Friday, December 30, 2016

Four new vipers were described in 2016

Bale Mountains Adder, Bitis harenna Gower et al. 2016
Bale Mountains Adder, Bitis harenna

Bale Mountains Adder is similar in scalation to Bitis parviocula. It is known from the holotype and one photograph taken of a specimen that was not collected. It inhabits the Bale Mountains of Ethiopia near the town of Dodola, which is on the main route between the Rift Valley and the chief settlements of the Bale Mountains region. Dodola lies on a heavily farmed plateau, and there is very little tree cover in the immediate vicinity of the town. The holotype is 665 mm long.

Talamancan palm-pitviper, Bothriechis nubestris Doan et al. 2016

The new species is a small to medium sized pitviper, 61 cm on average.It inhabits a small area in the northern Talamancan Cordillera of Costa Rica. The pit viper is a striking green-and-black, a coloration it shares with its close relative, the black-speckled palm-pitviper (Bothriechis nigroviridis). The two species look so similar that the Talamancan palm-pitviper
Talamancan palm-pitviperBothriechis nubestris 
went unrecognized for more than a century. 


Ilha dos Franceses LanceheadBothrops sazimai Barbo et al. 2016
This is a new insular species of  Bothrops from Ilha dos Franceses, a small island off the coast of Espírito Santo State, southeastern Brazil. The new species differs from mainland populations of B. jararaca in its small size, relative longer tail, relative smaller head length, and relative larger eyes. Like other island Bothrops,  Bothrops sazimai reaches high population densities, is nocturnal, semi- arboreal, and feeding on small lizards and centipedes. Due its unique and restricted area of occurrence, declining quality of habitat, and constant use of the island for tourism, the new species may be considered as critically endangered.
Ilha dos Franceses LanceheadBothrops sazimai


Walser Viper, Vipera walser Ghielmi et al. 2016 
Vipera walser is a new viper from the northwestern Italian Alps. Despite its overall morphological resemblance with Vipera berus, the new species is genetically distinct  from both V. berus and other vipers occurring in western Europe. Morphologically, the new species appear to be more similar to V. berus than to its closest genetic relatives occurring in the Caucasus The extant population shows a very low genetic variability based upon mitochondrial markers, suggesting that the taxon has suffered a serious population reduction or bottleneck in the past. The species is extremely range-restricted (inhabiting less than 500 km2) and occurs at in two disjunct sites within the high rainfall valleys of the Alps
Walser Viper, Vipera walser 
north of Biella. This new species should be classified as globally ‘endangered’ due to its small and fragmented range, and an inferred population decline. The near-future threats to the species are habitat changes associated with reduced grazing, along with human persecution, and collecting.


Citations

Barbo FE, Gasparini JL, Almeida AP, Zaher H, Grazziotin FG, Gusmão RB, Ferrarini JM, Sawaya RJ. 2016. Another new and threatened species of lancehead genus Bothrops (Serpentes, Viperidae) from Ilha dos Franceses, Southeastern Brazil. Zootaxa. 4097(4):511-29.

Doan TM, Mason AJ, Castoe TA, Sasa M, Parkinson CL. 2016. A cryptic palm-pitviper species (Squamata: Viperidae: Bothriechis) from the Costa Rican highlands, with notes on the variation within B. nigroviridis. Zootaxa.  4138(2):271-90.

Ghielmi S, Menegon M, Marsden SJ, Laddaga L, Ursenbacher S. 2016. A new vertebrate for Europe: the discovery of a range‐restricted relict viper in the western Italian Alps. Journal of Zoological Systematics and Evolutionary Research 54(3):161-73.

Gower DJ, Wade EO, Spawls S, Bohme W, Buechley ER, Sykes D, Colston TJ. 2016. A new large species of Bitis Gray, 1842 (Serpentes: Viperidae) from the Bale Mountains of Ethiopia. Zootaxa. 4093(1):41-63.

Thursday, December 29, 2016

Twelve new species of Anolis were described in 2016.

Anolis is the largest genus of lizards with more than 416 described species. Eight new species
were described by Kohler and Hedges (2016) 
Anolis chlorodius, Hispaniola
revising the green anoles of Hispaniola. Using morphological and molecular genetic data the authors recognize 16 species of green anoles on the island, eight of which they describe as new species (A. apletolepis, A. chlorodius, A. divius, A. eladioi, A. gonavensis, A. leucodera, A. prasinorius, and A. viridius). Three other species were raised from subspecific to species level (A. cyanostictus, A. demissus and A. pecuarius) and one was resurrected from synonymy with A. chlorocyanus (A. peynadoi).

Another new anole from Hispaniola, Anolis landestoyi, was described by Mahler et al. (2016). The new species, named Anolis landestoyi, was found in the Dominican 
Anolis landestoyi, Hispaniola
Republic but bears a strong resemblance to Cuba’s Chamaeleolis anoles.  Chamaeleolis anoles look less like typical anoles and more like chameleons: large, cryptic, slow-moving, and prone to clinging to lichen-covered branches high in forest canopies. Anolis landestoyi is restricted to a unique habitat only found in a small area in the western Dominican Republic that is rapidly disappearing due to illegal deforestation.

