Cytogenetics of four foam-nesting frog species of the Physalaemus gracilis group (Anura, Leptodactylidae).

Intending to increase the knowledge about cytogenetics of Physalaemus and the sparsely studied P. gracilis group, we analyzed the karyotypes of P. carrizorum, P. gracilis, P. lisei, and P. sp. aff. gracilis. We studied chromosome morphology, heterochromatin patterns, Ag-NORs location and mapped the repetitive DNA sequence PcP190. All species showed diploid karyotypes composed of 22 bi-armed chromosomes and similar C- bands and Ag-NOR patterns. C-bands were mainly centromeric and pericentromeric; non-centromeric C-bands were detected on the telomeres of pair 1 in P. lisei, although polymorphic, and interstitially on pair 10 of P. gracilis. This last character is useful to distinguish P. gracilis from its sibling species P. sp. aff. gracilis. The Ag-NOR sites were detected on the long arms of chromosome pair 8 but with a variable position among species. Clusters of PcP190 showed centromeric and pericentromeric positions coincident with conspicuous C-bands, on pairs 2 and 9 in P. gracilis and P. sp. aff. gracilis, pair 3 in P. carrizorum, and pair 7 in P. lisei. These results significantly increase the knowledge about Physalaemus cytogenetics and encourage further studies on the satellite PcP190 in other genera of Leiuperinae to better understand its taxonomic distribution and the evolutionary dynamics.

A reappraisal of Bufo levicristatus Boettger, 1885 (Anura: Bufonidae), a long forgotten toad from Paraguay.

In this work, we show that Bufo levicristatus Boettger, 1885 is a senior synonym of Bufo scitulus Caramaschi Niemeyer, 2003, and not a junior synonym of Bufo ornatus Spix, 1824, as previously considered. In addition, we present evidence that Bufo scitulus Caramaschi Niemeyer, 2003 complies with the International Code of Zoological Nomenclature requirements for a reversal of precedence over the name Bufo levicristatus Boettger, 1885, and so the name Bufo scitulus is to be maintained for this species.

Aberrant colourations in wild snakes: case study in Neotropical taxa and a review of terminology

The criteria used by previous authors to define colour aberrancies of snakes, particularly albinism, are varied and terms have widely been used ambiguously. The aim of this work was to review genetically based aberrant colour morphs of wild Neotropical snakes and associated terminology. We compiled a total of 115 cases of conspicuous defective expressions of pigmentations in snakes, including melanin (black/brown colour), xanthins (yellow), and erythrins (red), which involved 47 species of Aniliidae, Boidae, Colubridae, Elapidae, Leptotyphlopidae, Typhlopidae, and Viperidae. Most of them were hypopigmented conditions, mainly amelanism, but also anerythrism, axanthism, hypomelanism, leucism, piebaldism, and albinism (total absence of pigments). Hyperpigmented aberrancies were mostly melanism and xanthism, plus a few instances of erythrism. No associations with diurnality and fossorial behaviour were observed, neither for blanched nor hyperpigmented aberrancies. A discussion of the terms most commonly used for wild snakes is provided, with an account of cases of aberrant colourations in other South American reptiles. Finally, we propose a simple classification framework of wild snake colour aberrancies based on predominant dorsal colour and eye pigmentation for the adoption of a standardized terminology, which may be applicable to other squamates and chelonians. We advocate the use of a more accurate terminology in the scientific literature that would avoid the use of confusing terms like “partial albinism”.

Correction: A review of the elusive bicolored iris Snouted Treefrogs (Anura: Hylidae:Scinax uruguayus group).

[This corrects the article DOI: 10.1371/journal.pone.0222131.].

A new frog of the Leptodactylus fuscus species group (Anura: Leptodactylidae), endemic from the South American Gran Chaco.

