Croaking Science

Croaking Science: Basking frogs: a puzzle

March 1, 2026 by Admin

Roger Downie, Froglife and University of Glasgow

It is well known that many species of reptiles bask i.e. sit in the sun with their dorsal surfaces exposed, absorbing solar radiation in order to raise body temperature. This behaviour is common in lizards and snakes, especially those inhabiting temperate regions where night-time temperature can be low even in spring and summer. The heat generated allows the active temperature of these animals to be significantly greater than ambient, and it can also promote food digestion and absorption. The potential disadvantage is that lying still in the open increases the risk of predation: this risk is often mitigated by colour change that helps conceal the animal. Basking at night can help tropical region reptiles to cool off (Kidman et al, 2024).

However, basking in frogs seems an unlikely behaviour. Their highly permeable skins allow a high rate of evaporative water loss in dry air, especially at higher temperatures in open sunshine. We therefore think of frogs as mainly active at night and in humid conditions where water loss is low. However, some frog species are mainly diurnal, and some do bask: why, and how do they survive this seemingly lethal behaviour?

The best-known basking frogs are in the genera Chiromantis ( African foam-nesting treefrogs: 4 species); Phyllomedusa (neotropical leaf frogs; 67 species); and Hyperolius (African reed frogs: 228 species). Where they have been assessed, it turns out that these frogs have evaporative water loss rates 10-100 lower than in typical frogs. This is achieved in several ways: the skin may contain reflective crystals that reduce light absorption; in others, the skin is covered with water resistant waxes and lipids. In Phyllomedusa, the lipids are secreted by localised glands and spread over the skin surface by wiping movements of the long hind limbs.

Bokermannohyla alvarengai spends hours during the day sitting on lichen-covered rocks exposed to the sun.

Not all basking frogs fit this picture. Tattersall et al (2006) described a South American hylid Bokermannohyla alvarengai (30 species described in this poorly known genus) which inhabits a montane meadow environment in southeastern Brazil. This frog spends hours during the day sitting, in water-conserving posture, on lichen-covered rocks, rocks exposed to the sun. When the frogs warm up, they turn pale (from their overnight grey-brown mottled colour) and can be easily seen. Tattersall’s experiments showed that the colour change is linked to both increasing light and temperature, with the pale colour developing within minutes of light exposure. The natural history of this species is poorly known, but Tattersall et al suggest that basking may increase food digestion rate, gonadal development and responses to infection. The pale skin colour should reduce excessive radiation absorption. Observations showed that the undersides of frogs on rocks were damp, suggesting that in the early morning, humid air was trapped below the frog, providing some protection against desiccation. However, these frogs did not have particularly low levels of evaporative water loss, and could not be counted amongst the ‘waterproof’ frogs.

Another case is the Trinidad and Tobago frog Kenny (1969) named Hyla crepitans: he noted that during the day, this medium-sized treefrog can often be observed lying exposed to the sun on garden walls or leaves or tree trunks. At night, the frog’s upper surface colour is mottled golden brown with a distinct dark cross, but during the day, it is pale grey to white. Murphy (1997) agreed with these colour change and behaviour observations, but added that, at night in the wet season, the male frogs, spaced out 1.2-1.8 metres apart, call from floating vegetation in man-made ponds and ditches.

The Trinidad and Tobago population was re-assigned to Boana platanera.

Like many other neotropical frogs, Hyla crepitans has recently undergone significant taxonomic revision. As Hyla crepitans, this species was thought to have a huge range, from Brazil north to Venezuela and Colombia. First, the generic name was revised to Hypsiboas, then to Boana (Dubois, 2017). Then Orrico et al (2017) found that the southerly Brazilian population was distinct from that in the north, and renamed the northern species Boana xerophylla. Most recently, the northern population has been found to be composed of two separate species, with the Trinidad and Tobago population being re-assigned to Boana platanera ( Escalona Sulbaran et al, 2021).

During expeditions to Trinidad (2013-15) University of Glasgow staff and students found several sites along the road to the Caura valley in the Northern Range mountains where Boana platanera adults were easily observed. Each site had a nearly vertical rock face pointing essentially eastwards and close to the road, with a concrete drainage ditch between road and rock. The rocky faces were about 5 metres high, with scrubby vegetation on top, backed by secondary forest. At several points, the drainage ditches were almost horizontal and often contained mud and rocky debris and vegetation in heaps which blocked the passage of water. The result was that these ditches often retained water several centimetres deep for considerable periods after rain fell, so they acted as elongated temporary pools. These pools supported the breeding of several frog species, including B. platanera.

