Clark's coral snake
Micrurus clarki

MICRURUS CLARI-E.png

Venom of the species of the genus Micrurus are potentially dangerous to humans; its composition is predominantly neurotoxic, causing mild to absent local symptoms and significant systemic manifestations [1,2,3]. Currently, there is no published information about specific envenomation symptoms associated with bites of Micrurus clarki, however, such symptoms are probably similar to those recorded for other species of the genus Micrurus. Possibly the neurotoxins present in the venom of M. clarki belong to others already recognized in better studied species of coral snakes [2,4,5].

A person who has been bitten by a coral snake may experience symptoms as early as the first hour after the bite and they may increase in severity over the next 48 hours [4]. In mild cases, the symptoms experienced by the affected person will include loss of sensitivity and numbness or paraesthesia (tingling sensation) on the bitten area. In some cases, the bitten person exhibits no symptoms [6]. Systemic neurological symptoms appear in moderate and severe cases of envenomation depending on the amount of venom inoculated, and other factors specific to the affected person or the context of the bite [6]. In severe cases, neurological signs begin with double vision and droping of the eyelids (palpebral ptosis) and difficulty controlling the muscles associated with the oral region and esophagus (dysarthria and dysphagia, respectively) [4]. The action of coral snake venoms produces musculoskeletal paralysis, affecting the muscles involved in breathing. In severe cases, medical treatment may include management with mechanical ventilation [4].

There is no specific treatment for M. clarki envenomation. However, envenomation caused by this species can be treated with commercially available antidotes, which can cross neutralize and act against M. clarki toxins. The bite of this species should be considered dangerous, because the risk of respiratory insufficiency in the envenomation by a coral snake is very high [4]. Therefore, the elapsed time for applying appropriate medical treatment plays an important role in the survival of the patient. Applying non-medical treatments such as punctures, sucking, tourniquets, herbal poultices, potions, or prayers performed by the community should be avoided [6]. The Sutherland method for elapid snakebite first-aid, suggests that the application of a firm crepe bandage with immobilization of the limb may reduce the dispersal of the venom [7], but in any case, it is important to go as soon as possible to a medical center.

The severity of an envenomation must be determined within the first 12 hours after the bite, into mild, moderate, or severe, according to symptoms exhibited by the bitten person [8]. The amount of antivenom to be administered will depend on the severity of the envenoming and the procedure should only be performed by physicians once the case has been confirmed [8].

Preclinical studies performed with the venom of M. clarki injected into mice have demonstrated that the SAC-ICP (antivenom produced by the Instituto Clodomiro Picado de Costa Rica; Spanish acronym) obtained by immunization with Micrurus nigrocinctus nigrocinctus venom, could efficiently neutralize the toxicity of M. clarki [9]. In fact, the SAC-ICP also has been effective for neutralizing the venom of M. dumerilii from Colombian populations [10]. It is important to note that a new study restricts M. nigrocinctus to the southern part of its distribution [11]; therefore, it is necessary to establish whether individuals used for immunization experiments mentioned above [9] are M. n. nigrocinctus or M. mosquitensis [11].

Information about bites and venom of M. clarki is scarce [4,9,12]. In Colombia and Costa Rica, only two human fatalities have been recorded involving M. clarki envenoming [4]. In general, species of the genus Micrurus are considered dangerous and lethal to humans [2,3,11]. Coralsnakes have high diversity and are widely distributed, increasing the probability of a snakebite [4,9]. However, species of Micrurus are usually docile, and they tend to flee when they feel threatened [13,14]. Coralsnakes usually display deterrent behaviors, so bites are generally caused by direct and improper handling. In addition, their fangs are small (order of millimeters), and their buccal aperture is narrow (about an angle of 30°) making thicker clothes, split leather gloves and boots difficult to penetrate [12,15].

clarki is a coralsnake of moderate body size, exhibiting a relatively thin to robust and cylindrical body, with a differentiated head from the neck. It can be distinguished by having a tricolored pattern of red, black, and yellow rings, with a black head cap extending from snout to the posterior tips of the parietal scales, followed by a white nuchal band that does not reach the parietal scales and a black ring encompassing three to six dorsal scales in length (shorter ventrally). The dorsal surfaces exhibit 13–20 black rings along the body, encompassing two to three scales in length (both dorsal and ventral). On the tail, there are five to nine black rings separated by yellow rings. The males and females of M. clarki differ in the number of black tail rings, which are six to nine in males and five to six in females [4,16].

