ArticlePDF Available

Abstract and Figures

The evolution of lunglessness in tetrapods (amphibians, reptiles, birds, and mammals) is an exceedingly rare event. So far lunglessness is known to occur only in amphibians, in particular two families of salamanders 1 and 2 and a single species of caecilian [3]. Here, we report the first case of complete lunglessness in a frog, Barbourula kalimantanensis, from the Indonesian portion of Borneo (Figure 1A). Previously only known from two specimens 4 and 5, a recent expedition to central Kalimantan on Borneo rediscovered two new populations of this enigmatic aquatic frog (Figure 1B,C). This allowed for a more comprehensive assessment of the species' ecology and anatomy that led to the discovery of its lack of lungs. Loss of lungs in Amphibia is most likely due to their evolutionary history at the interface between aquatic and terrestrial habitats and their ancient ability to respire through the skin [5].
Content may be subject to copyright.
Current Biology Vol 18 No 9
R374
x
= 38.3 mm and in mass from 2.2 to
13.5 g,
x
= 6.5 g). However, we did
locate a glottis and lungs in a specimen
of the only other species in the genus,
Barbourula busuangensis, and another
frog species, Rana catesbeiana
(Figure 2). With no evidence of any lung
tissue and no glottis, B. kalimantanensis
is thus the first species of frog reported
to be lungless.
Among tetrapod vertebrates,
lunglessness has only evolved in
the amphibians: many salamander
species (two species in the family
Hynobiidae, genus Onychodactylus
[2], and more than 350 species in
the family Plethodontidae [1]) as well
as a single species of caecilian (the
other order of amphibians) [3] are
lungless. Thus, the complete loss of
lungs in tetrapods is a particularly
rare evolutionary event. The loss of
lungs is a reversal of one of the most
important physiological adaptations
for terrestrial life and has probably only
evolved independently three times. The
discovery of lunglessness in a secretive
Bornean frog species, supports the
idea that lungs are a malleable trait in
the Amphibia, the sister group to the
rest of the living tetrapods. Amphibians
may be more prone to lunglessness
since they are known to be able to
A lungless frog
discovered on
Borneo
David Bickford1,*, Djoko Iskandar2,
and Anggraini Barlian2
The evolution of lunglessness in
tetrapods (amphibians, reptiles, birds,
and mammals) is an exceedingly rare
event. So far lunglessness is known to
occur only in amphibians, in particular
two families of salamanders [1,2] and
a single species of caecilian [3]. Here,
we report the first case of complete
lunglessness in a frog, Barbourula
kalimantanensis, from the Indonesian
portion of Borneo (Figure 1A). Previously
only known from two specimens [4,5], a
recent expedition to central Kalimantan
on Borneo rediscovered two new
populations of this enigmatic aquatic
frog (Figure 1B,C). This allowed for a
more comprehensive assessment of
the species’ ecology and anatomy that
led to the discovery of its lack of lungs.
Loss of lungs in Amphibia is most likely
due to their evolutionary history at the
interface between aquatic and terrestrial
habitats and their ancient ability to
respire through the skin [5].
Despite multiple attempts to locate
more individuals of B. kalimantanensis,
prior to 2007, only two specimens of
this frog species were known to science
[4,5]. In August 2007, we visited the
type locality near Nanga Pinoh, Western
Kalimantan (0° 44’ S; 111° 40’ E) but
found that illegal gold mining had
destroyed all suitable habitats in the
vicinity. The originally cool, clear, fast-
flowing rivers are now warm and turbid.
Water quality around the type locality
is no longer suitable for the species,
but we were able to discover two new
populations of B. kalimantanensis
upstream of the type locality.
We established the lunglessness of
B. kalimantanensis specimens through
dissections and histological sections
of the anterior portion of the coelom
(around the heart) that revealed a
membrane lining the thoracic cavity,
but no evidence of lungs. In all other
frogs, there is a protected opening
to the airway (the glottis) as the oral
cavity narrows to form the esophagus.
We found no such opening during
dissections of eight specimens of
B. kalimantanesis (ranging in snout-vent
length from 26.9 to 50.5 mm,
readily utilize other methods for gas
exchange, namely cutaneous, gills,
buccopharyngeal and perhaps cloacal
(all thin-membrane) gas exchange
outside of the lungs [6,7].
