Sadala Rauli: An Unexpected Addition to Ecuador’s Biodiversity

A groundbreaking discovery has been made in the Ecuadorian Amazon’s lush tropical forests. Researchers Pedro Peñaherrera-R. and Diego F. Cisneros-Heredia, from the San Francisco de Quito University (USFQ) and the National Institute of Biodiversity (INABIO), have revealed a new species of giant crab spider.

This marks the first record of the ‘Sadala’ genus in the spider family tree of Ecuador.

The species was found in the heart of the Yasuní Biosphere Reserve, thriving in the pristine tropical forest under the protection of the USFQ’s Tiputini Biodiversity Station. While this particular spider species has been previously identified in countries such as Colombia and Brazil, its presence in Ecuador showcases the country’s diverse arachnid population.

This discovery was made in one of the world’s richest biodiversity hotspots, which also happens to be in Ecuador. Regrettably, this research reveals that numerous species face grave threats from habitat destruction, according to Peñaherrera-R.

Named ‘Sadala rauli’, in tribute to Raúl Peñaherrera de la Cadena, the grandfather of Pedro Peñaherrera-R., the species is currently known only from female specimens. These specimens bear a resemblance to the females of two Peruvian ‘Sadala’ species.

To distinguish these species, researchers focus on the morphology of the reproductive system, as the coloration between these species is highly similar.

The ‘giant crab spider’ moniker is derived from the distinctive stance these spiders take on vegetation, extending their legs to the sides and revealing their large size compared to more common spiders. ‘Sadala’ species are found across Central and South America, stretching from Panama to west-central Brazil.

Interestingly, a significant number of observations have been recorded on the citizen science portal ‘iNaturalist’, suggesting that Ecuador may be home to additional ‘S. rauli’ localities or even other yet-to-be-described species.

This calls for more extensive collection and research efforts to fully appreciate the richness and distribution of spider species in the region, which seems to be vastly underestimated.

Despite the fact that the diversity of spiders in the American tropics is enormous, it remains largely uncharted territory in Ecuador. With just about 1,000 known spider species, Ecuador has only scratched the surface, accounting for less than 25% of the spider diversity known in its Andean neighbors.

The findings of the study were published in Ecology and Evolution.

Image Credit: Habitus of Sadala rauli sp. nov., female paratype, at the Tiputini Biodiversity Station, province of Orellana, Ecuador.