A new species of Leptodactylus frog (Anura: Leptodactylidae) from the South American Gran Chaco, morphologically similar and previously confused with the widespread Leptodactylus mystacinus, is described through the use of multiple sources of evidence (molecular, external morphology, coloration, osteology, bioacoustics, and behavior). The phylogenetic analysis with partial sequences of mitochondrial rDNA genes (12S and 16S) recovered the new species within the L. fuscus group, being highly divergent (>3% genetic distance in 16S). The new species was recovered as sister taxa of L. mystacinus, from which it is distinguished by tympanum coloration, cephalic index, dorsum and legs coloration, and some osteological differences in nasals and prevomers. This new frog is characterized by a moderate body size (SVL 46.80-66.21 mm), distinctive color pattern (reddish dorsal surfaces of body with noticeable black stripes in the dorsolateral folds), a circular and dark tympanum with dark tympanic annuli, and behavior of males that call on top of fallen logs and tree branches close to the ground.

A review of the elusive bicolored iris Snouted Treefrogs (Anura: Hylidae:Scinax uruguayus group).

The genus Scinax currently includes more than 120 species, recovered in two major clades, the S. catharinae and the S. ruber clades. The latter comprises 75 species, most of which remain unassigned to any species groups, while 12 are included in the S. rostratus and S. uruguayus groups. In this paper we present a taxonomic review of the two species currently included in the S. uruguayus group, discussing some putative phenotypic synapomorphies of this group. Although S. pinima and S. uruguayus have been considered as distinct species, this has been based on scant evidence, and several authors doubted of their distinctiveness. Our study of available specimens of S. pinima and S. uruguayus corroborates that both are valid and diagnosable species based on phenotypic evidence. Furthermore, our results show that S. pinima previously known only from its type locality, has a much widespread distribution than previously thought (including the Brazilian states of Paraná, Santa Catarina, and Rio Grande do Sul), which, added to the biological information presented here allows to suggest the removal of this species from the "Data Deficient" IUCN Red List category to "Least Concern". Also, we describe a new species formerly reported as S. aff. pinima and S. uruguayus from NE Argentina and some localities from the Brazilian State of Rio Grande do Sul. All species are diagnosed and characterized using adult and larval morphology, osteology, vocalizations, cytogenetics, and natural history.

Early ontogeny and sequence heterochronies in Leiuperinae frogs (Anura: Leptodactylidae).

The study of early development in Neotropical Leiuperinae frogs (Anura, Leptodactylidae) has been addressed by several works in recent times. However, a comparative developmental approach under a phylogenetic context was not available. Herein we analyzed the morphological and ontogenetic diversity of embryos belonging to 22 species of the three largest genera in Leiuperinae. We find that in most cases, variations fit with the phylogeny at the inter- and intrageneric levels. Embryo kyphosis and whitish color are synapomorphies for the clade grouping Physalaemus and Engystomops. The presence of a third lower tooth row on the oral disc is plesiomorphic for Leiuperinae, only changing in derived clades. The configurations and developmental trajectories of the lower lip are exceptionally diverse. The developmental sequences optimized on the phylogenetic tree recover an early differentiated first lower tooth row a synapomorphy of Pseudopaludicola and Physalaemus, and an early differentiated second row as synapomorphy of Pleurodema. On the other hand, few features are highly conserved in the subfamily, such as the adhesive glands universally present in a type-C configuration. Our results also suggest that the morphology and ontogeny of embryos is in some cases associated to the environment where they develop. A large body size, poorly developed transient respiratory structures, large yolk provision and delayed development of the digestive tract occur convergently in embryos inhabiting cold, oxygenated environments. Embryos that develop in warmer water bodies in xeric environments show more complex and persistent transient respiratory structures and an early onset of hind limbs development. Our survey highlights that morphology and early development of anurans can be a valuable source of information for phylogenetic studies, and provide fundamental bases to explore and discuss how evolutionary changes can be shaped by environmental conditions.

Sensitivity of histology for the detection of the amphibian chytrid fungus Batrachochytrium dendrobatidis.

