Galápagos Archipelago Now Has Eastern Santa Cruz Island Tortoises

Summary: Eastern Santa Cruz Island Tortoises (Chelonoidis donfaustoi) now have separate species status from Western Santa Cruz Tortoises (Chelonoidis porteri).

Eastern Santa Cruz tortoise (Chelonoidis donfaustoi), Tuesday, Aug. 12, 2014, 10:49: aposematic herpetologist from Ames IA, CC BY SA 2.0 Generic, via Wikimedia Commons

Cerro Fatal and La Reserva are zones that the already known Galápagos giant tortoise species, Santa Cruz Island tortoises, and the newly identified Don Fausto's Eastern Santa Cruz tortoises respectively call home. Their tortoise populations now belong to separate species because of investigations described by a twelve-author team for the PLoS ONE online issue of Oct. 21, 2015.

Yale University evolutionary biologist Adalgisa Caccone currently calls only the estimated 1,750 to 3,750 Western Santa Cruz Island tortoises within “The Reserve” Chelonoidis porteri ("Porter’s tortoise"). Dr. Caccone and her 11 co-authors describe the estimated 250 Eastern Santa Cruz Island tortoises at “Deadly Hill” under the name Chelonoidis donfaustoi ("Don Fausto’s tortoise").

The revision extols Galápagos National Park retired ranger Fausto Llerena Sánchez for 43 service years, from 1971 to 2014, conserving captive, endangered tortoises and tortoise habitats.

Similar appearances, behaviors and genetics fit members of one species even though "the taxonomy of Galapagos tortoises has long been debated" regarding species and subspecies possibilities. Eco-tourists historically give rare second thoughts to the longstanding classification of superficially similar Eastern and Western Santa Cruz Island tortoises into one species with no subspecies. Western Santa Cruz Island tortoises consistently hint of "higher anterior" openings, "larger overall" sizes and "relatively larger" carapaces than Don Fausto's Eastern Santa Cruz Island tortoises. Observations of domes, openings, plates and sizes by United States Geological Survey herpetologist Thomas H. Fritts and Charles Darwin Foundation researcher Cruz Márquez inspire current reorganizations.

sites of two species of Santa Cruz Island tortoises: La Reserva for Western tortoises and Cerro Fatal for Eastern tortoises; agricultural land (light gray area) connects two sites: N. Poulakakis et al., CC BY 4.0 International, via PLOS ONE

Twenty kilometers (12.43 miles) of agricultural clearings join Cerro Fatal to La Reserva in the interior of Santa Cruz Island, second largest in the Galápagos archipelago. It keeps Don Fausto's Eastern Santa Cruz Island tortoises on 40-square-kilometer (15.44-square miles) arid lowlands and Western Santa Cruz Island tortoises on 156-square-kilometer (60.23-square-mile) cloud-forest highlands.

Biogeographical and morphological differences lead James Gibb of the State University of New York College of Environmental Science and Forestry and 11 colleagues to DNA analysis. DNA analyses manipulate a carapace and a skull from Cerro Fatal in 1991 and 2010, "natural populations" and the Western Santa Cruz Island holotype from 1902. The study's authors note an absence of site specifics from the London Tring Museum in England regarding the Chelonoidis porteri specimen collected by Rollo Howard Beck.

The study observes that DNA analyses offer indications of the holotype occurring from hybridization between Eastern Santa Cruz Island tortoises and Western Santa Cruz Island tortoises.

The study provides Eastern Santa Cruz tortoises with separate binomial nomenclature, scientific description and species status since analyses present "allele frequency differences at 12 microsatellite loci." DNA analyses qualify hybrid populations along or in Cerro Fatal and La Reserva for the description Santa Cruz Island tortoise and for the name Chelonoidis porteri. Taxonomic accuracy requires redescribing and renaming Western Santa Cruz Island tortoises, "part of the oldest lineage in the archipelago (diverged ~ 1.74 million years ago, Mya)."

Daniel Mulcahy of Washington, D.C.'s Smithsonian National Museum of Natural History shies away from reclassifying hybrids, La Reserva and "much younger (~0.43 Mya)" Cerro Fatal populations. He tempers reluctance with “They were very careful in what they did and very thorough with the data they collected and the way they analyzed it."

retired park ranger Fausto Llerena Sánchez with giant tortoise, Santa Cruz Island, Wednesday, Oct. 21, 2015 (Galápagos National Park handout via Reuters): El Espectador @elespectador, via Twitter Oct. 22, 2015

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Eastern Santa Cruz tortoise (Chelonoidis donfaustoi), Tuesday, Aug. 12, 2014, 10:49: aposematic herpetologist from Ames IA, CC BY SA 2.0 Generic, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Chelonoidis_donfaustoi_(15072109070).jpg; Andy Kraemer, CC BY SA 2.0, via Flickr @ https://www.flickr.com/photos/38984611@N03/15072109070/

sites of two species of Santa Cruz Island tortoises: La Reserva for Western tortoises and Cerro Fatal for Eastern tortoises; agricultural land (light gray area) connects two sites: N. Poulakakis et al., CC BY 4.0 International, via PLOS ONE @ http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0138779

retired park ranger Fausto Llerena Sánchez with giant tortoise, Santa Cruz Island, Wednesday, Oct. 21, 2015 (Galápagos National Park handout via Reuters): El Espectador @elespectador, via Twitter Oct. 22, 2015, @ https://twitter.com/elespectador/status/656988356404867072

For further information:

The Economist @TheEconomist. 25 October 2015. "Meet Chelonoidis donfaustoi, a new species of Galapagos turtle -- and the man it's named after." Twitter.
Available @ https://twitter.com/TheEconomist/status/658503033786101760

El Espectador @elespectador. 21 October 2015. "(En imágenes) 'Chelonoidis donfaustoi', la nueva especie de tortuga gigante en Galápagos." Twitter.
Available @ https://twitter.com/elespectador/status/656988356404867072

Marriner, Derdriu. 22 October 2015. "Chelonoidis donfaustoi: Eastern Santa Cruz Giant Galápagos Tortoise." Wizzley > Pets & Animals > Reptiles & Amphibians > Tortoises.
Available @ https://wizzley.com/chelonoides-donfaustoi-eastern-santa-cruz-giant-gal-pagos-tortoise/

Parq. Nac. Galápagos @parquegalapagos. 21 October 2015. "En Galápagos se describe nueva especie de tortuga gigante, Chelonoidis donfaustoi, en honor a ese gran guardaparque." Twitter.
Available @ https://twitter.com/parquegalapagos/status/656919113781112832

Parq. Nac. Galápagos @parquegalapagos. 21 October 2015. "Nueva especie de tortuga descrita en #Galápagos. Su nombre: Chelonoidis donfaustoi." Twitter.
Available @ https://twitter.com/parquegalapagos/status/656923304142491648

Poulakakis, Nikos, et al. 21 October 2015. "Description of a New Galapagos Giant Tortoise Species (Chelonoidis; Testudines; Testudinidae) from Cerro Fatal on Santa Cruz Island." PLOS ONE. DOI: http://dx.doi.org/10.1371/journal.pone.0138779
Available @ http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0138779

SUNY College of Environmental Science and Forestry. 21 October 2015. "New giant tortoise species found in Galapagos." ScienceDaily > Releases.
Available @ https://www.sciencedaily.com/releases/2015/10/151021151357.htm