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A collection of 10 high-impact extreme precipitation events occurring in Southeastern South America during the warm season has been analyzed using statistical (ESD) and dynamical downscaling approaches. Regional Climate Models from the CORDEX database for the South American domain at two horizontal resolutions, 50 km and 25 km, short-term simulations at 20 km and at 4 km convective-permitting resolution and statistical downscaling techniques based on the analogue method and the generalized linear model approach were evaluated. The analysis includes observational datasets based on gridded data, station data and satellite products that allow assessing the observational uncertainty that characterizes extreme events in the region. It is found that the ability of the modelling strategies in capturing the main features of the extreme rainfall varies across the events. The higher the horizontal resolution of the models, the more intense and localized the core of the rainfall event, being the location of the exit region of the low-level jet and the low-level moisture flux convergence during the initial stages of the events the most relevant features that determine models’ ability of capturing the location and intensity of the core of the heavy rainfall. ESD models based on the generalized linear approach overestimate the spatial extension of the events and underestimate the intensity of the local maxima. Weather-like convective-permitting simulations depict an overall good performance in reproducing both the rainfall patterns and the triggering mechanisms of the extreme events as expected, given that these simulations are strongly controlled by the initial conditions.

The main features of daily extreme precipitation and circulation types in southern South America (SSA) were evaluated and compared in both multiple observational datasets (rain gauges, CHIRPS, CPC and MSWEP) and simulations from four regional climate models (RCMs) driven by ERA-Interim during 1980–2010. The inter-comparison of extreme events, characterised in terms of their intensity, frequency and spatial coverage, varied across SSA showing large differences among observational datasets and RCMs and reflecting the current observational uncertainty when evaluating precipitation extremes at a daily scale. The spread between observational datasets was smaller than for the RCMs. Most of the RCMs successfully captured the spatial pattern of extreme precipitation across SSA, although RCA4 (REMO) usually underestimated (overestimated) precipitation intensities, particularly the maximum amounts in southeastern South America (SESA), where the extremes are remarkable. The synoptic circulation was described by a classification of circulation types (CTs) using Self-Organizing Maps (SOM). Specific CTs were found to significantly enhance the occurrence of extreme precipitation events in sectorized areas of SESA. The RCMs adequately reproduced the SOM node frequencies, although they tended to simplify the predominant CTs into a more reduced number of configurations. They appropriately represented the extreme precipitation frequencies conditioned by each CT, exhibiting some limitations in the location and intensity of the resulting precipitation systems. These sorts of evaluations contribute to a better understanding of the physical mechanisms responsible for extreme precipitation and of their future projections in a climate change scenario.

International audience; South Tropical South America (STSA), extended approximately between 10°N-30°S and 90°W-30°W, is a wide region where diverse interactions among biomass, land surface processes and atmospheric convection take place. These interactions modulate the local and regional climate and directly impact on the socio-environmental activities (Fu et al., 2013; Reis et al., 2018; Zhang et al., 2015). STSA hosts the Amazonia-the world's largest rainforest and one of the major sources of evapotranspiration-playing a critical role in the global balances of energy, water, moisture and carbon (Gatti et al., 2021; Llopart et al., 2020). The region presents unique biodiversity and geographical patterns, mainly due to the interaction of the Amazonia and the Andes mountain range, which have deep implications in the atmospheric dynamics, moisture transport and river discharge not only throughout STSA but also in remote regions of the continent (Arias, Garreaud, et al., 2021; Espinoza et al., 2020; Sierra et al., 2021). Precipitation (PP) over STSA presents a marked spatio-temporal variability, strongly controlled by the South American Monsoon System (SAMS), with rainfall maxima during its active phase during the austral summer (Marengo et al., 2012; Vera et al., 2006). The monsoonal circulation-which develops in response to seasonal changes in thermal land-sea contrasts-is connected to different documented atmospheric features, including a NW-SE band of convergence and convective activity over the southeast of South America and the adjacent South Atlantic ocean known as the South Atlantic Convergence Zone (SACZ), an anticyclonic center located