The dorsal markings of the frogs were distinct enough that by taking digital photographs, we were able to recognise each individual. In our most detailed study in 2014, we were able to recognise 60 frogs over the four separate sites studied, with each frog being faithful in its attendance at a particular site. All the frogs seen basking on the rock surfaces were males. Out of 20 surveys made over a span of 30 days, the presence of 10 male frogs on the walls averaged 7.5 times out of the 20, with a range of 2-14: i.e. basking was a highly variable activity. When a basking frog was seen in the morning, it was generally in the same position in the afternoon.

At dusk (darkness falls very quickly in Trinidad), one of the males on the wall would start to call, soon followed by the others, and they would leave the wall and jump into the water. Their colour would rapidly change from near white to golden brown and they would begin to jostle for position in the ditch. Usually if one frog aggressively approached another, one would quickly retreat, but we did also see active grappling occur. The genus Boana is commonly known as ‘gladiator frogs’ because of the male-male combat behaviour seen prior to mating. By 2026, 101 species of these frogs had been described, and combat behaviour has certainly not been observed in them all, but the behaviour we have seen in B. platanera fits the description. After a while, some of the male frogs were calling regularly, more or less evenly distributed 50-60 cm apart along the pool of water in the ditch, while a few others were displaced, also calling, on the concrete of the ditch or on the muddy blockage at the end. At some point, females arrived and we did observe some pairs in amplexus. Next morning, the number of spawn clumps seen at any one site was never more than three, irrespective of the number of males that had been seen basking and calling.

In the tropics, where long wet seasons can occur, and high water temperatures can allow rapid development of tadpoles, the explosive spring seasonal breeding of amphibians seen in temperate regions is not the norm. Breeding occurs when individual females are ready and appear at a breeding site. In the leaf-frog Phyllomedusa we found that this creates a problem for the males (Boyle et al, 2021) : attending the breeding site very regularly increases the opportunities to find a mate, but has the potential risks of high predation (frog calls allow predators to locate their frog prey) and lost opportunities for feeding; whereas attending the site sporadically has the opposite set of costs. In practice, site attendance by males was very variable, some attending most nights, others only occasionally. Our observations on the Caura site suggest a similar situation for B. platanera: variable male attendance and low female availability. The extra feature here is the basking behaviour, apparently restricted to males. At our site, the basking wall was very close to the aquatic breeding site, so rapid access to the site could be an advantage. However, this is unlikely to offset the potential hazards of dehydration (there is no evidence that these frogs are water-proofed), and visibility to predators. Perhaps the higher body temperatures achieved through basking would help digest food rapidly, providing the energy needed for combat. Or there may be other advantages we have not yet considered.

It is clear that these preliminary observations, not yet formally published, need further work in order to determine what advantage these frogs get from their intriguing basking behaviour.

I acknowledge several members of the University of Glasgow expeditions in 2013-15 for contributing to the observations outlined here, especially Tom Burns.

Click here for references

Boyle et al (2021). Breeding site attendance in Phyllomedusa trinitatis. Phyllomedusa 20, 53-66.

Dubois (2017). The nomenclatural status of Hysaplesia, Hylaplesia, Dendrobates and related nomina. Bionomina 11, 1-48.

Escalona Sulbaran et al (2021). Integrative taxonomy reveals a new treefrog hidden under the name Boana xerophylla. Zootaxa 4981, 401-448.

Kenny (1969). The amphibia of Trinidad. Studies on the fauna of Curacao and other Caribbean islands 29, 1-78.

Kidman et al (2024). How turtles keep cool: basking in tropical turtles. Journal of Thermal Biology 121, 103834.

Murphy (1997). Amphibians and Reptiles of Trinidad and Tobago. Kreiger Publishing.

Orrico et al (2017). Integrative taxonomy supports two species within Hypsiboas crepitans. Salamandra 53, 99-113.

Tattersall et al (2006). Skin colour and body temperature changes in basking Bokermannohyla. Journal of experimental biology 209, 1185-1196.

