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Adult female Agkistrodon bilineatus howardgloydi from Colonia Jobo de la Cruz, Guanacaste, Costa Rica. The color pattern of subadults and adults is paler in females. Photo by Louis W. Porras.
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Several lines of evidence suggest that numerous populations of cantils (Agkistrodon bilineatus, A. taylori), New World pitvipers with a distribution in Mesoamerica, are in rapid decline. We examined the IUCN conservation status for A. bilineatus, assessed for the entire range of the species, as well as the Environmental Vulnerability Scores (EVS) p...
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... Agkistrodon is a genus of vipers anatomically characterized by a vertical elliptical pupil and a large venom gland in the temporal region with a canalicular fang in the mandible Toxins 2024, 16, 142 4 of 30 region, followed by a series of smaller fangs [12,13]. The skull is relatively large and has short tusks [12,13]. ...
... Agkistrodon is a genus of vipers anatomically characterized by a vertical elliptical pupil and a large venom gland in the temporal region with a canalicular fang in the mandible Toxins 2024, 16, 142 4 of 30 region, followed by a series of smaller fangs [12,13]. The skull is relatively large and has short tusks [12,13]. The tail can be of moderate to long size, and newborns and juveniles of all species of this genus have a colored tail tip (yellow, white, or pink), turning to faded green, gray, and black when these animals become adults [12,13]. ...
... The skull is relatively large and has short tusks [12,13]. The tail can be of moderate to long size, and newborns and juveniles of all species of this genus have a colored tail tip (yellow, white, or pink), turning to faded green, gray, and black when these animals become adults [12,13]. These snakes usually attract their prey with their tails, simulating movements resembling waving (called caudal attraction) [13]. ...
Central America is home to one of the most abundant herpetofauna in the Americas, occupying only 7% of the continent's total area. Vipers and lizards are among the most relevant venomous animals in medical practice due to the consequences of envenomation from the bite of these animals. A great diversity of biomolecules with immense therapeutic and biotechnological value is contained in their venom. This paper describes the prominent leading representatives of the family Viperidae, emphasizing their morphology, distribution, habitat, feeding, and venom composition, as well as the biotechnological application of some isolated components from the venom of the animals from these families, focusing on molecules with potential anti-thrombotic action. We present the leading protein families that interfere with blood clotting, platelet activity, or the endothelium pro-thrombotic profile. In conclusion, Central America is an endemic region of venomous animals that can provide many molecules for biotechnological applications.
... Species of the genus Agkistrodon are typically categorized as dietary generalists. Although the food habits of North American species such as A. contortrix and A. piscivorus have received considerable research attention (reviewed in Gloyd and Conant 1990), less is known about the diets of the species commonly known as cantils, which includes A. bilineatus, A. howardgloydi, A. taylori, and A. russeolus, found in Mexico and Central America (Gloyd and Conant 1990;Solórzano et al. 1999;Porras et al. 2013). ...
... Yucatecan Cantils (Agkistrodon russeolus Gloyd 1972 [Serpentes: Viperidae], or Wolpoch, the Mayan name), are medium-sized (total length up to 1050 mm), relatively uncommon pitviper snakes, endemic to the Yucatá n Peninsula (YP; Porras et al. 2013). The species is represented apparently by disjunct populations, with most known records from the dry northern portion of the YP and few records from relatively moist areas in the southern and northeastern portions (Gloyd and Conant 1990;Lee 1996;Rautsaw et al. 2022). ...
... The species is represented apparently by disjunct populations, with most known records from the dry northern portion of the YP and few records from relatively moist areas in the southern and northeastern portions (Gloyd and Conant 1990;Lee 1996;Rautsaw et al. 2022). In the most recent reassessment of the conservation status of the cantils, Porras et al. (2013) classified A. russeolus as an endangered species applying International Union for Conservation of Nature criteria and placed it in the high vulnerability category to extinction according to the environmental vulnerability score index. The authors assigned these conservation categories to A. russeolus primarily due to its limited geographic distribution, the considerable growth of the human population density in its range (that leads to the destruction of natural habitats), and the direct human persecution of this snake species (that leads to killing on sight; Porras et al. 2013). ...
