DOI10.47051/DUNX1781

Published May 2, 2024. Open access.

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Arrowhead Watersnake (Helicops hagmanni)

Reptiles of Ecuador | Serpentes | Colubridae | Helicops hagmanni

English common names: Arrowhead Watersnake, Hagmann’s Keelback.

Spanish common names: Culebra acuática punta de flecha, culebra acuática de Hagmann.

Recognition: ♂♂ 63.4 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=46.0 cm. ♀♀ 94.5 cmMaximum distance from the snout to the tip of the tail. Snout–vent length=71.6 cm..1,2 Helicops hagmanni can easily be identified from other water snakes by having 23–29 dorsal scale rows and a forward facing arrow-shaped dark mark on the dorsal aspect of the head (Fig. 1).1–3 The dorsum is brown with five longitudinal rows of dark brown spots: there is a series of spots along the vertebral line, another on each side dorsolaterally, and another one along each lower flank margin. Ventrolaterally, the spaces between the spots are cream, enclosing contrasting maroon blotches. The venter is checkered, with black marks corresponding roughly to the dorsal blotches.3 The head is brown with clearly defined downward-facing postocular stripes in addition to the arrow-shaped mark.1–3 This species differs from H. angulatus by having dorsal spots instead of bands. From H. pastazae and H. petersi, it differs by having bright cream lower flanks enclosing contrasting black spots.

Figure showing an adult female of Helicops hagmanni

Figure 1: Adult female of Helicops hagmanni from Leticia, Amazonas department, Colombia.

Natural history: Helicops hagmanni is an aquatic snake that inhabits swamps, streams, and rivers.4 Arrowhead Watersnakes are typically active at night, but diurnal activity has also been recorded.1,5 They spend most of their time submerged in shallow water or crawling on mud and rocks beside the water’s edge.1 In Ecuador, one individual was seen crossing a road and heading towards a stream during the daytime.4 In Colombia, one was seen resting among roots in a stream at night.4 In Brazil, another one was seen perched about 2 meters above the ground on the vegetation adjacent to a small stream during the day.5 The diet in this species is composed exclusively of fish,1,6–8 whereas other Helicops have a broader diet that also includes tadpoles and lizards. When grabbed, the typical defense behavior of H. hagmanni consists of thrashing the body and producing cloacal discharges.1 This species lays clutches of 4–20 eggs during local low-water season.1,6

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Conservation: Least Concern Believed to be safe from extinction given current circumstances..9 Helicops hagmanni is listed in this category primarily because the species is considered common in Brazil and has a wide distribution spanning many protected areas. However, H. hagmanni is only considered abundant in the eastern part of its range. In the comparatively well-sampled Ecuadorian Amazon, this species has only been recorded four times, suggesting naturally low population densities rather than a lack of sampling of suitable habitats. Although there is no information on the population trend of the species, its numbers are expected to be declining alongside the decrease in water quality throughout the northern Ecuadorian Amazon river systems.

Distribution: Helicops hagmanni is widely distributed throughout the Amazon lowlands of Brazil, Colombia, Ecuador (Fig. 2), and Venezuela.10

Distribution of Helicops hagmanni in Ecuador

Figure 2: Distribution of Helicops hagmanni in Ecuador. 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),11 refers to the direction of the eyes in this group of snakes, oriented not directly outwards, but obliquely upwards.12,13 The specific epithet hagmanni honors Swiss-Brazilian zoologist Gottfried A. Hagmann, who collected the holotype.14 Hagmann (1874-1946) served as a zoology assistant and Inspector of the Zoological Garden at the Museu Goeldi. Due to misunderstandings with the museum’s founder and then director, Emilio Goeldi, he left the organization to work for a rubber plantation on Ilha Mexiana, situated at the mouth of the Amazon. Subsequently, he returned to Basel briefly before relocating back to Brazil around 1910, settling in the Santarém region until his passing in 1946. Hagmann acquired fazenda Taperinha, a farm in Baixo Amazonas, where he resided with his family and established a meteorological station. The area evolved into a significant hub for natural history research, attracting numerous scientists.15

See it in the wild: Helicops hagmanni has only been recorded four times in Ecuador, making it the rarest aquatic snake in the country. The most recent observation occurred in 2019 at the Río Ocano, Sucumbíos province. More intensive surveys in this locality could yield additional specimens.

Notes: In this account, records labeled as Helicops leopardinus from Ecuador,16 are considered to correspond to H. hagmanni.

