Phylogeny of the three brown banded land snail genus Humboldtiana (Pulmonata: Humboldtianidae)

The three brown banded land snail genus Humboldtiana (Pulmonata: Humboldtianidae) comprises 50 species of insular distribution from southern Texas to central México; its low vagility and dispersal potential are reflected in high levels of endemism and highly restricted distributions. A current scheme of classification recognizes six subgenera: Polyomphala, Oreades, Gymnopallax, Clydonacme, Aglotrochus, and Humboldtiana (the latter containing three species groups). In the present work, mitochondrial 16S rDNA and partial ITS region and ribosomal large subunit (5.8S + ITS-2 + 28S) sequences from 26 recognized species and 2 populations of unknown identity were studied to assess phylogenetic relationships of Humboldtiana species using parsimony and Bayesian analysis, and AU test was used to compare the different phylogenetic hypotheses. The same four major clades were recovered by both methods (buffoniana, queretaroana, montezumae and fortis), although none of them support the current scheme of classification, with the only exception being the subgenus Gymnopallax included in the clade buffoniana. The results suggest that speciation patterns observed in the genus Humboldtiana could be explained as a morphostatic radiation.