Climate hazards associated with compound events (CEs) have lately received increasing attention over South America (SA) due to their potential risks and amplification of impacts. This work addressed the evaluation of different temperature- and precipitation-based CE in SA considering the CORDEX-CORE ensemble of regional climate models (RCMs) and their driving earth system models (ESMs) in the reference period 1981–2010 and the late 21st century (2070–2099), for the Representative Concentration Pathways (RCPs) 2.6 and 8.5 scenarios. The assessment focused on model performance for the individual events—heatwaves (HWs), Extreme rainfall (ER) days, and dry-spells (DSs)—and their compound occurrence in terms of climatological frequency and duration. The spatial patterns of individual events were adequately reproduced by the RCMs, evidencing general overestimations in extreme precipitation intensities. In terms of CE, the frequencies of coincident HWs and DSs (sequential DSs and ER) were remarkable over central-eastern Brazil and southern SA (southeastern SA). The main features of CE were generally well-simulated by the RCMs, although they presented regional differences such as an underestimation of the maximum frequencies of these two CE in northeastern Brazil and southeastern SA, respectively. The high-resolution information was generally in line with the larger-scale driving ESMs. The climate change signal analysis generally showed robust future increases in CE frequency and duration in different areas of SA, as for coincident HWs and DSs (sequential DSs and ER) over northern SA and southern Brazil (southeastern SA). This was mostly consistent among the RCMs ensemble and notably strengthened in the worst-case scenario (RCP 8.5).

The aim of this work is to present preliminary results of the statistical and dynamical simulations carried out within the framework of the Flagship Pilot Study in southeastern South America (FPS-SESA) endorsed by the Coordinated Regional Climate Downscaling Experiments (CORDEX) program. The FPS-SESA initiative seeks to promote inter-institutional collaboration and further networking with focus on extreme rainfall events. The main scientific aim is to study multi-scale processes and interactions most conducive to extreme precipitation events through both statistical and dynamical downscaling techniques, including convection-permitting simulations. To this end, a targeted experiment was designed considering the season October 2009 to March 2010, a period with a record number of extreme precipitation events within SESA. Also, three individual extreme events within that season were chosen as case studies for analyzing specific regional processes and sensitivity to resolutions. Four dynamical and four statistical downscaling models (RCM and ESD respectively) from different institutions contributed to the experiment. In this work, an analysis of the capability of the set of the FPS-SESA downscaling methods in simulating daily precipitation during the selected warm season is presented together with an integrated assessment of multiple sources of observations and available CORDEX Regional Climate Model simulations. Comparisons among all simulations reveal that there is no single model that performs best in all aspects evaluated. The ability in reproducing the different features of daily precipitation depends on the model. However, the evaluation of the sequence of precipitation events, their intensity and timing suggests that FPS-SESA simulations based on both RCM and ESD yield promising results. Most models capture the extreme events selected, although with a considerable spread in accumulated values and the location of heavy precipitation., Thanks to CORDEX for endorsing the FPS-SESA. This work was supported by the University of Buenos Aires 2018-20020170100117BA grant; JMG, MLB, SAS, RPR funding from the Spanish Research Council (CSIC) I-COOP+ Program “reference COOPB20374”. JMG, JF and AL-G acknowledge support from the Spanish R&D Program through projects MULTI-SDM (CGL2015-66583-R) and INSIGNIA (CGL2016-79210-R), co-funded by the European Regional Development Fund (ERDF/FEDER). AL-G acknowledges support from the Spanish R&D Program through the predoctoral contract BES-2016-078158. Universidad de Cantabria simulations have been carried out on the Altamira Supercomputer at the Instituto de Física de Cantabria (IFCA-CSIC), member of the Spanish Supercomputing Network. MB acknowledges support from the Simons Associateship of the Abdus Salam International Centre for Theoretical Physics. RH acknowledges support from the project LTT17007 funded by the Ministry of Education, Youth, and Sports of the Czech Republic.

The chromosomal complements of nine species of Blenniidae (Aidablennius sphynx, Blennius ocellaris, Lypophris adriaticus, L. pavo, L. trigloides, Parablennius gattorugine, P. ponticus, P. sanguinolentus, P. tentacularis) from the Adriatic Sea were analysed with several banding methods and in-situ hybridization. In all species, the diploid set consists of 48 mostly acrocentric chromosomes and has a similar location (terminal centromeric) of NORs, except for L. pavo (interstitial pericentric) and P. ponticus (terminal on the long arm). There are major differences in karyotype with regard to the amount and distribution of heterochromatin. Parablennius tentacularis shows a distinctive sex-chromosome system involving 2n=48 males with a large totally heterochromatic Y chromosome, and males with 2n=47. This difference is likely to be the consequence of a translocation of an autosome on the original Y. This finding constitutes an additional instance of the great variability in origins of multiple sex chromosome systems in vertebrates.