Tadpole diversity needs more attention if anurans are to be effectively conserved

October 1, 2025 by Admin

Roger Downie

Froglife and University of Glasgow

A quarter of a century ago, James Hanken (1999) drew attention to the ironical situation that at a time when the serious worldwide declines in amphibian populations were becoming recognised, the number of described amphibian species was increasing at a faster rate than for any other vertebrate class. In 1985, the number of species was 4003; given the current rate of new descriptions, Hanken expected the number to reach 5000 by the turn of the century (1.7% more per year). Now, half-way through 2025, Frost’s database lists 8883 species (actually 3% more per year since 1985), 7828 of them anurans (frogs and toads), with no sign that the rate of new species description is likely to decline soon. But sadly, as these numbers continue to rise, so too do the threats: the Global Amphibian Assessment (GAA) in 2004 concluded that 32.5% of species were threatened with extinction, the highest proportion for any vertebrate class; GAA2 in 2022 revised that figure upwards to 40.7% (although part of the rise results from a decrease in the proportion of species classed as Data Deficient, 22.5 to 11.3%). That figure can only be a tentative estimate, since the conservation status of the newly-described species is rarely known.

If we are to roll back the wave of amphibian extinctions, a key step is to determine how many species exist and where they live (to non-biologists, it is probably a surprise to realise that after centuries of species recording, the world species catalogue is nowhere near complete). However, if we are to protect species into the future, we need to know much more than is contained in a basic species description. Hortal et al. (2015) listed the ‘shortfalls’ (or deficiencies) in our current knowledge about biodiversity under a set of headings named after prominent scientists, for example:

Linnean: description and cataloguing of species
Wallacean: distribution of species
Prestonian: abundance and population dynamics
Darwinian: relationships and variability

Faria et al.(2020) identified another class of shortfall: Haeckelian, named after the prominent 19^th century German embryologist Ernst Haeckel. This class encompasses knowledge of a species life-history stages. Now, a group of mainly Argentinian biologists has applied this idea to frogs and toads (Vera Candioti et al., 2023; Nori et al., 2025): they note that for more than 50% of species, we have only adult descriptions, with no information on embryonic, larval and juvenile stages, including on their habitats and habits. This clearly matters for species with biphasic life histories where the larval/tadpole stage is fundamentally different from the adult in form, habits and habitat, since measures aimed at conserving adults may be ineffective in assisting earlier stages. The authors note that the IUCN species assessment process does not yet take this information shortfall fully into account, finding that many species where knowledge of larval stages is entirely lacking are currently listed as of Least Concern.

Nori et al.’s (2025) paper describes a strategy for reducing the Haeckelian shortfall for anurans, using geographical and other data to identify the areas where focussed fieldwork should be capable of finding and documenting the missing larval stages, habits and habitats: these are parts of the tropical Andes, eastern Brazil, tropical Africa, India, southeast Asia and New Guinea.

In the UK, with our very limited anuran fauna, including limited larval diversity (all species having pond-dwelling algal browsers), it is hard for us to appreciate the vast diversity of larval forms found elsewhere, and to understand that much diversity remains to be discovered. A few recent examples illustrate this point:

Dias et al. (2024a) analysed the food processing mouth-parts of several so-called ‘sand-eating’ tadpoles from Madagascar: the ruffled ridges used for separating organic material from sand-grains are described as ‘astonishingly novel’ and not seen previously in any anuran larvae.
Dias et al. (2024b) described the adhesive oral discs of two Andean toad tadpoles as so different from those of relatives that they justified assignment to a new genus Adhaerobufo despite the adults being quite similar to relatives.
Romero-Carvajal et al.(2023) describe early development of a ‘plump toad’, one of eleven species found in the Andes, where early stages are previously unknown. Small numbers of large terrestrial eggs are produced, with no free-living tadpole stage; however, the pre-hatching stages include an elongated tail, unlike the findings for other direct-developing species.

Dias et al. (2024a) analysed the food processing mouth-parts of several so-called ‘sand-eating’ tadpoles from Madagascar

When I started research on the amphibians of Trinidad and Tobago in the 1980s, I was lucky that the existing account (Kenny, 1969) included illustrations and natural history notes on most of the tadpoles, and we were able to extend these to cover some new species, including the glassfrog and stream-frog tadpoles of Tobago. But much remains to be done. We made observations on some key variables: for example, the time taken from hatching to metamorphosis, as little as 12 days in some cases; the time taken for the period of metamorphosis itself, and the behaviour of newly metamorphosed froglets. All these are crucial to the success of the anuran life-cycle, but remain hugely under-researched for most species. Let’s hope that the focus provided by Vera Candioti and colleagues provides an impetus for the needed research.

Acknowledgement

Thanks to Robin Bruce for drawing my attention to Nori et al’s paper.

