Uropeltid Snakes Research Articles

A new species of Uropeltis Cuvier, 1829 (Serpentes: Uropeltidae) from the eastern escarpment of the southern Western Ghats, India

A new species of the uropeltid (‘shieldtail’) snake genus Uropeltis is described based on eight specimens from the southern part of peninsular India’s Western Ghats. Uropeltis caudomaculata sp. nov. is phenotypically and genetically most similar to U. pulneyensis (Beddome, 1863), but differs primarily in having more ventral scales and in being restricted to the eastern escarpment of the Western Ghats between Meghamalai and approximately 15 km East of Munnar rather than in the Palani Hills, as well as differing in DNA nucleotide sequences. From verified records, we consider U. pulneyensis to be known thus far only from the Palani Hills, and we designate a lectotype for the species. Reconsideration of the holotype of Silybura guentheri Beddome, 1878 from Meghamalai leads us to conclude that it should be removed from the subjective junior synonymy of U. pulneyensis and be considered a distinct though very poorly known species, Uropeltis guentheri comb. nov.

Biphasic burrowing in Atlantic hagfish (Myxine limosa).

Myxine limosa is a burrowing species of hagfish that occurs in the western north Atlantic in areas with muddy substrate and at depths generally greater than 100 meters. Burrowing of M. limosa has been observed from submersibles, but little is known about the behavior of these animals within the substrate or the biomechanical mechanisms involved. Here we investigated burrowing in M. limosa by observing individuals as they burrowed through transparent gelatin. A photoelastic setup using crossed polarizers allowed us to visualize stress development in the gelatin as the hagfish moved through it. We found that M. limosa created U-shaped burrows in gelatin using a stereotyped, two-phase burrowing behavior. In the first ("Thrash") phase, hagfish drove their head and their anterior body into the substrate using vigorous sinusoidal swimming movements, with their head moving side-to-side. In the second ("Wriggle") phase, swimming movements ceased, with propulsion coming exclusively from the anterior, submerged portion of body. The Wriggle phase involved side-to-side head movements and movements of the submerged part of the body that resembled the "internal concertina" strategy used by caecilians and uropeltid snakes. The entire burrowing process took on average 7.6 minutes to complete and ended with the hagfish's head protruding from the substrate and the rest of its body generally concealed. Understanding the burrowing activities of hagfishes could lead to improved understanding of sediment turnover in marine benthic habitats, new insights into the reproductive behavior of hagfishes, or even inspiration for the design of burrowing robots.

Two new species of the shieldtail snake genus Rhinophis Hemprich, 1820 (Serpentes: Uropeltidae), from the Rakwana and the Knuckles Massifs of Sri Lanka

Two new species of the uropeltid snake genus Rhinophis Hemprich, 1820 are described from Sri Lanka. Rhinophis martin sp. nov. is described from 11 type specimens from the Rakwana Massif, and another 22 specimens from the same region are referred to this new species. Rhinophis dinarzardae sp. nov. is described from eight type specimens from the Knuckles Massif, and another 64 specimens from the Knuckles and adjacent hills are referred to this new species. Rhinophis martin sp. nov. has apparently not been reported previously under any scientific name, but is distinct in scalation, colour pattern and DNA. Rhinophis dinarzardae sp. nov. has long-been confused with the superficially similar R. philippinus, from which it differs by having more ventral scales, by occurring in the northern part of the Knuckles Massif and adjacent hills to the West rather than in the Central Highlands upland region (and possibly areas to the South and West) of Sri Lanka, and in DNA sequence data. The new descriptions take the inventory of currently recognised, named uropeltid species in Sri Lanka to 20, all members of the genus Rhinophis.

On the taxonomy of Uropeltis petersi (Beddome, 1878) (Serpentes: Uropeltidae) and description of a new, closely related species from the Western Ghats of India.

A new species of the uropeltid snake genus Uropeltis Cuvier, 1829 is described from the environs of Munnar in the Anamalai hils of the Western Ghats of peninsular India. Uropeltis tricuspida sp. nov. superficially resembles the poorly known and closely related U. petersi, but differs from that species in having more ventral and subcaudal scales, and a tri- rather than bicuspid posterior tip to the terminal scute.