Rock lizards of the genus Iberolacerta constitute a promising model to examine the process of sex chromosome evolution, as these closely related taxa exhibit remarkable diversity in the degree of sex chromosome differentiation with no clear phylogenetic segregation, ranging from cryptic to highly heteromorphic ZW chromosomes and even multiple chromosome systems (Z1Z1Z2Z2/Z1Z2W). To gain a deeper insight into the patterns of karyotype and sex chromosome evolution, we performed a cytogenetic analysis based on conventional staining, banding techniques and fluorescence in situ hybridization in the species I. monticola, for which previous cytogenetic investigations did not detect differentiated sex chromosomes. The karyotype is composed of 2n = 36 acrocentric chromosomes. NORs and the major ribosomal genes were located in the subtelomeric region of chromosome pair 6. Hybridization signals of the telomeric sequences (TTAGGG)n were visualized at the telomeres of all chromosomes and interstitially in 5 chromosome pairs. C-banding showed constitutive heterochromatin at the centromeres of all chromosomes, as well as clear pericentromeric and light telomeric C-bands in several chromosome pairs. These results highlight some chromosomal markers which can be useful to identify species-specific diagnostic characters, although they may not accurately reflect the phylogenetic relationships among the taxa. In addition, C-banding revealed the presence of a heteromorphic ZW sex chromosome pair, where W is smaller than Z and almost completely heterochromatic. This finding sheds light on sex chromosome evolution in the genus Iberolacerta and suggests that further comparative cytogenetic analyses are needed to understand the processes underlying the origin, differentiation and plasticity of sex chromosome systems in lacertid lizards.

Abstract Sex chromosomes were studied in eight species of lacertid lizards using C-banding, G-banding and restriction enzyme treatment. All of the species showed female heterogamety. The W chromosome was a microchromosome in Lacerta graeca and Ophisops elegans. Two types of W were found in Lacerta vivipara; in specimens from The Netherlands it was metacentric, whereas in specimens from Russia it was acrocentric or subtelocentric. The W chromosome was homomorphic or nearly homomorphic but completely C-banded and heterochromatic in Lacerta agilis, Podarcis hispanica, Algyroides moreoticus and A. nigropunctatus. In was only possible to find sex chromosomes using the G-banding method in Podarcis sicula. The results obtained, together with data in the literature, suggest that sex chromosomes are likely to be present in all Lacertidae and that their differentiation took place repeatedly and independently in different taxa within the family. A model for sex chromosome evolution in the family, in which the starting point was the heterochromatization of the W chromosome, is proposed.

Retrotransposons are ubiquitous components of the DNA of many eukaryotic organisms. They move by an RNA intermediate and consist of two sub-types, the long terminal repeat (LTR) and the non-LTR retrotransposons. LTR retrotransposons have direct LTRs that range from ~100 bp to over 5 kb in size. Non-LTR retrotransposons consists of two sub-types, long interspersed nuclear elements (LINEs) and short interspersed nuclear elements (SINEs). LINEs code for the enzyme reverse transcriptase, and many LINEs also code for an endonuclease. The analysis of LINEs as molecular cladistic markers represents a particularly interesting complement to DNA sequence and morphological data. The presence of a given retrotransposon in related taxa suggests their orthologues integration, while the absence of particular elements can be considered an ancestral trait. The "living fossil" Latimeria menadoensis, belonging to the order Coelacanthiformes, is a very interesting organism for the evolutionary history of vertebrates. Our study aims to seek LINEs elements in the genome of this organism, to obtain new information and molecular markers for a more precise definition of the phyletic relationships that exist between this species and those that gave rise to tetrapods. Initial results highlight the presence of LINE transposons in L. menadoensis. We have isolated by PCR amplification a genomic fragment (~600 bp long) that shows similarity to a reverse transcriptases RVT_1, and a second one (~1500 bp long) that contains a region with high homology to an Exo_endo_phos endonuclease (pfam 03372). Both these fragments seem to belong to the LINE elements family that has the typical architecture "Endonuclease/RNA Reverse transcriptase-dependent DNA polymerase".

