title: Penis morphology in a Burmese amber harvestman.
abstract: A unique specimen of the fossil harvestman Halitherses grimaldii Giribet and Dunlop, 2005 (Arachnida: Opiliones) from the Cretaceous (ca. 99 Ma) Burmese amber of Myanmar reveals a fully extended penis. This is the first record of a male copulatory organ of this nature preserved in amber and is of special importance due to the age of the deposit. The penis has a slender, distally flattened truncus, a spatulate heart-shaped glans and a short distal stylus, twisted at the tip. In living harvestmen, the penis yields crucial characters for their systematics. Male genital morphology in H. grimaldii appears to be unique among the wider Dyspnoi clade to which this fossil belongs. The large eyes in the fossil differ markedly from other members of the subfamily Ortholasmatinae to which H. grimaldii was originally referred. Based on recent data, it has been argued that large eyes may be plesiomorphic for Palpatores (i.e. the suborders Eupnoi and Dyspnoi), potentially rendering this character plesiomorphic for the fossil too. Thus, the unique structure of the penis seen here, and the probable lack of diaphanous teeth, present in all other extant non-acropsopilionid Dyspnoi, suggest that H. grimaldii represents a new, extinct family of large-eyed dyspnoid harvestmen, Halithersidae fam. nov.; a higher taxon in amber diagnosed here on both somatic and genital characters.
authors.affiliation: Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstrasse 43, 10115, Berlin, Germany. jason.dunlop@mfn-berlin.de.
authors.forename: Jason A
authors.initials: JA
authors.lastname: Dunlop
authors.affiliation: Department of Geology and Paleontological Institute, University of Kansas, 1475 Jayhawk Boulevard, Lawrence, KS, 66045, USA.|Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, UK.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Selden
authors.affiliation: Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA, 02138, USA.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Giribet
mesh_terms: D018647:Amber; D000818:Animals; D001097:Arachnida / Q000033:anatomy & histology* / Q000145:classification*; D005580:Fossils; D008297:Male; D002052:Myanmar; D010413:Penis / Q000033:anatomy & histology; D013045:Species Specificity
chemical_list: D018647:Amber
keywords: Amber; Arachnida; Male genitalia; Myanmar; Opiliones; Systematics
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