Detailed studies on the natural history of snakes are essential for ecological hypothesis-driven research and effective conservation. Herein, we studied the diet composition and morphology of Yucatecan Cantils (Agkistrodon russeolus Gloyd 1972 [Serpentes: Viperidae]), an understudied viperid species endemic to the Yucatán Peninsula. We collected data from live free-ranging snakes; freshly road-killed snakes and snakes deliberately killed by local villagers; and museum specimens and literature sources. We compared their age classes, sexes, and color morphs. Data came from snakes from Yucatán, Quintana Roo, and Campeche in Mexico, and two records were from northern Belize, comprising most of the species' distribution range. Examination of 76 individuals resulted in 77 prey items from 68 snakes. Results indicated that A. russeolus is a generalist-opportunistic predator that feeds on a wide variety of vertebrates, but primarily on lizards and small mammals and less frequently on birds, snakes, and anurans. Geographic patterns in the diet and morphology of A. russeolus were evident: snakes from the coastal region were smaller in body size and less heavy bodied and with a heavily lizard-based diet, whereas snakes from both dry and moist forest regions were larger and heavier and their diet was primarily mammal based. We did not detect differences in diet composition among age classes because lizards and mammals were eaten at all stages of life, but an “ontogenetic telescope” was evident; that is, the importance of mammals increases with snake body size and the spectrum of prey types consumed also broadens. Males had longer tails than females, and females were light colored more often than males, but other morphological characteristics were similar between the sexes. The sexes and color morphs did not differ in diet composition. We did not detect dietary composition variations between seasons, and our data indicate that this species can feed year-round opportunistically. Because of increasing environmental pressures within its range, studies are urgently needed to elucidate other critical aspects of the ecology of this viperid species.
... The EVS system was later applied to the amphibians and reptiles of Mexico by Wilson et al. (2013). It was further modified by Porras et al. (2013) to better apply to animals outside of Honduras. Grünwald et al. (2015) applied the EVS system as modified by Porras et al. (2013) and defined Biogeographical Formations specific to reptiles and amphibians for the country of Mexico. ...
... It was further modified by Porras et al. (2013) to better apply to animals outside of Honduras. Grünwald et al. (2015) applied the EVS system as modified by Porras et al. (2013) and defined Biogeographical Formations specific to reptiles and amphibians for the country of Mexico. These more-inclusive Biogeographical Formations replaced the "Forest Formations" initially outlined by Wilson and McCranie (1992) in their application to Honduras. ...
... These more-inclusive Biogeographical Formations replaced the "Forest Formations" initially outlined by Wilson and McCranie (1992) in their application to Honduras. Herein we apply the EVS system as outlined by Porras et al. (2013) and Grünwald et al. (2015) to the Tropidodipsas fasciata species group as defined above. ...
We describe two new species of Tropidodipsas related to the T. fasciata species group as defined by Kofron (1987), and provide morphological and molecular data to support the novelty of both species. A partial molecular phylogeny of the Mexican species of snail-eating snakes (Serpentes, Dipsadidae) is presented, and we discuss evolutionary relationships as supported by our molecular results. We analyze specific relationships of the new species described herein with their closest relatives. We present a distribution map for all species of Tropidodipsas and include photographs of living individuals of each species. Finally, we discuss other taxonomic changes based on our molecular phylogeny as well as conservation priorities of the new species.
... Our taxonomic positions follow those discussed in Johnson et al. (2010), Porras et al. (2013), and expanded upon by Johnson et al. (2015b), which are predicated on modern phylogenetic principles. We regard species as separate evolutionary lineages and consider them the lowest evolutionary lineage segment placed on a phylogeny in a formal phylogenetically based taxonomy. ...
Among the principal causes producing detrimental effects on global biodiversity are introductions of alien species. Very few attempts to control introduced amphibians and reptiles in Middle America (Mexico and Central America) can be identified, so listings are provided for 24 exotic species, 16 translocated species, and 11 species that were removed from the introduced species listing because of lack of substantiating evidence that they are from established populations. Biosecurity methods are also identified that can be applied for preventing, controlling, and managing introduced and especially invasive species.
