Characterization of the complete mitochondrial genome of Drawida gisti (Metagynophora, Moniligastridae) and comparison with other Metagynophora species.

Here, the complete mitochondrial genome (mitogenome) of Drawida gisti was sequenced and compared with the mitogenomes of other Metagynophora species. The circular mitogenome was 14,648 bp in length and contained two ribosomal RNA genes (rRNAs), 13 protein-coding genes (PCGs), and 22 transfer RNA genes (tRNAs). The types of constitutive genes and the direction of the coding strand that appeared in Drawida mitogenome were identical to those observed in other Metagynophora species, except for a missing lengthy non-coding region. The conservative relationships between Drawida species were supported by the overall analyses of 13 PCGs, two rRNAs, and 22 tRNAs. A comparison of the Metagynophora mitogenomes revealed that the ATP8 gene possessed the highest polymorphism among the 13 PCGs and two rRNAs. Phylogenetic analysis suggested that the Moniligastridae contained Drawida, which is a primitive Metagynophora group. Our study provides a step forward toward elucidating the evolutionary linkages within Drawida and even Metagynophora.

Development and characterization of microsatellite markers in the earthworm Drawida gisti Michaelsen, 1931 and cross-amplification in two other congeners.

The earthworm (Drawida gisti) is an ecologically important sentinel species for soils that is widely distributed throughout Eastern Asia; however, the molecular tools required for genetic diversity studies of this earthworm are still rare. The aim of the study was to develop and characterize microsatellite markers in D. gisti and to evaluate their transferability to other Drawida species. We employed a RAD-seq approach to develop 12 microsatellite markers for D. gisti. The characterization and analysis of loci was achieved using 24 individuals of D. gisti from a natural population. The number of alleles per locus ranged from four to eleven, with an average of 6.5. Observed and expected heterozygosities varied from 0.708 to 0.958, and from 0.568 to 0.883, respectively. No loci presented significant deviations from the Hardy-Weinberg equilibrium, while linkage disequilibrium was detected between three loci. Cross-species amplification tests suggested that the transferability of ten loci was positive for the two congeners D. japonica and D. ghilarovi. This set of microsatellite markers may be used to evaluate the genetic diversity and population structures of D. gisti and related species in the future.