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We describe three new species: Canthon mezcalis Moctezuma, Sánchez-Huerta, and Halffter sp. nov. from the Valles Centrales region in Oaxaca, Mexico; Canthon hondurensis Moctezuma and Sánchez-Huerta sp. nov. from Honduras; and Canthon woodruffi Moctezuma and Sánchez-Huerta sp. nov. from Guanacaste, Costa Rica. Through the examination of external and genital morphology, Bayesian inference, and genetic distances based on the Kimura two-parameter model of nucleotide substitution, we confidently determined that the C. indigaceus species group is a monophyletic unit, which is integrated by a set of cryptic species.

In this study, data are presented for the designation of the new subgenus (Bajacanthon) for Canthon obliquus Horn, 1894 (Deltochilini). The new subgenus Bajacanthon is described based on a multiple evidence approach using morphological and molecular characters. This new subgenus has some unique characters, and is the remnant of an old South American migratory movement into the Mexican Transition Zone. This beetle species has survived in isolation in the south half of the peninsula of Baja California (Mexico). Results based on molecular clock inference showed that the split between the lineages leading to the subgenus Bajacanthon and Boreocanthon took place nearly 16 Mya, whereas the radiation within Bajacanthon was dated to 3.7 Mya.

BackgroundWe used Illumina paired-end sequencing to isolate and characterize microsatellites of Canthon cyanellus, a Neotropical roller dung beetle, encompassing several lineages within its distribution range.Methods and resultsWe examined C. cyanellus specimens collected at eight different localities in Mexico (two or three specimens per locality). We initially performed amplification tests with 16 loci, but two of which were unsuccessful. The 14 remaining microsatellites were polymorphic, with 2–16 alleles each. The expected and observed heterozygosity ranged from 0.11 to 0.76 and from 0.20 to 0.78, respectively.ConclusionsThese microsatellites will help to assess structure at the population and lineage levels, identify zones of potential hybridization between lineages, and draw a more precise geographic delimitation of C. cyanellus lineages.

We have investigated the phylogeographic structure and demographic history of Zamia paucijuga, based on 120 ITS2 and 117 psbK/l sequences from 13 populations distributed along the entire distribution range of the species. We have detected 15 ITS2 and four psbK/l haplotypes, for a total of 19. The genetic diversity estimated for psbK/l was relatively lower than the ITS2 diversity. These results imply that the average genetic diversity in Z. paucijuga is lower in comparison with other cycad species, but relatively higher than the diversity found in conifers. Non-hierarchical and hierarchical AMOVAs for ITS2 and psbK/l showed both low and high levels of genetic structure. This discrepancy likely reflects a decrease in gene flow intensity for seeds but high pollen gene flow, which correlates with the divergent inheritance processes in nuclear vis-à-vis organellar DNAs. SAMOVA tests for both loci (ITS2 and psbK/I) showed high correspondence with the regional geographic structure defined a priori, indicating that the use of both nuclear and chloroplast gene regions improves inferences concerning the evolutionary processes that affect population dynamics in Z. paucijuga. Furthermore, our results are consistent with the conclusions of other studies on the origin of the genus Zamia, which support locating the diversification times of Z. paucijuga populations in the Pleistocene.