... simus) and C. durissus represents the populations from South America. This distribution pattern of the different lineages in the northern and southern clades is very similar to that of other reptiles that inhabit the tropical deciduous forest in Mexico and Central America, including pitvipers from the same region, such as species of the genus Agkistrodon and Porthidium (Bryson et al. 2008;Porras et al. 2013;Zarza et al. 2019). Crotalus mictlantecuhtli is allopatric, but distributes near to C. ehecatl and C. tzabcan ranges, but without confirmed sympatry. ...
Members of the Crotalus durissus species complex are widely distributed from Mexico to Argentina in areas with mainly
seasonally dry tropical deciduous forest. Although four species (C. culminatus, C. durissus, C. simus and C. tzabcan) are
currently recognized, species limits remain to be tested. Previous genetic studies suggest that C. durissus and C. simus
may be paraphyletic and that at least one cryptic species may be present. We analyzed 2596 bp of DNA sequence data
from three mitochondrial and one nuclear gene to infer phylogenetic relationships in the Neotropical rattlesnakes. We
also examined museum and wild specimens as well as captive animals to analyze morphological characters. Our results
suggest that current taxonomy of the Crotalus durissus species complex does not reflect evolutionary history. We found
strong support for five independent lineages within Crotalus simus (sensu lato), with genetic and morphological evidence
for three previously recognized taxa and two new species, as well as three major lineages within C. durissus that each
represent species hypothesis to be tested with additional evidence. We also found support to retain C. totonacus in the
Crotalus molossus species complex. We suggest conservative taxonomic changes to the complex and related species, but
more evidence is needed (e.g., morphology, ecology and venom composition) to clarify relationships among species.
... Campbell and Lamar, in 2004, reported 4 species in the genus: A. bilineatus (3 subspecies), A. contortrix (5 subspecies), A. piscivorus (3 subspecies) and A. taylori. Later, in 2013, Porras and collaborators elevated the subspecies of Agkistrodon bilineatus to species level: A. bilineatus, A. russeolus and A. howardgloydi, leaving the genus with six species distributed in North and Central America ( Fig. 1) (Campbell and Lamar, 2004;Porras et al., 2013). The equine hyperimmunization protocols described in the present study were performed in 2014, and therefore this classification is used throughout the work. ...
In the present work, venoms from five species of the genus Agkistrodon were evaluated in terms of their enzymatic (Phospholipase A2 and caseinolytic) and biological (edema forming, hemorrhagic, procoagulant and lethal) effects. Horses were used to produce monovalent hyperimmune sera against each of three venoms (A. bilineatus, A. contortrix and A. piscivorus) and their neutralizing potency, expressed as Median Effective Dose (ED50), was determined against the venoms of all five species. In terms of PLA2 and caseinolytic activities, all venoms are extremely homogeneous. PLA2 activity is high, while caseinolytic activity is low when in contrast with that of the rattlesnake Crotalus simus. On the other hand, biological activities showed marked interspecific differences, particularly between the species from Mexico and those from the United States. Mexican species displayed higher edema-forming, hemorrhagic and lethal effects than US species, while none of the species studied presented procoagulant activity. All three monovalent hyperimmune sera showed good neutralizing potency against the analyzed venoms. Nonetheless, we observed relevant immunochemical differences among the venoms using ELISA and Western Blot assays. We conclude that the venoms of A. piscivorus (USA) and A. bilineatus would be ideal to use as immunogens for the production of a polyvalent antivenom with good neutralizing potency against the venoms of all the species of the genus. Keywords: Agkistrodon venoms, Antivenom neutralization, Edema, Hemorrhage, Immunochemistry
... Interestingly however, only 1 species is recognized on The Reptile Database website (accessed 5 July 2013). At present, we consider A. sapperi to be the valid name for the northern population by adhering to the evolutionary species concepts as discussed by Porras et al. (2013). Amastridium sapperi has an allopatric Research note New state record for the snake Amastridium sapperi (Squamata: Dipsadidae) from Hidalgo, Mexico distribution and discernible taxonomic characters, and thus is considered a separate evolutionary lineage. ...
... Esta última ocasiona la mayoría de los accidentes en las regiones húmedas tropicales de México, en América Central y el norte de Sudamérica, ya que es una especie bastante irritable e impredecible que puede alcanzar los 250 cm 12,13 . Otra especie venenosa, de importancia médica, que ocurre en el estado es el cantil yucateco -Agkistrodon russeolus 14 -, ya que aunque es de menor tamaño que las anteriores, es relativamente común y de acuerdo con diversos autores también tiene un temperamento irritable 10 . ...
