlight that each component in a signal (such as colour or size) may be influenced by different selection pressures and that by assessing components individually, we can gain a greater understanding of the evolution of signal diversity.
Data on nutrient contents of freshwater crabs are important for ecological studies and species conservation assessments, especially when the species concerned is threatened among others by habitat destruction and uncontrolled resources utilisation. Indeed comprehensive biological information is required to reconcile the needs between sustainable resources utilisation and conservation of the species. This study documents the nutrient contents of a freshwater crab, Isolapotamon bauense which is listed as 'Vulnerable' in the IUCN Red List of Threatened Species and also being harvested by local community for dietary supplement. Results show that muscles of the freshwater crab contain a substantial amount of nutrients in particular water content (male = 79.31 ± 2.30 %, female = 77.63 ± 0.56 %), protein (male = 77.47 ± 6.11 %, female = 63.28 ± 3.62 %), magnesium (male = 51.48 ± 16.10 mg/g, female = 39.73 ± 6.99 mg/g) and calcium (male = 25.50 ± 6.98 mg/g, female = 39.73 ± 6.99 mg/g). Means of nutrient contents between male and female crabs are not significantly different. It is estimated that an individual of I. bauense with weight range of 56-139 g contained on average of 0.35 ± 0.15 g of protein. Our estimation also shows that the number of individuals of the freshwater crab required to meet the recommended daily protein intakes of the community concerned is in the range 35-96 individuals for children, 130-188 individuals for adolescents, 171-179 individuals for men and 149-159 individuals for women. The results imply that harvesting of wild I. bauense as a source of protein supplement naturally may not be practical because of its relatively low population abundance, and conservation of the species for its ecological roles may thus be preferred.
A new species of the genus Tropidophorus is described from Putai, upper Baleh, Kapit districts, Sarawak, East Malaysia (Borneo). Tropidophorus sebi sp. nov. is diagnosable from congeners from Borneo by the combination of the following characters: head shields present, dorsal and lateral scales smooth; parietal scales in two pairs; supraciliaries eight; supraoculars four; supralabials seven; infralabials four; postmental undivided; longitudinal scale rows 58; ventrals 53; transverse scale rows at midbody 34; subcaudals 98; preanals enlarged, single; and subdigital lamellae of Toe IV 19. In addition, we determine the phylogenetic position of this species within the Tropidophorus group based on mitochondrial markers, and present a key to identification of the known Bornean species in the genus.
The island of Borneo lies within one of the most biodiverse regions in the world. Despite this, its documented gekkonid diversity is not commensurate with other areas of Southeast Asia. The megadiverse genus Cyrtodactylus is especially underrepresented. Limestone-karst ecosystems, in particular, harbor many endemic Cyrtodactylus species, but only one karst-dwelling species is currently recognized from Borneo. This paper adds two additional karst-dwelling Cyrtodactylus species-C. muluensis sp. nov. and C. limajalur sp. nov.-from Sarawak, Malaysia. Cyrtodactylus muluensis sp. nov. is endemic to Gunung Mulu and is distinguished from its congeners by having a precloacal groove, 31-38 ventral scales, a maximum SVL of at least 88 mm, enlarged subcaudals, 19-20 subdigital lamellae, and a banded dorsal body pattern. Cyrtodactylus limajalur sp. nov. is endemic to the Serian region and is distinguished from its congeners by having 33-42 ventral scales, enlarged subcaudals, a precloacal pit, a maximum SVL of at least 94 mm, 5-6 enlarged femoral scales, 19-22 subdigital lamellae, and five distinct bands on the dorsum. Both species are phylogenetically distinct and deeply divergent from all other congeners. The description of two new karst-dwelling species highlights the need to conserve karst habitats and the endemic species they harbor.