Respiration determines much of
an organism’s inherent biological
limits and life history. Hence, the
evolution and ecology of lunglessness
is a complex physiological
development entailing many
different mechanisms, possible
explanations, and evolutionary and
developmental pathways. Trade-
offs among kinematic and muscular
performance, buoyancy, and
metabolic rate somehow reach an
evolutionary and ecological balance.
In B. kalimantanensis, this balance
leads to loss of lungs as the main
respiratory surface for gas exchange.
B. kalimantanensis is presumably an
ectotherm and lives in cold (14–17°C)
fast-flowing (2–5 m/s) water, so loss
of lungs may be an adaptation to
the combination of higher oxygen
content in fast-flowing cold water,
the species’ presumed low metabolic
rate, severe flattening to increase the
surface area of the skin (Figure 1B,C),
and selection for negative buoyancy.
B. kalimantanensis, the only lungless
tetrapod in Southeast Asia, is currently
Figure 1. Habitat and appearance of the lungless frog Barbourula kalimantanensis.
(A) Map of Borneo, showing the Indonesian portion, Kalimantan, in the South-Central part of
the island, and (B) B. kalimantanensis in anterior view, and (C) lateral view showing extreme
flattening of the body.
Magazine
R375
listed as endangered [8] and illegal
gold mining resulting in increased
turbidity and mercury contamination
has severely degraded the type locality
and much of its presumed former range.
Compounding the problem, much of
the surrounding terrestrial habitat is
also under increasing threat from both
legal and illegal logging. Conservation
of this evolutionary enigma needs to be
prioritized and the remaining habitat in
which it can survive needs to be urgently
protected. The evolution, development,
and maintenance of lunglessness in this
frog will become important research foci.
How complete loss of lungs evolves and
under what kind of selective pressures
and genetic mechanisms has been
well debated in salamanders [9,10].
However, these are still open and more
manageable questions for an aquatic
primitive frog. To better understand the
extinction risk and endangered status
of this species, a much more complete
assessment of potential habitats needs
to be surveyed and the exact geographic
range for the species should be mapped.
In addition, virtually nothing is known
about how these frogs reproduce, eat
and escape predation. Further studies,
however, may be hampered by the
species’ rarity and endangerment. We
strongly encourage conservation of the
remaining habitats of this species.
Supplemental data
Supplemental data including experimental pro-
cedures are available at http://www.current-
biology.com/cgi/content/full/18/9/R374/DC1
Acknowledgments
We thank Rafe Brown, Rudolf Meier, and two
anonymous reviewers for helpful comments.
The project would not have been successful
without support from Darmawan Liswanto. In
the field, we were assisted immeasurably by
Mistar Kamsi, Umilaela, Angga Rachmansah,
Biofagri A.R., Medi Yansyah, Budi Susilo, Herry
Helmi, Doddy Aryadi, and the staff of the Taman
Nasional Bukit Baka – Bukit Raya. We thank the
Forestry Department, Sintang, Kalimantan Barat
for permission to conduct research in the area
and the Ministry of Education of the Republic
of Singapore for providing funding under Grant
#R-154-000-270-112.
References
1. Min, M.S., Yang, S.Y., Bonett, R.M., Vieites, D.R.,
Brandon, R.A., and Wake, D.B. (2005). Discovery
of the first Asian plethodontid salamander.
Nature 435, 87–90.
2. Dunn, E.R. (1923). The salamanders of the family
Hynobiidae. Proc. Amer. Acad. Arts Sci. 58,
445–523.
3. Nussbaum, R.A., and Wilkinson, M. (1995). A new
genus of lungless tetrapod: A radically divergent
caecilian (Amphibia: Gymnophiona). Proc. R.
Soc. Lond. B 261, 331–335.
4. Iskandar, D.T. (1978). A new species of
Barbourula: First record of a discoglossid from
Borneo. Copeia 1978, 564–566.
5. Iskandar, D.T. (1995). Note on the second
specimen of Barbourula kalimantanensis
(Amphibia: Anura: Discoglossidae). Raffles Bull.
Zool. 43, 309–311.
6. Cox, C.B. (1967). Cutaneous respiration and the
origin of the modern Amphibia. Proc. R. Soc.
Lond. B. 178, 37–47.
7. Duellman, W., and Trueb, L. (1986). Biology of the
Amphibia. (Baltimore: Johns Hopkins University
Press).