Two new anoles from Mexico were described by Köhler et al. (2016). Anolis (Norops) mccraniei occurs at elevations of 200–1,740 m throughout much of Honduras (except for the Atlantic slopes of the Cordillera Nombre de Dios
 in northern Honduras), as well as in extreme 
Anolis purpuronectes, Oaxaca, Mexico
northwestern El Salvador, northern Nicaragua, and eastern Guatemala. Anolis (Norops) wilsoni is restricted to the Atlantic slopes of the Cordillera Nombre de Dios in the departments of Atlántida and Colón in northern Honduras, at elevations from near sea level to 980 m.

The semi-aquatic Anolis purpuronectes was described by Gray, et al. 2016 from the western portion of the Chimalapas region in extreme northeastern Oaxaca and adjacent southeastern Veracruz, Mexico. They found this lizard sleeping on low vegetation within one metre of a stream, on boulders or logs in or along streams; on boulders, logs, or wet leaf litter; or within boulder crevices near small waterfalls. The type locality is a corridor of closed-canopy forest surrounded by highly disturbed areas.

Citations

Gray L, Meza-Lázaro R, Poe S, de Oca AN. A new species of semiaquatic Anolis (Squamata: Dactyloidae) from Oaxaca and Veracruz, Mexico. 2016. The Herpetological Journal. 26(4):253-62.

Köhler G, Hedges SB. 2016. A revision of the green anoles of Hispaniola with description of eight new species (Reptilia, Squamata, Dactyloidae). Novitates Caribaea 9: 1-135. E-print

Köhler G, Townsend JH, Petersen CB. 2016. A taxonomic revision of the Norops tropidonotus complex (Squamata, Dactyloidae), with the resurrection of N. spilorhipis (Álvarez del Toro and Smith, 1956) and the description of two new species. Mesoamerican Herpetology. 3:8-41.

Mahler DL, Lambert SM, Geneva AJ, Ng J, Hedges SB, Losos JB, Glor RE. 2016.  Discovery of a Giant Chameleon-Like Lizard (Anolis) on Hispaniola and Its Significance to Understanding Replicated Adaptive Radiations. The American Naturalist. 188(3):357-64.


Three new turtles described in 2016

Three new species of turtles were described during 2016. This brings the number of recognized species to 345. All three of the new species have relatively small distributions and are good candidates for threatened status.

The Yellow-bellied Snapping Turtle, Elseya flaviventralis

Goode's Thornscrub Tortoise, Gopherus evgoodei

The Yellow-bellied Snapping Turtle, Elseya flaviventralis Thomson & Georges, 2016 (family Chelidae), inhabits the Mary, South Alligator, East Alligator, Goyder and Mann River drainages of the northeastern portion of the Northern Territory (Arnhem Land region), Australia.

Goode's Thornscrub Tortoise, Gopherus evgoodei Edwards, Karl, Vaughn, Rosen, Meléndez-Torres & Murphy, 2016 (family Testudinidae). The new tortoise is a habitat specialist and is found exclusively in thornscrub and tropical broadleaf forests that comprise about 24,000 km2.

Isan Snail-eating Turtle, Malayemys isan Sumontha, Brophy, Kunya, Wiboonatthapol & Pauwels, 2016 (family Geoemydidae). This species inhabits northeastern Thailand, where it uses shallow, stagnant or slow-moving freshwater.

Isan Snail-eating Turtle, Malayemys isa

Citations

Brophy, Timothy R.; Sumontha, M.; Kunya, K.; Wiboonatthapol, S.; and Pauwels, O.S.G., 2016. A New Snail-Eating Turtle of the Genus Malayemys Lindholm, 1931 (Geoemydidae) from Thailand and Laos. Faculty Publications and Presentations. Paper 120. http://digitalcommons.liberty.edu/bio_chem_fac_pubs/120.

Edwards T, Karl AE, Vaughn M, Rosen PC, Torres CM, Murphy RW (2016) The desert tortoise trichotomy: Mexico hosts a third, new sister-species of tortoise in the Gopherus morafkaiG. agassizii group. ZooKeys 562: 131-158. https://doi.org/10.3897/zookeys.562.6124


Thomson S,  Georges A. 2016. A new species of freshwater turtle of the genus Elseya (Testudinata: Pleurodira: Chelidae) from the Northern Territory of Australia. Zootaxa 4061(1):18-28

Sunday, December 18, 2016

Northern Leopard Frog populations in the southwest

Rana pipiens. JCM
In the southwest, the Northern Leopard Frog, Rana (Lithobates) pipiens, is considered a threatened species, Much of this is due to droughts, land development, and falling water tables because of human water needs.

Invasive species are a major contributor to loss of biodiversity. However, translocations of a species within its own distribution are less frequently recognized, but have the potential for negative impacts on the native population. Genetic mixing may lead to loss of local adaptations or further decline through outbreeding depression. Cryptic invasions of new genetic material into populations that did not previously contain that genetic material may be quite difficult to recognize, but genetic tools can be used to recognize and monitor such intraspecific introductions. Conversely, translocations within species can be an important conservation tool to reduce inbreeding depression and replace lost genetic diversity.