Micrurus multiscutatus, M. multifasciatus and M. mipartitus inhabit the natural geographic range of M. clarki, but they are easily distinguishable by presenting a bicolor ring pattern. M. clarki is different from M. oligoanellatus, because this coralsnake has no black ring on the neck [17]. In Panamá and Colombia, M. clarki is sympatric with M. dumerilii [4]. M. dumerilii has a triadal or monadal pattern (according its geographic distribution) of red, black, and white rings on the body and a bicolored pattern of black and white rings on the tail; while M. clarki, as mentioned above, has a monadal pattern on the body and bicolored pattern on tail, with yellow color rings instead of white rings [17, 18]. In general, adult individuals of M. clarki are larger in body size than sympatric species of the same genus [4]. M. nigrocinctus is another species of coralsnake that could be confused with M. clarki; however, M. nigrocinctus has a black cap that barely reaches the parietals, while in M. clarki the black cap completely covers the parietals [4].

clarki is distributed in Central Pacific Costa Rica, in the lowlands of Western Panamá to Pacific Darién, and in the western and Atlantic region of Colombia [4,12]. In Colombia, records of this species are from the municipalities of Istmina (Andagoya), Río Sucio (Urabá) and the municipality of Condoto, Chocó department [1,4,19]. In addition, it has been registered in the municipality of Guapi in the department of Cauca and in the municipality of Dagua in the department of Valle del Cauca between 0–900 m asl.

Analyses of the potential distribution of M. clarki proposed that the distribution of this species in Colombia covers an area of approximately 188.102 km2, ranging from North of Santander (7°57'40"N, 72°41'0"W) to Nariño (77°21'28"W) [19]. However, the presence of M. clarki in some of the localities proposed in this study must be confirmed, because suitable habitat suggested by niche modeling does not mean that the species is present there. For example, we are not aware of confirmed records of M clarki in northern Santander (Figure 1).

Figure 1. Geographic distribution of Micrurus clarki in Colombia and its habitat suitability model. Based on bioclimatic variables, the habitat suitability model predicts the species' potential distribution in Colombia, identifying zones with suitable or unsuitable environmental conditions for its occurrence across the country. Values close to 1 indicate optimal environmental conditions (high probability of presence), while values close to 0 indicate unsuitable conditions (absence likely).

Uncommon. M. clarki is considered an uncommon species [4]. This coralsnake is primarily nocturnal and terrestrial, inhabiting tropical rainforests; but it is also found in tropical dry forests and in moist riparian forests [1,4,12]. This snake feeds on the marbled swamp eel (Synbranchus marmoratus), however, its diet is poorly known and dietary items only have been recorded for individuals from populations in Costa Rica [9,20]. Micrurus clarki is an oviparous snake [17], but clutch size is unknown. To date, there are no records on of the natural history of Colombian populations.

clarki is a nocturnal species, but it can be active during the day on the floor of dense and well-preserved forests. Therefore, encounters between humans and this snake are uncommon [1,4,12].

Least Concern. According to the IUCN, M. clarki is under the category of Least Concern, because it has a wide geographical distribution including pristine and disturbed habitats, and there are no known threats to its conservation [21]. However, there is insufficient knowledge regarding their threats and population status that in the future could be reflected in changes in their threat category. It is not registered with CITES [21], nor in the Resolution 1912 of 2017 of the Colombian Environmental Ministry [22].