8. IUCN, Conservation International, and
NatureServe. (2006). Global Amphibian
Assessment. <www.globalamphibians.org>.
9. Wilder, I.W., and Dunn, E.R. (1920). The
correlation of lunglessness in salamanders with
a mountain brook habitat. Copeia 84, 63–68.
10. Ruben, J.A., and Boucot, A.J. (1989). The
origin of the lungless salamanders (Amphibia:
Plethodontidae). Am. Nat. 134, 161–169.
1National University of Singapore, 14
Science Drive 4, 117543 Singapore. 2Institut
Teknologi Bandung, 10 Jalan Ganesa,
Bandung, 40132 Java, Indonesia.
*E-mail: rokrok@nus.edu.sg
Figure 2. Anatomy of lunglessness.
Comparison of (A) typical frog mouth and pharynx (Rana catesbeiana), showing glottis
(circled), tongue, and esophageal opening, and (B) B. kalimantanensis showing tongue, no
glottis (circled), and an enlarged esophageal opening leading directly to the stomach.
Role of fungi in the
biogeochemical fate
of depleted uranium
Marina Fomina1, John M. Charnock2,
Stephen Hillier3, Rebeca Alvarez4,
Francis Livens4
and Geoffrey M. Gadd1,*
The testing of depleted uranium (DU; a
97.25% U:0.75% Ti alloy) ammunition
and its use in recent war campaigns in
Iraq (1991 and 2003) and the Balkans
(1995 and 1999) has led to dispersion
of thermodynamically unstable DU
metal into the environment [1–3].
Although less radioactive, DU has
the same chemotoxicity as natural
uranium and poses a threat to human
populations [1]. Uranium tends to
form stable aqueous complexes and
precipitates with organic ligands [4],
suggesting that living organisms could
play an important role in geochemical
transformations and cycling. Fungi
are one of the most biogeochemically
active components of the soil
microbiota [5], particularly in the
aerobic plant-root zone. Although the
mutualistic symbiotic associations
(mycorrhizas) of fungi with plants
are particularly important in mineral
transformations [5], fungal effects on
metallic DU have not been studied.
Here, we report that free-living and
plant symbiotic (mycorrhizal) fungi can
colonize DU surfaces and transform
metallic DU into uranyl phosphate
minerals.
Fungal interactions with DU were
studied in microcosms simulating
a heterogeneous environment
(Figure S1A in Supplemental Data,
published with this article online).
All tested fungi exhibited high DU
tolerance and were able to colonize
DU surfaces, forming moisture-
retaining mycelial biofilms (Figure
S1A–D). The fungi also often formed
cord-like mycelial structures through
aggregation of longitudinally aligned
hyphae (Figures 1A,B and S1F,G),
commonly interpreted as a survival
response to metal stress [6].
DU coupons (triangular sectors of
DU alloy of approximate dimensions
15 mm x 15 mm x 11 mm, and 5 mm
height, and approximately 6.5–8.5 g in
weight) in the microcosms underwent
aerobic corrosion forming black
and yellow decomposition products
... The reason behind this is thought to be that cyanobacteria and a variety of plants that emerged later began to produce organic matter and vast amounts of oxygen gas from carbon dioxide and water through photosynthesis. The increase in the concentration of oxygen in the atmosphere provides an aerobic environment that allows organisms to acquire new energy metabolism, resulting in the flourishing of multicellular and terrestrial organisms with the emergence of various respiration methods [2][3][4][5][6][7][8][9][10][11] (Table 1). ...
... For example, in birds and dinosaurs, air flows through the lungs in one direction and is absorbed into the bloodstream. Some frogs and salamanders in Southeast Asia do not have lungs and sustain themselves through cutaneous respiration [2,4,5]. Furthermore, among mammals, particular species, such as naked mole rats, obtain energy by activating specialized fructose metabolic pathways under hypoxia; and the genetic approach revealed that sulfur respiration, as well as oxygen, can be utilized for energy metabolism in laboratory mice [6,7]. ...
... For example, loaches (Misgumus anguillicandatus), sea cucumbers, Corydoras, and Tetragnatha praedonia use their posterior intestines for respiration. [1][2][3] Earlier studies in the 1950s and 1960s explored such mechanisms ...