Thus, cryptic invasions can be either an aid or a hinder conservation efforts. In a recent paper O'Donnell et al.(2016) tested for the presence of non-native genotypes and assessed the extent and nature of introgression in populations of Northern Leopard Frog in the southwestern US, where populations have declined to a few remnant populations. The most abundant and diverse complex of populations in the region contained a mitochondrial haplotype that was not native to the western US. This haplotype is likely the  resulting of released pets, laboratory animals, or animals accidentally release during fish stocking. These non-native haplotypes were well integrated into a large complex of ponds and lakes, contributing to high genetic diversity in this area. The geographic extent of non-native genetic influence within this population makes eliminating or controlling the non-native component of this population not possible.

The authors recommend assessing the progress and fate of the introgression over time—along with population fitness parameters—to determine whether this introduction is beneficial or detrimental to population persistence. Meanwhile, translocations from nearby locations with similar environmental conditions have the best prospects for avoiding problems with outbreeding depression in other declining populations and will also most effectively preserve regional genetic diversity.

Citation
O’Donnell RP, Drost CA, Mock KE. Cryptic invasion of Northern Leopard Frogs (Rana pipiens) across phylogeographic boundaries and a dilemma for conservation of a declining amphibian. Biological Invasions 2016:1-4.

Saturday, December 17, 2016

A new Tantilla from the dry forests of Peru

A male Tantilla tjiasmantoi Koch & Veneagas, 2016.
Seasonally dry tropical forests have a distinct seasonality with several months of arid-like conditions when many plants lose their leaves. In South America, these forests are discontinuous and can occupy large areas such as the Caatinga in northeastern Brazil or small fragments as being found in inter-Andean valleys of Peru or Ecuador. The species compositions differ substantially from one seasonally dry forest to another. The Equatorial dry forest stretches from southern Ecuador to the northern part of Peru  where it extends southward in two small stripes. One stripe continues along the west coast of the Andes, the other penetrates the valley of the Marañón River and its tributaries. Sixty-one species are currently recognized within the genus Tantilla. Twelve species occur in mainland South America, of which only two are found in Peru: T. capistrata and T. melanocephala. Most Tantilla have a uniformly colored or a longitudinally striped dorsal color pattern. Only T. shawi Taylor, from Mexico, T. semicincta  from Colombia and Venezuela, and T. supracincta from Colombia, Costa Rica, Ecuador, Nicaragua, and Panama have a transverse-banded color pattern on the dorsal part of the body. Koch and Venegas (2016) describe a new Tantilla from the dry forest of the northern Peruvian Andes based on two specimens, which exhibit a conspicuous sexual dimorphism. Tantilla tjiasmantoi sp. nov. represents the third species of the genus in Peru and one with an unusual transverse-banded pattern. A detailed description of the skull morphology of the new species is given based on micro-computed tomography images. The habitat of this new species is seriously threatened due to human activity. Conservation efforts are urgently needed in the inter-Andean valley of the Maranon River.

Citation
Koch C, Venegas PJ. (2016) A large and unusually colored new snake species of the genus Tantilla (Squamata; Colubridae) from the Peruvian Andes. PeerJ 4:e2767 https://doi.org/10.7717/peerj.2767

Wednesday, December 14, 2016

The number of species of birds and what it says about the number of species of reptiles

This blog usually focuses on non-avian reptiles. However, the research reported here on birds has great implications for how we think about the number of species of reptiles. Birds are the most studied group of vertebrates, reptiles are much less studied. Thus if it is possible to double the number of bird species, the number of reptile species is much, much greater than any of the current estimates.

According the the Reptile Database between February 2008 and August 2016, the number of reptiles increased from 8734 to 10,450, in increase of 1716 species or 19.6%.  Just considering the years between 2010 and 2016 there have been 972 new species of reptiles described. While during that same period (2010 to 2016) only 51 species of birds were described. Thus it would seem that the number of species of reptiles particularly squamates (lizards and snakes) is dramatically higher than my estimate made in my 2011 post.

In time of climate change, habitat destruction, pollution, and other forms of environmental degradation are occurring more rapidly than in previous history - it is entirely possible that many species are becoming extinct before they have been described.
The above map was published in 2012 by Saving Species.The variety of life on Earth is not spread evenly, but is concentrated in very special places. Above the world map is color coded for density of vertebrate species. Colors indicate the highest concentrations of the number of animal species across the world's land masses. Deep reds and yellows cover much of the tropics, indicating a huge number of species. The world’s high latitudes and its deserts are blue, indicating relatively low vertebrate diversity. 
New research led by the American Museum of Natural History suggests that there are about 18,000 bird species in the world -- nearly twice as many as previously thought. The work focuses on "hidden" avian diversity -- birds that look similar to one another, or were thought to interbreed, but are actually different species. Recently published in the journal PLOS ONE, the study has serious implications for conservation practices.

"We are proposing a major change to how we count diversity," said Joel Cracraft, an author of the study and a curator in the American Museum of Natural History's Department of Ornithology. "This new number says that we haven't been counting and conserving species in the ways we want."

Birds are traditionally thought of as a well-studied group, with more than 95 percent of their global species diversity estimated to have been described. Most checklists used by bird watchers as well as by scientists say that there are roughly between 9,000 and 10,000 species of birds. But those numbers are based on what's known as the "biological species concept," which defines species in terms of what animals can breed together.

"It's really an outdated point of view, and it's a concept that is hardly used in taxonomy outside of birds," said lead author George Barrowclough, an associate curator in the Museum's Department of Ornithology.