Episodic sea level changes that repeatedly exposed and inundated the Sunda Shelf characterize the Pleistocene. Available evidence points to a more xeric central Sunda Shelf during periods of low sea levels, and despite the broad land connections that persisted during this time, some organisms are assumed to have faced barriers to dispersal between land-masses on the Sunda Shelf. Eutropis rugifera is a secretive, forest adapted scincid lizard that ranges across the Sunda Shelf. In this study, we sequenced one mitochondrial (ND2) and four nuclear (BRCA1, BRCA2, RAG1, and MC1R) markers and generated a time-calibrated phylogeny in BEAST to test whether divergence times between Sundaic populations of E. rugifera occurred during Pleistocene sea-level changes, or if they predate the Pleistocene. We find that E. rugifera shows pre-Pleistocene divergences between populations on different Sundaic land-masses. The earliest divergence within E. rugifera separates the Philippine samples from the Sundaic samples approximately 16 Ma; the Philippine populations thus cannot be considered conspecific with Sundaic congeners. Sundaic populations diverged approximately 6 Ma, and populations within Borneo from Sabah and Sarawak separated approximately 4.5 Ma in the early Pliocene, followed by further cladogenesis in Sarawak through the Pleistocene. Divergence of peninsular Malaysian populations from the Mentawai Archipelago occurred approximately 5 Ma. Separation among island populations from the Mentawai Archipelago likely dates to the Pliocene/Pleistocene boundary approximately 3.5 Ma, and our samples from peninsular Malaysia appear to coalesce in the middle Pleistocene, about 1 Ma. Coupled with the monophyly of these populations, these divergence times suggest that despite consistent land-connections between these regions throughout the Pleistocene E. rugifera still faced barriers to dispersal, which may be a result of environmental shifts that accompanied the sea-level changes.
We identified hypotheses for the cause and consequences of the loss of complexity in animal signals and tested these using a genus of visually communicating lizards, the Southeast Asian Draco lizards. Males of some species have lost the headbob component from their display, which is otherwise central to the communication of this genus. These males instead display a large, colorful dewlap to defend territories and attract mates. This dewlap initially evolved to augment the headbob component of the display, but has become the exclusive system of communication. We tested whether the loss of headbobs was caused by relaxed selection, habitat-dependent constraints, or size-specific energetic constraints on display movement. We then examined whether the consequences of this loss have been mitigated by increased signaling effort or complexity in the color of the dewlap. It appears the increased cost of display movement resulting from the evolution of large body size might have contributed to the loss of headbobs and has been somewhat compensated for by the evolution of greater complexity in dewlap color. However, this evolutionary shift is unlikely to have maintained the complexity previously present in the communication system, resulting in an apparent detrimental loss of information potential.
Effective communication requires animal signals to be readily detected by receivers in the environments in which they are typically given. Certain light conditions enhance the visibility of colour signals and these conditions can vary depending on the orientation of the sun and the position of the signaller. We tested whether Draco sumatranus gliding lizards modified their position relative to the sun to enhance the conspicuousness of their throat-fan (dewlap) during social display to conspecifics. The dewlap was translucent, and we found that lizards were significantly more likely to orient themselves perpendicular to the sun when displaying. This increases the dewlap's radiance, and likely, its conspicuousness, by increasing the amount of light transmitted through the ornament. This is a rare example of a behavioural adaptation for enhancing the visibility of an ornament to distant receivers.
Social animals are expected to face a trade-off between producing a signal that is detectible by mates and rivals, but not obvious to predators. This trade-off is fundamental for understanding the design of many animal signals, and is often the lens through which the evolution of alternative communication strategies is viewed. We have a reasonable working knowledge of how conspecifics detect signals under different conditions, but how predators exploit conspicuous communication of prey is complex and hard to predict. We quantified predation on 1566 robotic lizard prey that performed a conspicuous visual display, possessed a conspicuous ornament or remained cryptic. Attacks by free-ranging predators were consistent across two contrasting ecosystems and showed robotic prey that performed a conspicuous display were equally likely to be attacked as those that remained cryptic. Furthermore, predators avoided attacking robotic prey with a fixed, highly visible ornament that was novel at both locations. These data show that it is prey familiarity-not conspicuousness-that determine predation risk. These findings replicated across different predator-prey communities not only reveal how conspicuous signals might evolve in high predation environments, but could help resolve the paradox of aposematism and why some exotic species avoid predation when invading new areas.
