Abstract

We report the first mitochondrial genomes of two Orthalicoidea land snails from the Atacama Desert of northern Chile, Bostryx erythrostoma and Plectostylus broderipii. Using Illumina short-read sequencing, we assembled and annotated mitochondrial genomes of 15,525 bp and 14,978 bp, respectively, with strong A+T bias (69.75% in B. erythrostoma; 72.08% in P. broderipii). Both genomes retain the standard metazoan mitochondrial complement of 37 genes, including 13 protein-coding genes (PCGs), 22 tRNAs, and two rRNAs, with differences in total length mainly due to variation in non-coding regions rather than coding-gene content. Comparative analysis showed that the two species share the same order of the 13 PCGs, whereas differences are concentrated in local tRNA/rRNA rearrangements and intergenic architecture. Both mitogenomes also exhibit negative AT skew and positive GC skew under a standardized orientation. Phylogenetic inference based on a concatenated 13-PCG nucleotide supermatrix resolved both taxa within Orthalicoidea with strong support: B. erythrostoma grouped with a congeneric Bostryx reference, and this clade clustered with Rabdotus mooreanus and Naesiotus nux, whereas P. broderipii was inferred as sister to this orthalicoid cluster.