For the new work, Cracraft, Barrowclough, and their colleagues at the University of Nebraska, Lincoln, and the University of Washington examined a random sample of 200 bird species through the lens of morphology -- the study of the physical characteristics like plumage pattern and color, which can be used to highlight birds with separate evolutionary histories. This method turned up, on average, nearly two different species for each of the 200 birds studied. This suggests that bird biodiversity is severely underestimated, and is likely closer to 18,000 species worldwide.

The researchers also surveyed existing genetic studies of birds, which revealed that there could be upwards of 20,000 species. But because the birds in this body of work were not selected randomly -- and, in fact, many were likely chosen for study because they were already thought to have interesting genetic variation -- this could be an overestimate. The authors argue that future taxonomy efforts in ornithology should be based on both methods.

"It was not our intent to propose new names for each of the more than 600 new species we identified in the research sample," Cracraft said. "However, our study provides a glimpse of what a future taxonomy should encompass."

Increasing the number of species has implications for preserving biodiversity and other conservation efforts.

"We have decided societally that the target for conservation is the species," said Robert Zink, a co-author of the study and a biologist at the University of Nebraska, Lincoln. "So it follows then that we really need to be clear about what a species is, how many there are, and where they're found."

Citation
Barrowclough GF, Cracraft J, Klicka J, Zink RM. 2016 How Many Kinds of Birds Are There and Why Does It Matter? PLOS ONE, 2016; 11 (11): e0166307 DOI: 10.1371/journal.pone.0166307

Saturday, December 10, 2016

Two critically endangered sea snakes Aipysurus foliosquama and Aipysurus apraefrontalis

This is a photograph of the rare
short nosed sea snake discovered
on Ningaloo reef, Western Australia.
Photo credit: Grant Griffin, W.A.
Dept. Parks and Wildlife
Scientists from James Cook University have discovered two critically endangered species of sea snakes, previously thought to be extinct, off the coast of Western Australia.

It's the first time the snakes have been spotted alive and healthy since disappearing from their only known habitat on Ashmore Reef in the Timor Sea more than fifteen years ago.

"This discovery is really exciting, we get another chance to protect these two endemic Western Australian sea snake species," says study lead author Blanche D'Anastasi from the ARC Centre of Excellence for Coral Reef Studies at JCU.

"But in order to succeed in protecting them, we will need to monitor populations as well as undertake research into understanding their biology and the threats they face."

The discovery of the critically endangered short nose sea snake was confirmed after a Western Australia Parks and Wildlife Officer, Grant Griffin, sent a photo of a pair of snakes taken on Ningaloo Reef to Ms D'Anastasi for identification.

"We were blown away, these potentially extinct snakes were there in plain sight, living on one of Australia's natural icons, Ningaloo Reef," says Ms D'Anastasi.

"What is even more exciting is that they were courting, suggesting that they are members of a breeding population."

The researchers also made another unexpected discovery, uncovering a significant population of the rare leaf scaled sea snake in the lush seagrass beds of Shark Bay.

The discovery was made 1700 kilometres south of the snakes only known habitat on Ashmore Reef.

"We had thought that this species of sea snake was only found on tropical coral reefs. Finding them in seagrass beds at Shark Bay was a real surprise," says Ms D'Anastasi.

Both leaf scaled and short nosed sea snakes are listed as Critically Endangered under Australia's threatened species legislation, which means they have special protection. Despite the good news of the find, sea snake numbers have been declining in several marine parks, and scientists are at a loss to explain why.

"Many of the snakes in this study were collected from prawn trawl by-catch surveys, indicating that these species are vulnerable to trawling," says Dr Vimoksalehi Lukoschek from the Centre of Excellence for Coral Reef Studies.

"But the disappearance of sea snakes from Ashmore Reef, could not be attributed to trawling and remains unexplained.

"Clearly we need to identify the key threats to their survival in order to implement effective conservation strategies if we are going to protect these newly discovered coastal populations," Dr Lukoschek says.

The most common threat to sea snakes is usually thought to be incidental by-catch from trawling, and indeed, both species were sampled in trawl surveys in Shark Bay and Exmouth Gulf, suggesting that this is indeed a threat. However, trawling does not occur at the Timor Sea reefs because the reefs descend sharply into very deep waters. Thus the declines of these species could not be attributed to trawling. Trawling may be impacting coastal populations of these species. Other potential impacts on sea snakes include loss of habitats and/or prey, disease and recruitment failure due to coastal development, mining exploration and extraction, and climate change. However, until we identify the causes of previous extirpations of Aipysurus group species, it will be challenging to implement effective conservation strategies. Thus, in addition to the need for further field surveys to accurately document the true range extents and population  sizes of species (in coastal Western Australia and elsewhere), it also is critically important that targeted research be conducted to further our understanding of the biology and ecology of sea snakes, and address knowledge gaps about the key threatening processes.

Citation
B.R. D'Anastasi, L. van Herwerden, J.A. Hobbs, C.A. Simpfendorfer, V. Lukoschek. New range and habitat records for threatened Australian sea snakes raise challenges for conservation. Biological Conservation, 2016; 194: 66 DOI: 10.1016/j.biocon.2015.11.032

The human visual system has evolved specifically to detect snakes

Examples of a Random Image Structure Evolution (RISE) sequence for 
snake pictures. Participants looked at a sequence of 20 pictures with 
interpolation ration starting from 95% to 0% with steps of 5%. RISE
 sequence gradually changes from unorganized to well discernible. 
Photo credit: Nobuyuki Kawai

A Nagoya University research team uses new image processing tool to confirm human visual system has evolved specifically to detect snakes.