... Clinically, it is difficult to thin the intestinal mucosa. Therefore, Intestinal liquid ventilation (l-EVA) system was developed with liquid perfluorochemicals (1)(2)(3)(4)(5). We randomly assigned the mice into 2 groups: sham group (Group 9, n = 10) and an intestinal liquid ventilation group (Group 12, n = 12). ...
Article
Background Several aquatic organisms such as loaches have evolved unique intestinal breathing mechanisms to survive under extensive hypoxia. To date, it is highly controversial whether such capability can be adapted in mammalian species as another site for gas exchange. Here, we report the advent of the intestinal breathing phenomenon in mammalians by exploiting EVA (enteral ventilation via anus). Methods Two different modes of EVA were investigated in an experimental model of respiratory failure: intra-rectal oxygen O2 gas ventilation (g-EVA) or liquid ventilation (l-EVA) with oxygenated perfluorocarbon. After induction of type 1 respiratory failure, we analyzed the effectiveness of g-EVA and I-EVA in mouse and pig, followed by preclinical safety analysis in rat. Findings Both intra-rectal O2 gas and oxygenated liquid delivery were shown to provide vital rescue of experimental models of respiratory failure, improving survival, behavior, and systemic O2 level. A rodent and porcine model study confirmed the tolerable and repeatable features of an enema-like l-EVA procedure with no major signs of complications. Conclusions EVA has proven effective in mammalians such that it oxygenated systemic circulation and ameliorated respiratory failure. Due to the proven safety of perfluorochemicals in clinics, EVA potentially provides an adjunctive means of oxygenation for patients under respiratory distress conditions. Funding This work is funded by the Research Program on Emerging and Re-emerging Infectious Diseases, Research Projects on COVID-19 (JP20fk0108278, 20fk0108506h0001), from the Japan Agency for Medical Research and Development (AMED), to T.T.; Strategic Promotion for Practical Application of Innovative Medical Technology, Seeds A (A145), to T.T.; and KAKENHI 19K22657, to T.C.-Y. This research is partially supported by the AMED Translational Research Program; Strategic Promotion for Practical Application of Innovative Medical Technology (TR-SPRINT), to T.C.-Y.; and AMED JP18bm0704025h0001 (Program for Technological Innovation of Regenerative Medicine), to T.T.
... However, in several amphibians, the lungs have degenerated or been lost. Lungless taxa are present in all three amphibian orders: Anura, Gymnophiona, and Caudata [18][19][20]. In caudates (salamanders and newts), lunglessness has evolved in two distinct lineages: the family Plethodontidae and the genus Onychodactylus (belonging to the family Hynobiidae). ...
Article
Full-text available
There are two distinct lungless groups in caudate amphibians (salamanders and newts) (the family Plethodontidae and the genus Onychodactylus, from the family Hynobiidae). Lunglessness is considered to have evolved in response to environmental and/or ecological adaptation with respect to oxygen requirements. We performed selection analyses on lungless salamanders to elucidate the selective patterns of mitochondrial protein-coding genes associated with lunglessness. The branch model and RELAX analyses revealed the occurrence of relaxed selection (an increase of the dN/dS ratio=ω value) in most mitochondrial protein-coding genes of plethodontid salamander branches but not in those of Onychodactylus. Additional branch model and RELAX analyses indicated that direct-developing plethodontids showed the relaxed pattern for most mitochondrial genes, although metamorphosing plethodontids had fewer relaxed genes. Furthermore, aBSREL analysis detected positively selected codons in three plethodontid branches but not in Onychodactylus. One of these three branches corresponded to the most recent common ancestor, and the others corresponded with the most recent common ancestors of direct-developing branches within Hemidactyliinae. The positive selection of mitochondrial protein-coding genes in Plethodontidae is probably associated with the evolution of direct development.
... The loss of lungs in these salamanders seems to have been an adaptation to the oxygen-rich swift streams for decreasing the risk of downstream drift, where lungs were maladaptive because of the buoyancy. This hypothesis has found further support by the recent discovery of a lungless frog in Borneo, which also inhabits rapid cold O 2 -rich streams (Bickford et al., 2008). The loss of lungs was favored under the circumstances of a parallel evolution of cutaneous respiration in these species (Fong et al., 1995). ...