References

Dias, P.H.S. et al. (2024a). Stranger things: on the novel buccopharyngeal anatomy and functional morphology of ‘sand-eating’ Malagasy tadpoles. Zoological Journal of the Linnean Society 202, zlae127.

Dias, P.H.S. et al. (2024b). The remarkable larval morphology of Rhaebo nasicus with the erection of a new bufonid genus and insights into the evolution of suctorial tadpoles. Zoological Letters10, 17.

Faria, L. et al. (2021). The Haeckelian shortfall, or the tale of the missing semaphoronts. Journal of Zoological Systematics and Evolution Research 59, 359-369.

Hanken, J. (1999). Why are there so many new amphibian species when amphibians are declining? Trends in Ecology and Evolution 14, 7-8.

Hortal, J. et al. (2015). Seven shortfalls that beset large-scale knowledge of biodiversity. Annual Review of Ecology, Evolution and Systematics 46, 527-549.

Kenny, J. S. (1969). The amphibia of Trinidad. Studies on the Fauna of Curacao and other Caribbean Islands 29, 1-78.

Nori, J. et al. (2025). Global key areas for anuran tadpole discovery. Biological Journal of the Linnean Society 145, blaf017.

Romero-Carvajal, A. et al. (2023). Direct development or endotrophic tadpole? Morphological aspects of the early ontogeny of the plump toad Osornophryne occidentalis. Journal of Morphology 284, e21582.

Vera Candioti, F. et al. (2023). Global shortfalls of knowledge on anuran tadpoles. npj Biodiversity 2, 22.

New research on fossil trackways from Australia suggest an earlier divergence of land-living tetrapods from amphibians.

September 1, 2025 by Admin

Andrew Smart, Head of Science and Research

We spend all our efforts working to protect and provide new habitats and environments for our living reptiles and amphibians, but I thought it would be interesting to take a moment to consider a new discovery from Australia and its implications.

Two evolutionary moments of great significance, the separation of lungfish and ancestral tetrapods, and the separation of amphibious tetrapods and land-living (and reproducing) tetrapods are the focus of much study, particularly with novel methods used to assess the footprints and trackways left in the fossil record (paleoichnology).

A recent paper in the journal Nature analyses a slab of rock from the Snowy Plains Formation of Victoria, Taungurung Country (358 to 354 million years old). This slab of rock (picture below from Fig. 2 of Long et al (2025)) shows three lines of footprints made by an amniote tetrapod (the tracks show the impressions of claws – a characteristic of amniotes not shared in amphibians in the fossil record of that period). The animal left no body or tail drag marks and based on the dimensions of the modern water monitor, Varanus salvator, the authors estimate a lizard-like animal of some 80 cm in length.

Amniotes (so called because of the evolution of the amniotic membrane in the egg) were the first vertebrate group that could live on land and lay shelled eggs. Shelled eggs removed the need to return to water bodies to reproduce or to lay their eggs in humid conditions and so made more terrestrial habitat available for colonisation.

Prior to this recent find, reptilian (amniote tetrapod) divergence from amphibious tetrapods was estimated, from molecular studies (DNA analysis), at some 352 million years ago and the first likely reptile was Casineria (340 million years ago) found near Edinburgh in 1999. (Casineria is the subject of some debate because the fossil has no skull). In 1989 another early amniote skeleton was found from West Lothian carboniferous rocks and identified as 338 million years old (Smithson 1989).

Before this find, the first ‘reptile’ trackmaker was Notalacerta and the first clear reptile body fossil was Hylonomus (c. 310 million years ago). Hylonomus was a lizard-like species, 20 cm in length, that is believed to have used club moss stumps as shelter or nests sites. (Marchetti et al 2021).

The new trackway from Australia moves the divergence of amphibians and amniotes back by between 35 and 40 million years, suggesting tetrapod and amniote lineages must have their origins 380 million years ago.

The separation of tetrapod ancestral ‘fish’ from lungfish is supported by discovery in 2012 of Tungsenia, a Lower Devonian ‘ancestral tetrapod fish’ from China (Lu et al , 2012), suggesting that the earliest ancestor of terrestrial tetrapods diverged from lungfish around 409 million years ago.

The earliest amphibious tetrapod records are from tracks made in Poland (Niedźwiedzki et al, 2020) that indicate tetrapods of 2m or more lived in intertidal / lagoon environments some 398 million years ago (eighteen million years before the earliest tetrapod fossils were deposited). The authors suggested that the evolution of amphibious tetrapods occurred in intertidal zones rather than in freshwater, with tides providing an available food resource of stranded animals twice a day.

