Studying sources of incongruence in arthropod molecular phylogenies: Sea spiders (Pycnogonida) as a case study

Abstract

This study; 1 [1]; 2 [16]; 3 [17]. **Species not included at first in the multi-marker analyses. MNHN: specimen and DNA preserved in the collection of UMR 7205 (MNHN). Chimera used for outgroup taxa: a L. variegatus; b L. sp.; c L. obscurus; d L. forficatus; e Orthoporus sp.; f Unixenus mjobergi; g Thyropygus sp.; h Squilla empusa; i Kempina mikado; j T. longicaudatus; k T. sp.; l T. australiensis; m Locusta migratoria; n Gomphocerinae sp.; o Tenebrio molitor; p Tenebrio sp.; q Tribolium castaneum.

Basal articulation of the palps and ovigers in Antarctic Colossendeis (Pycnogonida; Colossendeidae)

“…Both palpal and ovigeral basal parts seems to have undergone similar patterns of evolution. According to the described palpal and ovigeral article reduction in the three basal-most extant families in Pycnogonida: Austrodecidae, Pycnogonidae, and Colossendeidae [2,5], the Colossendeiidae retain the primitive form of palp and oviger ( [4]: 305), with similar expression in males and females.…”

“…Some contributions based on molecular data suggested that the Austrodecidae (the only family included in Stiripasterida) is the basal-most group, being the sister group of the remaining extant families (all them in Eupantopodida) [2,5]. In this last clade, including 95 % of the extant pycnogonids species, the families Pycnogonidae and Colossendeidae are the basal-most groupings.…”

Nucleotide Composition of CO1 Sequences in Chelicerata (Arthropoda): Detecting New Mitogenomic Rearrangements

“…Each of the three markers (18S, 28S, and CO1) was amplified and sequenced using the primers employed in previous studies (Arabi et al 2010;Hassanin et al 2005), plus three new specific primers for the 28S (R4S: 5 0 -GAAGACCCTGTTGAGCTTGACT-3 0 /R4AS: 5 0 -GATTCTGACTTAGAGGCGTTCA-3 0 ) and CO1 (U1sco: 5 0 -TCWACDAATCATAAGGATATTGGDAC-3 0 ). PCR reactions were carried out in a 30-ll final volume using the following conditions: 109 reaction buffer with MgCl 2 , 3 ll; dNTP mix (6.6 mM), 3 ll; primers (10 lM), 1.5 ll; H 2 O, 19.3 ll; Sigma Red Taq DNA polymerase, 0.70 ll, and DNA template, 1 ll.…”

“…More specifically, Chelicerata can be divided into 12 orders: Pantopoda (Pycnogonida), Xiphosura (Merostomata), and the Arachnida orders Acari, Amblypygi, Araneae, Opiliones, Palpigradi, Pseudoscorpiones, Ricinulei, Scorpiones, Solifugae, and Uropygi (Shultz 2007;Weygoldt and Paulus 1979). In this report, we focused on the subphylum Chelicerata because previous studies have shown that several unrelated taxa in this clade have a mtDNA characterized by a global reversal of strand compositional bias, including one sea spider (Achelia bituberculata : Arabi et al 2010), opisthothele spiders (Argiope, Caligosa, Habronattus, Hypochylus, Nephila, and Ornithoctonus), scorpions (Buthus, Centruroides, Euscorpius, Mesobuthus, and Uroctonus) (Hassanin 2006;Hassanin et al 2005;Masta et al 2009), and two unrelated species of mites (Varroa destructor : Hassanin 2006 and Steganacarus magnus: Domes et al 2008). These observations suggest that many mitogenomic inversions occurred during the evolutionary history of Chelicerata.…”

“…In a recent paper on sea spiders, Arabi et al (2010) have shown that the AT and CG skews at third synonymous positions of CO1 sequences can be used to detect the two kinds of mitogenomic inversions. That is, by comparing the gene order of two pycnogonid species-Achelia bituberculata (Park et al 2007) and Nymphon gracile (Podsiadlowski and Braband 2006)-with the deduced organization of the common ancestor of Chelicerata, these authors related reverse strand biases in CO1 to (i) a global reversal of asymmetric mutational constraints, associated with the inversion of the CR in Achelia, versus (ii) a local reversal of asymmetric mutational constraints due to the inversion of a genomic fragment including CO1, in Nymphon.…”