Published August 4, 2021. Updated May 2, 2024. Open access. | Purchase book ❯ |
Mottled Watersnake (Helicops pastazae)
Reptiles of Ecuador | Serpentes | Colubridae | Helicops pastazae
English common names: Mottled Watersnake, Olive Watersnake, Shreve’s Keelback.
Spanish common name: Culebra acuática moteada, culebra de agua de Pastaza.
Recognition: ♂♂ 66.5 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=41.5 cm. ♀♀ 54.4 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=43.4 cm..1,2 Helicops pastazae can be distinguished from most Amazonian snakes by having dorsally oriented eyes and nostrils, a single internasal scale, round pupils, and keeled dorsal scales arranged in 23–25 rows at mid-body.1,3 The dorsum is grayish brown to tan brown with a series of broad mid-dorsal blotches alternating with smaller lateral blotches (Fig. 1).3 The belly has a chessboard pattern of black marks on a cream background.3 Juveniles usually have an incomplete pale neck band as well as a cream coloration that encompasses the muzzle and the angle of the jaw.3 This species differs from H. petersi by having a higher number of dorsal scale rows, a blunt snout, and a different color pattern.3 In H. pastazae the lateral blotches are distinctly smaller than the mid-dorsal ones. Helicops pastazae differs from H. angulatus, H. hagmanni, Hydrops martii, and H. triangularis by having keeled dorsal scales arranged in 23–25 rows at mid-body, more than 67 subcaudal scales, and a non-banded pattern.1,3
Figure 1: Individuals of Helicops pastazae from Ecuador: Yasuní National Park, Orellana province (); Gareno Lodge, Napo province (). ad=adult, j=juvenile.
Natural history: Helicops pastazae is a semi-aquatic snake that inhabits lentic bodies of water in areas of lowland and foothill rainforest. This species is found in streams, rivers, black water lagoons, and ponds in open as well as forested areas with various degrees of human intervention.4–6 It also occurs in swamps dominated by the palm Mauritia flexuosa.7 Mottled Watersnakes are nocturnal, but can occasionally be active during the daytime.8 They are aquatic and can be found at different depths. When in shallow waters, individuals usually have the body submerged and part of the head above the surface.8 Mottled Watersnakes move not only in water but also on mud and soil close to water bodies.9 During the daytime, individuals have been found hidden under rocks.10 Mottled Watersnakes are sit-and-wait foragers whose only recorded prey items are fish and tadpoles.5,11 It has been hypothesized that these snakes are opportunistic predators, visiting fish nets where they can more easily capture food.12 The typical defense behavior consists of making an S-coil, flattening the body and head dorsoventrally, and striking.10 When manipulated, they rotate the body, bite, and produce cloacal discharges.8,10 This species is oviparous. In Colombia, a clutch of 11 eggs was found buried under sand and decomposing material under a large rock.10 The hatchlings measured 14.9–18.6 cm in total length.10
Conservation: Least Concern Believed to be safe from extinction given current circumstances..7,13,14 Helicops pastazae is listed in this category given its wide distribution, occurrence in protected areas, lack of widespread threats, and tolerance to human-modified environments.7 Mottled Watersnakes inhabiting polluted water bodies are known to bioaccumulate heavy metals such as lead, cadmium, and chromium, but it is unclear how the contamination of their tissues affects their survival.2
Distribution: Helicops pastazae is widely distributed throughout the western Amazon lowlands and adjacent Andean foothills in Colombia, Ecuador (Fig. 2), Peru, and Venezuela. In Colombia and Venezuela, the species has been recorded mostly along the eastern Andean foothills.
Figure 2: Distribution of Helicops pastazae in Ecuador. The star corresponds to the type locality: Río Pastaza. See Appendix 1 for a complete list of the presence localities included in the map.
Etymology: The generic name Helicops, which comes from the Greek words helix (=turned) and ops (=eye),15 refers to the direction of the eyes in this group of snakes, oriented not directly outwards, but obliquely upwards.16,17 The specific epithet pastazae refers to the type locality: Pastaza river.
See it in the wild: Prime locations to find Helicops pastazae in the wild in Ecuador are Yasuní Scientific Station, Tiputini Biodiversity Station, and Mandaripanga Lodge. The snakes are most easily found at night by walking along shallow muddy water bodies having abundant fish.
Special thanks to Taz Waugh for symbolically adopting the Mottled Watersnake and helping bring the Reptiles of Ecuador book project to life.
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Acknowledgments: This account was published with the support of Secretaría Nacional de Educación Superior Ciencia y Tecnología (programa INEDITA; project: Respuestas a la crisis de biodiversidad: la descripción de especies como herramienta de conservación; No 00110378), Programa de las Naciones Unidas (PNUD), and Universidad San Francisco de Quito (USFQ).
Author: Alejandro ArteagaaAffiliation: Khamai Foundation, Quito, Ecuador.
Photographers: Jose VieirabAffiliation: Tropical Herping (TH), Quito, Ecuador.,cAffiliation: ExSitu, Quito, Ecuador. and Alejandro ArteagaaAffiliation: Khamai Foundation, Quito, Ecuador.