I celacantiformi sono fossili viventi di notevole importanza in quanto costituiscono il possibile anello di congiunzione tra pesci e tetrapodi. Attualmente sono state identificate solo due specie superstiti di celacanti, una africana Latimeria chalumnae ed una indonesiana Latimeria menadoensis. Lo studio di un esemplare maschile di Latimeria menadoensis, recentemente pescato nel mare di Sulawesi settentrionale (Settembre 2009) è stato inserito in un progetto nato dalla collaborazione tra l'Università Politecnica delle Marche e la Università Sam Ratulangi di Manado (Indonesia). L'analisi del contenuto di DNA attraverso la citofluorimetria di flusso di Latimeria menadoensis ha fornito un valore in accordo con le precedenti stime per Latimeria chalumnae. I dati derivati dal sequenziamento e dall'analisi dei geni dell'istone H3 e del rRNA 18S hanno confermato la vicinanza evolutiva fra la specie indonesiana e quella africana. Inoltre, allo scopo di chiarire le relazioni tra la L. menadoensis e i tetrapodi si è iniziata l'analisi dei geni DMRT1, coinvolto nel differenziamento sessuale, e vitellogenina, precursore delle proteine del tuorlo, che da dati recenti sembrano presentare un'evoluzione strettamente correlata a quella dei vertebrati.

A hitherto undescribed satellite DNA family (AvaII satDNA) has been isolated and characterised in Eumeces schneideri, a squamate reptile belonging to the family Scincidae. AvaII satDNA is characterised by a monomer length of 208 bp, a GC content of 59% and exhibits a certain degree of CpG methylation. FISH experiments with AvaII satDNA probe produced bright signals (i) at the end of the short arms of all subtelocentric chromosomes except for pair 14, in which the signal was at the end of the long arms, (ii) at the ends of both arms of the small metacentric chromosomes 12, and (iii) in a terminal position on the acrocentric chromosomes 11 and 13. AvaII satDNA repeats were not found in the metacentric pair 3, whereas only a weak interstitial signal occurred in the metacentric pairs 1 and 2. C-banding showed that this satellite represents most of the constitutive heterochromatin in the genome of this skink, and chromomycin A(3) staining produced a clear signal overlapping with the satellite, except for NOR-associated heterochromatin. In addition, quantitative dot blot analysis showed that these repetitive sequences constitute about 3% of the genomic DNA of this lizard. AvaII satDNA sequence analysis revealed the occurrence of short guanine residue stretches for which a function in structural stability of these sequences and a role in recombination with telomeric sequences can be hypothesised. Fibre FISH experiments showed that on some chromatin fibres telomeric sequences and AvaII satellite DNA repeats are intermingled or overlapping.

Three different sensors for hydrogen detection have been built and tested within a research project for the European Space Agency. One type is a FBG coated with a palladium layer, detecting the hydrogen by metal hindrance, the strains transmitted to the grating by shear. It works only as a detector and can not quantify the H2 percentage in a gas mixture. A main drawback, common with all palladium based sensors, was a strong temperature dependence, which makes its response time too large at low temperatures. The other two types were intensity based sensors; one of them was a micromirror, with a palladium thin layer at the cleaved end, detecting changes in the backreflected light. The other one as a tapered fibre coated also with palladium; hydrogen will change the refractive index of the palladium, and consequently the amount of losses in the evanescent wave. A trade-off analysis of sensor performances was done, comparing reproducibility, repetitiveness, robustness, multiplexability, response time and cost. FBG sensor was found to be the most reliable sensor among the optical fibres sensors considered, and the preferred one for space applications.

The karyotype of Histiodraco velifer from the Antartic Ocean was analyzed using various banding methods and in situ hybridization with a telomeric probe. A male and a female had a diploid set of 46 chromosomes (6 submetacentric + 40 acrocentric, FN = 52); the nucleolar organizer was CMA3-positive and was located on the short arm of a medium-sized submetacentric pair. All chromosomes stained uniformly with DAPI, whereas C-banding revealed heterochromatic blocks that were mostly located centromerically and telomerically and were resistant to ALUI digestion. The substantial identity of the karyotype of H. velifer with that of the other artedidraconids investigated so far suggests that chromosome changes must have played a less than significant role in the speciation among the lineages of this fish family endemic to Antarctica.