Some studies have suggested that the visual systems of humans and other primates are finely tuned to identify dangerous creatures such as snakes and spiders. This is understandable because, among our ancestors, those who were more able to see and avoid these animals would have been more likely to pass on their genes to the next generation. However, it has been difficult to compare the recognition of different animals in an unbiased way because of their different shapes, anatomical features, and levels of camouflage.

In a study reported recently in PLOS ONE, a pair of researchers at Nagoya University obtained strong support for the idea that humans have heightened visual awareness of snakes. The researchers applied an image manipulation tool and revealed that subjects could identify snakes in much more blurry images than they could identify other harmless animals in equivalent images.

The tool, called Random Image Structure Evolution (RISE), was used to create a series of 20 images of snakes, birds, cats, and fish, ranging from completely blurred to completely clear. The pair then asked subjects to views these images in order of increasing clarity until they could identify the animal in the picture.

"Because of the algorithm that it uses, RISE produces images that allow unbiased comparison between the recognition of different animals," first author Nobuyuki Kawai says. "In the images, the animals are 'camouflaged' in a uniform way, representing typical conditions in which animals are encountered in the wild."

The snakes were increasingly well-identified in the sixth to eighth of 20 images, while the subjects often needed to see the less blurred ninth or tenth images to identity the other animals. "This suggests that humans are primed to pick out snakes even in dense undergrowth, in a way that isn't activated for other animals that aren't a threat," co-author Hongshen He explains.

The findings confirm the Snake Detection Theory; namely, that the visual system of humans and primates has specifically evolved in a way that facilitates picking out of dangerous animals. This work augments understanding of the evolutionary pressures placed on our ancestors.

Citation
Nobuyuki Kawai, Hongshen He. Breaking Snake Camouflage: Humans Detect Snakes More Accurately than Other Animals under Less Discernible Visual Conditions. PLOS ONE, 2016; 11 (10): e0164342 DOI: 10.1371/journal.pone.0164342

Friday, December 9, 2016

The Frilled Lizard and its phylogeography

A typical defensive display of a Frilled Lizard.
The savanna-dwelling Australo-Papuan Frilled Lizards' spectacular threat display has made the lizard world famous. They are distributed across northern Australia and southern New Guinea. In a recent  Molecular Phylogenetics and Evolution article Pepper and colleagues (2017) examine the Frilled Lizard's phylogeography as it relates to changes in the savanna vegetation in the Plio/Pleistocene and the associated increase in aridity. The authors generated sequence data for one mitochondrial and four nuclear DNA loci (5052 base pairs) for 83 frilled lizards sampled throughout their range. They also quantified body proportion variation for 279 individuals. Phylogenetic analyses based on maximum likelihood and Bayesian species-tree methods resulted in three shallow clades that replace each other across the monsoon tropics. They found the expected pattern of male biased sexual size dimorphism in both maximum body size and head size but there was no sexual dimorphism in overall body shape or in frill size, relative to head size, supporting the hypothesis that the frill is used primarily as a threat display rather than a sexual display. The genetic clades are broadly consistent with known clinal variation in frill color that gradually shifts from west to east (red, orange, yellow/white) but otherwise show little morphological differentiation in body proportion measures. The biogeographic breaks between clades occur at the Carpentaria Gap and the lowlands surrounding the Ord River. Ecological niche modeling predicts where habitat suitability for Frilled Lizards in these regions. Extremely low intra-clade genetic diversity over vast geographic areas is indicative of recent gene flow that would likely have been facilitated by widespread savanna during interglacials, Or alternatively, may reflect population bottlenecks induced by extreme aridity during Pleistocene glacials. The shallow divergence between Australian and New Guinean samples is consistent with recent connections between Australia and New Guinea that would have been  via a savanna corridor across the Torres Strait. The authors do not support taxonomic recognition of any of the frilled lizard clades and consider C. kingii a single species with shallow phylogeographic structure and clinal variation in frill color.

Citation
Pepper M, Hamilton DG, Merkling T, Svedin N, Cser B, Catullo RA, Pryke SR, Keogh JS. Phylogeographic structure across one of the largest intact tropical savannahs: Molecular and morphological analysis of Australia’s iconic frilled lizard Chlamydosaurus kingii. 2017. Molecular Phylogenetics and Evolution. 106:217-27.

Thursday, December 8, 2016

Fossil Miocene amphibians and reptiles from Plakias, Crete


A modern alytid European frog, Bombina. JCM
The Neogene (the Miocene and Pliocene) extends from about 22.5 to 2.5 million years ago, and it has been termed "the age of snakes."  The global climate became seasonal, drier and cooler. Polar ice caps formed and thickened, and by the end of the Neogene the first of a series of glaciations of the current Ice Age began. Both the marine and continental flora and fauna contained modern looking species. Many older lineages of amphibians and reptiles had disappeared and were replaced by more modern lineages. Birds and mammals continued to dominant terrestrial vertebrate communities, and the first hominids, the ancestors of humans, evolved in Africa and dispersed into Eurasia. The Miocene composed the bulk of this time segment of Earth's history. In a new paper published in Geobios, Georgalis et al (2016) report on the fossil amphibian and reptiles from the late Miocene of Crete.

