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Trinomys Thomas (1921) is an endemic Brazilian Atlantic forest genus of the family Echimyidae, comprising ten species, from which only T. dimidiatus had its mitogenome described. The boundaries of morphological distinction among species of the genus are unclear, complicating its taxonomy. Herein, we report the complete mitochondrial genome sequences of Trinomys moojeni and Trinomys setosus retrieved from low-pass genome sequencing. The mitogenomes of T. moojeni and T. setosus are 16,713 and 16,825 bp long, with a CG-content of 37.5% and 36.1%, respectively. Both consist of 13 protein-coding genes (PCGs), 2 ribosomal RNA genes ( rRNA ), 22 transfer RNA genes ( tRNA ) and a D-loop region. We took advantage of our two sequenced mitogenomes and two other publicly available Echimyidae mitogenomes to build a phylogenetic framework based on the 13 PCGs. Altogether, these new mitogenomes expand the available molecular information available for Echimyidae, and contribute to clarify rodent taxonomy and phylogenetics.

The pBuM satellite DNA family was studied in seven Drosophila species from the buzzatii cluster (within the large Drosophila repleta group). The pBuM repeats are slightly AT-rich and show high levels of intraspecific sequence homogeneity. The pBuM family can be divided into two subfamilies. The pBuM-1 subfamily consists of tandemly arranged repetition units of approximately 190 bp, termed alpha. Alpha repeats were found in a high copy number in the genome of D. buzzatii, D. serido and D. antonietae. The pBuM-2 subfamily consists of tandemly arranged repetition units of 370 bp. Its origin is explained by an insertion of an approximately 180 bp foreign sequence (termed beta) in an alpha basic repeat unit, with subsequent homogenization/amplification events increasing its frequency. Alpha/beta repeats were found in a high copy number in the genome of D. serido, D. antonietae, D. seriema and D. gouveai. pBuM sequences were not detected in D. koepferae and D. borborema by hybridization experiments. The nucleotide analysis of 74 pBuM repeats revealed that apart from the beta insertion event, the evolution of the pBuM family has proceeded in a gradual fashion, mainly through accumulation and horizontal spread of nucleotide substitutions. Moreover, the data also indicate a faster evolutionary rate for the pBuM-2 subfamily than the pBuM-1 subfamily. Members of both subfamilies display a greater intraspecific than interspecific homogeneity, indicating a concerted mode of pBuM evolution. A scenario to explain the evolution of both satDNA subfamilies in the seven Drosophila species from the buzzatii cluster is proposed.