The chromosomal complements of nine species of Blenniidae (Aidablennius sphylnx, Blennius ocellaris, Lypophris adriaticus, L. pavo, L. trigloides, Parcablennius gattorugine, P. ponticus, P. sanguinolentus, P. tentacularis) from the Adriatic Sea were analysed with several banding methods and in-situ hybridization. In all species, the diploid set consists of 48 mostly acrocentric chromosomes and has a similar location (terminal centromeric) of NORs, except for L. pavo (interstitial pericentric) and P. ponticus (terminal on the long arm). There are major differences in karyotype with regard to the amount and distribution of heterochromatin. Parablennius tentacularis shows a distinctive sex-chromosome system involving 2n = 48 males with a large totally heterochromatic Y chromosome, and males with 2n = 47. This difference is likely to be the consequence of a translocation of an autosome on the original Y. This finding constitutes an additional instance of the great variability in origins of multiple sex chromosome systems in vertebrates.

Cytogenetic studies were performed in four species of two scorpaeniform teleost families: Scorpaenidae and Triglidae. The karyotypes of Trigla lucerna, Trigloporus lastoviza (Triglidae), Scorpaena porcus and S. notata (Scorpaenidae) were analysed using various banding methods and in situ hybridization with a telomeric probe. In the two Scorpaena species, modest morphological divergence corresponded to considerable karyotype reorganization, while in the two Triglidae substantial phenotypical divergence corresponded to limited chromosomal changes. These data stress the need for a taxonomical re-evaluation of these teleosts based on characters independent of morphology.

We have studied the chromosomes of 11 of the 15 known species of the notothenioid family Channichthyidae, the specialized whiteblooded Teleosts endemic to the Southern Ocean (ice-fishes). In the female sex, all studied species have the same diploid number of forty eight mostly acrocentric (uniarmed) chromosomes; however there is an interspecific variability in the chromosome morphology, type and quantity of repetitious DNA (usually seen as heterochromatin) localization of silver-stained nucleolar organizers. At least five of the studied species show a multiple sex-chromosome system possibly originated by the translocation of an autosome on an early Y gonosome morphologically similar to the X: the digametic males (2n = 47) show a X1Y X2 and the homogametic females (2n = 48) a X1X1X2X2 gonosomic constitution. This peculiar sex determining mechanism, otherwise rare in Teleosts, can be considered apomorphic in the same way as other morphofunctional characters usually interpreted as adaptive in these fishes.

The seasonal variations of chiasma frequency and distribution have been studied in the lizard: Podareis sicula. In this species, as in Phyllodactylus (King & Hayman, Chromosoma 69: 131–154, 1978), chiasma frequencies vary following a definite annual cycle, and clearly different trends are shown by interstitial and terminal chiasmata. A comparison between these seasonal chiasma frequency variations and those of environmental temperature shows the existence of a clear correlation between these two parameters. However, this correlation is different in the two types of chiasmata, and may be different within the same type of chiasma depending on the period of the year. A more significant correlation is observed between chiasma cycles and annual variations of the haematic levels of sexual steroid hormones. In particular we observe a highly significant correlation between interstitial chiasma frequencies and testosterone concentration. A less precise correlation between terminal chiasma frequencies and estradiol concentration is also observed. In Podarcis, as in Phyllodactylus, the sperm that will be used for fertilization derive from the spermatocytes showing the highest rate of interstitial chiasmata. This supports the hypothesis that the cyclic variations in interstitial chiasma frequencies represent a mechanism to ensure an adequate level of variability in a given population. The above mentioned correlation between chiasma frequencies and steroia hormone concentrations suggests that the seasonal chiasma cycles are controlled by the same environmental and hormonal factors regulating the spermatogenetic cycle.

1. 1. We have studied the DNA reassociation kinetics in 6 new reptile species and, in addition, we have carried out a comparative analysis of the genome composition of 7 turtles and 7 scaly-reptiles. 2. 2. In scaly-reptiles, as the phyletic distance increases, the differences in the most heterogeneous fractions (middle repetitive and single-copy DNAs) increase, too. In turtles such an increase is not found, but remarkable differences in single-copy DNA are observed also in congeneric species. 3. 3. Moreover, in Squamata as the genome size increases, repetitive DNA increases more drastically than single-copy DNA, whereas in Chelionia both fractions increase with the same rapidity. 4. 4. It is suggested that in turtles DNA evolution has followed a trend where deletion events have been very rare. In squamates, instead, there would have been a greater balance among amplifying events, divergences in the repetitive sequences and deletion. 5. 5. These results are in agreement with the hypotheses that turtles and squamates belong to two clearly distinct branches of amniotes.