Histology is often underappreciated for the detection of the amphibian pathogenic fungus Batrachochytrium dendrobatidis, the cause of the potentially lethal skin disease chytridiomycosis. We evaluated the sensitivity of histology to detect chytrids in 20 wild specimens of 2 frog species from Uruguay that were clinically normal, but confirmed by PCR to be infected by B. dendrobatidis. We detected maturing and sporulated sporangia in 15 of 20 (75%) frogs, which is more sensitive than previously reported for histology. The effort needed to identify chytrids in histologic skin sections of Physalaemus henselii and Pleurodema bibroni required examination of 3.2 and 8.7 mm of skin sections for each frog species, respectively.

Hyla prasina Burmeister, 1856 meets the requirements of Article 23.9.1 of the Code for a reversal of precedence over Hyla quoyi Bory de Saint-Vincent, 1828 (Anura, Hylidae).

In a recent work, Ohler and Dubois (2018) discussed the correct application of Article 23.9 of the Code (Anonymous, 1999; 2012) and illustrated it with some concrete cases in which the authors considered that the Article was misinterpreted. Article 23.9 of the Code allows the "reversal of precedence", that is, that when a senior homonym or synonym has not been used as a valid nomen after 1899 (Article 23.9.1.1) and its junior synonym or homonym has been used as valid for the same taxon in at least 25 works published by at least 10 authors in the immediately preceding 50 years and encompassing a span of not less than 10 years (Article 23.9.1.2), the junior homonym or synonym must be maintained as valid (Article 23.9.1). One of the cases considered by Ohler and Dubois (2018) is the treatment given by Caramaschi and Niemeyer (2010) to the names Hyla prasina Burmeister, 1856 (under the combination Hypsiboas prasinus), and Hyla quoyi Bory de Saint-Vincent, 1828.

Amphibian parasites of the Order Dermocystida (Ichthyosporea): current knowledge, taxonomic review and new records from Brazil.

Amphibian parasites of the Order Dermocystida (Ichthyosporea) are widespread pathogens known mainly from Europe and North America, which cause primarily a disease of skin and subcutaneous tissue in their hosts. The taxonomy of these organisms has been problematic given their conserved morphology, similar clinical disease and pathology. Currently recognized taxa belong to the three closely related genera, Amphibiocystidium, Amphibiothecum, and Rhinosporidium, whereas species of Dermocystidium and Sphaerothecum destruens include fish parasites. Here, we review the taxonomy of Dermocystida based on a molecular phylogenetic analysis, principally of amphibian parasites, including DNA sequences obtained from amphibian hosts collected in the central-eastern region of South America. A new taxonomic arrangement is proposed, which includes the designation of type material for Dermocystidium pusula, synonymization of Amphibiothecum with Dermocystidium, and the restriction of Amphibiocystidium to its type species A. ranae. We also review the taxonomic status of Dermosporidium hylarum until the present work included in the synonymy of the human and animal pathogen R. seeberi, and considered herein as a valid taxon, however. In addition, a new species of Sphaerothecum parasitic to amphibians is described, being the first record of this genus in the southern hemisphere and in an amphibian host.

Ichthyophonus sp. (Ichthyophonae, Ichthyophonida) infection in a South American amphibian, the hylid frog Hypsiboas pulchellus.

We report infection by Ichthyophonus sp. in a South American amphibian, the hylid frog Hypsiboas pulchellus in Uruguay. This frog had a large subcutaneous mass over the urostyle and dorsal musculature comprised of parasitic cysts with mild granulomatous inflammation but otherwise appeared healthy.

Dermocystid-chytrid coinfection in the neotropical frog Hypsiboas pulchellus (Anura: Hylidae).

We present gross and histologic evidence of coinfection in amphibians by fungal-like parasites of the order Dermocystidia (Amphibiocystidium sp.) and the fungus Batrachochytrium dendrobatidis. The condition was observed in frogs Hypsiboas pulchellus (Hylidae) from Uruguay in 2009 to 2012. This report is the first of dermocystids in Neotropical amphibians since 1940.