Author: Alejandro ArteagaaAffiliation: Khamai Foundation, Quito, Ecuador.

Photographer: Sebastián Di DoménicobAffiliation: Keeping Nature, Bogotá, Colombia.

How to cite? Arteaga A (2024) Arrowhead Watersnake (Helicops hagmanni). 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/DUNX1781

Literature cited:

  1. Martins M, Oliveira ME (1998) Natural history of snakes in forests of the Manaus region, Central Amazonia, Brazil. Herpetological Natural History 6: 78–150.
  2. 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
  3. Rossman DA (1975) Redescription of the South American colubrid snake Helicops hagmanni Roux. Herpetologica 31: 414–418.
  4. Field notes, Reptiles of Ecuador book project.
  5. de Lima Moraes LJC, de Fraga F (2015) Climbing behavior in the aquatic snake Helicops hagmanni Roux 1910 (Serpentes: Dipsadidae). Herpetology Notes 8: 19–20.
  6. Cunha OR, Nascimento FP (1993) Ofídios da Amazônia. As cobras da região leste do Pará. Papéis Avulsos Museu Paraense Emílio Goeldi 40: 9–87.
  7. Sturaro JM, Gomes JO (2008) Feeding behavior of the Amazonian Water Snake Helicops hagmanni Roux, 1910 (Reptilia: Squamata: Colubridae: Hydropsini). Boletim do Museu Paraense Emílio Goeldi 3: 225–228. DOI: 10.46357/bcnaturais.v3i3.675
  8. De Carvalho Teixeira C, de Assis Montag LF, dos Santos-Costa MC (2017) Diet composition and foraging habitat use by three species of water snakes, Helicops Wagler, 1830, (Serpentes: Dipsadidae) in Eastern Brazilian Amazonia. Journal of Herpetology 51: 215–222. DOI: 10.1670/15-161
  9. Calderón M, Ortega A, Nogueira C, Gagliardi G, Schargel W, Rivas G (2019) Helicops hagmanni. The IUCN Red List of threatened species. Available from: www.iucnredlist.org. DOI: 10.2305/IUCN.UK.2019-3.RLTS.T15178721A15178728.en
  10. Nogueira CC, Argôlo AJS, Arzamendia V, Azevedo JA, Barbo FE, Bérnils RS, Bolochio BE, Borges-Martins M, Brasil-Godinho M, Braz H, Buononato MA, Cisneros-Heredia DF, Colli GR, Costa HC, Franco FL, Giraudo A, Gonzalez RC, Guedes T, Hoogmoed MS, Marques OAV, Montingelli GG, Passos P, Prudente ALC, Rivas GA, Sanchez PM, Serrano FC, Silva NJ, Strüssmann C, Vieira-Alencar JPS, Zaher H, Sawaya RJ, Martins M (2019) Atlas of Brazilian snakes: verified point-locality maps to mitigate the Wallacean shortfall in a megadiverse snake fauna. South American Journal of Herpetology 14: 1–274. DOI: 10.2994/SAJH-D-19-00120.1
  11. Brown RW (1956) Composition of scientific words. Smithsonian Books, Washington D.C., 882 pp.
  12. 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
  13. 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
  14. Roux J (1910) Eine neue Helicops-Art aus Brasilien. Zoologischer Anzeiger 36: 439–440.
  15. Miranda de Sá D, Cândido da Silva AF (2019) The Brazilian Amazon: the world’s breadbasket: science, agriculture and ecology at the Agronomic Institute of the North in the 1940s and 1950s. Revista de História, São Paulo 178: 1–26. DOI: 10.11606/issn.2316-9141.rh.2019.145623
  16. Cisneros-Heredia DF (2006) Reptilia, Colubridae, Helicops angulatus and Helicops leopardinus: distribution extension, new country record. Check List 2: 36–37.

Appendix 1: Locality data used to create the distribution map of Helicops hagmanni in Ecuador (Fig. 2). Go to the section on symbols and abbreviations for a list of acronyms used.

CountryProvinceLocalitySource
ColombiaCaquetáCaserío VeneciaRossman 1975
EcuadorNapoPuerto NapoCisneros-Heredia 2006
EcuadorOrellanaPompeya Sur–Iro road, km 107Cisneros-Heredia 2006
EcuadorSucumbíosPacayacu, 20 km N ofiNaturalist; photo examined
EcuadorSucumbíosSacha LodgeCisneros-Heredia 2006