Boa atlantica, Gonzalez & Lima & Passos & Silva, 2024

Gonzalez, Rodrigo Castellari, Lima, Lorena Corina Bezerra de, Passos, Paulo & Silva, Maria José J., 2024, The good, the bad and the boa: An unexpected new species of a true boa revealed by morphological and molecular evidence, PLoS ONE (e 0298159) 19 (4), pp. 1-29 : 22

Boa atlantica sp. nov. occurs in the most populous area in Brazil, where the Portuguese colonization began in the XVI Century through an occupancy plan called ‘Capitanias Hereditárias’, which gave rise—with many boundary shifts across time—to the current political division of the country. The herpetofauna is well-known along the Brazilian coast, at least if compared to most inland areas, partially because this region concentrates the largest capitals of the country, including most of the research centres, scientists and natural history collections. On other hand, it is remarkable that early naturalist travelling to Brazil (e.g., [ 81]) or even nowadays (e.g., [ 73]), reported on such coastal population of boas, without noting its morphological distinction with respect to Amazon (i.e., B. c. constrictor ) or Cerrado (i.e., B. c. amarali ) populations.

Nevertheless, as stated before, there has never been a comprehensive taxonomic review of the genus to establish specific boundaries accurately, mainly considering cis-Andean taxa. In addition, several studies did not mention explicitly the presence of the genus Boa in the Atlantic Forest [ 68, 69, 72, 82]. By contrast, the few mentions of boas in the Atlantic Forest regard it as Boa constrictor without consistent application of trinomial nomenclature comprising subspecific ranks [ 3, 6, 9, 70, 71, 73, 74, 83 – 85].

Boa atlantica sp. nov. is very common in its distribution range, being found in lowland primary and secondary rainforests [ 71, 73], and even in large and populous cities with very anthropized environment, such as Rio de Janeiro (see Figs 7 and S 2 File). Boa atlantica sp. nov. may occur in sympatry with nominal species B. c. constrictor in its northernmost area of distribution in Passo do Camaragibe, state of Alagoas, Brazil, since the area is too close to the Caatinga. This can be explained considering the Brazilian Atlantic Forest has once been enormous, occupying a vast territory especially in the Atlantic coast [ 86 – 89]. Since the discovery and colonization of Brazil, this biome has been widely destroyed (due to farming, large cities, wood-market, and so on), with less than 12% of the forest currently remaining [ 87 – 90].

This situation is more overwhelming in the northeastern region of Brazil, where the remaining forest is patched or transformed into monocultures or pastures [ 86 – 89]. The destruction of the forest has had a rough and direct impact on the fauna distribution, since it is dependent on the local resources [ 91]. Likewise, the forest fragmentation and advancement of the Caatinga and Cerrado, respectively, into Northeast and Southeast Brazilian regions might explain the areas where B. atlantica sp. nov. has contact with B. c. amarali (Espírito Santo and possibly western Bahia States), and B. c. constrictor (Alagoas and western Bahia State, Brazil). The southernmost record is for Ilha Grande (Rio de Janeiro State, Brazil). In this case, there is a large gap between the records of B. c. amarali from São Paulo City and Boa atlantica sp. nov. in southern Rio de Janeiro State, since B. c. amarali does not occur in the coast of the state of São Paulo, Brazil.

The present study formally describes a new species from a population that has been known by scientists in the past 200 years. In a certain way, we can assume that Boa atlantica sp. nov. has been widely ignored by majority of taxonomist, since it has always been regarded as distinct from subspecies Boa c. constrictor or B. c. amarali , being usually referred only to as Boa constrictor without a consistent trinomial usage. Here we reinforce the importance of paying attention to the most common species, which, if not studied, may hide cryptic diversity. Just like our example here, Feinberg et al. [ 92] described a new species of Rana ( R. kauffeldi ) inside New York City. Although such discoveries may be unexpected in densely populated urban parts of the world, detailed comparative studies demonstrated that new species can still be found periodically even in well-studied places rarely associated with undocumented biodiversity [ 92]. We also stress the importance of protecting such species, since it is endemic to the Brazilian Coastal Atlantic Forest, a largely impacted and threatened ecoregion. Therefore, this new species was already threatened by habitat loss even and other threats even before it was formally described by science.

Figures

Fig 2. Phylogenetic tree inferred by using Maximum Likelihood and general time reversible model. The matrix is composed of 39 samples from South America, being 35 samples with the four concatenated markers (cyt-b, ND4, NTF3, and ODC resulting in 2305 positions in the final dataset) and the outgroup (Charina bottae, Corallus hortulana, Epicrates cenchria, and Eunectes murinus) with cytb only). The percentage of trees in which the associated taxa clustered together is shown above the branches (bootstrap). The tree is drawn to scale, with branch lengths measured in the number of substitutions per site. Group colours: Black: Outgroup; blue: B. occidentalis; green: B. atlantica sp. nov.; orange: B. constrictor and red: B. amarali. Photographs: A) B. c. amarali, no locality; B. c. constrictor, no locality, Brazil; C) B. c. constrictor, from Cuiabá, Mato Grosso, Brazil; B. atlantica sp. nov., from Rio de Janeiro, Brazil; B. occidentalis from Tucumán, Argentina. https://doi.org/10.1371/journal.pone.0298159.g002

Fig 7. Distribution of Boa atlantica sp. nov. based on the examined vouchers and tissue samples. A) Detailment in Rio de Janeiro City, including type locality. B) records in northern Rio de Janeiro and Espírito Santo States, C) records in Rio de Janeiro State. See also S4 Table. https://doi.org/10.1371/journal.pone.0298159.g007