Chapter
Full-text available
Changes in environment or conditions of life may, sometimes, make some functions unnecessary and the organs used for performing these functions will be used less or not used at all, thus, becoming an evolutionary encumbrance and an evolutionary pressure will arise for losing it.
... Respiration takes place solely across the integument and buccopharyngeal mucosa, and also across the gills in aquatic larval forms, when present. Lunglessness is not unique to plethodontids-it has evolved several times in other amphibians, including salamanders, frogs and caecilians [4]-but its adaptive significance is unresolved [5,6]. ...
Article
Full-text available
Numerous physiological and morphological adaptations were achieved during the transition to lungless respiration that accompanied evolutionary lung loss in plethodontid salamanders, including those that enable efficient gas exchange across extrapulmonary tissue. However, the molecular basis of these adaptations is unknown. Here, we show that lungless salamanders express in the larval integument and the adult buccopharynx-principal sites of respiratory gas exchange in these species-a novel paralogue of the gene surfactant-associated protein C (SFTPC), which is a critical component of pulmonary surfactant expressed exclusively in the lung in other vertebrates. The paralogous gene appears to be found only in salamanders, but, similar to SFTPC, in lunged salamanders it is expressed only in the lung. This heterotopic gene expression, combined with predictions from structural modelling and respiratory tissue ultrastructure, suggests that lungless salamanders may produce pulmonary surfactant-like secretions outside the lungs and that the novel paralogue of SFTPC might facilitate extrapulmonary respiration in the absence of lungs. Heterotopic expression of the SFTPC paralogue may have contributed to the remarkable evolutionary radiation of lungless salamanders, which account for more than two thirds of urodele species alive today.
... Certain taxa, such as some Asian Limnonectes (Dicroglossidae), some bufonids, and some hyperoliids are considered voiceless (Rödel et al. 2003), although in some cases, calls from putatively voiceless species have been reported (Matsui 1995;Orlov 1997;Tsuji & Lue 1998;Vences et al. 2004). The identification of Barbourula kalimantanesis (Bombinatoridae) as the first known lungless anuran species (Bickford et al. 2008) might indicate its voicelessness as well. ...
Article
Full-text available
Vocalizations of anuran amphibians have received much attention in studies of behavioral ecology and physiology, but also provide informative characters for identifying and delimiting species. We here review the terminology and variation of frog calls from a perspective of integrative taxonomy, and provide hands-on protocols for recording, analyzing, comparing, interpreting and describing these sounds. Our focus is on advertisement calls, which serve as premating isolation mechanisms and, therefore, convey important taxonomic information. We provide recommendations for terminology of frog vocalizations, with call, note and pulse being the fundamental subunits to be used in descriptions and comparisons. However, due to the complexity and diversity of these signals, an unequivocal application of the terms call and note can be challenging. We therefore provide two coherent concepts that either follow a note-centered approach (defining uninterrupted units of sound as notes, and their entirety as call) or a call-centered approach (defining uninterrupted units as call whenever they are separated by long silent intervals) in terminology. Based on surveys of literature, we show that numerous call traits can be highly variable within and between individuals of one species. Despite idiosyncrasies of species and higher taxa, the duration of calls or notes, pulse rate within notes, and number of pulses per note appear to be more static within individuals and somewhat less affected by temperature. Therefore, these variables might often be preferable as taxonomic characters over call rate or note rate, which are heavily influenced by various factors. Dominant frequency is also comparatively static and only weakly affected by temperature, but depends strongly on body size. As with other taxonomic characters, strong call divergence is typically indicative of species-level differences, whereas call similarities of two populations are no evidence for them being conspecific. Taxonomic conclusions can especially be drawn when the general advertisement call structure of two candidate species is radically different and qualitative call differences are thus observed. On the other hand, quantitative differences in call traits might substantially vary within and among conspecific populations, and require careful evaluation and analysis. We provide guidelines for the taxonomic interpretation of advertisement call differences in sympatric and allopatric situations, and emphasize the need for an integrative use of multiple datasets (bioacoustics, morphology, genetics), particularly for allopatric scenarios. We show that small-sized frogs often emit calls with frequency components in the ultrasound spectrum, although it is unlikely that these high frequencies are of biological relevance for the majority of them, and we illustrate that detection of upper harmonics depends also on recording distance because higher frequencies are attenuated more strongly. Bioacoustics remains a prime approach in integrative taxonomy of anurans if uncertainty due to possible intraspecific variation and technical artifacts is adequately considered and acknowledged.
