Sunday, February 25, 2024

[Herpetology • 2024] Eunectes akayimaDisentangling the Anacondas: Revealing a New Green Species and Rethinking Yellows

Eunectes murinus (Linnaeus, 1758) 
Eunectes akayima Rivas, De La Quintana, Mancuso, Pacheco, Rivas, Mariotto, Salazar-Valenzuela, Tepeña Baihua, Baihua, Burghardt, Vonk, Hernandez, García-Pérez, Fry & Corey-Rivas, 2024

E. notaeus Cope, 1862 

Anacondas, genus Eunectes, are a group of aquatic snakes with a wide distribution in South America. The taxonomic status of several species has been uncertain and/or controversial. Using genetic data from four recognized anaconda species across nine countries, this study investigates the phylogenetic relationships within the genus Eunectes. A key finding was the identification of two distinct clades within Eunectes murinus, revealing two species as cryptic yet genetically deeply divergent. This has led to the recognition of the Northern Green Anaconda as a separate species (Eunectes akayima sp. nov.), distinct from its southern counterpart (E. murinus), the Southern Green Anaconda. Additionally, our data challenge the current understanding of Yellow Anaconda species by proposing the unification of Eunectes deschauenseei and Eunectes beniensis into a single species with Eunectes notaeus. This reclassification is based on comprehensive genetic and phylogeographic analyses, suggesting closer relationships than previously recognized and the realization that our understanding of their geographic ranges is insufficient to justify its use as a separation criterion. We also present a phylogeographic hypothesis that traces the Miocene diversification of anacondas in western South America. Beyond its academic significance, this study has vital implications for the conservation of these iconic reptile species, highlighting our lack of knowledge about the diversity of the South American fauna and the need for revised strategies to conserve the newly identified and reclassified species. 

Keywords: cryptic diversity; Boidae; South America; Llanos; Pebas system; Orinoco basin; redundant species

Eunectes akayima sp. nov.

We propose the common name, Northern Green Anaconda, for Eunectes akayima sp. nov. Before the arrival of the Spaniards, northern Venezuela was occupied by various Indigenous nations, among which the Caribs were an important group. Several Carib nations remain including the Kariña, Panare, Yekuana, Pemones, and Akawaio. The word for anaconda in various Cariban languages is a variant of akayima/okoyimo/okoimo, in which akayi/okoyi/okoi means “snake” and the suffix -ima/-imo means “large”. The suffix -ima/-imo does not necessarily mean ‘large’ in a physical sense. Rather, it is used to denote the kind of largeness that indicates a different category of being. The literal translation of akayima is “The Great Snake” (S. Gildea pers. comm.). The species name akayima is pronounced as follows: əkəyimə in standard dictionary pronunciation font; ŭkŭyēmŭ using the phonics; and uh-kuh-yee-muh using the Plotkin method for English-like writing to capture Cariban language pronunciations [Plotkin, 1994]. The word akayima is also used to refer to the rainbow, probably associated with a feathered serpent in their belief system that came out after rains to dry its feathers [Gumilla, 1740]. We, therefore, acknowledge the culture of these Indigenous people who share their territories with this species by adopting their word for anaconda as the specific epithet for this new species. We propose the common name for E. murinus as Southern Green Anaconda, to promote taxonomic stability for the most widely distributed species and avoid confusion. Table 6 provides a comparison between the E. akayima sp. nov. holotype, one of its paratypes, and the E. murinus lectotype.
Previous work had identified other candidate species and subspecies of the anaconda in the Orinoco basin with somewhat similar distribution to E. akayima [Dunn & Conant, 1936]. However, all of these differences have been found to be inconsistent [Dirksen, 2002; Dirksen & Henderson, 2002; Dirksen & Bohme, 1998]; therefore, these synonyms are all invalid. In addition, the word “akayima” has been indigenously used to designate this species for at least hundreds (and perhaps even thousands) of years before the use of any of the other synonyms. It was certainly in use in 1758 when the Code started counting names as valid; so, akayima is clearly the senior synonym. This is, admittedly, an unorthodox position regarding the International Code of Zoological Nomenclature [1999], which prefers the names that have been published in Western science as “valid”. However, it is well due time that Western science starts recognizing the ancestral knowledge and cultural legacy of non-Westernized society. If we respect and honor the culture of these original nations, accepting akayima as the senior synonym is unavoidable.

This study provides the most extensive sampling of anacondas to date and raises new questions about the distinctive lineages, geological history, and conservation status of the Eunectes group. Historical, geographic, and landscape-scale events may have shaped the current distribution and composition of the species. Looking at the ecology of present-day anacondas, it would seem that the entire Amazon/Orinoco basin would be an area of free dispersal for anacondas. However, the presence of a new cryptic species in the north and the E. murinus in the south tells us that we still know very little about the gene flow dynamics of a large vertebrate in the world’s most diverse terrestrial ecosystem. The idea that there could be a population of E. notaeus living throughout the Amazon basin that has managed to evade detection thanks to a coloration that superficially resembles that of E. murinus is puzzling, and speaks loudly to the need for thorough sampling to better document the diversity we still have.

 Jesús A. Rivas, Paola De La Quintana, Marco Mancuso, Luis F. Pacheco, Gilson A. Rivas, Sandra Mariotto, David Salazar-Valenzuela, Marcelo Tepeña Baihua, Penti Baihua, Gordon M. Burghardt, Freek J. Vonk, Emil Hernandez, Juán Elías García-Pérez, Bryan G. Fry and Sarah Corey-Rivas. 2024. Disentangling the Anacondas: Revealing a New Green Species and Rethinking Yellows. Diversity. 16(2), 127. DOI: 10.3390/d16020127
(This article belongs to the Special Issue DNA Barcoding for Biodiversity Conservation and Restoration)