Trogloraptor is a genus of large spiders found in the caves of southwestern Oregon. It is the sole genus in the family Trogloraptoridae, and includes only one species, Trogloraptor marchingtoni. These spiders are predominantly yellow-brown in color with a maximum leg span of 3 in (7.6 cm). They are remarkable for having hook-like claws on the raptorial last segments of their legs.
The spiders were first collected in 2010 by Geo Graening, Neil Marchington, Ron Davis, and Daniel Snyder, cave conservationists from the Western Cave Conservancy. They were described in 2012 by a research team consisting of arachnologists Charles Griswold, Tracy Audisio, and Joel Ledford of the California Academy of Sciences. The male holotype was recovered from the M2 cave near Grants Pass, Oregon on July 29, 2010. The female holotype was recovered from a cave in Josephine County, Oregon on September 16, 2010.
Griswold, the lead researcher of the study, believes that the discovery might explain the legends of giant cave spiders in the area. The discovery is also historic because only two other new spider families have been described since 1990. The American arachnologist Norman Platnick commented that the discovery was "...as fascinating to arachnologists as the discovery of a new dinosaur is to paleontologists."
Trogloraptor includes only one species, Trogloraptor marchingtoni, and is the only genus in the monotypic family Trogloraptoridae. The family is believed to be a primitive member of the six-eyed spider superfamily Dysderoidea. Their closest living relatives are the goblin spiders of the family Oonopidae. However, Trogloraptor exhibits several unique features, like primitive respiratory systems, that justify their separation to a different family. The family probably diverged from other spiders about 130 million years ago, which would make it another notable relict taxon from North America.
Additional live specimens recovered in 2010 and 2011 from Oregon were all found deep inside dark caves. None have been found in the exterior surrounding the mouths of the caves. A single juvenile specimen, however, has been recovered from the understory debris of old growth redwood forests of northwest California. This specimen has different markings than T. marchingtoni and may represent a new undescribed species.
The family Trogloraptoridae may have had a wider distribution range given that redwood forests encompassed a far greater area in North America during the Pliocene (about 5 mya). Other species may still be present in caves throughout the United States.
Adult Trogloraptor have six eyes and a body length of about 7 to 10 mm (0.28 to 0.39 in) in males and 8 to 10 mm (0.31 to 0.39 in) in females. With its legs outstretched, the spider can reach up to 3 in (7.6 cm) in length.
The entire body is yellow-brown in color, except for a dark brown V-shaped mark on the cephalothorax, the orange-brown chelicerae, and the purple-brown opisthosoma with a series of light-colored faint chevron markings. The cephalothorax carapace is pear-shaped with a heart-shaped sternum. The abdomen is oval and sparsely covered with small bristles (setae). The males possess enlarged piriform pedipalps. They spin primitive webs with only a few strands, from which they hang from the roof of caves.
The spiders are unique in the flexible and teethed hook-like claws on the last segments (tarsus) of their legs. These elongated claws resemble those of spiders in the family Gradungulidae of Australia and New Zealand, but the two families are only distantly related. Hooked tarsal claws are also present to a lesser extent in the unrelated genera Doryonychus of Tetragnathidae, Hetrogriffus of Thomisidae, and Celaenia of Araneidae.
Griswold et al. believe that the claws may have a significant function in capturing prey. Similar to the Nelson cave spider of New Zealand (Spelungula cavernicola, a gradungulid), Trogloraptor probably dangles in the cave roof with legs outstretched, snatching at passing flying insects with their claws. However their exact prey remains unknown. Captured live specimens were raised in climate-controlled laboratory conditions in an effort to find out. These specimens were offered moths, crickets and other spiders as food; but these were declined and the specimens eventually starved after two weeks. This may indicate a preference for very specific prey.
Like most spiders, Trogloraptor possess venom glands. However, they are not known to be harmful to humans. The spiders themselves are very shy and unaggressive. When encountered, their reaction is primarily to escape illumination as quickly as possible.
- Griswold, C.; Audisio, T.; Ledford, J. (2012). "An extraordinary new family of spiders from caves in the Pacific Northwest (Araneae, Trogloraptoridae, new family)". ZooKeys 215: 77–102. doi:10.3897/zookeys.215.3547.
- Main, Douglas (August 17, 2012). "Rare Discovery: Hook-Legged Spider Found in Oregon Cave". OurAmazingPlanet. http://www.ouramazingplanet.com/3358-new-spider-family-discovered.html. Retrieved August 18, 2012.
- Daisy Yuhas (August 17, 2012). "Scientists Discover New Cave Spider Species... with Claws!". Scientific American. http://www.scientificamerican.com/gallery_directory.cfm?photo_id=1AC9C7D1-F12B-0179-DF7FE9529D8EF93D. Retrieved August 18, 2012.
- Perlman, David (August 15, 2012). "New spider family identified in Oregon". San Francisco Chronicle. http://www.sfgate.com/science/article/New-spider-family-identified-in-Oregon-3791910.php.
- Gillespie, R. G. (1991). "Predation Through Impalement of Prey: The Foraging Behavior of Doryonychus raptor (Araneae, Tetragnathidae)". Psyche: A Journal of Entomology 98 (4): 337–350. doi:10.1155/1991/84789. http://downloads.hindawi.com/journals/psyche/1991/084789.pdf.
- "Biologen entdecken neue Spinnen-Familie mit Klauen" (in German). Spiegel Online. August 17, 2012. http://www.spiegel.de/wissenschaft/natur/trogloraptor-forscher-entdeckten-neue-spinnenart-in-den-usa-a-850623.html. Retrieved August 18, 2012.