Oseopercepción: una puesta al día / Osseoperception: an update

La incorporación de implantes dentales al Sistema Estomatognático genera muchos cuestionamientos, entre ellos: ¿Cómo se explica que el paciente “sienta” a través de estos sistemas de anclaje?; ¿Por qué el paciente dice que mastica mejor que con las prótesis mucosoportadas?;¿Por qué a pesar de haber perdido dos componentes fisiológicos esenciales (dientes y periodonto) no se aprecian clínicamente importantes problemas dentro del sistema?; ¿Qué reordenamientos del sistema nervioso determinan la regulación motora luego de rehabilitado con estas técnicas? Es probable que las respuestas surjan a través del conocimiento de una nueva modalidad sensorial descriptacomo oseopercepción, la cual implica un reordenamiento de las áreas sensitivas y motoras de la corteza cerebral (neuroplasticidad).

Many questions arise from the introduction of dental implants into the stomatognathic system, for example: How can patients “feel” through these anchorage structures? Why does the patient feel that his mastication is improved with respect to the classic complete dentures? Why there are not remarkable alterations in the function of the stomatognathic system despite the loss of two essential componentsof this system? What rearrangements of the nervous system take place after the placement of dental implants that control the motor regulation of the stomatognathic system? Probably, the answer to these questions may come from the study of a new sensorymodality known as osseoperception, which involves a rearrangement of sensory and motor areas of the brain cortex (neuroplasticity).

A lost species or the loss of stripes? The case of Contomastix lizards from Cabo Polonio, Uruguay, with observations on C. lacertoides (Duméril & Bibron) and Cnemidophorus grandensis Cope (Squamata, Teiidae).

The main goal of this manuscript is the reevaluation of the taxonomic status of the teiid lizard Contomastix charrua, known only from Cabo Polonio, a small coastal rocky outcrop in southeastern Uruguay. This species was erected on the basis of the presence of a second pair of ceratobranchials and longer cornua in the hyoid bone, in addition to a reduced expression of the pattern of coloration as compared with C. lacertoides. Nevertheless, we found that both species have indistinguishable hyoid morphology, bearing C. lacertoides a noticeable second pair of ceratobranchials. Besides, we realized that the pattern of coloration in this species is more variable than previously considered. As a result of the present work, C. charrua is included in the synonymy of C. lacertoides. In addition, we provide some observations on the holotype of Cnemidophorus grandensis, a junior synonym of C. lacertoides.

El sentido del gusto / The sense of taste

El gusto es un sistema sensorial complejo que está vinculado a las conductas alimenticias del ser humano. Interactúa con el olfato, la sensibilidad táctil y térmica oral, y hasta con la visión y la audición. Se describen actualmente cinco variedades de gusto: dulce, salado, ácido, amargo y umami. Los receptores gustativos se encuentran fundamentalmente en la boca. En la transducción del estímulo gustativo participan dos mecanismos: canales iónicos para los gustos salado y ácido y receptores de membrana asociados a proteínas G para los restantes tres sabores. Se describe la vía gustativa y sus conexiones con el sistema límbicovinculadas con el placer-displacer de la gustación (hedonismo). Existen avances importantes relacionados con la codificación de los distintos estímulos gustativos, siendo la propuesta más fundamentada y aceptada la teoría de los ®patrones de actividad central¼. Algunos reflejos gustativos se producen al servicio de la masticación, por ejemplo los reflejos gustativos salivales para la formación del bolo, gustativo motor para la modulación de la frecuencia masticatoria y gustativo facial para comia y para laexpresión hedónica.

The sense of taste is a complex sensorial system related to the human feeding behavior. It interacts with the senses of smell, vision, audition and oral touch. Currently, five taste modalities are recognized: sweet, salty, sour, bitter and umami. Taste receptors are located mostly in the mouth. Two mechanisms are involved in the stimulus transduction in taste: ionic channels in the salty and sour tastes, and receptors associated to G-proteins in the transduction of the other three tastes. We describe thegustative neural pathway and their connections with the limbic system, related with the hedonic components of taste. We describe the theories advanced to explain the codification of the gustatory stimulus, with the ®central pattern activity¼ being the most accepted nowadays. Some taste reflexes have an accesory function in mastication, for example, the taste-salivary reflex helps in bolus formation, the taste-motor reflex regulates the masticatory frequency, and the gustofacial reflex helps with themastication and expresses the hedonic state.