The megophryid frogs Leptobrachella brevicrus, Leptolalax dringi and Megophrys dringi are species exclusively known from highly localised areas in isolated mountain ranges on Borneo. The tadpoles and adults in this study were collected at the shared type locality for the three species in Gunung Mulu National Park, Sarawak, Malaysia (Borneo). The species identities of larvae were determined via comparison to syntopic adults using DNA barcoding techniques based on partial 16S rRNA mitochondrial gene sequences. The genetic data supported the status of the three taxa as valid species. Descriptions of colouration in life and after preservation, external morphological features, morphometric measurements and ecological notes in comparison to congeneric species are supplied. The tadpoles of L. brevicrus and L. dringi show similar adaptations to a fossorial lifestyle. These include an elongated, vermiform body, a relatively long tail and small eyes. Both were found in the gravel beds of a small mountain stream. In contrast, the larvae of M. dringi are adapted to occupying and feeding at the surface of pools within the stream.
A new brightly-coloured (olive and red) species of microhylid frog of the genus Calluella Stoliczka 1872 is described from the upper elevations of Gunung Penrissen and the Matang Range, Sarawak, East Malaysia (Borneo). Calluella capsa, new species, is diagnosable in showing the following combination of characters: SVL up to 36.0 mm; dorsum weakly granular; a faint dermal fold across forehead; toe tips obtuse; webbing on toes basal; lateral fringes on toes present; outer metatarsal tubercle present; and dorsum greyish-olive, with red spots; half of venter bright red, the rest with large white and dark areas. The new species is the eighth species of Calluella to be described, and the fourth known from Borneo. A preliminary phylogeny of Calluella and its relatives is presented, and the new taxon compared with congeners from Malaysia and other parts of south-east Asia.
A new bufonid amphibian, belonging to a new monotypic genus, is described from the Andaman Islands, in the Bay of Bengal, Republic of India, based on unique external morphological and skeletal characters which are compared with those of known Oriental and other relevant bufonid genera. Blythophryne gen. n. is distinguished from other bufonid genera by its small adult size (mean SVL 24.02 mm), the presence of six presacral vertebrae, an absence of coccygeal expansions, presence of an elongated pair of parotoid glands, expanded discs at digit tips and phytotelmonous tadpoles that lack oral denticles. The taxonomic and phylogenetic position of the new taxon (that we named as Blythophryne beryet gen. et sp. n.) was ascertained by comparing its 12S and 16S partial genes with those of Oriental and other relevant bufonid lineages. Resulting molecular phylogeny supports the erection of a novel monotypic genus for this lineage from the Andaman Islands of India.
Convergence in communication appears rare compared with other forms of adaptation. This is puzzling, given communication is acutely dependent on the environment and expected to converge in form when animals communicate in similar habitats. We uncover deep-time convergence in territorial communication between two groups of tropical lizards separated by over 140 million years of evolution: the Southeast Asian Draco and Caribbean Anolis. These groups have repeatedly converged in multiple aspects of display along common environmental gradients. Robot playbacks to free-ranging lizards confirmed that the most prominent convergence in display is adaptive, as it improves signal detection. We then provide evidence from a sample of the literature to further show that convergent adaptation among highly divergent animal groups is almost certainly widespread in nature. Signal evolution is therefore curbed towards the same set of adaptive solutions, especially when animals are challenged with the problem of communicating effectively in noisy environments.
Most new cryptic species are described using conventional tree- and distance-based species delimitation methods (SDMs), which rely on phylogenetic arrangements and measures of genetic divergence. However, although numerous factors such as population structure and gene flow are known to confound phylogenetic inference and species delimitation, the influence of these processes is not frequently evaluated. Using large numbers of exons, introns, and ultraconserved elements obtained using the FrogCap sequence-capture protocol, we compared conventional SDMs with more robust genomic analyses that assess population structure and gene flow to characterize species boundaries in a Southeast Asian frog complex (Pulchrana picturata). Our results showed that gene flow and introgression can produce phylogenetic patterns and levels of divergence that resemble distinct species (up to 10% divergence in mitochondrial DNA). Hybrid populations were inferred as independent (singleton) clades that were highly divergent from adjacent populations (7%-10%) and unusually similar (<3%) to allopatric populations. Such anomalous patterns are not uncommon in Southeast Asian amphibians, which brings into question whether the high levels of cryptic diversity observed in other amphibian groups reflect distinct cryptic species-or, instead, highly admixed and structured metapopulation lineages. Our results also provide an alternative explanation to the conundrum of divergent (sometimes nonsister) sympatric lineages-a pattern that has been celebrated as indicative of true cryptic speciation. Based on these findings, we recommend that species delimitation of continuously distributed "cryptic" groups should not rely solely on conventional SDMs, but should necessarily examine population structure and gene flow to avoid taxonomic inflation.