The excavation site was at Plakias (early Tortonian, MN 9), Crete, Greece. Most of the material recovered was fragmentary and precludes precise taxonomic assignment. However, the herpetofauna of Plakias was diverse and composed at least six different taxa: an alytid frog, a crocodilian, two turtles (a pan-trionychid and a geoemydid) and two squamates (an amphisbaenian and a colubroid snake). The crocodilian material represents the first such fossils described from Greece and furthermore, one of the latest occurrences of this group in Europe. The pan-trionychid and the geoemydid represent the oldest occurrences of these groups in Greece and further add to their scarce Miocene record from this country. The first description of a fossil amphisbaenian from Greece is also provided. The new specimens from Plakias add to our knowledge of the Miocene herpetofaunas of southeastern Europe. The single colubroid snake specimen adds further to the published record of Miocene snakes from Greece, whereas the amphisbaenian vertebra from Plakias represents the first described fossil of this group from the country, suggesting that amphisbaenians had a continuous range in the northern Mediterranean area.


Citation
Georgalis, G.L., Villa, A., Vlachos, E. and Delfino, M., 2016. Fossil amphibians and reptiles from Plakias, Crete: A glimpse into the earliest late Miocene herpetofaunas of southeastern Europe. Geobios.

Wednesday, December 7, 2016

Impact of food on an ambush specialist - the Puff Adder

The puff adder, Bitis arietans.
The effect of food availability on the spatial ecology of snakes  is under studied. Snake are low-energy specialists, particularly species that specialize in ambush foraging.  Ambush specialists can feed infrequently and  endure long periods without food. Because they have low-energy requirements, one possible tactic for feeding may be to simply ambush for longer periods when prey availability is low, and decrease the potential costs associated with locating new ambush sites. In a forthcoming paper Glaudas and Alexander  (2017) used radiotelemetry, supplemental feeding, and remote video cameras on free-ranging male puff adders (Bitis arietans) in South Africa to test the hypothesis that food intake affects the foraging ecology of extreme low-energy, ambush foragers. They also quantified their natural feeding rates. Supplementally fed puff adders improved their body condition, spent less time foraging, and decreased distance traveled compared to control snakes. However, movement frequency and home range size did not differ between the two groups. These findings indicate that control snakes traveled farther within similar-sized home ranges compared to fed snakes and did so at no survival cost. Further, naturally foraging puff adders successfully caught a prey of small size once every 10 days on average. Hence, despite their “sit-and-wait” foraging strategy and their low-energy intake/requirements, underfed puff adders travel widely to presumably find appropriate ambush sites that maximize prey capture. This study provides the first strong evidence that the spatial activity of a terrestrial vertebrate species with extremely low energetic demands is significantly affected by
food intake.

Citation

Glaudas X, Alexander GJ. 2017. Food supplementation affects the foraging ecology of a low-energy, ambush-foraging snake. Behavioral Ecology and Sociobiology. 71(1):5.

Galapagos Land Iguana - seed dispersal agent

A Galápagos Land Iguana (Conolophus subcristatus).
Photo credit Traveset et al.
The isolation of ocean islands like the Galápagos prevents the arrival of large mammals, which disperse the seeds of many plants by ingesting them. In the absence of mammals, this function is filled by birds, tortoises, lizards and iguanas. To date, no investigation had been carried out into the role iguanas play with at least ten species of plants.

The survival of many native and introduced plants depends in part on the role of animals in pollination and seed dispersal. The ingestion and subsequent expulsion of seeds in animal faeces means a proportion of them return to the soil at a more distant location.

In addition to birds, the Galápagos giant tortoise is the animal that disperses most of seeds over great distances on the islands, followed by the endemic land iguanas, of which there are three species which feed on fruit and vegetation near ground level, as they do not climb. However apart from anecdotal records, their potential for seed dispersal had not to date been confirmed.

A study published in the journal 'Integrative Zoology' demonstrates for the first time how by dispersing seeds, the Galápagos land iguana (Conolophus subcristatus) contributes to the survival of indigenous and introduced plants plant species on Fernandina Island, which covers 642 km2 of land.

"We knew that female iguanas on this island cover large distances, around 10 kilometres, and climb up to 1,500 metres of altitude to lay their eggs at the island's volcanic crater," Anna Traveset from the Mediterranean Institute for Advanced Studies (CSIC-UIB), the lead author of the study, outlines.

Between February 2010 and 2011, the researchers collected 160 faeces samples, in which they identified 5,705 seeds from 32 plant species. According to the team, at least 80% of the seeds (around 4,545) were damaged.

With the remaining seeds, which remained intact after passing through the reptile's intestines, the team ran an experiment in which they planted 849 seeds from 29 plant species; only around 4% of these were germinated over 200 days later.

"Considering the local abundance of land iguanas and the large amount of seeds ingested by these animals, even if only a small proportion germinates, they can be considered important for plant dissemination to new areas in this young island," Traveset writes in the article.