A study of genome sizes and repetitive and nonrepetitive nucleotide fractions in some reptiles, selachians, and amphibians showed that not one of these organisms possesses the percentage of single-copy DNA presumed to be typical of animals (70%). The data on the samples investigated, when compared with those existing in literature on other vertebrates, indicate certain general characteristics of the genome of this important animal group, which in this work are interpreted in terms of their adaptive functions. Each of the main systematic categories of the subphylum (classes or orders) has peculiar features as to the genome size and percentage of unique or repetitive DNA fractions. Among anamniotes (i.e., teleosts, selachians, and amphibians) the percentages of the single-copy DNA are lower than among amniotes (i.e., reptiles, birds, and mammals) and inversely proportional to genome sizes, which does not occur in amniotes. Also on the basis of some karyologic evidence, the hypothesis is put forth that such differences may reflect the adoption, in the course of evolution of the amniotes, of new genetic strategies which have deeply influenced the genomic molecular structure.

(1986). Taxonomy and phylogenetic inference. Bollettino di zoologia: Vol. 53, No. sup001, pp. 53-60.

The evolution of genome size and base composition of DNA from various reptiles has been studied. DNA amount was measured cytophotometrically and GC concentration estimated by thermal denaturation. The Reptilia appear to be a fairly homogeneous group with respect to DNA quantity, although chelonians stand out because of their higher inter- and intrafamilial variability and DNA content. Quantitative DNA variations do not show a single evolutionary trend, but rather seem to have followed different patterns within each group. The differences in genome size between related species seem to be mainly the result of duplication or loss of DNA sequences characterized by a similar mean denaturation temperature. This agrees with observations of other authors that quantitative variations in reptiles are mainly due to differences in the amount of repetitive DNA. Several hypotheses on the significance of quantitative DNA variations in reptiles are discussed.

The Pelobatids have a basal karyotype of 26 chromosomes, with 6 pairs of large and 7 of small chromosomes (6+7). From this karyotype, shown by Leptobrachium, Pelobates and Scaphiopus, those of Megophrys and Spea (5+8) may be derived, as well as that of L. pelodytoides, with only 24 chromosomes. Pelodytes has 24 chromosomes and a karyotype 7+5 differing from that of typical Pelobatids under several respects. © 1977 Birkhäuser Verlag.

The DNA interspersion pattern in 3 Selachians (R. asterias, T. marmorata and S. stellaris) has been studied through the reassociation kinetics of short (0.3 Kb) and long (2.5 Kb) DNA fragments. Preliminary results show that most of the DNA (approximately 80%) of these organisms is arranged according to a short-period interspersion pattern. A notable resemblance to the pattern previously described in the teleostean Salmo trutta has been observed. © 1982 Birkhäuser Verlag.

1. 1. The DNA reassociation kinetics have been studied in 6 selachian species: Raja asterias, Raja montagui, Dasyatis violacea, Torpedo marmorata, Torpedo ocellata and Oxynotus centrina. 2. 2. The results obtained show that the genomes of the two Torpedo, Dasyatis and Oxynotus are polyploid if compared with those of the two rays, though this finds no correspondence in the diploid chromosome number. 3. 3. The phenomena of polyploidization would often be followed by wide chromosome rearrangements and by a progressive divergence of the various repetitive DNA sequences. 4. 4. The existence of polyploidy in almost all the main superorders of living Selachians suggests that this mechanism of genomic evolution may have played an important role in the phylogeny of this class.

A comparison has been performed among chromosome sets, genome sizes and DNA fractions characterized by a different repetitivity of the nucleotide sequences in two species of Alytes, one of Discoglossus and one of Bombina (family of Discoglossidae; Amphibia Salientia). Alytes appears as the karyologically less differentiated genus, whereas Bombina distinguishes itself by the sizes of genome and of single-copy fraction, larger than in other discoglossids and outstanding also with respect to the other anurans so far studied; Discoglossus has a karyotype with characteristics transitional between those of the other two genera, but showing a greater complexity in the middle repetitive fraction. These anurans are, therefore, rather heterogeneous and different from one another from the viewpoint of their chromosome morphology and quantitative and qualitative DNA characteristics, so that it is not possible to determine a closer relationship between two of these genera with respect to the third. © 1982 Taylor & Francis Group, LLC.