The name Micrurus comes from the Greek word mikros that refers to “small”, and the specific epithet clarki, was assigned in honor of doctor H.C. Clark, who is considered a pioneer in tropical medicine and who collected the holotype specimen [9]. Micrurus clarki is commonly known as Clark's coral snake (serpiente coral de Clark, in Spanish) and Clarks Korallenotter. In addition, it is usually called coral, coralilla, coral macho, gargantilla [4].

Table 1. Summary of important biological, venomic, epidemiological and medical traits.

★★
Toxicity and biological activity			Venom activity profile		General biological traits
LD50 (μg/mice):	15.3 (7.1–23.5 µg)	Proteolytic: Unknown		Total Length (cm): ♂♀ 50 (38-92)
MCD (μg/mL):	Unknown	Neurotoxic: Yes		Weight (g): Unknown
MDD (μg/mice):	Unknown	Myotoxic: Yes		Reproduction: oviparous
MED (μg/mice):	Unknown	Hemotoxic: Unknown		Diet: Snakes, caecilians, eels (Synbranchus marmoratus)
MHD (μg/mice):	Unknown			Distribution: Pacific mainland
Proteome
PLA2: 36.5%	SVSP: 1.0%	SVMP: 1.6%		NGF: No
CRISP: No	CTL: No	DIS: No		KUN: 0.9%
BPPs: No	VEFG: No	3FTx: 48.2%
Crotoxin: No	Crotamine: No	LAAO: No
Main envenomation symptoms		Grade of envenomation		Risk
Hemorrhage: No	Ecchymosis: Yes	Mild: Unknown		Bites per year: Unknown
Nausea: Yes	Hematemesis: No	Moderate: Unknown		Bites per 1,000 people yearly: Unknown
Hypotension: No	Blisters: No	Severe: Unknown		Sequalae caused per year: Unknown
Edema: Yes	Vomiting: Yes			Deaths caused per year: Unknown
Coagulopathy: No	Diarrhea: No
Sialorrhea: Yes	Local Pain: Yes
Hematuria: No	Necrosis: No
Renal failure: No

★★: Moderate reliable: Confidence for this species is limited or almost non-existent for Colombian populations. Therefore, most of our knowledge comes from populations outside the national territory LD50: median lethal dose; MCD: minimum coagulant dose; MDD: minimum defibrinating dose; DEM: minimum edema-forming dose; DHM: minimum hemolytic dose; PLA2: phospholipases A2; SVSP: serine proteases, SVMP: metalloproteinases; NGF: nerve growth factor; CRISP: cysteine-rich secretory protein; CTL: C-type lectin/lectin-like, DIS: disintegrins, KUN: Kunitz peptides; BPPs: bradykinin-potentiating peptides; VEFG: vascular endothelial growth factor; 3FTx: three-finger toxins; LAAO: L-amino acid oxidases.

