title: Computed tomography recovers data from historical amber: an example from huntsman spiders.
abstract: Computed tomography (CT) methods were applied to a problematic fossil spider (Arachnida: Araneae) from the historical Berendt collection of Eocene (ca. 44-49 Ma) Baltic amber. The original specimens of Ocypete crassipes Koch and Berendt 1854 are in dark, oxidised amber and the published descriptions lack detail. Despite this, they were subsequently assigned to the living Pantropical genus Heteropoda Latreille, 1804 and are ostensibly the oldest records of huntsman spiders (Sparassidae) in general. Given their normally large size, and presumptive ability to free themselves more easily from resin, it would be surprising to find a sparassid in amber and traditional (optical) methods of study would likely have left O. crassipes as an equivocal record--probably a nomen dubium. However, phase contrast enhanced X-ray CT revealed exquisite morphological detail and thus 'saved' this historical name by revealing characters which confirm that it's a bona fide member both of Sparassidae and the subfamily Eusparassinae. We demonstrate here that CT studies facilitate taxonomic equivalence even between recent spiders and unpromising fossils described in older monographs. In our case, fine structural details such as eye arrangement, cheliceral dentition, and leg characters like a trilobate membrane, spination and claws, allow a precise referral of this fossil to an extant genus as Eusparassus crassipes (Koch and Berendt 1854) comb. nov.
authors.affiliation: Museum für Naturkunde, Leibniz Institute for Research on Evolution and Biodiversity at the Humboldt University Berlin, 10115 Berlin, Germany. jason.dunlop@mfn-berlin.de
authors.forename: Jason A
authors.initials: JA
authors.lastname: Dunlop
authors.forename: David
authors.initials: D
authors.lastname: Penney
authors.forename: Natalie
authors.initials: N
authors.lastname: Dalüge
authors.forename: Peter
authors.initials: P
authors.lastname: Jäger
authors.forename: Andrew
authors.initials: A
authors.lastname: McNeil
authors.forename: Robert S
authors.initials: RS
authors.lastname: Bradley
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Withers
authors.forename: Richard F
authors.initials: RF
authors.lastname: Preziosi
mesh_terms: D018647:Amber / Q000737:chemistry*; D000818:Animals; D005580:Fossils; D010163:Paleontology / Q000379:methods*; D013112:Spiders / Q000033:anatomy & histology* / Q000145:classification*; D014057:Tomography, X-Ray Computed
chemical_list: D018647:Amber