Article
Full-text available
The lungs and skin are important respiratory organs in Anura, but the pulmonary structure of amphibians remains unclear due to the lack of a suitable procedure. This study improved the procedure used for fixing lungs tissues and used light microscopy, transmission electron microscopy and scanning electron microscopy to reveal the differences in the lung and skin morphologies between Pelophylax nigromaculatus (P. nigromaculatus) and Bufo gargarizans (B. gargarizans). In P. nigromaculatus and B. gargarizans, the cystic lungs comprise a continuous outer pulmonary wall on which primary, secondary, and tertiary septa attach, and a number of regular lattices form from raised capillaries and the pulmonary epithelium on the surfaces of the pulmonary wall and septa. Each lattice in P. nigromaculatus consists of several elliptical sheets and flat bottom, and the septa are distributed with denser sheets and have a larger stretching range than the pulmonary wall. The lattice in B. gargarizans consists of thick folds and an uneven bottom with several thin folds, and the septa have more developed thick and thin folds than the pulmonary wall. However, the density of the pulmonary microvilli, the area of a single capillary, the thicknesses of the blood-air barrier, pulmonary wall and septum, and the lung/body weight percentage obtained for B. gargarizans were higher than those found for P. nigromaculatus. In P. nigromaculatus, the dorsal skin has dense capillaries and a ring surface structure with mucus layer on the stratum corneum, and the ventral skin is slightly keratinized. In B. gargarizans, the stratum corneum in both the dorsal and ventral skins is completely keratinized. A fine ultrastructure analysis of P. nigromaculatus and B. gargarizans revealed that the pulmonary septa are more developed than the pulmonary walls, which means that the septa have a stronger respiratory function. The more developed lungs are helpful for the adaptation of B. gargarizans to drought environments, whereas P. nigromaculatus has to rely on more vigorous skin respiration to adapt to a humid environment.
Article
Many vital motor behaviors–including locomotion, swallowing, and breathing–appear to be dependent upon the activity of and coordination between multiple endogenously rhythmogenic nuclei, or neural oscillators. Much as the functional development of sensory circuits is shaped during maturation, we hypothesized that coordination of oscillators involved in motor control may likewise be maturation‐dependent; i.e., coupling and coordination between oscillators changes over development. We tested this hypothesis using the bullfrog isolated brainstem preparation to study the metamorphic transition of ventilatory motor patterns from early rhythmic buccal (water) ventilation in the tadpole to the mature pattern of rhythmic buccal and lung (air) ventilation in the adult. Spatially‐distinct oscillators drive buccal and lung bursts in the isolated brainstem; we found these oscillators to be active but functionally uncoupled in the tadpole. Over the course of metamorphosis, the rhythms produced by the buccal and lung oscillators become increasingly tightly coordinated. These changes parallel the progression of structural and behavioral changes in the animal, with adult levels of coupling arising by the metamorphic stage (forelimb eruption). These findings suggest that oscillator coupling undergoes a maturation process similar to the refinement of sensory circuits over development. This article is protected by copyright. All rights reserved.
Thesis
L'olfaction existe très tôt chez les organismes primitifs, comme en témoigne les études de biologie moléculaire des gènes orthologues de l'olfaction. Les Protochordés, lointains ancêtres des Vertébrés, ne possèdent pas d'organe olfactif individualisé mais quelques cellules olfactives regroupées au niveau péri-buccal. L'organe olfactif apparaît chez les Agnathes, Vertébrés primitifs, comme un tube borgne ouvert vers l'extérieur par une narine unique. Chez les Dipneustes, l'organe olfactif s'ouvre en arrière dans la cavité buccale, mais il ne participe pas à la respiration. La formation des choanes améliore l'olfaction grâce à la pompe buccale qui fait circuler l'eau activement à travers l'organe olfactif. Les Amphibiens, premiers représentants des Tétrapodes, sont les premiers à utiliser leur organe olfactif pour respirer. Chez les Crocodiliens qui utilisent également leur nez poursentir et respirer, l'apparition d'un palais osseux secondaire permet le maintien de laperméabilité des voies aériennes pendant l'alimentation. Chez les Mammifères, l'apparition des ethmoturbinaux au sein de l'ethmoïde augmente considérablement la surface de la muqueuse olfactive et les capacités olfactives. Chez l'Homme l'os ethmoïdal s'est réorganisé suite à la rétraction du museau et au rapprochement des yeux avec pour conséquence une diminution importante de la muqueuse olfactive. L'homme est considéré comme un animal microsmatique.La Phylogenèse du nez montre l'exaptation de l'organe olfactif par l'appareil respiratoire.