Karyotypic Data on 28 Species of Scinax (Amphibia: Anura Hylidae) Diversity and Informative Variation

The hylid frog genus Scinax is the most species-rich within Hylinae, with more than 100 recognized species grouped in the S. catharinae and S. ruber clades. The karyotypes of 14 species of the S. catharinae clade and 14 of the S. ruber clade were analyzed, several of them for the first time. All studied species presented 2n  =  2x  =  24 biarmed chromosomes (FN  =  48) and no identifiable sex chromosomes. There are two alternate states associated with the size and morphology of pair 1, corresponding to the S. catharinae clade and to the S. ruber clade. The morphology of pairs 2 and 6 also differentiate the species of both major clades. Species of the S. ruber clade in general have Ag-NORs in pair 11, as is commonly observed among hylines with 2n  =  24. The Ag-NORs' position in the long arms of pair 11 is interstitial in S. fuscomarginatus, S. fuscovarius, S. nasicus, S. similis, S. squalirostris, and S. uruguayus, and terminal in S. acuminatus, S. curicica, S. duartei, S. granulatus, S. hayii, and S. perereca. The single exception among species of the S. ruber clade is S. alter, which has terminal Ag-NORs at the long arms of pair 3. Most species of the S. catharinae clade have Ag-NORs in pair 6, representing a putative synapomorphy of this clade, while the Ag-NORs in pair 11 that occur in S. canastrensis are most parsimoniously interpreted as a reversion. C-banding is predominantly centromeric, but in the S. catharinae clade there is a greater amount of heterochromatin than in the S. ruber clade. This study corroborates the occurrence of informative variation, some already considered in a previous cladistic analysis, and reports new characters, outlining the significance of cytogenetic data for the systematics of Scinax.

Chytridiomycosis in frogs from Uruguay.

Amphibian chytridiomycosis caused by Batrachochytrium dendrobatidis is reported in Uruguayan native amphibians for the first time. Histological evidence of infection was observed in tadpoles of Hypsiboas pulchellus, Odontophrynus maisuma, Physalaemus henselii, and Scinax squalirostris. The effects of chytridiomycosis on these species are still unknown. However, the disease is of potential concern for the conservation of the apparently declining species P. henselii and also for O. maisuma, given its restricted distribution in habitats which are being increasingly disturbed.

Oseopercepción: la sensibilidad mediada por los implantes oseointegrados / Osseoperception: the sensibility mediated by osseointegrated implants

En la búsqueda de soluciones al problema de la edentación parcial o total, los implantes dentales se han ganado un lugar destacadodebido a su predecibilidad, estética, comodidad y función mejorada respecto a otras opciones restauradoras. El anclaje óseode los implantes brinda estabilidad a la restauración y tiene la capacidad de transmitir las fuerzas directamente al hueso. Estoúltimo permite, a su vez, poner en marcha una nueva modalidad sensorial descripta recientemente como oseopercepción. Estainformación periférica provoca un reordenamiento de los mapas sensitivos y motores en la corteza cerebral, lo que implica unamejoría en la percepción consciente del estímulo respecto a la situación de edentación y nueva información para el ajuste de lafunción motora mandibular. La evidencia experimental demuestra que las rehabilitaciones sobre implantes dentales presentanumbrales de detección táctil pasivos y activos aumentados en comparación con los dientes naturales. Se discute si esta capacidaddiscriminativa proviene de receptores residuales del ligamento periodontal o si depende de brotes de nuevas fibras nerviosas en lainterfase hueso-implante o bien de otros receptores ubicados a distancia de los mismos.

aesthetics, comfort and better function when compared to other restorative solutions. The bone anchored implants give stabilityto the restoration, and allow the transmission of forces directly to the bone. This fact is the basis of a new sensorial modalitycalled osseoperception. This new peripheral information leads to rearrangements of sensory-motor cortical maps, which improvesthe conscious perception of stimuli with respect to the edentulous situation and permit adjustment of motor mandible function.The passive and active tactile thresholds are higher in osseointegrated implants than in natural teeth. It is still unknown whetherthis discriminative ability depends on remnant receptors from the periodontal ligament, on the sprouting of nerve fibres in thebone-implant interface, or on other receptors placed not so close to the implants.