Sumida (2025) discusses the implications of Long et al’s new discovery and the evidence suggests that if:

ancestral tetrapods diverged from lungfish c. 410 million years ago.
amphibious tetrapod trackways demonstrate evidence from 390 million years ago
fossil reptiles were present 318 million years ago (Hylonomus 318 million years ago and tracks of Notalacerta 320 to 330 million years ago)

then the new trackway evidence of reptiles from around 355 million years ago indicates that the evolutionary gap during which amniotic tetrapods separated from amphibious tetrapods is much shorter in time than previously suggested. Previously estimated as 85 to 90 million years, this has now become a gap of ‘only’ fifty million years, suggesting that tetrapod evolution proceeded more quickly, and the Devonian tetrapod record is much less complete, than previously believed.

References

Long, J.A., Niedźwiedzki, G., Garvey, J., Clement, A.M., Camens, A.B., Eury, C.A., Eason, J. and Ahlberg, P.E., 2025. Earliest amniote tracks recalibrate the timeline of tetrapod evolution. Nature, 641, 1193-1200.

Lu, J., Zhu, M., Long, J.A., Zhao, W., Senden, T.J., Jia, L. and Qiao, T., 2012. The earliest known stem-tetrapod from the Lower Devonian of China. Nature communications, 3(1), p.1160.

Marchetti, L., Voigt, S., Buchwitz, M., MacDougall, M.J., Lucas, S.G., Fillmore, D.L., Stimson, M.R., King, O.A., Calder, J.H. and Fröbisch, J., 2021. Tracking the origin and early evolution of reptiles. Frontiers in Ecology and Evolution, 9, p.696511.

Niedźwiedzki, G., Szrek, P., Narkiewicz, K., Narkiewicz, M. and Ahlberg, P.E., 2010. Tetrapod trackways from the early Middle Devonian period of Poland. Nature, 463(7277), 43-48.

Smithson, T.R., 1989. The earliest known reptile. Nature, 342(6250), 676-678.

Sumida S. S. 2025. Unexpectedly early reptile claw prints found. Nature, 641, 1103-1104.

What’s in a name? Common and Standard English names for amphibians and reptiles

August 1, 2025 by Admin

Roger Downie, Froglife and University of Glasgow

In the May 2025 edition of Croaks, Downie (2025) discussed the rules and conventions governing the Latin binomial scientific names for animal species, such as Rana temporaria (the Common Frog) and Bufo bufo (the Common Toad). In brackets, I’ve given versions of the common or Standard English names of these two species. Notice that the Latin names are shown in italics whereas the English names are in normal font. In this short article, I’ll discuss the origins, uses and rules behind common names.

Many common (or vernacular) names for animals and plants arose long before natural historians got down to naming, describing and classifying living organisms. McInerny and Minting (2016) list the Scots and Gaelic names for R. temporaria and B. bufo (box 1). These lists illustrate the diversity and colourfulness of vernacular names given to prominent species of wildlife, often associated with vivid folk tales and superstitions.

There are occasional confusions and lack of specificity, with ‘paddock’ used for both frogs and toads.

They also show the occasional confusions and lack of specificity, with ‘paddock’ used for both frogs and toads. Much research (see, for example Diamond [1966] and Altran [1998]) has shown that native peoples all over the world have long been able to distinguish and name species, often in good accordance with the species boundaries later determined by scientists. This is particularly the case where species are important to people, as food items, or for medicines, or clothing, or because the species is a threat.

When researching an article on the common names of Trinidad and Tobago’s frogs (Downie, 2013), I wondered if the Caribbean’s native people had any documented names and found a fascinating list of Arawak natural history words (Forte, 1996), the Arawaks being one of the peoples to have lived in Trinidad in pre-Columbian times. Ten kinds of frogs are listed, mostly with names clearly derived from the sounds of their calls: ‘katakata’ for a small aquatic frog; ‘tontonle’ for a small ground frog; ‘buraburaro’ for a riverside frog. Some of these names can be linked to species now known to science.

Rather more of the Arawak names for reptiles (43 in total) can be associated with particular species: ‘maholoro’ = boa constrictor; ‘labb-aria’= fer de lance; ‘konoke-se’= bushmaster; ‘kamodo’ =anaconda; ‘duradura’ =alligator. It is probably not surprising that the Arawaks had more words for potentially dangerous reptiles than for harmless frogs.

