An extraordinary new family of spiders from caves in the Pacific Northwest (Araneae, Trogloraptoridae, new family)

Abstract The new spider genus and species Trogloraptor marchingtoni Griswold, Audisio & Ledford is described as the type of the new family Trogloraptoridae. The oblique membranous division of the basal segment of the anterior lateral spinnerets of Trogloraptor suggests that this haplogyne family is the sister group of the other Dysderoidea (Dysderidae, Oonopidae, Orsolobidae and Segestriidae). Trogloraptor is known only from caves and old growth forest understory in the Klamath-Siskiyou region of Oregon and California.


Introduction
The spider fauna of North America is a rich one, with at least 68 families including 569 genera and comprising more than 3700 species . In the last generation significant progress has been made at understanding this fauna. For example, continent-wide taxonomic treatments of major families have appeared, e.g., Araneidae (Levi 1968 to present), Gnaphosidae (Platnick 1975 and subsequent) and Theridiidae (Levi 1953 and subsequent), the largest genera of jumping spiders (Salticidae) have been revised, i.e., Habronattus (Griswold, 1987), Pelegrina (Maddison, 1996) and Phidippus (Edwards, 2004) and the Canadian government has produced a series of guides to Canadian spiders, e.g., Dondale and Redner (1982). Perhaps most important was Vince Roth's key to families and genera (Roth 1982), which has been updated as the comprehensive and profusely illustrated Spiders of North America: an identification manual . This makes it relatively easy to identify to family and even to genus any spider from America north of Mexico. Nevertheless, there are still surprises in store in this well known region, especially in remote or inaccessible places, such as caves. The troglofauna of the Pacific Northwest is poorly surveyed and several arachnid groups are known to have multiple undescribed species (Ledford et al. in prep.). In this paper we describe a remarkable haplogyne spider that fits into no known family, living or extinct (Jocqué and Dippenaar-Schoeman 2006;Penney and Selden 2011). Trogloraptor marchingtoni gen. et sp. n., type of the new family Trogloraptoridae, is described from caves in the Pacific Northwest, and a diagnostic table (Table 1) and character discussion are presented to distinguish it from all other spider families.

Materials and methods
Species descriptions refer to a single adult individual for each sex, which is identified as a type or by the locality at which it was collected. All measurements are in millimeters and quantify the size of a structure at its widest or longest point. A section reporting the variation in the most conspicuous and variable features follows each description and represents multiple individuals (n), encompassing the full range in overall size.
Prior to examination with a Leo 1450VP Scanning Electron Microscope, all structures were cleaned with a fine brush and critical point dried. Spinneret preparations followed the methods of Griswold et al. (2005) consisting of a brief cleaning in an ultrasonicator and a gentle squeeze of the abdomen using forceps locked in place with a paperclip followed by overnight immersion in 100% ethanol in order to extend and separate the spinnerets. Large structures were examined using a Leica MZ 12.5 or MZ 16 stereomicroscope. Vulvae were carefully excised and placed in a pancreatin solution for 24-48 hours to digest extraneous tissue (Álvarez-Padilla and Hormiga 2007) then placed in water and manually cleaned. Light micrographs were prepared using a Nikon DXM1200 digital camera attached to a Leica MZ 16 stereomicroscope or a Leica DM 4000 compound microscope; multiple, stacked images were montaged using the program Helicon Focus®. The male pedipalp was checked for haematodochal expansion by placing it into boiling water for 2-3 minutes in a vial of hot 92% lactic acid solution (Sigma Aldrich, St Louis MO, USA), after which the pedipalp was transferred to distilled water (Ledford et al. 2011). The internal anatomy of the pedipalpal bulb and course of the reservoir were examined by immersing it in a solution of methyl salicylate   (Miller et al. 2009). Abbreviations used in the text and figures are as follows: AC, aciniform gland spigots; ALE, anterior lateral eyes; ALS, anterior lateral spinnerets; AME, anterior median eyes; AT, atrium; BM, Brent McGregor; CG, Charles Griswold; ITC, inferior tarsal claw; JL, Joel Ledford; MAP, major ampullate gland spigot(s); mAP, minor ampullate gland spigot(s); Nu, nubbin (an aborted spigot); OAL, ocular area length; PER, posterior eye row; PI, piriform gland spigots; PLE, posterior lateral eyes; PLS, posterior lateral spinnerets; PME, posterior median eyes; PMS, posterior median spinnerets; RC, receptaculum; RD, Ron Davis; STC, superior tarsal claw(s). All specimens are deposited in the California Academy of Sciences (CAS).