A near-complete species-level phylogeny of uropeltid snakes harnessing historical museum collections as a DNA source

Uropeltidae is a clade of small fossorial snakes (ca. 64 extant species) endemic to peninsular India and Sri Lanka. Uropeltid taxonomy has been confusing, and the status of some species has not been revised for over a century. Attempts to revise uropeltid systematics and undertake evolutionary studies have been hampered by incompletely sampled and incompletely resolved phylogenies. To address this issue, we take advantage of historical museum collections, including type specimens, and apply genome-wide shotgun (GWS) sequencing, along with recent field sampling (using Sanger sequencing) to establish a near-complete multilocus species-level phylogeny (ca. 87% complete at species level). This results in a phylogeny that supports the monophyly of all genera (if Brachyophidium is considered a junior synonym of Teretrurus), and provides a firm platform for future taxonomic revision. Sri Lankan uropeltids are probably monophyletic, indicating a single colonisation event of this island from Indian ancestors. However, the position of Rhinophis goweri (endemic to Eastern Ghats, southern India) is unclear and warrants further investigation, and evidence that it may nest within the Sri Lankan radiation indicates a possible recolonisation event. DNA sequence data and morphology suggest that currently recognised uropeltid species diversity is substantially underestimated. Our study highlights the benefits of integrating museum collections in molecular genetic analyses and their role in understanding the systematics and evolutionary history of understudied organismal groups.

A new species of Rhinophis Hemprich, 1820 (Serpentes: Uropeltidae) from southwestern Sri Lanka.

A new species of the uropeltid snake genus Rhinophis Hemprich, 1820 is described from near Balangoda, southwestern Sri Lanka. Rhinophis mendisi sp. nov. superficially resembles R. homolepis (Hemprich, 1820) in colour pattern and in its prominent, conical tail shield, but differs from that species in having far fewer ventrals (159-177, n = 13 versus > 195 in the types of R. homolepis and its subjective junior synonym R. gerrardi). The five type specimens and one of the referred specimens of the new species were collected probably between 1894 and 1925, and the only known additional, referred specimens (n = 8) were collected from within ca. 30 km of the type locality in 1972. A lectotype is designated for Mitylia gerrardi Gray, 1858, a subjective junior synonym of R. homolepis.

A new species of Rhinophis Hemprich, 1820 (Reptilia: Uropeltidae), from cloud forest of the Knuckles massif of Sri Lanka.

A new species of uropeltid snake is described from the Knuckles Conservation Forest, Matale District, Sri Lanka. Rhinophis gunasekarai sp. nov. is superficially most similar to Rhinophis phillipsi in having yellow lines on the dorsum, blotches on the lateral body, and a relatively small tail shield, but it differs from that species in having substantially fewer ventrals, and a unique number and disposition of the dorsal yellow lines and lateral blotches. The new description brings the uropeltid fauna of Sri Lanka to 17 currently recognized species, all Rhinophis.

Warning signals promote morphological diversification in fossorial uropeltid snakes (Squamata: Uropeltidae)

AbstractMany species possess warning colourations that signal unprofitability to predators. Warning colourations are also thought to provide prey with a ‘predator-free space’ and promote niche expansion. However, how such strategies release a species from environmental constraints and facilitate niche expansion is not clearly understood. Fossoriality in reptiles imposes several morphological limits on head and body size to facilitate burrowing underground, but many fossorial snakes live close to the surface and occasionally move above ground, exposing them to predators. In such cases, evolving antipredator defences that reduce predation on the surface could potentially relax the morphological constraints associated with fossoriality and promote morphological diversification. Fossorial uropeltid snakes possess varying degrees of conspicuous warning colourations that reduce avian predation when active above ground. We predicted that species with more conspicuous colourations will exhibit more robust body forms and show faster rates of morphological evolution because constraints imposed by fossoriality are relaxed. Using a comparative phylogenetic approach on the genus Uropeltis, we show that more conspicuous species tend to have more robust morphologies and have faster rates of head-shape evolution. Overall, we find that the evolution of warning colourations in Uropeltis can facilitate niche expansion by influencing rates of morphological diversification.

Conspicuous colours reduce predation rates in fossorial uropeltid snakes.