In fact, some plants appear to benefit greatly from this action. According to the paper, 63% of the seeds belonged to native plants, a third of which were endemic to the Galápagos Islands. Six per cent were from introduced species and the remainder (31%) could not be identified.

Citation
Traveset A, Nogales M, Vargas, Rumeu B, Olesen JM, Jaramillo P, Heleno R. 2016. Galápagos land iguana (Conolophus subcristatus) as a seed disperser. Integrative Zoology, 2016; 11 (3): 207 DOI: 10.1111/1749-4877.12187

Friday, November 11, 2016

Three new species in the Tegu teguixin Group

The Cryptic Golden Tegu, Tupinambis cryptus,one of the newly 
described species. Tob is an adult from Trinidad middle
 is a juvenile from Tobago. Bottom is a female on a termite nest,
 probably looking of a place to deposit her eggs. JCM, Graham White.
The golden tegu lizard, previously thought to be a single species, may actually comprise four distinct clades, including three new cryptic species, according to a study published August 3, 2016 in the open-access journal PLOS ONE by John Murphy from the Field Museum of Natural History, USA and colleagues.

Tegus are among the largest Neotropical lizards, and while some species occur only in Brazil, Tupinambis teguixin inhabits much of northern South America. Commonly known as the golden tegu, T. teguixin is also sometimes called the "black and white" tegu and can be confused with the closely related species, Salvator merianae. To help resolve the systematics and nomenclature of this species, the authors examined museum samples of golden tegus for genetic and morphological differences across its geographical distribution. The authors noted subtle differences in leg scale morphology, as well as the shape of eye and lip areas, and identified substantial genetic divergence across the tegus large range.

The authors split the species currently recognized as T. teguixin into four morphologically distinct but geographically overlapping species, including three new cryptic species -- T. cryptus, T. cuzcoensis, and T. zuliensis -- that look similar to the human eye but are genetically distinct. The authors suggest that further research in northeastern South America might identify additional species within the T. teguixin group, which would aid in planning for tegu conservation.

"We demonstrate for the first time that two lineages of the Golden Tegu,Tupinambis teguixin, are living side by side at multiple locations in South America, and that T. teguixin is composed of at least four distinct species," said John Murphy. "This situation is known in many other species. What is surprising is that it has gone unrecognized in a species heavily exploited by humans for more than 200 years."
Citation
John C. Murphy, Michael J. Jowers, Richard M. Lehtinen, Stevland P. Charles, Guarino R. Colli, Ayrton K. Peres, Catriona R. Hendry, R. Alexander Pyron. Cryptic, Sympatric Diversity in Tegu Lizards of the Tupinambis teguixin Group (Squamata, Sauria, Teiidae) and the Description of Three New Species. PLOS ONE, 2016; 11 (8): e0158542 DOI: 10.1371/journal.pone.0158542

A re-evaluation of the four-legged snake Tetrapodophis amplectus

Reconstruction of Tetrapodophis.
In 2015, Martill et al. described Tetrapodophis amplectus, a fossil snake with four legs. Tetrapodophis was found in the Bürgermeister-Müller-Museum, a natural history museum in Solnhofen, Germany, while students were on a field trip to the museum.  The Brazilian fossil was part of an exhibit on the Cretaceous and estimated to be 110 million years old. The fossil was part of a larger exhibition on Cretaceous fossils.
The snake, was 20 cm from head to toe, although it may have grown much larger. The head is the size of an adult fingernail, and the smallest tail bone is only a quarter of a millimeter long. But the most remarkable thing about it is the presence of four limbs each ending in digits. The front legs are about 1cm long. The back legs are slightly longer and the feet are larger than the hands. The authors hypothesized that they may have been used to grasp prey or mates. The fossil Tetrapodophis apparently had food in its guts when it was preserved, the remains appeared to be from a salamander.
The authors considered Tetraphodophis a snake, not a lizard because of the elongated body; the tooth implantation, the direction of the teeth, and the pattern of the teeth and the bones of the lower jaw are all snake-like. The fossil also suggests a single row of ventral scales.
In the same issue of Science, Evans (2015) notes that snakelike bodies evolved at least 26 times in squamates and that body elongation is always correlated with limb reduction and that the forelimbs are usually lost first. She also observed that the threshold body length at which limb reduction begins is about 70 body vertebrae (or precaudal vertebrae). Tetrapodophis is remarkable in having about 160 precaudal vertebrae and retaining its anterior limbs. Evans also notes Tetrapodophis is like lizards in having distinct vertebral regions of the vertebral column.  It has 10 or 11 short-ribbed neck vertebrae adjacent to the tiny forelimbs. Some generalized terrestrial lizards and a neck of about this same length. Thus, as in long-bodied lizards, elongation of the snake skeleton occurred in the trunk region and not the neck. If Tetrapodophis is indeed a stem-snake, then body elongation preceded loss of the forelimbs.
In second look at the fossil by Lee et al. (2016) suggests Tetrapodophis may not, in fact be a snake at all. Instead they suggest it may be a dolichosaurid, a Cretaceous four-legged marine lizard with an elongated, snake-like body.
Tetrapodophis lacks characters that would be expected in a snake, including re-curved teeth. Lee and colleagues reevaluated the ecomorphology of this fossil using a multivariate morphometric analysis and reexamination of the limb anatomy. Their analysis suggests that the body proportions are unusual and similar to both burrowing and surface-active squamates. They also show it exhibits enlarged first metapodials and reduced tarsal-carpal ossification. These traits imply Tetrapodophis was aquatic.
Unfortunately, the fossil is privately owned and after Lee’s team took photos and measurements, the specimen was removed from the museum so that it can no longer be studied.  

