Molecular phylogeny and biogeography of the dwarf boas of the family Tropidophiidae (Serpentes: Alethinophidia)

Abstract

Although present in the South American continent, dwarf boas (Tropidophiidae) show their greatest extant diversification in the Caribbean region, reaching their highest diversity in Cuba. Despite their remarkable species richness, phylogenetic affinities among species of Tropidophis and Trachyboa are still poorly known. Here, we provide a multi-locus phylogenetic hypothesis of the family that includes 25 of the 37 known continental and insular species, including most of its highly diverse Cuban endemic radiation (16 out of 17 species sampled). We also provide a time-calibrated tree derived from our molecular data. Our phylogenetic results indicate that the genus Tropidophis and its mainland and Cuban radiations are paraphyletic, while the Caribbean radiation forms a well-supported clade. We therefore synonymize Trachyboa with Tropidophis and provide new definitions for the species groups. Our time-calibrated tree suggests that tropidophiids originated along the northwestern Andean region of continental South America, diverging from its known sister-group genus Anilius during the late Cretaceous. The Atlantic Rainforest radiation diverged from the Andean radiation during the late Eocene. A mainland tropidophiid ancestor subsequently dispersed from northern South America to the Caribbean region in the latest Eocene. Dispersal likely took place through a near-continuous terrestrial land bridge that connected South America to the Greater Antilles during the late Eocene to early Oligocene (35–33 Ma). The existence of this land bridge, whether formed by the Aves Ridge (GAARlandia Hypothesis) or by a more southernly positioned landmass connecting the Greater Antilles and the northern Lesser Antilles Ridge (GRANoLA hypothesis), remains a topic of debate, which we address in this paper. After that main dispersal event, West Indian tropidophiids underwent over ten speciation events, rapidly colonizing the Caribbean islands. We also address the vertebral morphology of fossil and extant Tropidophiidae, with our observations challenging the current classification of several fossil taxa within crown-Tropidophiidae.

Key words:

• extinct species
• Island speciation
• snake systematics
• Trachyboa
• Tropidophis
• vertebral morphology

Acknowledgements

We are grateful to Manuel Iturriaga Monsisbay and Luis Díaz for giving access to specimens from the IES and MNHNCu and for allowing us to sample the tissues sequenced here. Tissue samples and specimens were exported and sequenced with permits from the Ministerio de la Agricultura de Cuba (certificates no. R.S. 6642015 and R.S. 7792015 emitted on 10 and 15 June 2015) and CITES (certificate no. 003476 emitted on 10 June 2015). We thank the following colleagues for providing the photos of Tropidophis illustrating our study: H. Mauricio Ortega-Andrade (Tro. cacuangoae), Mario H. Yánez-Muñoz (Tro. boulengeri, Tro. taczanowski), Edelcio Muscat (Tro. paucisquamis), Jenna L. Welch (Tro. haetianus), Felipe F. Curcio (Tro. preciosus, Tro. grapiuna), and Jeff Lemm (Tro. pardalis, Tro. melanurus, Tro. feicki, Tro. semicinctus). The image of Tro. maculatus was generated by AI using Midjourney. HZ is deeply indebted to Manuel Iturriaga Monsisbay (IES), David Maceira, and Alexander Sanchez Ruiz (BIOECO) for providing logistic and scientific support during his visits to La Habana and Santiago de Cuba in 2014 and 2015. Kraig Adler provided valuable literature and comments on the dates of publication of Ramon de la Sagra’s “Historia física, política y natural de la Isla de Cuba”. We thank the Associate Editor and an anonymous reviewer for constructively critical comments on the submitted manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplemental material

Supplemental material for this article can be accessed here: http://dx.doi.org/10.1080.14772000.2024.2319289.

Associate Editor: Dr David Gowe

Additional information

Funding

OME-N was supported by scholarhips from Fundação de Amparo à Pesquisa do Estado de São Paulo [FAPESP grant number 2021/13671-7] and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior [CAPES grant number 88887.667258/2022-00]. FGG was supported by scholarships from Fundação de Amparo à Pesquisa do Estado de São Paulo [FAPESP grant number 2012/08661-3 and 2022/12660-4] and Conselho Nacional de Desenvolvimento Científico e Tecnológico [CNPq grant numbers 405518/2021-8 and 312016/2021-2]. This work was supported by grants from the Fundação de Amparo à Pesquisa do Estado de São Paulo [FAPESP grant numbers 2002/13602-4, 2011/50146-6, and 2016/50127-5] to HZ.