Uropeltid snakes (Family Uropeltidae) are non-venomous, fossorial snakes that are found above ground occasionally, during which time they are exposed to predation. Many species are brightly coloured, mostly on the ventral surface, but these colours are expected to have no function below the ground. Observations have shown that the cephalic resemblance (resemblance to heads) of uropeltid tails may direct attacks of predators towards the hardened tails, thereby potentially increasing handling times for predators. Experiments have also shown that predators learn to avoid prey that are non-toxic and palatable but are difficult to capture, hard to process or require long handling time when such prey advertise their unprofitability through conspicuous colours. We here postulate that uropeltid snakes use their bright colours to signal long handling times associated with attack deflection to the tails, thereby securing reduced predation from predators that can learn to associate colour with handling time. Captive chicken experiments with dough models mimicking uropeltids indicate that attacks were more common on the tail than on the head. Field experiments with uropeltid clay models show that the conspicuous colours of these snakes decrease predation rates compared to cryptic models, but a novel conspicuous colour did not confer such a benefit. Overall, our experiments provide support for our hypothesis that the conspicuous colours of these snakes reduce predation, possibly because these colours advertise unprofitability due to long handling times.

A new species of Rhinophis Hemprich, 1820 (Serpentes: Uropeltidae) from the central hills of Sri Lanka.

A new species of uropeltid snake, Rhinophis roshanpererai sp. nov., is described based on three specimens from Badulla District, Sri Lanka. The new species is distinguished from its congeners by the number of dorsal scale rows and ventral scales, a colour pattern that lacks pale stripes, and by having a very small tail shield with four or three prominent spines. Based on lack of records from similar habitats and elevations elsewhere in Sri Lanka, the new species likely has a very small range in the central highlands. The description of the new species brings the total nominal species of Rhinophis to 20, with four of the 16 Sri Lankan species having been described since 2009.

A reassessment of Melanophidium Günther, 1864 (Squamata: Serpentes: Uropeltidae) from the Western Ghats of peninsular India, with the description of a new species.

A new species of the uropeltid snake genus, Melanophidium Günther, 1864 is described based on a series of eight specimens. Melanophidium khairei sp. nov. is the fourth species described in the genus, and the first for 144 years. Superficially M. khairei sp. nov. resembles M. punctatum Beddome, 1871 in being piebald and punctate (and it was previously misidentified as M. punctatum), but in many scalation characters it more closely resembles M. wynaudense (Beddome, 1863). The new species occurs in southern Maharashtra, Goa, and northern Karnataka, in the Western Ghats region of peninsula India. It is the most northerly member of its genus. Lectotypes and paralectotypes are designated for M. wynaudense, M. bilineatum Beddome, 1870, and M. punctatum. A new key to the species of Melanophidium is presented. Aspects of the morphology, taxonomy and distribution of the three previously described species of Melanophidium are reviewed and revised.

Comparative skull morphology of uropeltid snakes (Alethinophidia: Uropeltidae) with special reference to disarticulated elements and variation.

Uropeltids form a diverse clade of highly derived, fossorial snakes that, because of their phylogenetic position among other alethinophidian lineages, may play a key role in understanding the early evolution of cranial morphology in snakes. We include detailed osteological descriptions of crania and mandibles for eight uropeltid species from three nominal genera (Uropeltis, Rhinophis, and Brachyophidium) and emphasize disarticulated elements and the impact of intraspecific variation on previously proposed morphological characters used for phylogenetic analysis. Preliminary analysis of phylogenetic relationships strongly supports a clade composed exclusively of species of Plectrurus, Uropeltis, and Rhinophis. However, monophyly of each of those genera and Melanophidium is not upheld. There is moderate support that Sri Lankan species (e.g., Rhinophis and Uropeltis melanogaster) are monophyletic with respect to Indian uropeltids. Previously proposed characters that are phylogenetically informative include the shape of the nasals, length of the occipital condyle, level of development of the posteroventral process of the dentary, and participation of the parietal in the optic foramen. Additionally, thirty new features that may be systematically informative are identified and described, but were not verified for their utility. Such verification must await availability of additional disarticulated cranial material from a larger sample of taxa. All characters require further testing through increased focus on sources and patterns of intraspecific variation, inclusion of broader taxonomic samples in comparative studies, and exploration of skeletal development, sexual dimorphism, and biogeographic patterns. Additionally, trends in the relative enlargement of the sensory capsules, reduction in cranial ossification and dentition, fusion of elements, and the appearance of novel morphological conditions, such as the structure and location of the suspensorium, may be related to fossoriality and miniaturization in some uropeltid taxa, and may complicate analysis of relationships within Uropeltidae and among alethinophidian snakes.