Taxonomy
Synapomorphies. The extraordinary, subsegmented raptorial leg tarsi are unique among spiders and clearly autapomorphic for the family. Etymology. The generic name refers to the cave habitat and raptorial tarsi. Diagnosis. By the characters of the family. Synapomorphies. As for the family.
Natural history. This species has been collected in the dark zone of caves, hanging beneath a few strands of silk that are attached to the cave roof (Figs 5-8). Boulders and rotting logs were searched near the entrance to M2 Cave without finding any Trogloraptor. Nothing has been observed of its predatory or mating behavior. Living specimens were reared in climate controlled conditions and constructed a loose tangle of web from which they hung beneath. Multiple attempts to feed the specimens a variety of prey items failed, which may indicate a preference for specific prey.   H. Wood and F. Álvarez-Padilla, 3 juveniles, CASENT9047599;Lake Cave near No Name Cave, 9.05 km S Wilderville, 13 July 2011, N. Marchington, T. Audisio, C. Griswold, J. Ledford, D. Ubick, H. Wood and F. Álvarez-Padilla, 1♂ (molted to maturity in captivity) CASENT9047600; Chapman Cave, 12 July 2011, N. Marchington, 2 juveniles, CASENT9039436.
Note. A juvenile Trogloraptor specimen has been collected under debris in old growth redwood forest in far northwest California. The markings of this juvenile differ from the cave species, T. marchingtoni. The northwest California specimen has dusky markings laterally on leg femora, a dusky Y marking extending back from the PLE to the posterior

Conclusions
Western North America, especially the Klamath-Siskiyou region of northern California and southern Oregon is rich in biodiversity, particularly with respect to its endemic plants and invertebrates (Myers et al. 2000). This area is particularly notable for relicts, i.e., primitive relatives of otherwise widespread taxa. The coast redwood, Sequoia sempervirens, is a notable example. The coastal tailed frog (Ascapus truei Stejneger, 1899, As-caphidae) and mountain beaver (Aplodontia rufa (Rafinesque, 1817)), Aplodontiidae) are considered the world's most primitive living frog and rodent, respectively (Nielson et al. 2001;Adkins et al. 2001). Primitive arachnids and myriapods also occur in the Pacific Northwest. Shear and Leonard (2003) described the new millipede family Microlympiidae for a minute species from the Olympic Mountains of Washington. Several families of Travunioid harvestman are found here (Briggs 1971). The pseudoscorpion genera Pseudogarypus (Pseudogarypidae), Oreolpium (Garypinidae) and Pseudotyrannochthonius (Pseudotyrannochthoniidae) all have relict distributions in the Pacific Northwest. These are also among the most ancient of pseudoscorpion lineages (Harvey 1998;Harvey and Štáhlavský 2009). Atypoid mygalomorphs (Coyle 2005a(Coyle , 2005bRamirez and Chi 2004), Hypochilidae (Hedin 2001;Paquin and Hedin 2005), the 8-eyed caponiid Calponia (Ubick, 2005) and the cribellate leptonetid genus Archoleptoneta (Ledford and Griswold 2010) comprise relatively ancient spider lineages characterized by the retention of ancestral character states. If Trogloraptoridae are the most primitive living members of the Dysderoidea we have another case of a notable relict from Western North America. If such a large and bizarre spider could have gone undetected for so long, who knows what else may lurk undiscovered in this remarkable part of the world.