Cryptic diversity in the whip spider genus Paraphrynus (Amblypygi: Phrynidae): integrating morphology, karyotype and DNA.

The whip spider (Amblypygi) genus Paraphrynus Moreno, 1940 is distributed from the southern U.S.A. to the Greater Antilles and northern South America. Mexico is the diversity hotspot of the genus where many morphologically similar species occur, often in close geographical proximity. The present contribution aimed to resolve the diversity and phylogenetic relationships within the aztecus group of species, which includes the type species, Paraphrynus mexicanus (Bilimek, 1867), resulting in the description of a new species from Mexico, Paraphrynus pseudomexicanus sp.n. This is the first study to integrate morphology, karyotype, and DNA for species delimitation in whip spiders. Karyotype data have not been previously used for the taxonomy of these arachnids. Sequence analysis included seven species of the aztecus group, two other species of Paraphrynus, and an outgroup species of the putative sister genus, Phrynus Lamarck, 1801. Two nuclear genes (18S rDNA and 28S rDNA) and three mitochondrial genes (12S rDNA, 16S rDNA, and Cytochrome c Oxidase Subunit I) were analyzed phylogenetically. Hypotheses of karyotype evolution of Paraphrynus are consistent with conclusions based on the morphological and molecular data. The ancestral karyotype of the aztecus group probably consisted of a relatively low number of bi-armed chromosomes. Diploid numbers decreased by cycles consisting of inversion and consequent centric fusion during the evolution of the clade comprising P. mexicanus and P. pseudomexicanus.