Vernacular names of the kinds shown above demonstrate the long-standing interest in wildlife shown by peoples all over the world, but they are of limited use in modern writing about species, because of their diversity and frequent lack of specificity. Given that each described species has been assigned a unique Latin name, is there any need for so-called ‘common’ names? One factor is that Latin names are often long, cumbersome and difficult to pronounce and spell. They are also subject to change as a result of taxonomic revisions: one of the species I have researched in Trinidad, now Leptodactylus fuscus, has had 19 different Latin names, beginning with Rana fusca, while a common name, the whistling frog, has remained unchanged. Common names therefore have value as communication tools.

Where do common names come from? Some derive from ancient names, at least in part: frog, toad, newt and snake are all ancient English words for kinds of animal. To convert them into useful common or Standard English names for particular species, they need extra qualifying words to show which frog, newt or snake is being referred to, such as great crested newt. Frank and Ramus (1995) compiled what they intended as a ‘complete’ list of common names linked to scientific names of all known amphibians and reptiles. For the many mainly tropical species where existing common names in English were lacking, they invented names. ‘Completeness’ is hard to achieve. The number of named amphibian species in 1992, around the time Frank and Ramus were writing, was 4533 (Kohler et al., 2005), whereas the latest figure (Frost, 2025) is 8885, an almost 100% increase. In addition, taxonomic revisions have made some of Frank and Ramus’s families of names obsolete.

A very thoughtful discussion and listing of common names (for Caribbean amphibians and reptiles) is provided by Hedges et al. (2019). They give three principles underlying their choices of common names: 1) Uniqueness– a common name should be unique in the world (as the Latin names are) to avoid overlap and confusion e.g. Green Anole is unhelpful as a name for a single North American species of lizard since there are several species of green-coloured anoles in South America and the Caribbean. 2) Usefulness– a common name, unlike the Latin name in most cases, should provide some useful information about the species. For this reason, they discourage the inclusion of the type locality (i.e. the place from where the species was first collected and named), since this is often misleading over the extent of the range of a species; they also discourage using the name of the scientist who first described or collected the species in the common name, since it provides no information about the species. However, geographic, taxonomic and morphological information is useful, and worth including in the common name. As an example, Sphaerodactylus oxyrhinus Gosse 1850 could be called Gosse’s Gecko, but Hedges et al. prefer Jamaican Sharp-nosed Geckolet as providing both geographic and morphological information. 3) Consistency– this principle covers the grammar and style of names.

Helpfully for this article, the (American) Society for the Study of Amphibians and Reptiles has just published the 9^th edition of its guidelines for the naming of species in Standard English (Nicholson, 2025), the result of a long process of discussion and review. I will not attempt a full summary of this 87-page document, which is of use mainly to scientists writing research papers and journal editors, but do give a few key points. When referring to a particular species, the Standard English name has the initials capitalised, but when not referring to a particular species, lower case is used e.g. ‘I saw a few green-brown frogs in the pond this morning’; when two words are joined, they are linked by a hyphen; when a descriptor refers to a feature of an animal, the suffix -ed is used. These points lead to Great-crested Newt as the correct form, rather than any of the alternatives. In addition, a compound name should be spelled as a single word if a) the second part is any of the words frog, toad, snake etc e.g. Treefrog, not Tree-frog or Tree Frog; b ) the second part refers to a part of the body e.g. Whiptail, not Whip-tail; c) the name describes an activity of the animal e.g. Pondslider.

This article may seem a bit dry and nit-picky, but I hope it is helpful to readers. Using the correct terms for species is important for the development of understanding. Looking back at the first paragraph, I think that the common names used fail the criterion of uniqueness: possibly European common frog, or even Eurasian?

References

Altran, S. (1998). Folk biology and the anthropology of science. Behaviour and Brain Science 21, 547-569.

Diamond, J. (1996). Zoological classification of a primitive people. Science 151, 1102-1104.

Downie, J.R. (2013). What common names should we use for Trinidad and Tobago’s frogs? The Living World 2013, 32-37.

Downie, J.R. (2025). What’s in a name? Rules and conventions for naming species. Froglife eNewsletter May 2025.

Forte, J (editor)(1996). The Fanshawe/Boyan glossary of Arawak names in natural history. Amerindian Research Unit, University of Guyana.

Frank, N. and Ramus, E. (1995). A complete guide to scientific and common names of reptiles and amphibians of the world. NG publishing, Pottsville, Pennsylvania.

