Moving beyond the surface : comparative head and neck myology of threadsnakes (Epictinae, Leptotyphlopidae, Serpentes), with comments on the ‘scolecophidian’ muscular system

Studies on the cephalic myology of snakes provide a series of relevant data on their biology and systematics. Despite the great amount of descriptive studies currently available for the group, much of the knowledge remains obscure for most scolecophidian taxa. This study aimed to describe in detail the cephalic (head and neck) myology of members of the tribe Epictinae, Leptotyphlopidae. We provide the first report of the presence of extrinsic ocular muscles, and a double Musculus pterygoideus acessorius in Leptotyphlopidae. A welldeveloped M. levator anguli oris is exclusive to the subtribes Renina and Epictina, being reduced in Tetracheilostomina species. Both inter- and intraspecific variations are reported for the head and neck muscles, and such results provide additional data and raise an interesting discussion on the neck-trunk boundaries in snakes. We also provide a discussion on the terminology of a few head muscles in Leptoyphlopidae in comparison to the other lineages of ´Scolecophidia´ (Anomalepididae and Typhlopoidea)

Growing towards disparity: geometric morphometrics reveals sexual and allometric differences in Aparasphenodon brunoi (Anura: Hylidae: Lophyohylinae) head shape

Sexual dimorphism and allometry feature is the main categories of intraspecific variation found in the animal kingdom, and techniques such as Geometric Morphometrics are effective to investigate variations in shape. Considering that many vertebrates exhibit substantial allometry and sexual dimorphism, we test the hypotheses that (1) Aparasphenodon brunoi displays ontogenetic and static allometry; and that (2) there is sexual dimorphism in head shape in this species. We analyzed 75 specimens of A. brunoi from Parque Nacional da Restinga de Jurubatiba and found significant ontogenetic and static allometries in head shape, as well as sexual dimorphism after size correction. Regarding sexual dimorphism, females tend to have larger heads, besides slightly anteriorly positioned nostrils, smaller eyes, larger canthal ridges, narrower and longer frontoparietal ridges, and larger and laterally shifted squamosal ridges. We discuss the relevance of head morphology variation in the species, as well as the presumed consequences on the species fitness.Dimorfismo sexual e alometria são as principais categorias de variação intraespecífica encontradas em metazoários e técnicas como a Morfometria Geométrica são eficazes para investigar variações na forma. Considerando que muitos vertebrados exibem considerável alometria e dimorfismo sexual, testamos as seguintes hipóteses: (1) Aparasphenodon brunoi exibe alometria ontogenética e estática; e (2) existe dimorfismo sexual na forma da cabeça nesta espécie. Analisamos 75 espécimes de A. brunoi do Parque Nacional da Restinga de Jurubatiba e encontramos alometrias ontogenética e estática significativas na forma da cabeça, além de dimorfismo sexual após a correção do tamanho. Em relação ao dimorfismo sexual, as fêmeas tendem a ter cabeças maiores, além de narinas ligeiramente posicionadas mais anteriormente, olhos menores, cristas cantais maiores, cristas frontoparietais mais estreitas e mais longas e cristas esquamosais maiores e deslocadas lateralmente. Discutimos a relevância da variação da morfologia da cabeça na espécie, bem como as consequências presumidas na aptidão da mesma.Asociación Herpetológica Argentin

Growing towards disparity: geometric morphometrics reveals sexual and allometric differences in Aparasphenodon brunoi (Anura: Hylidae: Lophyohylinae) head shape

Sexual dimorphism and allometry feature is the main categories of intraspecific variation found in the animal kingdom, and techniques such as Geometric Morphometrics are effective to investigate variations in shape. Considering that many vertebrates exhibit substantial allometry and sexual dimorphism, we test the hypotheses that (1) Aparasphenodon brunoi displays ontogenetic and static allometry; and that (2) there is sexual dimorphism in head shape in this species. We analyzed 75 specimens of A. brunoi from Parque Nacional da Restinga de Jurubatiba and found significant ontogenetic and static allometries in head shape, as well as sexual dimorphism after size correction. Regarding sexual dimorphism, females tend to have larger heads, besides slightly anteriorly positioned nostrils, smaller eyes, larger canthal ridges, narrower and longer frontoparietal ridges, and larger and laterally shifted squamosal ridges. We discuss the relevance of head morphology variation in the species, as well as the presumed consequences on the species fitness.Dimorfismo sexual e alometria são as principais categorias de variação intraespecífica encontradas em metazoários e técnicas como a Morfometria Geométrica são eficazes para investigar variações na forma. Considerando que muitos vertebrados exibem considerável alometria e dimorfismo sexual, testamos as seguintes hipóteses: (1) Aparasphenodon brunoi exibe alometria ontogenética e estática; e (2) existe dimorfismo sexual na forma da cabeça nesta espécie. Analisamos 75 espécimes de A. brunoi do Parque Nacional da Restinga de Jurubatiba e encontramos alometrias ontogenética e estática significativas na forma da cabeça, além de dimorfismo sexual após a correção do tamanho. Em relação ao dimorfismo sexual, as fêmeas tendem a ter cabeças maiores, além de narinas ligeiramente posicionadas mais anteriormente, olhos menores, cristas cantais maiores, cristas frontoparietais mais estreitas e mais longas e cristas esquamosais maiores e deslocadas lateralmente. Discutimos a relevância da variação da morfologia da cabeça na espécie, bem como as consequências presumidas na aptidão da mesma.Asociación Herpetológica Argentin

Growing towards disparity: geometric morphometrics reveals sexual and allometric differences in Aparasphenodon brunoi (Anura: Hylidae: Lophyohylinae) head shape

