Credit: N. Hazy
Spiders of the genus Phoneutria – also known as banana spiders – are aggressive and among the most venomous spiders in the world, with a venom that has a toxic effect on nerves. These large nocturnal spiders usually live in environments disturbed by humans and are often found on banana plantations in the New Tropics.
One of those spiders, P. boliviensis, Is a medically important species that is widely distributed in Central and South America, and much attention has already been paid to its behavior, habitat, toxin composition, toxicity and bites to humans in previous research work. However, after examining a large collection of museum specimens, biologists from George Washington University (N. Hazzi and G. Hormiga) began to question whether the named specimens were P. boliviensis They were actually of the same type.
It all started when N. Hezi examines samples of banana spiders that experts in the past identified as P. boliviensis. The research team soon realized that the morphological features currently used to define this species were not sufficient. Next, they discovered two well-defined morphological groups for P. boliviensis Separated by the Andes mountain range, and it is a geographical barrier that separates many other species.
To demonstrate that these two “forms” were two distinct species, the authors conducted fieldwork in the Amazon, Andes, and Central America, and collected samples from these venomous spiders to explore whether the genomic signal also indicated two species. They discovered that the genetic differences separating the two forms were similar compared to the genetic differences that separated other known species of banana spiders. Using the morphological, genomic, and geographic distribution data, the authors concluded this P. boliviensis It does not represent one type, but rather two different types. They revealed the truth P. boliviensis Only the second species, P. depilata (an ancient name that the research team has verified), has been found in the Andes, Choco, and Caribbean regions. Their findings have been published in an open-access, peer-reviewed journal. Zookies.
To obtain more distribution records for this species, the research team used the iNaturalist citizen science platform. Since the two species are among the few spiders that can be recognized using only images, the platform has turned out to be a very useful tool. Data provided by the iNaturalist community helped determine the whereabouts of the two Phoneutria species. Oddly enough, for these two species, iNaturalist provided higher and more distributed records than the scientists’ database.
“To our knowledge, this is the first study using iNaturalist to collect incidence records on toxic species to estimate distribution patterns,” the researchers say.
This is how spiders can be distinguished using only pictures: P. boliviensis It has two white and yellow side bands in the anterior region of the shield, while P. depilata has four chains of yellow dots on the ventral side of the abdomen. Additionally, to identify P. depilata, information is needed on where the photo was taken, as this is the only type of Phoneutria found in the Andes, Choco, and Central America. However, the most reliable approach to identifying these species requires examination under a vacuum microscope.
Interestingly, P. depilata was incorrectly named P. boliviensis Through numerous studies, including work on toxin composition and toxicity, ecology, geographic distribution, and human epidemiology of bites. Records of human bites of this species have been reported in Costa Rica and on banana plantations in Colombia, most of which have mild to moderate poisoning symptoms. Except for short sternal references by field explorers in the Amazon, little is known about P. depilata.
The study provides detailed diagnostics with images to distinguish both species and distribution maps.
This valuable information will assist in identifying risk areas for occasional bites and assist health professionals in identifying the species involved, particularly for P. depilata. This is an important finding that will affect studies on toxicology, and open new opportunities for comparing the toxin composition and the effect of these two types. “
Hazzi NA, Hormiga G (2021) Morphological and molecular evidence supports taxonomic separation of tropical spiders of medicinal importance Phoneutria depilata (Strand, 1909) and P. boliviensis (FO Pickard-Cambridge, 1897) (Araneae, Ctenidae). Zookies 1022: 13-50. https: /
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