We collected two specimens of an undescribed species of Lygosoma from pitfall traps in an urban rainforest in Kuching and from the base of a forested hill in western Sarawak, East Malaysia. The new species is diagnosable from all south-east Asian congeners by morphological characters, and most closely resembles Lygosoma herberti from the Thai-Malay Peninsula. The new species shows substantial molecular divergence from its closest relatives in two protein-coding genes, one mitochondrial (ND1) and one nuclear (R35) that we sequenced for several south-east Asian congeners. We describe the new species on the basis of this distinct morphology and genetic divergence. It is the third species of Lygosoma known from Borneo, and highlights the continuing rise in lizard species diversity on the island. In addition, the discovery of this species from a small urban rainforest underscores the importance of preserving intact rainforest areas of any size in maintaining species diversity.
The purpose of this paper is to solve an overlooked nomenclatural problem involving two taxa of Colubridae, both described as Coluber korros. The first one is Coluber korros Schlegel, 1837, now Ptyas korros, a well-known and widespread species in south-east Asia. Its senior homonym is Coluber korros Lesson, 1831, a long forgotten taxon. Furthermore, these taxa are undoubtedly non-conspecific. We tentatively identify the holotype of this latter taxon as a large specimen of Coelognathus radiatus (F. Boie, 1827) and we specify its type locality as "Region of Kolkata, West Bengal State, eastern India" (the same specification of type-locality can hence be applied to the elapid Naja kaouthia Lesson, 1831). Nevertheless, following the strict principle of priority, Coluber korros Lesson, 1831 has priority over Coluber korros Schlegel, 1837. Based on the Code, we use Article 23.9 on reversal of precedence in order to preserve the use of the well-known taxon Coluber korros Schlegel, 1837 (now Ptyas korros) against its senior primary homonym Coluber korros Lesson, 1831. Finally, we consider Coluber boncorage Lesson, 1831 to be a nomen dubium.
One of the most urgent contemporary tasks for taxonomists and evolutionary biologists is to estimate the number of species on earth. Recording alpha diversity is crucial for protecting biodiversity, especially in areas of elevated species richness, which coincide geographically with increased anthropogenic environmental pressures - the world's so-called biodiversity hotspots. Although the distribution of Puddle frogs of the genus Occidozyga in South and Southeast Asia includes five biodiversity hotspots, the available data on phylogeny, species diversity, and biogeography are surprisingly patchy. Samples analyzed in this study were collected throughout Southeast Asia, with a primary focus on Sundaland and the Philippines. A mitochondrial gene region comprising ~ 2000 bp of 12S and 16S rRNA with intervening tRNA Valine and three nuclear loci (BDNF, NTF3, POMC) were analyzed to obtain a robust, time-calibrated phylogenetic hypothesis. We found a surprisingly high level of genetic diversity within Occidozyga, based on uncorrected p-distance values corroborated by species delimitation analyses. This extensive genetic diversity revealed 29 evolutionary lineages, defined by the > 5% uncorrected p-distance criterion for the 16S rRNA gene, suggesting that species diversity in this clade of phenotypically homogeneous forms probably has been underestimated. The comparison with results of other anuran groups leads to the assumption that anuran species diversity could still be substantially underestimated in Southeast Asia in general. Many genetically divergent lineages of frogs are phenotypically similar, indicating a tendency towards extensive morphological conservatism. We present a biogeographic reconstruction of the colonization of Sundaland and nearby islands which, together with our temporal framework, suggests that lineage diversification centered on the landmasses of the northern Sunda Shelf. This remarkably genetically structured group of amphibians could represent an exceptional case for future studies of geographical structure and diversification in a widespread anuran clade spanning some of the most pronounced geographical barriers on the planet (e.g., Wallace's Line). Studies considering gene flow, morphology, ecological and bioacoustic data are needed to answer these questions and to test whether observed diversity of Puddle frog lineages warrants taxonomic recognition.