– THOMPSON M,
Genus Lachesis
Lachesis muta
Homoeopathic name and abbreviation: Lachesis muta; Lach.
Distribution: Central and South America
Synonyms: Lachesis mutus, Trigonocephalus, Bothrops, Crotalus mutus.
Common names: Surukuku, Churukuku, bushmaster.
Description: The lachesis or bushmaster inhabits the hot countries of South America; it attains a length of upwards of seven feet, and its poison fangs are nearly one inch long; the skin is reddish brown, marked along the back with large rhomboidal spots of blackish brown colour, each of which encloses two spots of the colour of the body. The poison resembles saliva, is less viscous, limpid, odourless, without any marked taste, in colour somewhat greenish at the extremity of the fang; it easily forms into drops, and falls without threading; exposed to the air it soon concentrates into a dry, yellow mass, which for an indefinite time preserves its poisonous qualities. Linnaeus named it Crotalus mutus, the deaf rattlesnake. Lachesis are egg layers which is unusual in pit vipers.
Range: Amazonian South America, Guiana shield, Atlantic rainforests of southeastern Brazil, interandean valley of Columbia, northwestern Ecuador, Pacific coastal Columbia, Rainforest zones of Panama, Costa Rica and Southcentral Nicaragua.
Venom: This poison introduced into wound, or injected into vein, produced the most dreadful symptoms, and generally death. Lachesis venom is much less potent than that of Bothrops but it is the amount of venom that they produce.
Authority: Linnaeus, 1766.
History and authority: Introduced and proved by Dr. Hering in 1828. Allen’s Encyclop. Mat. Med. Vol. V, 432.
Comments:
The genus Lachesis (family Viperidae) contains a single species, L. muta, which is disjunctly in parts of lower Central America and northern South America. This gigantic snake is the largest species of New World venomous snakes and is the longest viper in the world. It is unique among New World vipers in that it lays eggs rather than giving birth to live young.
A total of 25 cases of human envenomation by Lachesis has been reported. In a Costa Rican study, 3 of 4 reported cases of bites by L. m. stenophrys were fatal; the forth victim sustained a severe upper extremity contracture. All were treated in medical facilities and given antivenin. Death occurred on the third to fifth day and resulted from shock secondary to massive swelling, suppuration of tissues, and overwhelming infection. Major organ haemorrhage was not a problem. In 1985 another envenomation by this subspecies occurred in Costa Rica and proved fatal despite hospital treatment and antivenin administration.
Two cases of envenomation by L. m. muta have been reported in detail from Leticia, Colombia; they were characterised by pain, marked swelling of the extremity, early hypotension (shock), bradycardia, and abdominal cramps with diarrhea. Both victims were treated with Instituto Butantn antivenin (Bothrops-Crotalus), and recovery was uneventful.
HABITAT This snake occurs in tropical rainforests and lower montane wet forests that receive more than 2,000mm, and usually more than 4,000mm, of rainfall per annum, In a few regions (Nicaragua and Ilanos of Colombia) it apparently enters tropical dry forests (or seasonally dry forests) in riparian situations. Lachesis is an inhabitant of primary forest, often living near large buttressed trees (Ceiba, Swietenia, etc.) or adjacent to fallen trees. Upon occasion it may be encountered in secondary forest situations but in areas recently cleared or adjacent to virgin forest.
DESCRIPTION This terrestrial snake is the longest of all vipers, commonly exceeding 2,000mm in total length, with exceptional specimens reportedly reaching or exceeding 3,600mm. There is an unsubstantiated report of a specimen 4,267mm in total length.
REMARKS our subspecies have been described for L. muta: L. stenophrys (Figs. 252, 253, 257-59) from the Atlantic lowlands of Costa Rica and Panama, crossing over to the Pacific in central Panama; L. m. melanocephala (Fig. 250) from the Pacific lowlands of south eastern Costa Rica; L. m. muta (Fig. 249) from the equatorial forests of Colombia, Venezuela, Trinidad, Guyana, Suriname, French Guiana, Brazil, Ecuador, Peru, and Bolivia; and L. m. rhombeata (Fig. 251) from the Atlantic forests of east-central Brazil (erroneously reported from Bolivia).
These snakes are crepuscular and nocturnal. It is our experience that the aggressiveness of this species has been exaggerated greatly. Most Lachesis specimens we have encountered in the field, or have reliable reports of, have been rather unaggressive. However, specimens found active after dark may be quick to strike and display a formidable defence posture, including neck inflation and audible tail vibration. Snakes from the Pacific lowlands of Costa Rica are atypical in usually being highly aggressive anytime they are disturbed

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