Frost, D.R. (2025). Amphibian species of the world: an online reference (accessed 15/5/2025).

Hedges, S.B. et al.(2019). Definition of the Caribbean Islands biogeographic region, with checklist and recommendations for standardised common names of amphibians and reptiles. Caribbean Herpetology 67, 1-53.

Kohler, J. et al.(2005). New amphibians and global conservation: a boost in species discoveries in a highly endangered vertebrate group. Bioscience 55, 693-696.

McInerny, C. and Minting, P. (2016). The amphibians and reptiles of Scotland. Glasgow Natural History Society.

Nicholson, K.E. (editor)(2025). Scientific and standard English names of amphibians and reptiles of North America north of Mexico, with comments regarding confidence in our understanding. Ninth Edition. Society for the Study of Amphibians and Reptiles.

Box 1 Common names in Scotland

Species	Scots	Gaelic
Rana temporaria	Paddle-doo, Paddock, Puddock, Paddy	Losgann, Craigean, Leumachan, magan
Bufo bufo	Corby, Gangrell, Paddock, Taid, Yird taid	Muile-mhagach, Bofalan, Logann, Dubh, Leumachan, Magog, Miul-mahag, Much-ruhag

Recent publication: Virus found in a strain of Batrachochytrium dendrobatis, Bd;

June 1, 2025 by Admin

Written by Andrew Smart, Head of Science & Research

A recent publication by Rebecca Clemons and colleagues has found a DNA virus in strains of Bd, the fungus that causes chytridiomycosis.

Bd is one of the fungal pathogens that cause the disease chytridiomycosis in amphibians, resulting in skin infections that can led to mortality. Bd is associated with declines and some extinctions in over 500 amphibian species.

One of the factors contributing to panzootic (global infectious disease outbreak) expansion is ‘escape’ from fungal enemies such as viruses. Many fungi are reduced in virulence by mycoviruses (viruses infecting fungi) which are ‘hyperparasites’ (parasites of parasites), some of which are RNA viruses and some single-stranded DNA viruses. The research team screened various strains of Bd to look for evidence of DNA viruses and discovered they occurred in all of the five strains examined but at high, medium and low frequencies; the lowest by far being the global panzootic strain.

Further experimental work with live fungal hosts found that there was significantly higher mortality rate in frogs (dwarf clawed frogs Hymenochirus boettgeri were used) infected by the Bd strain containing the mycovirus.

The mycovirus was named BdDV-1 and experiments found that strains with the mycovirus had reduced fungal growth rates in laboratory culture conditions. However, further experimental work with live fungal hosts found that there was significantly higher mortality rate in frogs (dwarf clawed frogs Hymenochirus boettgeri were used) infected by the Bd strain containing the mycovirus. Conversely, animals that died from the Bd mycovirus positive strain shed a lower number of zoospores (infective fungal life stages) than those infected by Bd without the mycovirus.

This variation in results based on laboratory growth and virulence in live animals warrants further investigation, but this first identification of a mycovirus in Bd may lead to long-term developments that could influence the impact of Bd on amphibians. However, there is also a risk that hybridization between Bd strains could increase the virulence of existing global panzootic strains. Initial work by Clemons and colleagues also found that Bsal, another cause of chytridiomycosis, did not show evidence of these DNA viruses, so we must continue to be vigilant and do our best to maintain biosecurity and avoid spreading infection where we can.

You can read the full paper here.

Climbing salamanders: perspectives from great heights

January 1, 2025 by Admin

Written by Laurence Jarvis (external contributor)

Climbing salamanders within the genus Aneides are a fascinating group with varied behaviour and ecology. There are currently 10 recognised species, found predominantly across North America and Canada, notably California and British Columbia. The genus belongs to the Plethodontidae, which is the largest salamander family, comprising approximately 518 species. Most plethodontid salamanders are endemic to North America and, unlike many European salamanders, lack lungs and instead completely rely on gaseous exchange through their skin. They have evolved to live in a large range of habitats including streams, trees, on land and underground. Most are direct developers, laying eggs on land which hatch into live juveniles which resemble miniature adults.

