Integrative taxonomy and evolutionary history of a newly revealed spider Dysdera ninnii complex (Araneae: Dysderidae)
Abstrakt
The spider genus Dysdera is a species-rich clade of specialized woodlice predators, composed typically of complexes of sibling species. Here, we analyse the Dysdera ninnii complex, distinguishing three species that exhibit slight but constant differences in the morphology of their copulatory organs, and in their genetic background.
We describe two new species (Dysdera moravica sp. nov. and Dysdera microdonta sp. nov.). All three species occur in the region of north-eastern Italy, Slovenia, and northwesternCroatia.
Dysdera moravica sp. nov. expanded to central Europe. They possess the same diploid number and X0 sex chromosome determination.
The analysis of mitochondrial (cytochrome c oxidase subunit I, COI) and nuclear ribosomal (internal transcribed spacer 2, ITS2) DNA markers revealed two clades, one formed by D. ninnii and D. microdonta sp. nov., and a second by D. moravica sp. nov. Species of the first clade are not well defined by DNA markers.
We noticed only weak separation of maternally inherited COI, and even overlap of autosomally inherited ITS2 sequences. We suggest that either short speciation time, unfinished lineage sorting, or rare hybridization events caused this pattern.
In one sample of D. microdonta sp. nov. we detected the coxA gene of a Rickettsia species, which is the first record of this parasitic bacteria from the spider family Dysderidae. Dysdera microdonta sp. nov. occurs at higher altitudes than D. ninnii, and their distribution ranges form a long contact zone.
Remarkably, we did not record any overlap of the two distribution ranges, suggesting that the lack of a precopulatory interspecific barrier causes a loss of reproduction potential. We hypothesize that because of the unsolved interspecific barrier together with only tiny differences in morphology and COI sequences, and no differences in karyotypes and ITS2 sequences, the D. ninnii species complex is evolutionarily young.