Article
Full-text available
Barbourula kalimantanensis n. sp. is described based on an unique frog from Pinoh River, a small tributary of the Kapuas in West Kalimantan, Indonesia. It is the first record of the anuran family Discoglossidae in Borneo, south of the equator.
Article
Full-text available
Lunglessness is rare in the Tetrapoda and previously recorded only in salamanders (Amphibia: Caudata). Here we report lunglessness in another group of tetrapods, the poorly known tropical caecilians (Amphibia: Gymnophiona). Typhlonectes eiselti is a lungless, aquatic caecilian from South America known only from the single holotype specimen, NMW 9144 (Vienna Museum of Natural History). At a total length of 725 mm, NMW 9144 is by far the largest known lungless tetrapod. It also has a startling array of other radically divergent morphological features, many unique, and some correlated with lunglessness including: sealed choanae (paired internal nostrils); complete absence of pulmonary blood vessels; a repatterned skull with post-occipital jaw articulation; and a novel cranial muscle associated with an elongate and redirected stapes. This remarkable combination of highly derived characters sets Typhlonectes eiselti apart from all other caecilians and places it on a novel evolutionary trajectory. A new genus is described to accommodate this form.
Article
Full-text available
Nearly 70% of the 535 species of salamanders in the world are members of a single family, the Plethodontidae, or lungless salamanders. The centre of diversity for this clade is North and Middle America, where the vast majority (99%) of species are found. We report the discovery of the first Asian plethodontid salamander, from montane woodlands in southwestern Korea. The new species superficially resembles members of North American genera, in particular the morphologically conservative genus Plethodon. However, phylogenetic analysis of the nuclear encoded gene Rag-1 shows the new taxon to be widely divergent from Plethodon. The new salamander differs osteologically from putative relatives, especially with respect to the tongue (attached protrusible) and the derived tarsus. We place the species in a new genus on the basis of the morphological and molecular data. The distribution of the new salamander adds to the enigma of Old World plethodontids, which are otherwise restricted to the western Mediterranean region, suggesting a more extensive past distribution of the family.
Article
It has been generally accepted that lungelessness in plethodontid salamanders results from a selection for increased ballast in aquatic, Late Cretaceous ancestors that inhabited fast-moving, cool Appalachian mountain brooks. However, late Mesozoic mountain-stream environments consistent with that scenario were probably absent from the region: geological evidence indicates that late Mesozoic Appalachia was a chronically warm, low-elevation, non-montane region with little relief and topography. An alternative hypothesis for the origin of plethodontid salamanders is considered. We suggest that proto-plethodontids may have been only semi-aquatic or terrestrial. Supporting evidence includes a plethodontid-like reliance on cutaneous respiration in certain extant ambystomatid salamanders. -Authors
Article
Though they already possessed lungs, the ancestors of the modern Amphibia, or ‘Lissamphibia’, evolved an accessory respiratory surface, reducing the scales and using the moist, naked surface of the body for this purpose. This can be explained on the assumption that the ancestral lissamphibian had not evolved the costal method of ventilating the lungs, and relied solely on hyoid ventilation, as do the lungfish and the Lissamphibia themselves. It seems unlikely that this method would have been adequate for active land life. The adoption of accessory cutaneous respiration would then have been wholly advantageous in allowing colonization of the land, even though the resulting high rate of water loss from the skin would restrict the range of terrestrial habitats that could be exploited.
Note on the second specimen of Barbourula kalimantanensis (Amphibia: Anura: Discoglossidae)
  • Iskandar
Iskandar, D.T. (1995). Note on the second specimen of Barbourula kalimantanensis (Amphibia: Anura: Discoglossidae). Raffles Bull. Zool. 43, 309-311.
  • W Duellman
  • L Trueb
Duellman, W., and Trueb, L. (1986). Biology of the Amphibia. (Baltimore: Johns Hopkins University Press).
Biology of the Amphibia.
  • Duellman W.
  • Trueb L.