''Trogloraptor'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of large

spider Spiders (order (biology), order Araneae) are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude spider silk, silk. They are the largest order of arachnids and ran ...

s found in the

cave Caves or caverns are natural voids under the Earth's Planetary surface, surface. Caves often form by the weathering of rock and often extend deep underground. Exogene caves are smaller openings that extend a relatively short distance undergrou ...

s of southwestern

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

. It is the sole genus in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Trogloraptoridae, and includes only one

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

, ''Trogloraptor marchingtoni''. These spiders are predominantly yellow-brown in color with a maximum leg span of . They are remarkable for having hook-like claws on the

raptorial In biology (specifically the anatomy of arthropods), the term ''raptorial'' implies much the same as ''predatory'' but most often refers to modifications of an arthropod leg, arthropod's foreleg that make it function for the grasping of prey whi ...

last segments of their legs. ''Trogloraptor'' belongs to one of only three new spider families described since 1990. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

is in honor of the amateur cave biologist and deputy sheriff Neil Marchington.

Discovery

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 Arachnology is the science, scientific study of arachnids, which comprise spiders and related invertebrates such as scorpions, Pseudoscorpionida, pseudoscorpions, Opiliones, harvestmen, Tick, ticks, and mites. Those who study spiders and other a ...

Charles Griswold, Tracy Audisio and Joel Ledford of the

California Academy of Sciences The California Academy of Sciences is a research institute and natural history museum in San Francisco, San Francisco, California, that is among the largest List of natural history museums, museums of natural history in the world, housing over ...

. The male

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

was recovered from the M2 cave near

Grants Pass Grants Pass is a city in and the county seat of Josephine County, Oregon, United States. The city is located on Interstate 5 in Oregon, Interstate 5, northwest of Medford, Oregon, Medford, along the Rogue River (Oregon), Rogue River. The populatio ...

, Oregon, on July 29, 2010. The female holotype was recovered from a cave in

Josephine County Josephine County is one of the 36 counties in the U.S. state of Oregon. As of the 2020 census, the population was 88,090. The county seat is Grants Pass. The county is named after Virginia Josephine Rollins (1834–1912), a settler who was t ...

, Oregon, on September 16, 2010. Lead researcher Griswold claimed that ''Trogloraptor'' might explain the legends of giant cave spiders in the area. The discovery is also notable because only two other new spider families have been described since 1990. The American arachnologist

Norman Platnick Norman Ira Platnick (December 30, 1951 – April 8, 2020) was an American biological systematist and arachnologist. At the time of his death, he was a professor emeritus of the Richard Gilder Graduate School and Peter J. Solomon Family Curator E ...

commented that it was "...as fascinating to arachnologists as the discovery of a new

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

is to

paleontologist Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geolo ...

s."

Taxonomy

''Trogloraptor'' includes only one species, ''Trogloraptor marchingtoni'', and is the only genus in the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

family Trogloraptoridae. It was initially suggested that ''Trogloraptor'' was a primitive member of the six-eyed spider

superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...

Dysderoidea The Dysderoidea are a clade or superfamily of araneomorph spiders. The monophyly of the group, initially consisting of the four families Dysderidae, Oonopidae, Orsolobidae and Segestriidae, has consistently been recovered in phylogenetic stud ...

. However, ''Trogloraptor'' exhibits several unique features, including primitive

respiratory system The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies grea ...

s, that justify its assignment to a separate family. The family probably diverged from other spiders about 130

million years ago Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds. Usage Myr is in common use in fields such as Earth science and cosmology. Myr is also used w ...

, which would make it another notable

relict A relict is a surviving remnant of a natural phenomenon. Biology A relict (or relic) is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas. Geology and geomorphology In geology, a r ...

taxon In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

from

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

. A 2014 study based on

ribosomal DNA The ribosomal DNA (rDNA) consists of a group of ribosomal RNA encoding genes and related regulatory elements, and is widespread in similar configuration in all domains of life. The ribosomal DNA encodes the non-coding ribosomal RNA, integral struc ...

found that ''Trogloraptor'' fell outside the Dysderoidea and concluded that it should not be included in this

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

. The

is in honor of Neil Marchington. The generic name ''Trogloraptor'' means "cave robber", in reference to the spider's habitat and hooked raptorial tarsi.

Distribution

Additional live specimens recovered in 2010 and 2011 from Oregon were all found deep inside caves. Except for a single juvenile specimen recovered from the

understory In forestry and ecology, understory (American English), or understorey (English in the Commonwealth of Nations, Commonwealth English), also known as underbrush or undergrowth, includes plant life growing beneath the Canopy (biology), forest ca ...

debris of

old growth An old-growth forest or primary forest is a forest that has developed over a long period of time without disturbance. Due to this, old-growth forests exhibit unique ecological features. The Food and Agriculture Organization of the United Natio ...

redwood Sequoioideae, commonly referred to as redwoods, is a subfamily of Pinophyta, coniferous trees within the family (biology), family Cupressaceae, that range in the Northern Hemisphere, northern hemisphere. It includes the List of superlative tree ...

forests of northwest

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

, none have been found outside the caves. This specimen has different markings than ''T. marchingtoni'' and may represent a new undescribed species. The family Trogloraptoridae may have had a wider distribution given that

redwood forest ''Sequoia sempervirens'' ()''Sunset Western Garden Book,'' 1995: 606–607 is the sole living species of the genus '' Sequoia'' in the cypress family Cupressaceae (formerly treated in Taxodiaceae). Common names include coast redwood, coasta ...

s encompassed a far greater area in

during the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58mya). Other species may still be present in other caves.

