Friday, August 24, 2018

[Herpetology • 2018] Origin and Hidden Diversity within the Poorly Known Pseudalsophis Galápagos Snake Radiation (Serpentes: Dipsadidae)

 live specimens of the Galápagos snakes: 
(5) Pseudalsophis thomasi sp. nov. yellow morph from Santiago Island, (6) Pseudalsophis thomasi sp. nov. brown morph from Santiago Island, (7) Pseudalsophis hephaestus sp. nov. from Santiago Island, (8) Pseudalsophis steindachneri from Santa Cruz Island, (9) Pseudalsophis slevini from Pinzón Island, (10) Pseudalsophis darwini sp. nov. from Tortuga Island. 

Zaher, Yánez-Muñoz, Rodrigues, Graboski, Machado, et al., 2018
Galápagos snakes are among the least studied terrestrial vertebrates of the Archipelago. Here, we provide a phylogenetic analysis and a time calibrated tree for the group, based on a sampling of the major populations known to occur in the Archipelago. Our study revealed the presence of two previously unknown species from Santiago and Rábida Islands, and one from Tortuga, Isabela, and Fernandina. We also recognize six additional species of Pseudalsophis in the Galápagos Archipelago (Pseudalsophis biserialis from San Cristobal, Floreana and adjacent islets; Pseudalsophis hoodensis from Española and adjacent islets; Pseudalsophis dorsalis from Santa Cruz, Baltra, Santa Fé, and adjacent islets; Pseudalsophis occidentalis from Fernandina, Isabela, and Tortuga; Pseudalsophis slevini from Pinzon, and Pseudalsophis steindachneri from Baltra, Santa Cruz and adjacent islets). Our time calibrated tree suggests that the genus Pseudalsophis colonized the Galápagos Archipelago through a single event of oceanic dispersion from the coast of South America that occurred at approximately between 6.9 Ma and 4.4 Ma, near the Miocene/Pliocene boundary. 

Key words: Dipsadidae, divergence time estimation, island speciation, molecular phylogeny, Pseudalsophis, Serpentes

Figure 4. Photographs of live specimens of the Galápagos snakes:
Pseudalsophis hoodensis from Española Island (4.1), Pseudalsophis biserialis from San Cristóbal Island (4.2), Pseudalsophis occidentalis from Fernandina Island (4.3), Pseudalsophis dorsalis from Santa Fé Island (4.4), Pseudalsophis thomasi sp. nov. yellow morph from Santiago Island (4.5), Pseudalsophis thomasi sp. nov. brown morph from Santiago Island (4.6), Pseudalsophis hephaestus sp. nov. from Santiago Island (4.7), Pseudalsophis steindachneri from Santa Cruz Island (4.8), Pseudalsophis slevini from Pinzón Island (4.9), Pseudalsophis darwini sp. nov. from Tortuga Island (4.10). 

Pseudalsophis thomasi sp. nov.

ETYMOLOGY: A patronym honouring Robert A. Thomas for expanding our knowledge of the systematics and taxonomy of New World snakes.

Pseudalsophis hephaestus sp. nov.

ETYMOLOGY: From the Greek Ἥφαιστος (Hephaestus), name of the son of Zeus and Hera, God of fire and volcanoes (but also of blacksmiths, carpenters, and artisans), in allusion to the volcanic environment in which this species lives.

Pseudalsophis darwini sp. nov. 
ETYMOLOGY: The specific name, a noun in the genitive case, honours Charles Darwin for his invaluable contribution to our knowledge of the Galápagos Archipelago and to Science.

Figure 9. Phylogenetic and morphological diversification of Pseudalsophis in the Galápagos Archipelago.
 (9.1) depicts the phylogeny mapped onto the Archipelago’s map. Silhouettes represent the continental (green); large insular (blue), and small insular (red) morphotypes recognized in this study, and their occurrences in the islands. Question marks indicate populations that are known to occur in a specific island but were not sampled for genetic material.  

Hussam Zaher, Mario H. Yánez-Muñoz, Miguel T. Rodrigues, Roberta Graboski, Fabio A. Machado, Marco Altamirano-Benavides, Sandro L. Bonatto and Felipe G. Grazziotin. 2018.  Origin and Hidden Diversity within the Poorly Known Galápagos Snake Radiation (Serpentes: Dipsadidae). Systematics and Biodiversity.  DOI: 10.1080/14772000.2018.1478910