On a rare, South Indian burrowing snake <i>Platyplectrurus trilineatus</i> (Beddome, 1867)

Examination of five juvenile preserved specimens of Platyplectrurus trilineatus , an endemic, poorly-known Uropeltid snake species from the Western Ghats Mountains of Southwestern India provided further insights into its taxonomy. The sample examined here agreed well with the existing descriptions in literature in colouration and most aspects of scalation but had larger range of ventral scale count and smaller supraocular relative to prefrontal. Character definition (in the case of ventrals) and ontogenic variation (in the case of supraocular size) might have possibly created these discrepancies. These differences indicate that a better sampling of both specimens and characters would throw more light on this species. Keywords: morphology; characterization; lepidosis; habitus; colouration DOI: http://dx.doi.org/10.4038/tapro.v3i1.3228 TAPROBANICA , April, 2011. Vol. 03, No. 01: pp. 11-14

Two new species of Rhinophis Hemprich (Serpentes: Uropeltidae) from Sri Lanka

Two new species of uropeltid (shieldtail) snake are described from Sri Lanka; Rhinophis lineatus sp. nov. from Harasbedda, near Ragala, and Rhinophis zigzag sp. nov. from Bibilegama, near Passara. The new species are distinguished from congeners in morphometric and meristic external characters, and in having very distinctive colour patterns. Scale-row reduction data are presented for the two new species; this is a new development for uropeltid systematics, and its potential utility is highlighted. The nature of the overlap between the two anal scales is also highlighted as a potentially useful character. The two new species were included in previous phylogenetic analyses of allozyme and albumin immunological data, but their phylogenetic relationships are not yet well resolved.

Cranial osteology and preliminary phylogenetic assessment of Plectrurus aureus Beddome, 1880 (Squamata: Serpentes: Uropeltidae)

Uropeltid snakes are among the most poorly understood clades within Alethinophidia. Their small size, limited geographic distribution, high incidence of endemism, and fossorial behaviour all contribute to the general paucity of systematic collections of these snakes, especially of adequate skeletal preparations, in most museum collections. Their hypothesized position within the higher-order phylogeny of alethinophidian snakes calls attention to the need for additional morphological work on the group. Hypotheses of uropeltid phylogenetic relationships based on morphological analyses are few, and continue to be hampered by limited taxon-sampling and character matrices that rely predominantly on features that are visible on articulated skulls. We utilized high-resolution X-ray computed tomography (HRCT) to investigate the cranial osteology of Plectrurus aureus Beddome, 1880, a species for which no osteological data were previously available. We provide a detailed description of the skull and mandible, and comment on morphological characters and potential phylogenetic relationships. Clarity in character descriptions is of paramount importance, and additional morphological characters are desirable. HRCT provides a nondestructive way to identify new systematically informative morphological characters from digitally disarticulated specimens. The small size of many uropeltid species, including P. aureus, will help to frame a greater appreciation of the limitations of traditional HRCT protocols for revealing detailed anatomical features of small vertebrates.

Digital Endocasts of the Cranial Cavity and Osseous Labyrinth of the Burrowing Snake Uropeltis woodmasoni (Alethinophidia: Uropeltidae)

The endocranial space, nerve pattern, and inner ear of a specimen of Uropeltis woodmasoni are described from digital endocasts rendered from high-resolution X-ray computed tomography scans. The cast of the endocranial space reveals short, stout olfactory bulbs as well as general shortening of the brain along the longitudinal axis. The pattern of innervation agrees with descriptions reported for other uropeltid snakes, although this individual exhibits skull asymmetry in the pathway of the glossopharyngeal nerve and the bifurcation of the jugular canal. There are no internal connections between the perilymphatic canal leading to the foramen pseudorotundum, the recessus scala tympani, and the jugular canal, a situation that differs from those of other alethinophidian snakes. The inner ear is compactly packaged with smoothly curved semicircular canals located in close proximity to the vestibule. Semicircular canal size is comparable to those of larger snakes, and the small size of the skull (9.4 mm) coupled with relative enlargement of the sensory regions of the brain and otic capsule is consistent with the morphological pattern of miniaturized vertebrates, although compounding factors, including phylogeny, ontogeny, and variation, are currently not well understood.