Description

Adult ''Trogloraptor'' have six eyes and a body length of about in males and in females. With its legs outstretched, the spider can reach up to in length. The entire body is yellow-brown, except for a dark brown V-shaped mark on the

cephalothorax The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...

, the orange-brown

chelicera The chelicerae () are the mouthparts of the subphylum Chelicerata, an arthropod group that includes arachnids, horseshoe crabs, and sea spiders. Commonly referred to as "jaws", chelicerae may be shaped as either articulated fangs, or as a type ...

e, and the purple-brown abdomen (

opisthosoma The opisthosoma is the posterior part of the body in some arthropods, behind the prosoma ( cephalothorax). It is a distinctive feature of the subphylum Chelicerata (arachnids, horseshoe crabs and others). Although it is similar in most respects ...

) with a series of faint light-colored

chevron Chevron (often relating to V-shaped patterns) may refer to: Science and technology * Chevron (aerospace), sawtooth patterns on some jet engines * Chevron (anatomy), a bone * '' Eulithis testata'', a moth * Chevron (geology), a fold in rock la ...

markings. The

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

is pear-shaped with a heart-shaped

sternum The sternum (: sternums or sterna) or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major bl ...

. The abdomen is oval and sparsely covered with small bristles (

setae In biology, setae (; seta ; ) are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Depending partly on their form and function, protostome setae may be called macrotrichia, chaetae ...

). The males possess enlarged piriform

pedipalp Pedipalps (commonly shortened to palps or palpi) are the secondary pair of forward appendages among Chelicerata, chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to ...

s. 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 Gradungulidae, also known as large-clawed spiders, is a spider family endemic to Australia and New Zealand. They are medium to large-sized haplogyne spiders with three claws and two pairs of book-lungs similar to Mygalomorphae. Some species buil ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

and

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

, but the two families are only distantly related. Hooked tarsal claws are also present to a lesser extent in the unrelated genera ''

Doryonychus ''Doryonychus'' is a monotypic genus of Hawaiian long-jawed orb-weavers containing the single species, ''Doryonychus raptor''. It was first described by Eugène Louis Simon in 1900, and is known only from the Hawaiian island of Kauai. See also ...

'' of

Tetragnathidae Long-jawed orb weavers or long jawed spiders (Tetragnathidae) are a family of araneomorph spiders first described by Anton Menge in 1866. They have elongated bodies, legs, and chelicerae, and build small orb webs with an open hub with few, wide-s ...

, '' Hetrogriffus'' of

Thomisidae The Thomisidae are a family of spiders, including about 170 genera and over 2,100 species. The common name crab spider is often linked to species in this family, but is also applied loosely to many other families of spiders. Many members of thi ...

and ''

Celaenia ''Celaenia'' is a genus of South Pacific orb-weaver spiders first described by Tamerlan Thorell Tord Tamerlan Teodor Thorell (3 May 1830 – 22 December 1901) was a Sweden, Swedish arachnologist. Thorell studied spiders with Giacomo Doria a ...

'' of

Araneidae Orb-weaver spiders are members of the spider family Araneidae. They are the most common group of builders of spiral wheel-shaped webs often found in gardens, fields, and forests. The English word "orb" can mean "circular", hence the English name ...

Ecology

''Trogloraptor'' spin simple webs with only a few strands, hung from the roofs of caves. Griswold ''et al.'' stated 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 dangle upside down from their webs, snatching at passing flying insects with their claws. However their exact

prey Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not ki ...

remains unknown. Captured live specimens were raised in climate-controlled laboratory conditions in an effort to find out. These specimens were offered

moth Moths are a group of insects that includes all members of the order Lepidoptera that are not Butterfly, butterflies. They were previously classified as suborder Heterocera, but the group is Paraphyly, paraphyletic with respect to butterflies (s ...

crickets Crickets are orthopteran insects which are related to bush crickets and more distantly, to grasshoppers. In older literature, such as Imms,Imms AD, rev. Richards OW & Davies RG (1970) ''A General Textbook of Entomology'' 9th Ed. Methuen 886 ...

and other spiders as food; but these were declined and the specimens starved after two weeks. This may indicate a preference for very specific prey. Like most spiders, ''Trogloraptor'' possess

venom Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...

glands. However, the venom is not known to be harmful to humans. The spiders themselves are very shy and unaggressive. They immediately flee illumination.

References

External links

Western Cave Conservancy
{{Taxonbar, from=Q18642907 Cave spiders Araneomorphae Monotypic Araneomorphae genera Endemic spiders of the United States Biota of Oregon Fauna of the Northwestern United States