The arboreal salamander (Aneides lugubris) is the largest of the genus, growing up to 100 mm with a rounded, robust body. As its name suggests, it is excellent at climbing and may ascend trees up to 18 metres, using specially adapted toes with expanded tips¹. Uniquely amongst salamanders, the tail is prehensile enabling it to cling to the branches of trees. Arboreal salamanders are highly aggressive, possessing rows of sharp teeth. Both males and females have been reported with scars on their bodies as a result of aggressive combat¹. Despite these tendencies, arboreal salamanders perform parental care and either the male or female will guard their clutch of around 5-26 eggs whilst they develop. Like other members of the genus, the eggs are laid in damp areas of rotting wood such as under tree bark. After hatching the small juveniles remain with their parents in family groups.

Figure 1. The Arboreal salamander (Aneides lugubris) is a highly mobile species living within Californian forests.

Wandering salamanders (A. vagrans) are as equally mobile and arboreal as A. lugubris and will climb trees very readily. They have been reported to ascent up to 87 metres in Douglas fir forests of British Colombia². If disturbed individuals exhibit an unusual behaviour of jumping from the tree canopy and performing an aerial skydive to land safely. Unlike other species which may jump and glide from a height, such as flying squirrels or frogs, wandering salamanders do not possess obvious adaptations such as flaps of skin to slow their fall. Therefore, this behaviour seems unexpected. Recent research by Brown et al. (2022)³ examined the morphology and aerodynamics of individuals as they fell under experimental conditions in a wind tunnel. They found that, compared to other species within the genus, wandering salamanders have more flattened bodies and slightly wider toes, which they spread during their fall. In addition, individuals stretch out their limbs in a skydive posture and undulate their bodies. The researchers showed that these combined behaviours slowed their fall and prevented damage on impact with the ground.

Climbing salamanders are unusual amongst amphibians since the adults of several species are monomorphic, that is, both males and females are of equal size. The vast majority of amphibians (over 90%) show a degree of sexual dimorphism, with females often being larger than males. However, in plethodontid salamanders, males are often larger than females. It is thought this is because they are highly territorial and use their size to defend territories. Many other frog and toad species possess other dimorphic traits which may include differences in skin colour or development of secondary sex characters such as nuptial pads. The Sacramento Mountains Salamander (A. hardii) is one of the Aneides salamanders that is sexually dimorphic with males being larger and possessing wider heads than females. Other members of the Aneides genus are monomorphic, with females also having large bodies and wider heads like males.

Since many other plethodontid salamanders are sexually dimorphic it is thought that increased male size over females is the ancestral state⁴. Research by Staub (2021)⁴ examining the evolution of plethodontid salamanders suggests that the monomorphism observed in species of the Aneides genus has evolved later. These monomorphic species are therefore described as having ‘derived monomorphism’, since they have evolved from sexually dimorphic ancestors⁴. The exact reason for the similar size in both males and females is uncertain but Staub et al. (2024)⁵ postulated that higher levels of androgen hormone in females may explain their equal size to males. However, their experimental work did not confirm this. Therefore, further research is required to determine whether there are differences in steroid sensitivity or signalling within females, rather than different levels of hormone⁵.

Figure 2. The wandering salamander (Aneides vagrans) may jump from treetops and perform a skydive to land safely.

Climbing salamanders are a unique group and whilst several species are common and widespread, six species within the genus are listed as either Near Threatened or Vulnerable. Habitat loss is a continual problem with unsustainable logging causing the declines in several species. The Shasta Black Salamander (A. iecanus) is now classed as Vulnerable, and has suffered rapid declines due to the construction of the Shasta Reservoir in California. Like other plethodontids, climbing salamanders are also vulnerable to climate change and several species have suffered due to longer and drier summers across their range. Conserving these threatened species is a challenge and combined conservation efforts are required to protect these fascinating species.

Click for References

1AmphibiaWeb (2024). <https://amphibiaweb.org> Aneides lugubris. University of California, Berkeley, CA, USA. Accessed 12 Dec 2024.

²AmphibiaWeb (2024). <https://amphibiaweb.org> Aneides vagrans. University of California, Berkeley, CA, USA. Accessed 12 Dec 2024.

³Brown C.E., Sathe E.A., Dudley R. and Deban S.M. (2022). Gliding and parachuting by arboreal salamanders. Current Biology, 32 (10): R453-R454.

⁴Staub N.L. (2021). The evolution of derived monomorphism from sexual dimorphism: a case study on salamanders. Integrative Organismal Biology, 3 (1): p.obaa044.

⁵Staub N.L., Hayes S.G. and Mendonca M.T. (2024). Levels of Sex Steroids in Plethodontid Salamanders: A Comparative Study Within the Genus Aneides. Ecology and Evolution, 14 (11): p.e70550.

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