The amazing ZalSa clade: a compendium of their phylogeny, biogeography and perspectives ahead

ABEL PÉREZ GONZÁLEZ

Barcelona

Congreso; XXXVII Annual meeting of the Willi Hennig Society; 2018

The ?ZalSa? clade includes the opilionid superfamilies Samooidea and Zalmoxoidea. Due to the highly plesiomorphic exomorphology most ZalSa taxa were originally described as Phalangodidae, the basal-most clade of Grassatores. Detailed morphological studies, mainly on genital morphology, and molecular phylogenies have played a decisive role in the new systematic arrangement of Opiliones. This ?systematic revolution? is visible in the ZalSa clade where many families have been re-diagnosed, newly ranked or newly proposed in the last decades. ZalSa has been consistently recovered in phylogenetic studies, nevertheless its internal relationships continue to change with the increase of taxon sampling. The results of previous and ongoing phylogenetic studies show an amazing and complex evolution in the Neotropics with several clades that could be recognized as a new family. Nevertheless, the phylogeny of old world Samooidea remains practically unknown with an undocumented high diversity in Africa and Madagascar. The morphological evolution is very intriguing, and several clades have converged upon various exomorphology characters some of them sexually dimorphic. The group is also an exceptional model for biogeographical studies with a remarkable ancient Trans-pacific dispersal event, disjunct troglobitic lineages distributed across the arid diagonal of South America, and lineages with Antillean radiations that serve as ideal subjects to test the GAARLandia land bridge hypothesis.