Across Lydekker’s Line – first report of mite harvestmen (Opiliones : Cyphophthalmi : Stylocellidae) from New Guinea
Ronald M. Clouse A B and Gonzalo Giribet AA Department of Organismic & Evolutionary Biology and Museum of Comparative Zoology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, USA.
B Corresponding author. Email: clouse@fas.harvard.edu
Invertebrate Systematics 21(3) 207-227 https://doi.org/10.1071/IS06046
Submitted: 3 November 2006 Accepted: 10 April 2007 Published: 27 June 2007
Abstract
Opiliones (harvestmen) in the suborder Cyphophthalmi are not known to disperse across oceans and each family in the suborder is restricted to a clear biogeographic region. While undertaking a revisionary study of the South-east Asian family Stylocellidae, two collections of stylocellids from New Guinea were noted. This was a surprising find, since the island appears never to have had a land connection with Eurasia, where the rest of the family members are found. Here, 21 New Guinean specimens collected from the westernmost end of the island (Manokwari Province, Indonesia) are described and their relationships to other cyphophthalmids are analysed using molecular sequence data. The specimens represent three species, Stylocellus lydekkeri, sp. nov., S. novaguinea, sp. nov. and undescribed females of a probable third species, which are described and illustrated using scanning electron microscope and stereomicroscope photographs. Stylocellus novaguinea, sp. nov. is described from a single male and it was collected with a juvenile and the three females of the apparent third species. Molecular phylogenetic analyses indicate that the new species are indeed in the family Stylocellidae and they therefore reached western New Guinea by dispersing through Lydekker’s line – the easternmost limit of poor dispersers from Eurasia. The New Guinean species may indicate at least two episodes of oceanic dispersal by Cyphophthalmi, a phenomenon here described for the first time. Alternatively, the presence in New Guinea of poor dispersers from Eurasia may suggest novel hypotheses about the history of the island.
Additional keywords: Arachnida, biogeography, dispersal, molecular data, phylogeny.
Acknowledgements
We are indebted to Peter J. Schwendinger for providing access to the new species and to Louis Deharveng, Peter J. Schwendinger, Alex Riedl and Cahyo Rahmadi for providing the material for the molecular study. Janet Beccaloni (BMNH), Norman I. Platnick and Lorenzo Prendini (AMNH), Nikolaj Scharff (ZMUC), Peter J. Schwendinger (MHNG) and James Hogan (Oxford Museum) sent type specimens for study. Sarah Boyer, two anonymous reviewers and Camilla Myers provided useful comments on an earlier draft of this manuscript. Richard Schalek (CNS, Harvard University) provided SEM support. Mary Sears, Ronnie Broadfoot and Dorothy Barr of the Ernst Mayr Library (MCZ) helped locate literature. This material is based on work supported by the National Science Foundation under Grant No. 0236871.
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