10.5061/DRYAD.T1G1JWSZ4
Ballesteros, Jesús
University of Wisconsin-Madison
Santibáñez López, Carlos
0000-0001-6062-282X
University of Wisconsin-Madison
Kováč, Ľubomír
0000-0001-8194-2128
University of Pavol Jozef Šafárik
Gavish-Regev, Efrat
Hebrew University of Jerusalem
Sharma, Prashant
0000-0002-2328-9084
University of Wisconsin-Madison
Ordered phylogenomic subsampling enables diagnosis of systematic errors in
the placement of the enigmatic arachnid order Palpigradi
Dryad
dataset
2019
2019-11-27T00:00:00Z
2019-11-27T00:00:00Z
en
640290766 bytes
3
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
The miniaturized arachnid order Palpigradi has ambiguous phylogenetic
affinities, due to its odd combination of plesiomorphic and derived
morphological traits. This lineage has never been sampled in phylogenomic
datasets because of its small body size and fragility of most species, a
sampling gap of immediate concern to recent disputes over arachnid
monophyly. To redress this gap, we sampled a population of the
cave-inhabiting species Eukoenenia spelaea from Slovakia and inferred its
placement in the phylogeny of Chelicerata using dense phylogenomic
matrices of up to 1450 loci, drawn from high-quality transcriptomic
libraries and complete genomes. The complete matrix included exemplars of
all extant orders of Chelicerata. Analyses of the complete matrix
recovered palpigrades as the sister group of the long-branch order
Parasitiformes (ticks) with high support. However, sequential deletion of
long-branch taxa revealed that the position of palpigrades is prone to
topological instability. Phylogenomic subsampling approaches that
maximized taxon or dataset completeness recovered palpigrades as the
sister group of camel spiders (Solifugae), with modest support. While this
relationship is congruent with the location and architecture of the coxal
glands, a long-forgotten character system that opens in the pedipalpal
segments only in palpigrades and solifuges, we show that nodal support
values in concatenated supermatrices can mask high levels of underlying
topological conflict in the placement of the enigmatic Palpigradi.