Citations
Evans S. 2016. Four legs too many? Science. 349(6246):374-5.

Lee MS, Palci A, Jones ME, Caldwell MW, Holmes JD, Reisz RR. 2016. Aquatic adaptations in the four limbs of the snake-like reptile Tetrapodophis from the Lower Cretaceous of Brazil. Cretaceous Research. 30, 66:194-199.

Martill DM, Tischlinger H. Longrich NR 2015. A four-legged snake from the Early Cretaceous of Gondwana. Science, 349(6246): 416-419.


Wednesday, October 26, 2016

A new toxin from the Blue Coral Snake

(a) Specimen of Calliophis bivirgatus, the blue coral
snake (Photo by Tom Charlton). (b) Dissected preserved 
112 cm Calliophis bivirgatus specimen with 29 cm elongated 
venom glands (arrows).
The Asian Coral snakes in the genus Calliophis feed upon other snakes, including other snake-eating venomous species of Elapidae such as kraits (Bungarus) and king cobras (Ophiophagus). A unique evolutionary scenario ensues, a chemical arms race between predator and prey in which the risk of role reversal becomes a key selection pressure driving the evolution of toxins that rapidly render prey incapable of retaliation or escape. Snakes that hunt animals capable of inflicting serious retaliatory wounds often release their intended prey after envenomation. In this situation, selection may favour the evolution of toxins that rapidly disable prey, either to prevent it moving too far to be recovered or to prevent the possibility of it attacking and injuring the snake.

With its combination of electric blue dorsolateral stripes and neon red head, tail, and ventral scales, the blue coral snake, Calliophis bivirgatus, is arguably one of the world’s most striking species of snake. An encounter with one is high on the list for many reptile enthusiasts and nature photographers visiting southern Thailand, Malaysia, Singapore, and western Indonesia. The species is of additional interest to anatomists and toxinologists studying the evolution and diversification of the snake venom system as it (along with its congener C. intestinalis) possesses novel elongated venom glands that extend up to one quarter of the length of its body. It is also of medical significance as, in spite of only a small handful of confirmed bites, it has been responsible for at least one human fatality, is suspected of causing at least one more, and has no known antivenom. In spite of these high levels of interest, the venom has been subject to relatively few studies. Studies that examined the toxin content of the venom concluded that all the three-finger toxins present were exclusively cytotoxic in their effects. However, this limited scope of activity attributed to the venom was reflective of the very narrow scope of assays performed and cytotoxicity was largely assumed based on similarity of partial sequences to other toxin types from other snakes rather than full activity characterisation. One study, which examined the usefulness of Taiwan antivenom, preincubated the venom with antivenom (a clinically unrealistic situation) and even then required very high doses to exert any meaningful level of inhibition.

In a new paper Yang et al. (2016) show that the venom is unique in producing spastic paralysis, in contrast to the flaccid paralysis typically produced by neurotoxic snake venoms. The toxin responsible, is named calliotoxin (δ-elapitoxin-Cb1a), a three-finger toxin (3FTx). The calliotoxin molecule has a form of neurotoxicity, previously known from cone snail and scorpion venoms, and is identified for the first time from the venom of a snake. Calliotoxin shifts the voltage-dependence of NaV1.4 activation to more hyperpolarised potentials, inhibits inactivation, and produces large ramp currents, consistent with its profound effects on contractile force in an isolated skeletal muscle preparation. Voltage-gated sodium channels (NaV) are a particularly attractive pharmacological target as they are involved in almost all physiological processes including action potential generation and conduction. Accordingly, venom peptides that interfere with NaV function provide a key defensive and predatory advantage to a range of invertebrate venomous species including cone snails, scorpions, spiders, and anemones. Enhanced activation or delayed inactivation of sodium channels by toxins is associated with the extremely rapid onset of tetanic/excitatory paralysis in envenomed prey animals. A strong selection pressure exists for the evolution of such toxins where there is a high chance of prey escape. However, despite their prevalence in other venomous species, toxins causing delay of sodium channel inhibition have never previously been described in vertebrate venoms. Here we show that NaV modulators, convergent with those of invertebrates, have evolved in the venom of the long-glanded coral snake. Calliotoxin represents a functionally novel class of 3FTx and a structurally novel class of NaV toxins that will provide significant insights into the pharmacology and physiology of NaV. The toxin represents a remarkable case of functional convergence between invertebrate and vertebrate venom systems in response to similar selection pressures. These results underscore the dynamic evolution of the Toxicofera reptile system and reinforces the value of using evolution as a roadmap for biodiscovery.

Citation
Yang DC, Deuis JR, Dashevsky D, Dobson J, Jackson TN, Brust A, Xie B, Koludarov I, Debono J, Hendrikx I, Hodgson WC. 2016. The Snake with the Scorpion’s Sting: Novel Three-Finger Toxin Sodium Channel Activators from the Venom of the Long-Glanded Blue Coral Snake (Calliophis bivirgatus). Toxins. 8(10):303.