Sexual dimorphism and allometry feature is the main categories of intraspecific variation found in the animal kingdom, and techniques such as Geometric Morphometrics are effective to investigate variations in shape. Considering that many vertebrates exhibit substantial allometry and sexual dimorphism, we test the hypotheses that (1) Aparasphenodon brunoi displays ontogenetic and static allometry; and that (2) there is sexual dimorphism in head shape in this species. We analyzed 75 specimens of A. brunoi from Parque Nacional da Restinga de Jurubatiba and found significant ontogenetic and static allometries in head shape, as well as sexual dimorphism after size correction. Regarding sexual dimorphism, females tend to have larger heads, besides slightly anteriorly positioned nostrils, smaller eyes, larger canthal ridges, narrower and longer frontoparietal ridges, and larger and laterally shifted squamosal ridges. We discuss the relevance of head morphology variation in the species, as well as the presumed consequences on the species fitness.Dimorfismo sexual e alometria são as principais categorias de variação intraespecífica encontradas em metazoários e técnicas como a Morfometria Geométrica são eficazes para investigar variações na forma. Considerando que muitos vertebrados exibem considerável alometria e dimorfismo sexual, testamos as seguintes hipóteses: (1) Aparasphenodon brunoi exibe alometria ontogenética e estática; e (2) existe dimorfismo sexual na forma da cabeça nesta espécie. Analisamos 75 espécimes de A. brunoi do Parque Nacional da Restinga de Jurubatiba e encontramos alometrias ontogenética e estática significativas na forma da cabeça, além de dimorfismo sexual após a correção do tamanho. Em relação ao dimorfismo sexual, as fêmeas tendem a ter cabeças maiores, além de narinas ligeiramente posicionadas mais anteriormente, olhos menores, cristas cantais maiores, cristas frontoparietais mais estreitas e mais longas e cristas esquamosais maiores e deslocadas lateralmente. Discutimos a relevância da variação da morfologia da cabeça na espécie, bem como as consequências presumidas na aptidão da mesma.Asociación Herpetológica Argentin

An evolutionary paradox on threadsnakes: Phenotypic and molecular evidence reveal a new and remarkably polymorphic species of Siagonodon (Serpentes: Leptotyphlopidae: Epictinae) from Amazonia

Threadsnakes are known for their conserved external morphology and historically controversial systematics, challenging taxonomic, biogeographic and evolutionary researches in these fields. Recent morphological studies—mostly based on µCT data of the skull and lower jaw—have resolved systematic issues within the group, for instance leading to the description of new taxa or re-positioning little-known scolecophidian taxa in the tree of life. Herein we describe a new polymorphic species of the genus Siagonodon from Amazonia based on morphological (external, osteology and hemipenis) and molecular data, and provide the first hemipenial description for the genus. We also reassign Siagonodon acutirostris to the genus Trilepida based on osteological data in combination with molecular evidence. The new species described represents an evolutionary paradox for scolecophidians because the species displays a remarkable variation in the shape of the snout region that is otherwise always highly conserved in this clade. Finally, this study reinforces the importance of protected areas as essential in maintaining vertebrate populations, including those that are not yet formally described

Elective cancer surgery in COVID-19-free surgical pathways during the SARS-CoV-2 pandemic: An international, multicenter, comparative cohort study

PURPOSE As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19–free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19–free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19–free surgical pathways. Patients who underwent surgery within COVID-19–free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19–free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score–matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19–free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION Within available resources, dedicated COVID-19–free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks

Elective Cancer Surgery in COVID-19-Free Surgical Pathways During the SARS-CoV-2 Pandemic: An International, Multicenter, Comparative Cohort Study.

PURPOSE: As cancer surgery restarts after the first COVID-19 wave, health care providers urgently require data to determine where elective surgery is best performed. This study aimed to determine whether COVID-19-free surgical pathways were associated with lower postoperative pulmonary complication rates compared with hospitals with no defined pathway. PATIENTS AND METHODS: This international, multicenter cohort study included patients who underwent elective surgery for 10 solid cancer types without preoperative suspicion of SARS-CoV-2. Participating hospitals included patients from local emergence of SARS-CoV-2 until April 19, 2020. At the time of surgery, hospitals were defined as having a COVID-19-free surgical pathway (complete segregation of the operating theater, critical care, and inpatient ward areas) or no defined pathway (incomplete or no segregation, areas shared with patients with COVID-19). The primary outcome was 30-day postoperative pulmonary complications (pneumonia, acute respiratory distress syndrome, unexpected ventilation). RESULTS: Of 9,171 patients from 447 hospitals in 55 countries, 2,481 were operated on in COVID-19-free surgical pathways. Patients who underwent surgery within COVID-19-free surgical pathways were younger with fewer comorbidities than those in hospitals with no defined pathway but with similar proportions of major surgery. After adjustment, pulmonary complication rates were lower with COVID-19-free surgical pathways (2.2% v 4.9%; adjusted odds ratio [aOR], 0.62; 95% CI, 0.44 to 0.86). This was consistent in sensitivity analyses for low-risk patients (American Society of Anesthesiologists grade 1/2), propensity score-matched models, and patients with negative SARS-CoV-2 preoperative tests. The postoperative SARS-CoV-2 infection rate was also lower in COVID-19-free surgical pathways (2.1% v 3.6%; aOR, 0.53; 95% CI, 0.36 to 0.76). CONCLUSION: Within available resources, dedicated COVID-19-free surgical pathways should be established to provide safe elective cancer surgery during current and before future SARS-CoV-2 outbreaks