How to cite? Arteaga A (2024) Mottled Watersnake (Helicops pastazae). In: Arteaga A, Bustamante L, Vieira J (Eds) Reptiles of Ecuador: Life in the middle of the world. Available from: www.reptilesofecuador.com. DOI: 10.47051/SQDS6134
Literature cited:
- Schöneberg Y, Köhler G (2021) Distribution and identification of the species in the genus Helicops Wagler, 1830 (Serpentes, Colubridae, Xenodontinae). ARPHA Preprints 1: e67869. DOI: 10.3897/arphapreprints.e67869
- Hurtado-Morales MJ, Rodríguez M, Amézquita A (2021) Heavy metal concentration in Neotropical Aquatic Snakes (Helicops pastazae) and its potential as a bioindicator of water pollution. Research Square 1: 1–15. DOI: 10.21203/rs.3.rs-291191/v1
- Rossman DA (1976) Revision of the South American colubrid snakes of the Helicops pastazae complex. Occasional papers of the Museum of Zoology, Louisiana State University 50: 1–15.
- Whitworth A, Beirne C (2011) Reptiles of the Yachana Reserve. Global Vision International, Exeter, 130 pp.
- Almendáriz A, Barriga R, Rivadeneira D (2017) Feeding behavior of Helicops pastazae Shreve 1934 (Serpentes, Colubridae, Dipsadinae) in the Ecuadorian Amazon. Herpetology Notes 10: 449–451.
- Cortes-Ávila L, Toledo JJ (2013) Estudio de la diversidad de serpientes en áreas de bosque perturbado y pastizal en San Vicente del Caguán (Caquetá), Colombia. Actualidades Biológicas 35: 185–197.
- Cisneros-Heredia DF, Ortega A, Rivas G, Calderón M, Muñoz A, Embert D, Aparicio J, Aguayo R (2016) Helicops pastazae. The IUCN Red List of threatened species. Available from: www.iucnredlist.org. DOI: 10.2305/IUCN.UK.2016-1.RLTS.T15179049A15179095.en
- Field notes, Reptiles of Ecuador book project.
- Photo by Luis Silva Villa.
- García-Cobos D, Gómez-Sánchez DA (2019) Reproductive mode and defensive behaviour of the South American aquatic snake Helicops pastazae (Serpentes: Dipsadidae). Herpetology Notes 12: 447–451.
- Muñoz-Saba Y, Calvo-Roa N, Gómez-Sandoval PA, Casallas-Pabón D, Lynch JD, Barrientos LS, Gómez-Sánchez DA (2019) Guía de campo de los mamíferos, anfibios y reptiles de Santa María (Boyacá, Colombia). Serie Guías de Campo del Instituto de Ciencias Naturales, Bogotá, 317 pp.
- Field notes of Ramiro Barriga and Francisco Provenzano.
- Reyes-Puig C (2015) Un método integrativo para evaluar el estado de conservación de las especies y su aplicación a los reptiles del Ecuador. MSc thesis, Pontificia Universidad Católica del Ecuador, 73 pp.
- Morales-Betancourt MA, Lasso CA, Páez VP, Bock BC (2005) Libro rojo de reptiles de Colombia. Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, Bogotá, 257 pp.
- Brown RW (1956) Composition of scientific words. Smithsonian Books, Washington D.C., 882 pp.
- Wagler JG (1830) Natürliches System der Amphibien: mit vorangehender Classification der Säugetiere und Vögel: ein Beitrag zur vergleichenden Zoologie. J.G. Cotta'scchen, München, 354 pp. DOI: 10.5962/bhl.title.58730
- Duméril AMC, Bibron G, Duméril AHA (1854) Erpétologie générale ou Histoire Naturelle complète des Reptiles. Librairie Encyclopédique de Roret, Paris, 780 pp. DOI: 10.5962/bhl.title.45973
Appendix 1: Locality data used to create the distribution map of Helicops pastazae in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used. Asterisk (*) indicates type locality.