A Distributional Analysis of the Uropeltid Snakes of India and Sri Lanka

A Distributional Analysis of the Uropeltid Snakes of India and Sri Lanka

Phylogenetic relationships and molecular evolution in uropeltid snakes (Serpentes: Uropeltidae): allozymes and albumin immunology.

Multilocus electrophoretic methods and microcomplement fixation comparisons of serum albumin are used to assess phylogenetic relationships among species of uropeltid snakes, to infer aspects of their population biology and biogeography, and to evaluate their relationships to other primitive snakes (Henophidia). There is very good agreement between phylogenetic inferences derived from the electrophoretic data and those derived from the albumin immunological data. Protein variation detected by electrophoresis is relatively high among 17 operational taxonomic units (OTUs) examined. The mean number of alleles per locus (5.1 across all OTUs), levels of polymorphism (25% of loci), and heterozygosity (4–6%), are typical of, or greater than, values reported for other snakes. Species of uropeltids are genetically highly differentiated, as measured by genetic distances (lowest interspecific Nei's unbiased genetic distances, 0.22‐0.27 among several Sri Lankan species; 2.3 between Teretrurus of India and other uropeltines). The phylogenetic tree most consistent with both the immunological and electrophoretic data shows uropeltines from Sri Lanka to be monophyletic, but the Indian species are paraphyletic with respect to those from Sri Lanka. Rhinophis travancoricus of India is inferred to be the sister taxon to the Sri Lankan radiation. As the genera are presently understood, neither Rhinophis nor Uropeltis appears to be monophyletic. A biogeographic scenario derived from the phylogenetic hypothesis suggests an early diversification of uropeltids in India, followed by a single invasion into the lowlands of Sri Lanka. Subsequent evolution on Sri Lanka resulted in occupation of montane biotopes. Cylindrophis is the sister group to uropeltines and is considered a member of the Uropeltidae. The immunological data indicate no phylogenetic association between uropeltids and other ‘anilioid’ taxa, specifically Anilius, Loxocemus or Xenopeltis, although we cannot rule out a very remote relationship. We specifically reject the hypothesis that uropeltines and scolecophidians form a clade relative to henophidians. High levels of genetic variation and a trend toward negative FIS values for polymorphic loci in three populations suggest generally large effective population sizes and outbreeding in these species. The niche‐width variation hypothesis for allozyme loci is not supported by the uropeltid data. In comparison to other vertebrates, the relationship between Nei's genetic distance and albumin immunological distance in uropeltids suggests either conservative albumin evolution or strong differentiation at electrophoretic loci.

Axial Differences in the Musculature of Uropeltid Snakes: The Freight-Train Approach to Burrowing

The shield-tailed snakes (family Uropeltidae) extend and widen the tunnels in which they live by alternately curving and straightening the anterior portion of their vertebral columns within the skin, a burrowing method that proves to be most effective for tunneling amid roots and rocks, as well as for producing tunnels wider than the trunk through unpredictably heterogeneous substrates. The muscles of the anterior portion of the uropeltid trunk are larger and thicker than those of the posterior and are further modified by the inclusion of large amounts of myoglobin, numerous mitochondria, and diverse other ultrastructural and enzymatic specializations, which presumably represent adaptations for sustained work loads. The very much thinner, serially homologous, but unmodified musculature of the posterior trunk occupies only a much smaller fraction of the cross-sectional area. This regional modification increases the effectiveness of the posterior body for storing viscera and developing embryos.

Regional Specialization of Reptilian Scale Surfaces: Relation of Texture and Biologic Role

The iridescent body scales of the fossorial uropeltid snakes produce these interference colors by keratinous ridges spaced at 2500 A. The pattern inhibits wetting of the surface and adhesion of soil particles and thus reduces friction between the snake's trunk and walls of its tunnel. The epidermal scales of the blunt tail show a sharply defined pattern of spines and ridges with convergent flutings. Dirt caught here forms a plug that protects the snake's caudal end. The sharp transition of surface textures suggests (i) that selection for each of the two roles is great, and (ii) that the interference colors of many fossorial snakes indicate that friction as well as dirt adhesion are being reduced.