First molecular phylogeny of the major clades of Pseudoscorpiones (Arthropoda: Chelicerata) Jérôme Murienne a,c, * , Mark S. Harvey b , Gonzalo Giribet a a Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA b Department of Terrestrial Zoology, Western Australian Museum, Locked Bag 49, Welshpool, WA 6986, Australia c UMR 5202 CNRS, Département Systématique et Evolution, case 50, Muséum national d’Histoire naturelle, 45 rue Buffon, 75005 Paris, France article info Article history: Received 13 March 2008 Revised 27 May 2008 Accepted 5 June 2008 Available online 17 June 2008 Keywords: Arachnida Venom gland evolution Pseudoscorpions abstract The phylogenetic relationships of the major lineages of the arachnid order Pseudoscorpiones are investi- gated for the first time using molecular sequence data from two nuclear ribosomal genes and one mito- chondrial protein-encoding gene. The data were analyzed using a dynamic homology approach with the new program POY v.4 under parsimony as the optimality criterion. The data show monophyly of Pseudo- scorpiones as well as many of its superfamilies (Feaelloidea, Chthonioidea, Cheiridioidea and Sternopho- roidea), but not for Neobisiodea or Garypoidea. Cheliferoidea was not monophyletic either due to the position of Neochelanops, which grouped with some garypoids. In all the analyses, Feaelloidea constituted the sister group to all other pseudoscorpions; Chthonioidea is the sister group to the remaining families, which constitute the group Iocheirata sensu Harvey—a clade including pseudoscorpions with venom glands within the pedipalpal fingers. This phylogenetic pattern suggests that venom glands evolved just once within this order of arachnids. Ó 2008 Elsevier Inc. All rights reserved. 1. Introduction The arachnid order Pseudoscorpiones is one of the oldest lineages of terrestrial organisms with the group represented in Middle Devonian shales from the Panther Mountain Formation of New York (Shear et al., 1989, 1991). The order is currently repre- sented by 3385 named species which are placed in 439 genera and 25 families (Harvey, 2007, 2008) which contributes, however, only a small proportion of total named arachnid diversity due to the large numbers of named spiders and mites (Harvey, 2007), but rivals in numbers with the more familiar scorpions and harvestmen (Coddington et al., 2004). Pseudoscorpions occupy virtually all terrestrial habitats on earth, but are most common in leaf litter, soil or under bark of trees and logs. They can be frequently found in caves, and many species occur in sea-shore littoral habitats. They are generally quite small with the body lengths of adults ranging from 0.5 to 5 mm; however, some species attain lengths surpassing 1 cm. Pseudoscor- pions are free-living, but some unusual strategies are adopted by some taxa, of which the most notable is their tendency towards phoretic behavior where individuals attach themselves using their pedipalps to other organisms such as other arachnids, insects, mammals or birds, which may facilitate transport to different hab- itats (Vachon, 1940; Beier, 1948; Muchmore, 1971; Zeh and Zeh, 1992a,b; Judson, 2005). Reproduction occurs via the deposition of a spermatophore on the substrate by the male, which is then picked up by the female. Spermatophore deposition is usually per- formed by males in the absence of females, but active courtship is performed between pairs within the superfamily Cheliferoidea (Weygoldt, 1969). Many pseudoscorpions have venom glands within the pedipalpal fingers, thus representing only one of three arachnid orders with venomous capabilities, apart from spiders and scorpions. The venomous pseudoscorpion clade was identified and named by Harvey (1992). The order Pseudoscorpiones is clearly monophyletic and sup- ported by several apomorphies (Shultz, 2007) of which the only features unique to the group are the presence of silk glands dis- charging via the movable cheliceral finger, and the presence of a serrula exterior and serrula interior on the cheliceral fingers. Pseudoscorpiones have, for over a century, been regarded as the sister group to Solifugae which are included in the clade Haplocne- mata (Börner, 1904; Weygoldt and Paulus, 1979; Shultz, 1990; Wheeler and Hayashi, 1998; Giribet et al., 2002; Shultz, 2007) or Apatellata (van der Hammen, 1986, 1989). Haplocnemata have been retrieved as sister group to Scorpiones forming the clade Novogenuata (Shultz, 1990; Wheeler and Hayashi, 1998; Giribet et al., 2002); as sister group to Opiliones (Giribet et al., 2002); as sister group to Scorpiones + Opiliones (=Stomothecata), forming 1055-7903/$ - see front matter Ó 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.ympev.2008.06.002 * Corresponding author. Address: UMR 5202 CNRS, Département Systématique et Evolution, case 50, Muséum national d’Histoire naturelle, 45 rue Buffon, 75005 Paris, France. E-mail addresses: jmurienne@oeb.harvard.edu (J. Murienne), mark.harvey@ museum.wa.gov.au (M.S. Harvey), ggiribet@oeb.harvard.edu (G. Giribet). Molecular Phylogenetics and Evolution 49 (2008) 170–184 Contents lists available at ScienceDirect Molecular Phylogenetics and Evolution journal homepage: www.elsevier.com/locate/ympev