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| Boa atlantica Gonzalez, Bezerra de Lima, Passos & Silva, 2024 |
Abstract
Snakes of the genus Boa are outstanding elements of the New World biota with a broad sociological influence on pop culture. Historically, several taxa have been recognized in the past 300 years, being mostly described in the early days of binomial nomenclature. As a rule, these taxa were recognized based on a suite of phenotypic characters mainly those from the external morphology. However, there is a huge disagreement with respect to the current taxonomy and available molecular phylogenies. In order to reconcile both lines of evidence, we investigate the phylogenetic reconstruction (using mitochondrial and nuclear genes) of the genus in parallel to the detailed study of some phenotypic systems from a geographically representative sample of the cis-Andean mainland Boa constrictor. We used cyt-b only (744bp) from 73 samples, and cyt-b, ND4, NTF3, and ODC partial sequences (in a total of 2305 bp) from 35 samples, comprising nine currently recognized taxa (species or subspecies), to infer phylogenetic relationships of boas. Topologies recovered along all the analyses and genetic distances obtained allied to a unique combination of morphological traits (colouration, pholidosis, meristic, morphometric, and male genitalia features) allowed us to recognize B. constrictor lato sensu, B. nebulosa, B. occidentalis, B. orophias and a distinct lineage from the eastern coast of Brazil, which we describe here as a new species, diagnosing it from the previously recognized taxa. Finally, we discuss the minimally necessary changes in the taxonomy of Boa constrictor complex; the value of some usually disregarded phenotypic character system; and we highlight the urgency of continuing environmental policy to preserve one of the most impacted Brazilian hotspots, the Atlantic Forest, which represents an ecoregion full of endemism.
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| Dorsal (A), ventral (B), and lateral (C) views of the head of the holotype of Boa atlantica sp. nov.(MNRJ 27242) from Rio de Janeiro, Atlantic coast of Brazil. |
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| Dorsal (A) and ventral (B) views of the holotype of Boa atlantica sp. nov. (MNRJ 27242) from Rio de Janeiro, Atlantic coast of Brazil. |
Boa atlantica sp. nov.
Diagnosis. Boa atlantica sp. nov. can be distinguished from the other congeners by the following unique combination of characters: (i) ventrals 228–243; (ii) subcaudals 47–58 in males, and 31–56 in females; (iii) anterior dorsal scale rows 51–66; (iv) midbody dorsal scale rows 69–90; (v) posterior dorsal scale rows 42–54; (vi) dorsal body spots 17–23; (vii) tail spots 4–6 in males, 2–6 in females; (viii) longitudinal head stripe usually continuous; (ix) head stripe without lateral projections; (x) elliptical, circular or double-oval dorsal interspots; (xi) posterior dorsal interspots not blotched; (xii) no change in dorsal spots towards the tail; (xiii) lateral ocelli dark brown, black or faint reddish, white bordered; (xiv) belly cream with tones of orange, brown and black, scattered of black dots and large groups of black spots; (xv) belly with progressive darkening towards the tail; (xvi) black spots on ventral surface of tail.
Etymology: The species epithet atlantica is a Latin adjective that refers to the Atlantic coast but mainly the Atlantic Forest ecoregion, the homeland of several endemic species, including this new Boa. The preservation of this biome is crucial for conservation, nonetheless, it has been suffering deforestation since the colonial times and only 12% of it remains standing. This situation is under serious threat since the past Brazilian policies lack empathy for conservation issues and seem to foster deforestation even further.
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| Pre-cloacal region and tails of mainland South-American boas. B. atlantica sp. nov. (MNRJ 27243): a) superior view, b) lateral view; B. constrictor (USNM 566533): c) superior view, d) lateral view; B. amarali (UFG 134): e) superior view, f) lateral view; B. occidentalis (FML28405): g) superior view, h) lateral view. |
Rodrigo Castellari Gonzalez, Lorena Corina Bezerra de Lima, Paulo Passos and Maria José J. Silva. 2024. The Good, the Bad and the Boa: An unexpected New Species of A True Boa revealed by morphological and molecular evidence. PLoS ONE. 19(4): e0298159. DOI: 10.1371/journal.pone.0298159