| Country | Province | Locality | Source |
| Colombia | Caquetá | Florencia | Rossman 1976 |
| Colombia | Putumayo | Puerto Asís | Rossman 1976 |
| Colombia | Putumayo | Puerto Boy | Rossman 1976 |
| Ecuador | Morona Santiago | Estación Biológica Wisui | Chaparro et al 2011 |
| Ecuador | Morona Santiago | Macuma | Rossman 1976 |
| Ecuador | Morona Santiago | Río Llushin | Rossman 1976 |
| Ecuador | Napo | Gareno Lodge | This work; Fig. 1 |
| Ecuador | Napo | Huaorani Lodge | Reptiles of Ecuador book database |
| Ecuador | Napo | Yachana Reserve | Whitworth & Beirne 2011 |
| Ecuador | Orellana | Campo Shiripuno | Photo by Néstor Acosta |
| Ecuador | Orellana | Descanso | iNaturalist; photo examined |
| Ecuador | Orellana | El Coca | Diego Piñán, pers. comm. |
| Ecuador | Orellana | Estación Experimental de la Amazonía | Photo by Paul Szekely |
| Ecuador | Orellana | Guiyero | Reptiles of Ecuador book database |
| Ecuador | Orellana | Mandaripanga Lodge | Reptiles of Ecuador book database |
| Ecuador | Orellana | Nuevo Rocafuerte | Torres-Carvajal et al. 2019 |
| Ecuador | Orellana | Río Higinio | Photo by Kary Hernández |
| Ecuador | Orellana | Río Rosa | Pazmiño-Otamendi & Rodríguez-Guerra 2022 |
| Ecuador | Orellana | Tiputini Biodiversity Station | iNaturalist; photo examined |
| Ecuador | Orellana | Tiputini River | Almendáriz et al. 2017 |
| Ecuador | Orellana | Waorani lagoon | Almendáriz et al. 2017 |
| Ecuador | Orellana | Yarina Lodge | Reptiles of Ecuador book database |
| Ecuador | Orellana | Yasuní Scientific Station | This work; Fig. 1 |
| Ecuador | Pastaza | Andoas | AMNH 49094; VertNet |
| Ecuador | Pastaza | Bloque 10-Agip Oil | Torres-Carvajal et al. 2019 |
| Ecuador | Pastaza | Cabeceras del Río Bobonaza | Rossman 1976 |
| Ecuador | Pastaza | Cabeceras del Río Bobonaza, 2 km downstream from | Rossman 1976 |
| Ecuador | Pastaza | Canelos | Rossman 1976 |
| Ecuador | Pastaza | Chichirota | Rossman 1976 |
| Ecuador | Pastaza | Cobaya Cocha | AMNH 49160; VertNet |
| Ecuador | Pastaza | Cusuime | Ortega-Andrade 2010 |
| Ecuador | Pastaza | Guache | AMNH 49094; VertNet |
| Ecuador | Pastaza | Headwaters of Río Capahuari | Rossman 1976 |
| Ecuador | Pastaza | Jandiayacu | Reptiles of Ecuador book database |
| Ecuador | Pastaza | Mera | Rossman 1976 |
| Ecuador | Pastaza | Montalvo | Rossman 1976 |
| Ecuador | Pastaza | Pomona | Pazmiño-Otamendi & Rodríguez-Guerra 2022 |
| Ecuador | Pastaza | Pucayacu (Río Pucayacu) | Rossman 1976 |
| Ecuador | Pastaza | Río Arajuno, headwaters of | Rossman 1976 |
| Ecuador | Pastaza | Río Bobonaza | AMNH 49053; VertNet |
| Ecuador | Pastaza | Río Bufeo | Rossman 1976 |
| Ecuador | Pastaza | Río Chambira | AMNH 49131; VertNet |
| Ecuador | Pastaza | Río Conambo | Rossman 1976 |
| Ecuador | Pastaza | Río Copataza | Rossman 1976 |
| Ecuador | Pastaza | Río Copataza, mouth of | Rossman 1976 |
| Ecuador | Pastaza | Río Huiyayacu | Rossman 1976 |
| Ecuador | Pastaza | Río Lliquino | Rossman 1976 |
| Ecuador | Pastaza | Río Oglán | Rossman 1976 |
| Ecuador | Pastaza | Río Pastaza* | Shreve 1934 |
| Ecuador | Pastaza | Río Pindo | Rossman 1976 |
| Ecuador | Pastaza | Río Puyo | Rossman 1976 |
| Ecuador | Pastaza | Río Rutuno | Rossman 1976 |
| Ecuador | Pastaza | Río Villano | Rossman 1976 |
| Ecuador | Pastaza | Santa Rosa, Río Tigre | AMNH 49172; VertNet |
| Ecuador | Pastaza | Sarayacu | Rossman 1976 |
| Ecuador | Pastaza | Shell | iNaturalist; photo examined |
| Ecuador | Pastaza | Villano | Reptiles of Ecuador book database |
| Ecuador | Sucumbíos | Dureno, 10 km N of | iNaturalist; photo examined |
| Ecuador | Sucumbíos | Lago Agrio | Photo by John Castillo |
| Ecuador | Sucumbíos | San Pablo de Kantesiya | MHNG 2398.007; collection database |
| Ecuador | Sucumbíos | Santa Elena | iNaturalist; photo examined |
| Perú | Amazonas | Aguaruna Village | MVZ 163277; VertNet |
| Perú | Amazonas | Chigkan Entse | USNM 260765; VertNet |
| Perú | Amazonas | Chiriaco, 20 km SW of | Rossman 1976 |
| Perú | Amazonas | Pongo Mori | MVZ 163280; VertNet |
| Perú | Amazonas | Sua, Río Cenepa | USNM 260766; VertNet |
| Perú | Amazonas | Tseasim | USNM 260763; VertNet |
| Perú | Loreto | Guache | AMNH 113660; VertNet |
| Perú | Loreto | Puesto Tarqui | AMNH 57342; VertNet |