Contenido

Castaño-Mora, O.; Cárdenas-A, G.; Hernández-R, E.; Castro-H, F. Reptiles en el Chocó biogeográfico. In Diversidad biótica IV, Rangel-CH. J.O., Eds.; Instituto de Ciencias Naturales, Universidad Nacional de Colombia: Bogotá, Colombia 2004; pp. 599-632.
Tanaka, G.; Furtado, Md.F.; Portaro, F.C.V.; Sant'Anna, OA.; Tambourgi, DV. Diversity of Micrurus snake species related to their venom toxic effects and the prospective of antivenom neutralization. PLoS Negl Trop Dis 2010, 4,e622.
Gopalakrishnakone, P.; Inagaki, H.; Mukherjee, A.K.; Rahmy, T.R.; Vogel, C.W. Snake venoms.; Springer: Berlin, Germany, 2017; p. 466.
Campbell, J.A.; Lamar, W. The venomous reptiles of the western hemisphere (Vol. 1).; Comstock Publishing: New York , 2004; ISBN 978-0801441417,
da Silva Jr, N.J. As cobras-corais do Brasil: biologia, taxonomia, venenos e envenenamentos; PUC – Goiás, Estado de Goiás; 2016; pp. 415.
Castillo-Beltrán, M.C., Hurtado-Gómez, J. P., Corredor-Espinel, V., & Ruiz-Gómez, F. J. A polyvalent coral snake antivenom with broad neutralization capacity. PLoS neglected tropical diseases, 2019 13,https://doi.org/10.1371/journal.pntd.0007250.
Sutherland, S.K.; Coulter, A.R.; Harris, R.D. Rationalisation of first-aid measures for elapid snakebite. Wilderness & environmental medicine, 2005 16, 164-167.
Rodríguez Vargas, A. Accidente Ofídico. In: Guía para el manejo de emergencias toxicológicas; Ministerio de Salud, Bogotá, 2017, pp. 499-507
Lomonte, B.; Sasa, M.; Rey-Suárez, P.; Bryan, W.; Gutiérrez, J.M. Venom of the coral snake Micrurus clarki: Proteomic profile, toxicity, immunological cross-neutralization, and characterization of a three-finger toxin. Toxins 2016, 8,138.
Rey-Suárez, P.; Lomonte, B. Immunological cross-recognition and neutralization studies of Micrurus mipartitus and Micrurus dumerilii venoms by two therapeutic equine antivenoms. Biologicals 2020, 68,40-45.
Jowers, M.J.; Smart, U.; Sánchez-Ramírez, S.; Murphy, J.C.; Gómez, A.; Bosque, R.J.; Sarker, G.C.; Noonan, B.P.; Faria, J.F.; Harris, D.J.; da Silva Jr, N.J.; Prudente, AL.; Weber, J.; Kok, P.J.R.; Rivas, A.G.; Jadin, R.C.; Sasa, M.; Muñoz-Mérida, A.; Moreno-Rueda, G.; Smith, E.N. Unveiling underestimated species diversity within the Central American Coralsnake, a medically important complex of venomous taxa. Scientific Reports, 2023, 13, 11674.
Roze, J.A. Description of species and subspecies, with keys to the subspecies. In Coral snakes of the Americas: Biology, identification, and venoms, Roze, J.A., Eds.; Krieger Publishing Company: New York, 1996; ISBN 978-0894648472.
Acuña, K.S. Aspectos biomédicos del accidente ofídico. Universitas médica 2012, 53,68–82.
Lynch, J.D.; Angarita-Sierra, T.; Ruiz, F.J. Programa nacional para la conservación de las serpientes presentes en Colombia; 2014; ISBN 9789588901183.
Peterson, M.E. Snake bite: Coral snakes. Clinical techniques in small animal practice 2006, 21, 183–186.
Schmidt, K.P. Notes on Central American and Mexican coral snakes. Field Museum of Natural History, Zoological 1936, 20,205–216.
Uetz P, Koo, M.S.; Aguilar, R.; Brings, E.; Catenazzi, A.; Chang, A.T.; Chaitanya, R.; Freed, P.; Gross, J.; Hammermann, M.; Hosek, J.; Lambert, M.; Sergi, Z.; Spencer, C.L.; Summers, K.; Tarvin, R.; Vredenburg, V.T.; Wake, D.B. A Quarter century of reptile and amphibian databases. Herpetological Review, 2021, 52: 246–255.
Leenders, T. Reptiles of Costa Rica: A field guide (Zona Tropical Publications). Comstock Publishing Associates: United Stater, 2019; ISBN: 1501739530.
Pitalua-L, Y.; Rengifo-M, J.T.; Rivas- A, L. Aportes a la distribución del género Micrurus (Serpentes: Elapidae) en el departamento del Chocó, Colombia. Rev. Colombiana Cienc. Anim. 2018, 10, 131–142.
IUCN.URL: https://www.iucnredlist.org: (7 enero 2022)
CITES. Apéndices I, II y III. URL: https://cites.org/esp/app/appendices.php. (27 diciembre 2021).
Minanbiente Resolución 1912 del 15 de septiembre 2017.