El objetivo de este estudio fue evaluar los patrones geográficos y temporales del ofidismo en el estado de Yucatán, ya que a la fecha no existe información publicada al respecto. Se obtuvieron todos los casos de accidentes ofídicos en la región para el período 2003-2012 a partir del Programa de Zoonosis de los Servicios de Salud de Yucatán. Se contabilizaron un total de 821 casos y una incidencia de 41.9 accidentes por cada 100,000 habitantes. Anualmente, el promedio de casos e incidencia fue de 82.1 y 4.1 (accidentes/100,000 habitantes), respectivamente. El mayor número de mordeduras por serpiente se produjo en 2005, mientras que en 2003 se registró la menor cantidad. Geográficamente, se observó un gran contraste en el número de accidentes ofídicos entre los municipios, algunos de ellos alcanzando niveles sumamente altos de incidencia. Esta variación geográfica puede ser consecuencia de factores como la distribución y abundancia de las serpientes venenosas por un lado, y aspectos como la densidad poblacional y las actividades laborales de las comunidades humanas por otro. Este estudio ayudará a las autoridades y dependencias de salud a conocer preliminarmente la magnitud del ofidismo en el estado de Yucatán y desarrollar mejores estrategias para mitigarlo.
... iucn.org) as well as provided each terrestrial species with an Environmental Vulnerability Score (EVS). Under the IUCN categorizations, all Nicaraguan snake species are considered as of Least Concern except for two species considered as Data Deficient, four as Vulnerable, and eight as Near Threatened (including Agkistrodon, now considered its Nicaraguan populations, A. howardgloydi, as an Endangered species [Porras et al. 2013]). The Environmental Vulnerability Score is a value that can indicate the potential vulnerability of each species in the country to environmental damage and is calculated with the use of three components: the extent of geographical range, the extent of ecological distribution in Nicaragua, and the degree of human prosecution (Wilson and McCranie 2003). ...
We report new localities in Nicaragua for thirteen poorly known snake species that were collected for the second (Dipsas articulata and Ungaliophis panamensis), third (Coniophanes bipunctatus, Lachesis stenophrys, Sibon annulatus, Sibon dimidiatus, Tantilla reticulata, and Tropidodipsas sartorii), fourth (Atropoides mexicanus, Enuliophis sclateri, Imantodes inornatus, and Nothopsis rugosus), and fifth (Corallus annulatus) times in the country. We also provide distributional range extensions for all viper species known to occur in Nicaragua (Agkistrodon howardgloydi, Atropoides mexicanus, Bothriechis schlegelii, Bothrops asper, Crotalus simus, Lachesis stenophrys, Porthidium nasutum, and Porthidium ophryomegas), one coral snake (Micrurus alleni), and four mildly venomous snakes (Conophis lineatus, Leptodrymus pulcherrimus, Leptophis ahaetulla, and Xenodon rabdocephalus), and the first records for four snake species (Imantodes gemmistratus, Lachesis stenophrys, Pseudoelaphe flavirufa, and Tantilla armillata) from within the Nicaraguan national protected areas system.
... Interestingly however, only 1 species is recognized on The Reptile Database website (accessed 5 July 2013). At present, we consider A. sapperi to be the valid name for the northern population by adhering to the evolutionary species concepts as discussed by Porras et al. (2013). Amastridium sapperi has an allopatric Research note New state record for the snake Amastridium sapperi (Squamata: Dipsadidae) from Hidalgo, Mexico distribution and discernible taxonomic characters, and thus is considered a separate evolutionary lineage. ...
The dipsadid snake Amastridium sapperi is reported for the first time from the state of Hidalgo, Mexico. The single male specimen was found in a shaded coffee grove, which agrees well with the habitat preference shown by other male specimens reported from Mexico. This snake is broadly distributed, but rarely encountered and was not evaluated by either the Semarnat or IUCN systems of conservation assessment, although it has been evaluated using the EVS measure. Also included are details of body length, scutellation, dentition, coloration, testicular development, diet, habitat, and conservation status.
