Aquatic Snake Blog

A New Species of Helicops from Minas Gerais, Brazil

Helicops nentur. Helicops is a genus of 16 species of Neotropical watersnakes. Using morphological and genetic data, Costa and colleagues (2016) identify a new species of this genus in the most recent issue of Herpeptologica. The new species occurs from southeastern to northern Minas Gerais, Brazil. The new species, Helicops nentur has 17-17-15 dorsal scale rows;… Read more

August 26, 2016
Abstract: Diet, female reproduction and conservation of Jagor’s water snake, Enhydris jagorii in Bung Ka Loh wetland, Uttaradit province, Thailand

Diet, female reproduction and conservation of Jagor’s water snake, Enhydris jagorii in Bung Ka Loh wetland, Uttaradit province, Thailand Chattraphas Pongcharoena, b, Harold K. Vorisc, Tosak Seelanand, Art-Ong Pradatsundarasarb, Kumthorn Thirakhuptb, Jagor’s water snake (Enhydris jagorii) is a freshwater snake that is endemic to the Chao Phraya-Ta Chin basin, Thailand. However, habitat change and destruction are the main… Read more

July 10, 2016
Hydrops caesurus Scrocchi, Ferreira, Giraudo, Avila and Motte 2005

Hydrops caesurus Scrocchi, Ferreira, Giraudo, Avila and Motte 2005. Type locality: Departamento Itapúa, Isla Paloma, Canal de los Jesuitas, Paraguay. Hydrops triangularis bolivianus — Williams and Couturier 1984 Hydrops triangularis — Álvarez and Aguirre 1995 Distribution. Northeast Argentina and Paraguay. The distribution is disjunct from other members of the genus. It inhabits temperate and subtropical latitudes. Type locality: Departamento… Read more

July 10, 2016
Hydrops martii (Wagler, 1824)

Elaps Martii Wagler 1824. Type locality: Provincia Maranhao, Rio Itapicuru, Brazil Hydrops Martii — Wagler 1830: 170 Homalopsis Martii — Schlegel 1837: 356 Hydrops callostictus Günther 1868: 421 Calopisma martii — Jan and Sordelli 1868 Hydrops triangularis martii — Amaral 1930 Hydrops martii — Dowling 2002 Distribution: Distribution: Amazon basin from Colombia and eastern Peru to Maranhao, Brazil. Known from tributaries of Rio… Read more

July 10, 2016
Hydrops triangularis (Wagler, 1824)

Elaps triangularis Wagler 1824: 5. Type locality: Ega (= Tefé) Lago Tefé, at confluence with Rio Amazon, Brazil. Hydrops triangularis – Wagler 1830: 170 Hydrops triangularis bassleri Roze 1957:83 Hydrops triangularis bolivianus Roze 1957:86 Hydrops triangularis fasciatus Roze 1957:76 Hydrops triangularis neglectus Roze 1957:81 Hydrops triangularis venezuelensis Roze 1957:78 Distribution. Amazonas, Orinoco and Guyana drainages includes Bolivia, Venezuela, Guyana, Surinam, French Guiana, Trinidad,… Read more

July 10, 2016
Helicops angulatus (Linnaeus, 1758)

Coluber angulatus Linnaeus 1758: 217. Type locality: “Asia” (in error).Coluber alidras Linnaeus 1758:Coluber Surinamensis Shaw 1802: 460Natrix aspera Wagler 1824: 37Helicops angulatus — Wagler 1830: 171Helicops fumigatus Cope 1868: 308Helicops cyclops Cope 1868: 309Uranops angulatus — Sclater 1891: 45Helicops angulata — Beebe 1946: 28 Distribution, Venezuela (Amazonas, Apure, Bolivar, Monagas, Delta Amacuro, Sucre, Portuguesa, Anzoátegui, Guárico, Cojedes), Colombia, Brazil (Pará, Rondonia, Goias, Mato Grosso, Sergipe,… Read more

July 10, 2016

The most basal Thamnophiine clade recovered by Zaher et al. (2019) included the Liodytes, Clonophis, Haldea, and Virginia genera. These are a mixture of fossorial, terrestrial, and semi-aquatic species. Clonophis exploits an unusual aquatic habitat – crayfish burrows; both Haldea and Virginia are small fossorial species. Liodytes contain some of the most aquatic North American snakes.
The ancestor of North American natricids immigrated from Eurasia sometime before the early Miocene (~19–18 Ma). We know this because the earliest known Western Hemisphere natricid fossils date to the early Miocene, and we know they shared an ancestor because of shared anatomy and DNA.

There are no highly specialized aquatic pythons that converge with the anacondas – the highly aquatic boas. However, some python species are best considered semi-aquatic. The largest pythons (Malayopython reticulatus, Python sebae, Python natalensis, Python bivittatus) use aquatic situations to hunt and thermoregulate. The largest pythons are habitat generalists, but they are also frequently associated with water. The large body size may be possible because of their buoyance in water, making movement more efficient.

The highly aquatic and unique file snakes have loose, baggy skin and minor, rough scales, each with sensory organs. Their short tails are round, prehensile, flat, and sword-like; the eyes and valvular nostrils are dorsally or dorsolateral. Their lack of muscle tone is spectacular and can only be fully appreciated by handling one, a physiological feature restricting them to an entirely aquatic lifestyle. The rough, file-like surface of the skin and its loose folds are used in catching and holding slippery, mucus-covered fish. Their maxillary teeth are similar in size, long, and fluted on the sides and posterior surfaces. The fluted condition is found in many fish-eating snakes.

The two species that compose the genus Farancia are considered some of the most aquatic snakes in North America, but both species are known to wander overland (Steen et al. 2013). Droughts may trigger their movement from a wetland, and excessive rainfall may also trigger their movement. Females will also move overland to nest. Both species take aquatic prey. Semlitsch et al. (1988) have described juvenile emergence in both the Fall and Spring and note that hatchlings may benefit from Fall emergence by feeding before their first winter. However, Fall emergence may present the hatchlings with dried or reduced aquatic habitats, while spring emergence would have abundant habitat and food (larval salamanders).
The members of the genus are known to have maternal attendance of eggs, a highly specific diet of elongated prey, American eels (Anguilla rostrata), and the eel-like salamanders of the genera Siren and Amphiuma.

The largest boas, the highly aquatic anacondas (Eunectes), are relatively well known. The oldest and largest member of the clade (Titanoboa) was aquatic, and today, the most aquatic members of the family are the anacondas of the genus Eunectes.

Anacondas are Neotropical snakes found east of the Andes. Four extant species and one fossil species compose the genus. The clade includes the largest snake, the Green Anaconda, Eunectes murinus, which reaches at least 8 m and has the greatest mass (in females) of any extant snake (250 kg). Eunectes is derived from a Greek word that means “good swimmer.” The aquatic habitats of these snakes are well documented. Pizzatto et al. (2007) found an aquatic habitat to be a synapomorphy for this genus. The large body size, a relatively long tail, and the dorsal positioning of the eyes and nares are all traits associated with life in water.

Aquatic Snake Blog

A New Species of Helicops from Minas Gerais, Brazil

Abstract: Diet, female reproduction and conservation of Jagor’s water snake, Enhydris jagorii in Bung Ka Loh wetland, Uttaradit province, Thailand

Hydrops caesurus Scrocchi, Ferreira, Giraudo, Avila and Motte 2005

Hydrops martii (Wagler, 1824)

Hydrops triangularis (Wagler, 1824)

Helicops angulatus (Linnaeus, 1758)