Aspectos controversiales sobre la compensación de la contracción y la tensión de polimerización en las resinas de fotocurado de aplicación directa / Controversial aspects on compensation of contraction and polimerization stress in light-cured direct composites

La contracción volumétrica y las tensiones generadas durante la polimerización son dos principales limitaciones de las resinascompuestas. Entre las soluciones propuestas para compensar estos fenómenos, figuran tener en cuenta el factor de configuración,el cargado incremental en capas de resina compuesta, la fotopolimerización a través de las paredes dentarias remanentes, lafotopolimerización con un gradiente creciente de intensidad luminosa, y el uso de “liners” cavitarios de resinas de bajo móduloelástico. A pesar de que estas técnicas son consideradas importantes para disminuir los efectos negativos de la contracción y delas tensiones de polimerización, múltiples investigaciones generan dudas sobre la eficacia de las mismas. De todas formas presentansuficientes ventajas clínicas adicionales como para que siga siendo justificado su uso.

Volumetric contraction and polymerization stress are main limitations of dental composites. Among the techniques proposed tocompensate these phenomena were, taking into account the configuration factor, incremental cavity layering, photopolymerizationthrough the remaining dental structures, photopolymerization with a growing gradient of light energy and the use of compositesof low elastic modulus as cavity liners. Even though these techniques are considered important to reduce the negative effects ofcontraction and polymerization stress, the results of many researches produce reservations about their efficacy. Anyway, theypossess enough additional clinical advantages to justify their use.

Neurofisiología de los mecanorreceptores periodontales humanos / Neurophysiology of human periodontal mechanoreceptors

Los mecanorreceptores del ligamento periodontal son del tipo SA II, es decir receptores tónicos, de adaptación lenta, que envíanpotenciales de acción tanto en la fase estática como dinámica durante la aplicación de fuerzas sobre los dientes. En el sectoranterior de la arcada dentaria, los receptores involucrados en regular la función de sostener un alimento presentan un comportamientohiperbólico, con máxima capacidad discriminativa en el rango de fuerzas de 0 a 1,2 N. Los receptores involucrados en laregulación del corte de alimentos presentan un comportamiento lineal, respondiendo efectivamente hasta los 22 N, pero conmenor capacidad discriminativa frente a fuerzas de baja intensidad. El sector posterior es la zona de la arcada en la que se ejerceuna mayor fuerza masticatoria. Los mecanorreceptores en esta zona son menos sensibles a la aplicación de la carga. Los dientesanteriores están involucrados en el sostén y corte de los alimentos, mientras que los posteriores están adaptados para la trituración.La ausencia de aferencias sensoriales a partir de los mecanorreceptores periodontales resulta en un control distorsionado delos movimientos masticatorios.

Human periodontal mechanoreceptors are SA II type, tonic or slowly adapting receptors, which fire action potentials during thestatic and dynamic phases of stimulus application. In the anterior teeth, receptors involved in holding fragments of food, displayan hyperbolic stimulus-response curve, with a maximum discriminative capacity in the range of forces between 0 - 1,2 N. Thereceptors involved in splitting food present a lineal stimulus-response curve up to 22 N, but with less discriminative capacity oflow intensity forces. In the posterior teeth, which are loaded with higher forces during masticatory function, mechanoreceptorsare less sensitive to forces. Anterior teeth are involved in holding and splitting of food, while posterior teeth are specialized infragmentation. The loss of sensory afferences from periodontal mechanoreceptors leads to distorted masticatory movements.